| Index: third_party/sqlite/sqlite-src-3070603/src/pager.c
|
| diff --git a/third_party/sqlite/sqlite-src-3070603/src/pager.c b/third_party/sqlite/sqlite-src-3070603/src/pager.c
|
| new file mode 100644
|
| index 0000000000000000000000000000000000000000..e6d1cdebf1007a087e41ff418336f9160de5f4d9
|
| --- /dev/null
|
| +++ b/third_party/sqlite/sqlite-src-3070603/src/pager.c
|
| @@ -0,0 +1,6816 @@
|
| +/*
|
| +** 2001 September 15
|
| +**
|
| +** The author disclaims copyright to this source code. In place of
|
| +** a legal notice, here is a blessing:
|
| +**
|
| +** May you do good and not evil.
|
| +** May you find forgiveness for yourself and forgive others.
|
| +** May you share freely, never taking more than you give.
|
| +**
|
| +*************************************************************************
|
| +** This is the implementation of the page cache subsystem or "pager".
|
| +**
|
| +** The pager is used to access a database disk file. It implements
|
| +** atomic commit and rollback through the use of a journal file that
|
| +** is separate from the database file. The pager also implements file
|
| +** locking to prevent two processes from writing the same database
|
| +** file simultaneously, or one process from reading the database while
|
| +** another is writing.
|
| +*/
|
| +#ifndef SQLITE_OMIT_DISKIO
|
| +#include "sqliteInt.h"
|
| +#include "wal.h"
|
| +
|
| +
|
| +/******************* NOTES ON THE DESIGN OF THE PAGER ************************
|
| +**
|
| +** This comment block describes invariants that hold when using a rollback
|
| +** journal. These invariants do not apply for journal_mode=WAL,
|
| +** journal_mode=MEMORY, or journal_mode=OFF.
|
| +**
|
| +** Within this comment block, a page is deemed to have been synced
|
| +** automatically as soon as it is written when PRAGMA synchronous=OFF.
|
| +** Otherwise, the page is not synced until the xSync method of the VFS
|
| +** is called successfully on the file containing the page.
|
| +**
|
| +** Definition: A page of the database file is said to be "overwriteable" if
|
| +** one or more of the following are true about the page:
|
| +**
|
| +** (a) The original content of the page as it was at the beginning of
|
| +** the transaction has been written into the rollback journal and
|
| +** synced.
|
| +**
|
| +** (b) The page was a freelist leaf page at the start of the transaction.
|
| +**
|
| +** (c) The page number is greater than the largest page that existed in
|
| +** the database file at the start of the transaction.
|
| +**
|
| +** (1) A page of the database file is never overwritten unless one of the
|
| +** following are true:
|
| +**
|
| +** (a) The page and all other pages on the same sector are overwriteable.
|
| +**
|
| +** (b) The atomic page write optimization is enabled, and the entire
|
| +** transaction other than the update of the transaction sequence
|
| +** number consists of a single page change.
|
| +**
|
| +** (2) The content of a page written into the rollback journal exactly matches
|
| +** both the content in the database when the rollback journal was written
|
| +** and the content in the database at the beginning of the current
|
| +** transaction.
|
| +**
|
| +** (3) Writes to the database file are an integer multiple of the page size
|
| +** in length and are aligned on a page boundary.
|
| +**
|
| +** (4) Reads from the database file are either aligned on a page boundary and
|
| +** an integer multiple of the page size in length or are taken from the
|
| +** first 100 bytes of the database file.
|
| +**
|
| +** (5) All writes to the database file are synced prior to the rollback journal
|
| +** being deleted, truncated, or zeroed.
|
| +**
|
| +** (6) If a master journal file is used, then all writes to the database file
|
| +** are synced prior to the master journal being deleted.
|
| +**
|
| +** Definition: Two databases (or the same database at two points it time)
|
| +** are said to be "logically equivalent" if they give the same answer to
|
| +** all queries. Note in particular the the content of freelist leaf
|
| +** pages can be changed arbitarily without effecting the logical equivalence
|
| +** of the database.
|
| +**
|
| +** (7) At any time, if any subset, including the empty set and the total set,
|
| +** of the unsynced changes to a rollback journal are removed and the
|
| +** journal is rolled back, the resulting database file will be logical
|
| +** equivalent to the database file at the beginning of the transaction.
|
| +**
|
| +** (8) When a transaction is rolled back, the xTruncate method of the VFS
|
| +** is called to restore the database file to the same size it was at
|
| +** the beginning of the transaction. (In some VFSes, the xTruncate
|
| +** method is a no-op, but that does not change the fact the SQLite will
|
| +** invoke it.)
|
| +**
|
| +** (9) Whenever the database file is modified, at least one bit in the range
|
| +** of bytes from 24 through 39 inclusive will be changed prior to releasing
|
| +** the EXCLUSIVE lock, thus signaling other connections on the same
|
| +** database to flush their caches.
|
| +**
|
| +** (10) The pattern of bits in bytes 24 through 39 shall not repeat in less
|
| +** than one billion transactions.
|
| +**
|
| +** (11) A database file is well-formed at the beginning and at the conclusion
|
| +** of every transaction.
|
| +**
|
| +** (12) An EXCLUSIVE lock is held on the database file when writing to
|
| +** the database file.
|
| +**
|
| +** (13) A SHARED lock is held on the database file while reading any
|
| +** content out of the database file.
|
| +**
|
| +******************************************************************************/
|
| +
|
| +/*
|
| +** Macros for troubleshooting. Normally turned off
|
| +*/
|
| +#if 0
|
| +int sqlite3PagerTrace=1; /* True to enable tracing */
|
| +#define sqlite3DebugPrintf printf
|
| +#define PAGERTRACE(X) if( sqlite3PagerTrace ){ sqlite3DebugPrintf X; }
|
| +#else
|
| +#define PAGERTRACE(X)
|
| +#endif
|
| +
|
| +/*
|
| +** The following two macros are used within the PAGERTRACE() macros above
|
| +** to print out file-descriptors.
|
| +**
|
| +** PAGERID() takes a pointer to a Pager struct as its argument. The
|
| +** associated file-descriptor is returned. FILEHANDLEID() takes an sqlite3_file
|
| +** struct as its argument.
|
| +*/
|
| +#define PAGERID(p) ((int)(p->fd))
|
| +#define FILEHANDLEID(fd) ((int)fd)
|
| +
|
| +/*
|
| +** The Pager.eState variable stores the current 'state' of a pager. A
|
| +** pager may be in any one of the seven states shown in the following
|
| +** state diagram.
|
| +**
|
| +** OPEN <------+------+
|
| +** | | |
|
| +** V | |
|
| +** +---------> READER-------+ |
|
| +** | | |
|
| +** | V |
|
| +** |<-------WRITER_LOCKED------> ERROR
|
| +** | | ^
|
| +** | V |
|
| +** |<------WRITER_CACHEMOD-------->|
|
| +** | | |
|
| +** | V |
|
| +** |<-------WRITER_DBMOD---------->|
|
| +** | | |
|
| +** | V |
|
| +** +<------WRITER_FINISHED-------->+
|
| +**
|
| +**
|
| +** List of state transitions and the C [function] that performs each:
|
| +**
|
| +** OPEN -> READER [sqlite3PagerSharedLock]
|
| +** READER -> OPEN [pager_unlock]
|
| +**
|
| +** READER -> WRITER_LOCKED [sqlite3PagerBegin]
|
| +** WRITER_LOCKED -> WRITER_CACHEMOD [pager_open_journal]
|
| +** WRITER_CACHEMOD -> WRITER_DBMOD [syncJournal]
|
| +** WRITER_DBMOD -> WRITER_FINISHED [sqlite3PagerCommitPhaseOne]
|
| +** WRITER_*** -> READER [pager_end_transaction]
|
| +**
|
| +** WRITER_*** -> ERROR [pager_error]
|
| +** ERROR -> OPEN [pager_unlock]
|
| +**
|
| +**
|
| +** OPEN:
|
| +**
|
| +** The pager starts up in this state. Nothing is guaranteed in this
|
| +** state - the file may or may not be locked and the database size is
|
| +** unknown. The database may not be read or written.
|
| +**
|
| +** * No read or write transaction is active.
|
| +** * Any lock, or no lock at all, may be held on the database file.
|
| +** * The dbSize, dbOrigSize and dbFileSize variables may not be trusted.
|
| +**
|
| +** READER:
|
| +**
|
| +** In this state all the requirements for reading the database in
|
| +** rollback (non-WAL) mode are met. Unless the pager is (or recently
|
| +** was) in exclusive-locking mode, a user-level read transaction is
|
| +** open. The database size is known in this state.
|
| +**
|
| +** A connection running with locking_mode=normal enters this state when
|
| +** it opens a read-transaction on the database and returns to state
|
| +** OPEN after the read-transaction is completed. However a connection
|
| +** running in locking_mode=exclusive (including temp databases) remains in
|
| +** this state even after the read-transaction is closed. The only way
|
| +** a locking_mode=exclusive connection can transition from READER to OPEN
|
| +** is via the ERROR state (see below).
|
| +**
|
| +** * A read transaction may be active (but a write-transaction cannot).
|
| +** * A SHARED or greater lock is held on the database file.
|
| +** * The dbSize variable may be trusted (even if a user-level read
|
| +** transaction is not active). The dbOrigSize and dbFileSize variables
|
| +** may not be trusted at this point.
|
| +** * If the database is a WAL database, then the WAL connection is open.
|
| +** * Even if a read-transaction is not open, it is guaranteed that
|
| +** there is no hot-journal in the file-system.
|
| +**
|
| +** WRITER_LOCKED:
|
| +**
|
| +** The pager moves to this state from READER when a write-transaction
|
| +** is first opened on the database. In WRITER_LOCKED state, all locks
|
| +** required to start a write-transaction are held, but no actual
|
| +** modifications to the cache or database have taken place.
|
| +**
|
| +** In rollback mode, a RESERVED or (if the transaction was opened with
|
| +** BEGIN EXCLUSIVE) EXCLUSIVE lock is obtained on the database file when
|
| +** moving to this state, but the journal file is not written to or opened
|
| +** to in this state. If the transaction is committed or rolled back while
|
| +** in WRITER_LOCKED state, all that is required is to unlock the database
|
| +** file.
|
| +**
|
| +** IN WAL mode, WalBeginWriteTransaction() is called to lock the log file.
|
| +** If the connection is running with locking_mode=exclusive, an attempt
|
| +** is made to obtain an EXCLUSIVE lock on the database file.
|
| +**
|
| +** * A write transaction is active.
|
| +** * If the connection is open in rollback-mode, a RESERVED or greater
|
| +** lock is held on the database file.
|
| +** * If the connection is open in WAL-mode, a WAL write transaction
|
| +** is open (i.e. sqlite3WalBeginWriteTransaction() has been successfully
|
| +** called).
|
| +** * The dbSize, dbOrigSize and dbFileSize variables are all valid.
|
| +** * The contents of the pager cache have not been modified.
|
| +** * The journal file may or may not be open.
|
| +** * Nothing (not even the first header) has been written to the journal.
|
| +**
|
| +** WRITER_CACHEMOD:
|
| +**
|
| +** A pager moves from WRITER_LOCKED state to this state when a page is
|
| +** first modified by the upper layer. In rollback mode the journal file
|
| +** is opened (if it is not already open) and a header written to the
|
| +** start of it. The database file on disk has not been modified.
|
| +**
|
| +** * A write transaction is active.
|
| +** * A RESERVED or greater lock is held on the database file.
|
| +** * The journal file is open and the first header has been written
|
| +** to it, but the header has not been synced to disk.
|
| +** * The contents of the page cache have been modified.
|
| +**
|
| +** WRITER_DBMOD:
|
| +**
|
| +** The pager transitions from WRITER_CACHEMOD into WRITER_DBMOD state
|
| +** when it modifies the contents of the database file. WAL connections
|
| +** never enter this state (since they do not modify the database file,
|
| +** just the log file).
|
| +**
|
| +** * A write transaction is active.
|
| +** * An EXCLUSIVE or greater lock is held on the database file.
|
| +** * The journal file is open and the first header has been written
|
| +** and synced to disk.
|
| +** * The contents of the page cache have been modified (and possibly
|
| +** written to disk).
|
| +**
|
| +** WRITER_FINISHED:
|
| +**
|
| +** It is not possible for a WAL connection to enter this state.
|
| +**
|
| +** A rollback-mode pager changes to WRITER_FINISHED state from WRITER_DBMOD
|
| +** state after the entire transaction has been successfully written into the
|
| +** database file. In this state the transaction may be committed simply
|
| +** by finalizing the journal file. Once in WRITER_FINISHED state, it is
|
| +** not possible to modify the database further. At this point, the upper
|
| +** layer must either commit or rollback the transaction.
|
| +**
|
| +** * A write transaction is active.
|
| +** * An EXCLUSIVE or greater lock is held on the database file.
|
| +** * All writing and syncing of journal and database data has finished.
|
| +** If no error occured, all that remains is to finalize the journal to
|
| +** commit the transaction. If an error did occur, the caller will need
|
| +** to rollback the transaction.
|
| +**
|
| +** ERROR:
|
| +**
|
| +** The ERROR state is entered when an IO or disk-full error (including
|
| +** SQLITE_IOERR_NOMEM) occurs at a point in the code that makes it
|
| +** difficult to be sure that the in-memory pager state (cache contents,
|
| +** db size etc.) are consistent with the contents of the file-system.
|
| +**
|
| +** Temporary pager files may enter the ERROR state, but in-memory pagers
|
| +** cannot.
|
| +**
|
| +** For example, if an IO error occurs while performing a rollback,
|
| +** the contents of the page-cache may be left in an inconsistent state.
|
| +** At this point it would be dangerous to change back to READER state
|
| +** (as usually happens after a rollback). Any subsequent readers might
|
| +** report database corruption (due to the inconsistent cache), and if
|
| +** they upgrade to writers, they may inadvertently corrupt the database
|
| +** file. To avoid this hazard, the pager switches into the ERROR state
|
| +** instead of READER following such an error.
|
| +**
|
| +** Once it has entered the ERROR state, any attempt to use the pager
|
| +** to read or write data returns an error. Eventually, once all
|
| +** outstanding transactions have been abandoned, the pager is able to
|
| +** transition back to OPEN state, discarding the contents of the
|
| +** page-cache and any other in-memory state at the same time. Everything
|
| +** is reloaded from disk (and, if necessary, hot-journal rollback peformed)
|
| +** when a read-transaction is next opened on the pager (transitioning
|
| +** the pager into READER state). At that point the system has recovered
|
| +** from the error.
|
| +**
|
| +** Specifically, the pager jumps into the ERROR state if:
|
| +**
|
| +** 1. An error occurs while attempting a rollback. This happens in
|
| +** function sqlite3PagerRollback().
|
| +**
|
| +** 2. An error occurs while attempting to finalize a journal file
|
| +** following a commit in function sqlite3PagerCommitPhaseTwo().
|
| +**
|
| +** 3. An error occurs while attempting to write to the journal or
|
| +** database file in function pagerStress() in order to free up
|
| +** memory.
|
| +**
|
| +** In other cases, the error is returned to the b-tree layer. The b-tree
|
| +** layer then attempts a rollback operation. If the error condition
|
| +** persists, the pager enters the ERROR state via condition (1) above.
|
| +**
|
| +** Condition (3) is necessary because it can be triggered by a read-only
|
| +** statement executed within a transaction. In this case, if the error
|
| +** code were simply returned to the user, the b-tree layer would not
|
| +** automatically attempt a rollback, as it assumes that an error in a
|
| +** read-only statement cannot leave the pager in an internally inconsistent
|
| +** state.
|
| +**
|
| +** * The Pager.errCode variable is set to something other than SQLITE_OK.
|
| +** * There are one or more outstanding references to pages (after the
|
| +** last reference is dropped the pager should move back to OPEN state).
|
| +** * The pager is not an in-memory pager.
|
| +**
|
| +**
|
| +** Notes:
|
| +**
|
| +** * A pager is never in WRITER_DBMOD or WRITER_FINISHED state if the
|
| +** connection is open in WAL mode. A WAL connection is always in one
|
| +** of the first four states.
|
| +**
|
| +** * Normally, a connection open in exclusive mode is never in PAGER_OPEN
|
| +** state. There are two exceptions: immediately after exclusive-mode has
|
| +** been turned on (and before any read or write transactions are
|
| +** executed), and when the pager is leaving the "error state".
|
| +**
|
| +** * See also: assert_pager_state().
|
| +*/
|
| +#define PAGER_OPEN 0
|
| +#define PAGER_READER 1
|
| +#define PAGER_WRITER_LOCKED 2
|
| +#define PAGER_WRITER_CACHEMOD 3
|
| +#define PAGER_WRITER_DBMOD 4
|
| +#define PAGER_WRITER_FINISHED 5
|
| +#define PAGER_ERROR 6
|
| +
|
| +/*
|
| +** The Pager.eLock variable is almost always set to one of the
|
| +** following locking-states, according to the lock currently held on
|
| +** the database file: NO_LOCK, SHARED_LOCK, RESERVED_LOCK or EXCLUSIVE_LOCK.
|
| +** This variable is kept up to date as locks are taken and released by
|
| +** the pagerLockDb() and pagerUnlockDb() wrappers.
|
| +**
|
| +** If the VFS xLock() or xUnlock() returns an error other than SQLITE_BUSY
|
| +** (i.e. one of the SQLITE_IOERR subtypes), it is not clear whether or not
|
| +** the operation was successful. In these circumstances pagerLockDb() and
|
| +** pagerUnlockDb() take a conservative approach - eLock is always updated
|
| +** when unlocking the file, and only updated when locking the file if the
|
| +** VFS call is successful. This way, the Pager.eLock variable may be set
|
| +** to a less exclusive (lower) value than the lock that is actually held
|
| +** at the system level, but it is never set to a more exclusive value.
|
| +**
|
| +** This is usually safe. If an xUnlock fails or appears to fail, there may
|
| +** be a few redundant xLock() calls or a lock may be held for longer than
|
| +** required, but nothing really goes wrong.
|
| +**
|
| +** The exception is when the database file is unlocked as the pager moves
|
| +** from ERROR to OPEN state. At this point there may be a hot-journal file
|
| +** in the file-system that needs to be rolled back (as part of a OPEN->SHARED
|
| +** transition, by the same pager or any other). If the call to xUnlock()
|
| +** fails at this point and the pager is left holding an EXCLUSIVE lock, this
|
| +** can confuse the call to xCheckReservedLock() call made later as part
|
| +** of hot-journal detection.
|
| +**
|
| +** xCheckReservedLock() is defined as returning true "if there is a RESERVED
|
| +** lock held by this process or any others". So xCheckReservedLock may
|
| +** return true because the caller itself is holding an EXCLUSIVE lock (but
|
| +** doesn't know it because of a previous error in xUnlock). If this happens
|
| +** a hot-journal may be mistaken for a journal being created by an active
|
| +** transaction in another process, causing SQLite to read from the database
|
| +** without rolling it back.
|
| +**
|
| +** To work around this, if a call to xUnlock() fails when unlocking the
|
| +** database in the ERROR state, Pager.eLock is set to UNKNOWN_LOCK. It
|
| +** is only changed back to a real locking state after a successful call
|
| +** to xLock(EXCLUSIVE). Also, the code to do the OPEN->SHARED state transition
|
| +** omits the check for a hot-journal if Pager.eLock is set to UNKNOWN_LOCK
|
| +** lock. Instead, it assumes a hot-journal exists and obtains an EXCLUSIVE
|
| +** lock on the database file before attempting to roll it back. See function
|
| +** PagerSharedLock() for more detail.
|
| +**
|
| +** Pager.eLock may only be set to UNKNOWN_LOCK when the pager is in
|
| +** PAGER_OPEN state.
|
| +*/
|
| +#define UNKNOWN_LOCK (EXCLUSIVE_LOCK+1)
|
| +
|
| +/*
|
| +** A macro used for invoking the codec if there is one
|
| +*/
|
| +#ifdef SQLITE_HAS_CODEC
|
| +# define CODEC1(P,D,N,X,E) \
|
| + if( P->xCodec && P->xCodec(P->pCodec,D,N,X)==0 ){ E; }
|
| +# define CODEC2(P,D,N,X,E,O) \
|
| + if( P->xCodec==0 ){ O=(char*)D; }else \
|
| + if( (O=(char*)(P->xCodec(P->pCodec,D,N,X)))==0 ){ E; }
|
| +#else
|
| +# define CODEC1(P,D,N,X,E) /* NO-OP */
|
| +# define CODEC2(P,D,N,X,E,O) O=(char*)D
|
| +#endif
|
| +
|
| +/*
|
| +** The maximum allowed sector size. 64KiB. If the xSectorsize() method
|
| +** returns a value larger than this, then MAX_SECTOR_SIZE is used instead.
|
| +** This could conceivably cause corruption following a power failure on
|
| +** such a system. This is currently an undocumented limit.
|
| +*/
|
| +#define MAX_SECTOR_SIZE 0x10000
|
| +
|
| +/*
|
| +** An instance of the following structure is allocated for each active
|
| +** savepoint and statement transaction in the system. All such structures
|
| +** are stored in the Pager.aSavepoint[] array, which is allocated and
|
| +** resized using sqlite3Realloc().
|
| +**
|
| +** When a savepoint is created, the PagerSavepoint.iHdrOffset field is
|
| +** set to 0. If a journal-header is written into the main journal while
|
| +** the savepoint is active, then iHdrOffset is set to the byte offset
|
| +** immediately following the last journal record written into the main
|
| +** journal before the journal-header. This is required during savepoint
|
| +** rollback (see pagerPlaybackSavepoint()).
|
| +*/
|
| +typedef struct PagerSavepoint PagerSavepoint;
|
| +struct PagerSavepoint {
|
| + i64 iOffset; /* Starting offset in main journal */
|
| + i64 iHdrOffset; /* See above */
|
| + Bitvec *pInSavepoint; /* Set of pages in this savepoint */
|
| + Pgno nOrig; /* Original number of pages in file */
|
| + Pgno iSubRec; /* Index of first record in sub-journal */
|
| +#ifndef SQLITE_OMIT_WAL
|
| + u32 aWalData[WAL_SAVEPOINT_NDATA]; /* WAL savepoint context */
|
| +#endif
|
| +};
|
| +
|
| +/*
|
| +** A open page cache is an instance of struct Pager. A description of
|
| +** some of the more important member variables follows:
|
| +**
|
| +** eState
|
| +**
|
| +** The current 'state' of the pager object. See the comment and state
|
| +** diagram above for a description of the pager state.
|
| +**
|
| +** eLock
|
| +**
|
| +** For a real on-disk database, the current lock held on the database file -
|
| +** NO_LOCK, SHARED_LOCK, RESERVED_LOCK or EXCLUSIVE_LOCK.
|
| +**
|
| +** For a temporary or in-memory database (neither of which require any
|
| +** locks), this variable is always set to EXCLUSIVE_LOCK. Since such
|
| +** databases always have Pager.exclusiveMode==1, this tricks the pager
|
| +** logic into thinking that it already has all the locks it will ever
|
| +** need (and no reason to release them).
|
| +**
|
| +** In some (obscure) circumstances, this variable may also be set to
|
| +** UNKNOWN_LOCK. See the comment above the #define of UNKNOWN_LOCK for
|
| +** details.
|
| +**
|
| +** changeCountDone
|
| +**
|
| +** This boolean variable is used to make sure that the change-counter
|
| +** (the 4-byte header field at byte offset 24 of the database file) is
|
| +** not updated more often than necessary.
|
| +**
|
| +** It is set to true when the change-counter field is updated, which
|
| +** can only happen if an exclusive lock is held on the database file.
|
| +** It is cleared (set to false) whenever an exclusive lock is
|
| +** relinquished on the database file. Each time a transaction is committed,
|
| +** The changeCountDone flag is inspected. If it is true, the work of
|
| +** updating the change-counter is omitted for the current transaction.
|
| +**
|
| +** This mechanism means that when running in exclusive mode, a connection
|
| +** need only update the change-counter once, for the first transaction
|
| +** committed.
|
| +**
|
| +** setMaster
|
| +**
|
| +** When PagerCommitPhaseOne() is called to commit a transaction, it may
|
| +** (or may not) specify a master-journal name to be written into the
|
| +** journal file before it is synced to disk.
|
| +**
|
| +** Whether or not a journal file contains a master-journal pointer affects
|
| +** the way in which the journal file is finalized after the transaction is
|
| +** committed or rolled back when running in "journal_mode=PERSIST" mode.
|
| +** If a journal file does not contain a master-journal pointer, it is
|
| +** finalized by overwriting the first journal header with zeroes. If
|
| +** it does contain a master-journal pointer the journal file is finalized
|
| +** by truncating it to zero bytes, just as if the connection were
|
| +** running in "journal_mode=truncate" mode.
|
| +**
|
| +** Journal files that contain master journal pointers cannot be finalized
|
| +** simply by overwriting the first journal-header with zeroes, as the
|
| +** master journal pointer could interfere with hot-journal rollback of any
|
| +** subsequently interrupted transaction that reuses the journal file.
|
| +**
|
| +** The flag is cleared as soon as the journal file is finalized (either
|
| +** by PagerCommitPhaseTwo or PagerRollback). If an IO error prevents the
|
| +** journal file from being successfully finalized, the setMaster flag
|
| +** is cleared anyway (and the pager will move to ERROR state).
|
| +**
|
| +** doNotSpill, doNotSyncSpill
|
| +**
|
| +** These two boolean variables control the behaviour of cache-spills
|
| +** (calls made by the pcache module to the pagerStress() routine to
|
| +** write cached data to the file-system in order to free up memory).
|
| +**
|
| +** When doNotSpill is non-zero, writing to the database from pagerStress()
|
| +** is disabled altogether. This is done in a very obscure case that
|
| +** comes up during savepoint rollback that requires the pcache module
|
| +** to allocate a new page to prevent the journal file from being written
|
| +** while it is being traversed by code in pager_playback().
|
| +**
|
| +** If doNotSyncSpill is non-zero, writing to the database from pagerStress()
|
| +** is permitted, but syncing the journal file is not. This flag is set
|
| +** by sqlite3PagerWrite() when the file-system sector-size is larger than
|
| +** the database page-size in order to prevent a journal sync from happening
|
| +** in between the journalling of two pages on the same sector.
|
| +**
|
| +** subjInMemory
|
| +**
|
| +** This is a boolean variable. If true, then any required sub-journal
|
| +** is opened as an in-memory journal file. If false, then in-memory
|
| +** sub-journals are only used for in-memory pager files.
|
| +**
|
| +** This variable is updated by the upper layer each time a new
|
| +** write-transaction is opened.
|
| +**
|
| +** dbSize, dbOrigSize, dbFileSize
|
| +**
|
| +** Variable dbSize is set to the number of pages in the database file.
|
| +** It is valid in PAGER_READER and higher states (all states except for
|
| +** OPEN and ERROR).
|
| +**
|
| +** dbSize is set based on the size of the database file, which may be
|
| +** larger than the size of the database (the value stored at offset
|
| +** 28 of the database header by the btree). If the size of the file
|
| +** is not an integer multiple of the page-size, the value stored in
|
| +** dbSize is rounded down (i.e. a 5KB file with 2K page-size has dbSize==2).
|
| +** Except, any file that is greater than 0 bytes in size is considered
|
| +** to have at least one page. (i.e. a 1KB file with 2K page-size leads
|
| +** to dbSize==1).
|
| +**
|
| +** During a write-transaction, if pages with page-numbers greater than
|
| +** dbSize are modified in the cache, dbSize is updated accordingly.
|
| +** Similarly, if the database is truncated using PagerTruncateImage(),
|
| +** dbSize is updated.
|
| +**
|
| +** Variables dbOrigSize and dbFileSize are valid in states
|
| +** PAGER_WRITER_LOCKED and higher. dbOrigSize is a copy of the dbSize
|
| +** variable at the start of the transaction. It is used during rollback,
|
| +** and to determine whether or not pages need to be journalled before
|
| +** being modified.
|
| +**
|
| +** Throughout a write-transaction, dbFileSize contains the size of
|
| +** the file on disk in pages. It is set to a copy of dbSize when the
|
| +** write-transaction is first opened, and updated when VFS calls are made
|
| +** to write or truncate the database file on disk.
|
| +**
|
| +** The only reason the dbFileSize variable is required is to suppress
|
| +** unnecessary calls to xTruncate() after committing a transaction. If,
|
| +** when a transaction is committed, the dbFileSize variable indicates
|
| +** that the database file is larger than the database image (Pager.dbSize),
|
| +** pager_truncate() is called. The pager_truncate() call uses xFilesize()
|
| +** to measure the database file on disk, and then truncates it if required.
|
| +** dbFileSize is not used when rolling back a transaction. In this case
|
| +** pager_truncate() is called unconditionally (which means there may be
|
| +** a call to xFilesize() that is not strictly required). In either case,
|
| +** pager_truncate() may cause the file to become smaller or larger.
|
| +**
|
| +** dbHintSize
|
| +**
|
| +** The dbHintSize variable is used to limit the number of calls made to
|
| +** the VFS xFileControl(FCNTL_SIZE_HINT) method.
|
| +**
|
| +** dbHintSize is set to a copy of the dbSize variable when a
|
| +** write-transaction is opened (at the same time as dbFileSize and
|
| +** dbOrigSize). If the xFileControl(FCNTL_SIZE_HINT) method is called,
|
| +** dbHintSize is increased to the number of pages that correspond to the
|
| +** size-hint passed to the method call. See pager_write_pagelist() for
|
| +** details.
|
| +**
|
| +** errCode
|
| +**
|
| +** The Pager.errCode variable is only ever used in PAGER_ERROR state. It
|
| +** is set to zero in all other states. In PAGER_ERROR state, Pager.errCode
|
| +** is always set to SQLITE_FULL, SQLITE_IOERR or one of the SQLITE_IOERR_XXX
|
| +** sub-codes.
|
| +*/
|
| +struct Pager {
|
| + sqlite3_vfs *pVfs; /* OS functions to use for IO */
|
| + u8 exclusiveMode; /* Boolean. True if locking_mode==EXCLUSIVE */
|
| + u8 journalMode; /* One of the PAGER_JOURNALMODE_* values */
|
| + u8 useJournal; /* Use a rollback journal on this file */
|
| + u8 noReadlock; /* Do not bother to obtain readlocks */
|
| + u8 noSync; /* Do not sync the journal if true */
|
| + u8 fullSync; /* Do extra syncs of the journal for robustness */
|
| + u8 ckptSyncFlags; /* SYNC_NORMAL or SYNC_FULL for checkpoint */
|
| + u8 syncFlags; /* SYNC_NORMAL or SYNC_FULL otherwise */
|
| + u8 tempFile; /* zFilename is a temporary file */
|
| + u8 readOnly; /* True for a read-only database */
|
| + u8 memDb; /* True to inhibit all file I/O */
|
| +
|
| + /**************************************************************************
|
| + ** The following block contains those class members that change during
|
| + ** routine opertion. Class members not in this block are either fixed
|
| + ** when the pager is first created or else only change when there is a
|
| + ** significant mode change (such as changing the page_size, locking_mode,
|
| + ** or the journal_mode). From another view, these class members describe
|
| + ** the "state" of the pager, while other class members describe the
|
| + ** "configuration" of the pager.
|
| + */
|
| + u8 eState; /* Pager state (OPEN, READER, WRITER_LOCKED..) */
|
| + u8 eLock; /* Current lock held on database file */
|
| + u8 changeCountDone; /* Set after incrementing the change-counter */
|
| + u8 setMaster; /* True if a m-j name has been written to jrnl */
|
| + u8 doNotSpill; /* Do not spill the cache when non-zero */
|
| + u8 doNotSyncSpill; /* Do not do a spill that requires jrnl sync */
|
| + u8 subjInMemory; /* True to use in-memory sub-journals */
|
| + Pgno dbSize; /* Number of pages in the database */
|
| + Pgno dbOrigSize; /* dbSize before the current transaction */
|
| + Pgno dbFileSize; /* Number of pages in the database file */
|
| + Pgno dbHintSize; /* Value passed to FCNTL_SIZE_HINT call */
|
| + int errCode; /* One of several kinds of errors */
|
| + int nRec; /* Pages journalled since last j-header written */
|
| + u32 cksumInit; /* Quasi-random value added to every checksum */
|
| + u32 nSubRec; /* Number of records written to sub-journal */
|
| + Bitvec *pInJournal; /* One bit for each page in the database file */
|
| + sqlite3_file *fd; /* File descriptor for database */
|
| + sqlite3_file *jfd; /* File descriptor for main journal */
|
| + sqlite3_file *sjfd; /* File descriptor for sub-journal */
|
| + i64 journalOff; /* Current write offset in the journal file */
|
| + i64 journalHdr; /* Byte offset to previous journal header */
|
| + sqlite3_backup *pBackup; /* Pointer to list of ongoing backup processes */
|
| + PagerSavepoint *aSavepoint; /* Array of active savepoints */
|
| + int nSavepoint; /* Number of elements in aSavepoint[] */
|
| + char dbFileVers[16]; /* Changes whenever database file changes */
|
| + /*
|
| + ** End of the routinely-changing class members
|
| + ***************************************************************************/
|
| +
|
| + u16 nExtra; /* Add this many bytes to each in-memory page */
|
| + i16 nReserve; /* Number of unused bytes at end of each page */
|
| + u32 vfsFlags; /* Flags for sqlite3_vfs.xOpen() */
|
| + u32 sectorSize; /* Assumed sector size during rollback */
|
| + int pageSize; /* Number of bytes in a page */
|
| + Pgno mxPgno; /* Maximum allowed size of the database */
|
| + i64 journalSizeLimit; /* Size limit for persistent journal files */
|
| + char *zFilename; /* Name of the database file */
|
| + char *zJournal; /* Name of the journal file */
|
| + int (*xBusyHandler)(void*); /* Function to call when busy */
|
| + void *pBusyHandlerArg; /* Context argument for xBusyHandler */
|
| +#ifdef SQLITE_TEST
|
| + int nHit, nMiss; /* Cache hits and missing */
|
| + int nRead, nWrite; /* Database pages read/written */
|
| +#endif
|
| + void (*xReiniter)(DbPage*); /* Call this routine when reloading pages */
|
| +#ifdef SQLITE_HAS_CODEC
|
| + void *(*xCodec)(void*,void*,Pgno,int); /* Routine for en/decoding data */
|
| + void (*xCodecSizeChng)(void*,int,int); /* Notify of page size changes */
|
| + void (*xCodecFree)(void*); /* Destructor for the codec */
|
| + void *pCodec; /* First argument to xCodec... methods */
|
| +#endif
|
| + char *pTmpSpace; /* Pager.pageSize bytes of space for tmp use */
|
| + PCache *pPCache; /* Pointer to page cache object */
|
| +#ifndef SQLITE_OMIT_WAL
|
| + Wal *pWal; /* Write-ahead log used by "journal_mode=wal" */
|
| + char *zWal; /* File name for write-ahead log */
|
| +#endif
|
| +};
|
| +
|
| +/*
|
| +** The following global variables hold counters used for
|
| +** testing purposes only. These variables do not exist in
|
| +** a non-testing build. These variables are not thread-safe.
|
| +*/
|
| +#ifdef SQLITE_TEST
|
| +int sqlite3_pager_readdb_count = 0; /* Number of full pages read from DB */
|
| +int sqlite3_pager_writedb_count = 0; /* Number of full pages written to DB */
|
| +int sqlite3_pager_writej_count = 0; /* Number of pages written to journal */
|
| +# define PAGER_INCR(v) v++
|
| +#else
|
| +# define PAGER_INCR(v)
|
| +#endif
|
| +
|
| +
|
| +
|
| +/*
|
| +** Journal files begin with the following magic string. The data
|
| +** was obtained from /dev/random. It is used only as a sanity check.
|
| +**
|
| +** Since version 2.8.0, the journal format contains additional sanity
|
| +** checking information. If the power fails while the journal is being
|
| +** written, semi-random garbage data might appear in the journal
|
| +** file after power is restored. If an attempt is then made
|
| +** to roll the journal back, the database could be corrupted. The additional
|
| +** sanity checking data is an attempt to discover the garbage in the
|
| +** journal and ignore it.
|
| +**
|
| +** The sanity checking information for the new journal format consists
|
| +** of a 32-bit checksum on each page of data. The checksum covers both
|
| +** the page number and the pPager->pageSize bytes of data for the page.
|
| +** This cksum is initialized to a 32-bit random value that appears in the
|
| +** journal file right after the header. The random initializer is important,
|
| +** because garbage data that appears at the end of a journal is likely
|
| +** data that was once in other files that have now been deleted. If the
|
| +** garbage data came from an obsolete journal file, the checksums might
|
| +** be correct. But by initializing the checksum to random value which
|
| +** is different for every journal, we minimize that risk.
|
| +*/
|
| +static const unsigned char aJournalMagic[] = {
|
| + 0xd9, 0xd5, 0x05, 0xf9, 0x20, 0xa1, 0x63, 0xd7,
|
| +};
|
| +
|
| +/*
|
| +** The size of the of each page record in the journal is given by
|
| +** the following macro.
|
| +*/
|
| +#define JOURNAL_PG_SZ(pPager) ((pPager->pageSize) + 8)
|
| +
|
| +/*
|
| +** The journal header size for this pager. This is usually the same
|
| +** size as a single disk sector. See also setSectorSize().
|
| +*/
|
| +#define JOURNAL_HDR_SZ(pPager) (pPager->sectorSize)
|
| +
|
| +/*
|
| +** The macro MEMDB is true if we are dealing with an in-memory database.
|
| +** We do this as a macro so that if the SQLITE_OMIT_MEMORYDB macro is set,
|
| +** the value of MEMDB will be a constant and the compiler will optimize
|
| +** out code that would never execute.
|
| +*/
|
| +#ifdef SQLITE_OMIT_MEMORYDB
|
| +# define MEMDB 0
|
| +#else
|
| +# define MEMDB pPager->memDb
|
| +#endif
|
| +
|
| +/*
|
| +** The maximum legal page number is (2^31 - 1).
|
| +*/
|
| +#define PAGER_MAX_PGNO 2147483647
|
| +
|
| +/*
|
| +** The argument to this macro is a file descriptor (type sqlite3_file*).
|
| +** Return 0 if it is not open, or non-zero (but not 1) if it is.
|
| +**
|
| +** This is so that expressions can be written as:
|
| +**
|
| +** if( isOpen(pPager->jfd) ){ ...
|
| +**
|
| +** instead of
|
| +**
|
| +** if( pPager->jfd->pMethods ){ ...
|
| +*/
|
| +#define isOpen(pFd) ((pFd)->pMethods)
|
| +
|
| +/*
|
| +** Return true if this pager uses a write-ahead log instead of the usual
|
| +** rollback journal. Otherwise false.
|
| +*/
|
| +#ifndef SQLITE_OMIT_WAL
|
| +static int pagerUseWal(Pager *pPager){
|
| + return (pPager->pWal!=0);
|
| +}
|
| +#else
|
| +# define pagerUseWal(x) 0
|
| +# define pagerRollbackWal(x) 0
|
| +# define pagerWalFrames(v,w,x,y,z) 0
|
| +# define pagerOpenWalIfPresent(z) SQLITE_OK
|
| +# define pagerBeginReadTransaction(z) SQLITE_OK
|
| +#endif
|
| +
|
| +#ifndef NDEBUG
|
| +/*
|
| +** Usage:
|
| +**
|
| +** assert( assert_pager_state(pPager) );
|
| +**
|
| +** This function runs many asserts to try to find inconsistencies in
|
| +** the internal state of the Pager object.
|
| +*/
|
| +static int assert_pager_state(Pager *p){
|
| + Pager *pPager = p;
|
| +
|
| + /* State must be valid. */
|
| + assert( p->eState==PAGER_OPEN
|
| + || p->eState==PAGER_READER
|
| + || p->eState==PAGER_WRITER_LOCKED
|
| + || p->eState==PAGER_WRITER_CACHEMOD
|
| + || p->eState==PAGER_WRITER_DBMOD
|
| + || p->eState==PAGER_WRITER_FINISHED
|
| + || p->eState==PAGER_ERROR
|
| + );
|
| +
|
| + /* Regardless of the current state, a temp-file connection always behaves
|
| + ** as if it has an exclusive lock on the database file. It never updates
|
| + ** the change-counter field, so the changeCountDone flag is always set.
|
| + */
|
| + assert( p->tempFile==0 || p->eLock==EXCLUSIVE_LOCK );
|
| + assert( p->tempFile==0 || pPager->changeCountDone );
|
| +
|
| + /* If the useJournal flag is clear, the journal-mode must be "OFF".
|
| + ** And if the journal-mode is "OFF", the journal file must not be open.
|
| + */
|
| + assert( p->journalMode==PAGER_JOURNALMODE_OFF || p->useJournal );
|
| + assert( p->journalMode!=PAGER_JOURNALMODE_OFF || !isOpen(p->jfd) );
|
| +
|
| + /* Check that MEMDB implies noSync. And an in-memory journal. Since
|
| + ** this means an in-memory pager performs no IO at all, it cannot encounter
|
| + ** either SQLITE_IOERR or SQLITE_FULL during rollback or while finalizing
|
| + ** a journal file. (although the in-memory journal implementation may
|
| + ** return SQLITE_IOERR_NOMEM while the journal file is being written). It
|
| + ** is therefore not possible for an in-memory pager to enter the ERROR
|
| + ** state.
|
| + */
|
| + if( MEMDB ){
|
| + assert( p->noSync );
|
| + assert( p->journalMode==PAGER_JOURNALMODE_OFF
|
| + || p->journalMode==PAGER_JOURNALMODE_MEMORY
|
| + );
|
| + assert( p->eState!=PAGER_ERROR && p->eState!=PAGER_OPEN );
|
| + assert( pagerUseWal(p)==0 );
|
| + }
|
| +
|
| + /* If changeCountDone is set, a RESERVED lock or greater must be held
|
| + ** on the file.
|
| + */
|
| + assert( pPager->changeCountDone==0 || pPager->eLock>=RESERVED_LOCK );
|
| + assert( p->eLock!=PENDING_LOCK );
|
| +
|
| + switch( p->eState ){
|
| + case PAGER_OPEN:
|
| + assert( !MEMDB );
|
| + assert( pPager->errCode==SQLITE_OK );
|
| + assert( sqlite3PcacheRefCount(pPager->pPCache)==0 || pPager->tempFile );
|
| + break;
|
| +
|
| + case PAGER_READER:
|
| + assert( pPager->errCode==SQLITE_OK );
|
| + assert( p->eLock!=UNKNOWN_LOCK );
|
| + assert( p->eLock>=SHARED_LOCK || p->noReadlock );
|
| + break;
|
| +
|
| + case PAGER_WRITER_LOCKED:
|
| + assert( p->eLock!=UNKNOWN_LOCK );
|
| + assert( pPager->errCode==SQLITE_OK );
|
| + if( !pagerUseWal(pPager) ){
|
| + assert( p->eLock>=RESERVED_LOCK );
|
| + }
|
| + assert( pPager->dbSize==pPager->dbOrigSize );
|
| + assert( pPager->dbOrigSize==pPager->dbFileSize );
|
| + assert( pPager->dbOrigSize==pPager->dbHintSize );
|
| + assert( pPager->setMaster==0 );
|
| + break;
|
| +
|
| + case PAGER_WRITER_CACHEMOD:
|
| + assert( p->eLock!=UNKNOWN_LOCK );
|
| + assert( pPager->errCode==SQLITE_OK );
|
| + if( !pagerUseWal(pPager) ){
|
| + /* It is possible that if journal_mode=wal here that neither the
|
| + ** journal file nor the WAL file are open. This happens during
|
| + ** a rollback transaction that switches from journal_mode=off
|
| + ** to journal_mode=wal.
|
| + */
|
| + assert( p->eLock>=RESERVED_LOCK );
|
| + assert( isOpen(p->jfd)
|
| + || p->journalMode==PAGER_JOURNALMODE_OFF
|
| + || p->journalMode==PAGER_JOURNALMODE_WAL
|
| + );
|
| + }
|
| + assert( pPager->dbOrigSize==pPager->dbFileSize );
|
| + assert( pPager->dbOrigSize==pPager->dbHintSize );
|
| + break;
|
| +
|
| + case PAGER_WRITER_DBMOD:
|
| + assert( p->eLock==EXCLUSIVE_LOCK );
|
| + assert( pPager->errCode==SQLITE_OK );
|
| + assert( !pagerUseWal(pPager) );
|
| + assert( p->eLock>=EXCLUSIVE_LOCK );
|
| + assert( isOpen(p->jfd)
|
| + || p->journalMode==PAGER_JOURNALMODE_OFF
|
| + || p->journalMode==PAGER_JOURNALMODE_WAL
|
| + );
|
| + assert( pPager->dbOrigSize<=pPager->dbHintSize );
|
| + break;
|
| +
|
| + case PAGER_WRITER_FINISHED:
|
| + assert( p->eLock==EXCLUSIVE_LOCK );
|
| + assert( pPager->errCode==SQLITE_OK );
|
| + assert( !pagerUseWal(pPager) );
|
| + assert( isOpen(p->jfd)
|
| + || p->journalMode==PAGER_JOURNALMODE_OFF
|
| + || p->journalMode==PAGER_JOURNALMODE_WAL
|
| + );
|
| + break;
|
| +
|
| + case PAGER_ERROR:
|
| + /* There must be at least one outstanding reference to the pager if
|
| + ** in ERROR state. Otherwise the pager should have already dropped
|
| + ** back to OPEN state.
|
| + */
|
| + assert( pPager->errCode!=SQLITE_OK );
|
| + assert( sqlite3PcacheRefCount(pPager->pPCache)>0 );
|
| + break;
|
| + }
|
| +
|
| + return 1;
|
| +}
|
| +#endif /* ifndef NDEBUG */
|
| +
|
| +#ifdef SQLITE_DEBUG
|
| +/*
|
| +** Return a pointer to a human readable string in a static buffer
|
| +** containing the state of the Pager object passed as an argument. This
|
| +** is intended to be used within debuggers. For example, as an alternative
|
| +** to "print *pPager" in gdb:
|
| +**
|
| +** (gdb) printf "%s", print_pager_state(pPager)
|
| +*/
|
| +static char *print_pager_state(Pager *p){
|
| + static char zRet[1024];
|
| +
|
| + sqlite3_snprintf(1024, zRet,
|
| + "Filename: %s\n"
|
| + "State: %s errCode=%d\n"
|
| + "Lock: %s\n"
|
| + "Locking mode: locking_mode=%s\n"
|
| + "Journal mode: journal_mode=%s\n"
|
| + "Backing store: tempFile=%d memDb=%d useJournal=%d\n"
|
| + "Journal: journalOff=%lld journalHdr=%lld\n"
|
| + "Size: dbsize=%d dbOrigSize=%d dbFileSize=%d\n"
|
| + , p->zFilename
|
| + , p->eState==PAGER_OPEN ? "OPEN" :
|
| + p->eState==PAGER_READER ? "READER" :
|
| + p->eState==PAGER_WRITER_LOCKED ? "WRITER_LOCKED" :
|
| + p->eState==PAGER_WRITER_CACHEMOD ? "WRITER_CACHEMOD" :
|
| + p->eState==PAGER_WRITER_DBMOD ? "WRITER_DBMOD" :
|
| + p->eState==PAGER_WRITER_FINISHED ? "WRITER_FINISHED" :
|
| + p->eState==PAGER_ERROR ? "ERROR" : "?error?"
|
| + , (int)p->errCode
|
| + , p->eLock==NO_LOCK ? "NO_LOCK" :
|
| + p->eLock==RESERVED_LOCK ? "RESERVED" :
|
| + p->eLock==EXCLUSIVE_LOCK ? "EXCLUSIVE" :
|
| + p->eLock==SHARED_LOCK ? "SHARED" :
|
| + p->eLock==UNKNOWN_LOCK ? "UNKNOWN" : "?error?"
|
| + , p->exclusiveMode ? "exclusive" : "normal"
|
| + , p->journalMode==PAGER_JOURNALMODE_MEMORY ? "memory" :
|
| + p->journalMode==PAGER_JOURNALMODE_OFF ? "off" :
|
| + p->journalMode==PAGER_JOURNALMODE_DELETE ? "delete" :
|
| + p->journalMode==PAGER_JOURNALMODE_PERSIST ? "persist" :
|
| + p->journalMode==PAGER_JOURNALMODE_TRUNCATE ? "truncate" :
|
| + p->journalMode==PAGER_JOURNALMODE_WAL ? "wal" : "?error?"
|
| + , (int)p->tempFile, (int)p->memDb, (int)p->useJournal
|
| + , p->journalOff, p->journalHdr
|
| + , (int)p->dbSize, (int)p->dbOrigSize, (int)p->dbFileSize
|
| + );
|
| +
|
| + return zRet;
|
| +}
|
| +#endif
|
| +
|
| +/*
|
| +** Return true if it is necessary to write page *pPg into the sub-journal.
|
| +** A page needs to be written into the sub-journal if there exists one
|
| +** or more open savepoints for which:
|
| +**
|
| +** * The page-number is less than or equal to PagerSavepoint.nOrig, and
|
| +** * The bit corresponding to the page-number is not set in
|
| +** PagerSavepoint.pInSavepoint.
|
| +*/
|
| +static int subjRequiresPage(PgHdr *pPg){
|
| + Pgno pgno = pPg->pgno;
|
| + Pager *pPager = pPg->pPager;
|
| + int i;
|
| + for(i=0; i<pPager->nSavepoint; i++){
|
| + PagerSavepoint *p = &pPager->aSavepoint[i];
|
| + if( p->nOrig>=pgno && 0==sqlite3BitvecTest(p->pInSavepoint, pgno) ){
|
| + return 1;
|
| + }
|
| + }
|
| + return 0;
|
| +}
|
| +
|
| +/*
|
| +** Return true if the page is already in the journal file.
|
| +*/
|
| +static int pageInJournal(PgHdr *pPg){
|
| + return sqlite3BitvecTest(pPg->pPager->pInJournal, pPg->pgno);
|
| +}
|
| +
|
| +/*
|
| +** Read a 32-bit integer from the given file descriptor. Store the integer
|
| +** that is read in *pRes. Return SQLITE_OK if everything worked, or an
|
| +** error code is something goes wrong.
|
| +**
|
| +** All values are stored on disk as big-endian.
|
| +*/
|
| +static int read32bits(sqlite3_file *fd, i64 offset, u32 *pRes){
|
| + unsigned char ac[4];
|
| + int rc = sqlite3OsRead(fd, ac, sizeof(ac), offset);
|
| + if( rc==SQLITE_OK ){
|
| + *pRes = sqlite3Get4byte(ac);
|
| + }
|
| + return rc;
|
| +}
|
| +
|
| +/*
|
| +** Write a 32-bit integer into a string buffer in big-endian byte order.
|
| +*/
|
| +#define put32bits(A,B) sqlite3Put4byte((u8*)A,B)
|
| +
|
| +
|
| +/*
|
| +** Write a 32-bit integer into the given file descriptor. Return SQLITE_OK
|
| +** on success or an error code is something goes wrong.
|
| +*/
|
| +static int write32bits(sqlite3_file *fd, i64 offset, u32 val){
|
| + char ac[4];
|
| + put32bits(ac, val);
|
| + return sqlite3OsWrite(fd, ac, 4, offset);
|
| +}
|
| +
|
| +/*
|
| +** Unlock the database file to level eLock, which must be either NO_LOCK
|
| +** or SHARED_LOCK. Regardless of whether or not the call to xUnlock()
|
| +** succeeds, set the Pager.eLock variable to match the (attempted) new lock.
|
| +**
|
| +** Except, if Pager.eLock is set to UNKNOWN_LOCK when this function is
|
| +** called, do not modify it. See the comment above the #define of
|
| +** UNKNOWN_LOCK for an explanation of this.
|
| +*/
|
| +static int pagerUnlockDb(Pager *pPager, int eLock){
|
| + int rc = SQLITE_OK;
|
| +
|
| + assert( !pPager->exclusiveMode || pPager->eLock==eLock );
|
| + assert( eLock==NO_LOCK || eLock==SHARED_LOCK );
|
| + assert( eLock!=NO_LOCK || pagerUseWal(pPager)==0 );
|
| + if( isOpen(pPager->fd) ){
|
| + assert( pPager->eLock>=eLock );
|
| + rc = sqlite3OsUnlock(pPager->fd, eLock);
|
| + if( pPager->eLock!=UNKNOWN_LOCK ){
|
| + pPager->eLock = (u8)eLock;
|
| + }
|
| + IOTRACE(("UNLOCK %p %d\n", pPager, eLock))
|
| + }
|
| + return rc;
|
| +}
|
| +
|
| +/*
|
| +** Lock the database file to level eLock, which must be either SHARED_LOCK,
|
| +** RESERVED_LOCK or EXCLUSIVE_LOCK. If the caller is successful, set the
|
| +** Pager.eLock variable to the new locking state.
|
| +**
|
| +** Except, if Pager.eLock is set to UNKNOWN_LOCK when this function is
|
| +** called, do not modify it unless the new locking state is EXCLUSIVE_LOCK.
|
| +** See the comment above the #define of UNKNOWN_LOCK for an explanation
|
| +** of this.
|
| +*/
|
| +static int pagerLockDb(Pager *pPager, int eLock){
|
| + int rc = SQLITE_OK;
|
| +
|
| + assert( eLock==SHARED_LOCK || eLock==RESERVED_LOCK || eLock==EXCLUSIVE_LOCK );
|
| + if( pPager->eLock<eLock || pPager->eLock==UNKNOWN_LOCK ){
|
| + rc = sqlite3OsLock(pPager->fd, eLock);
|
| + if( rc==SQLITE_OK && (pPager->eLock!=UNKNOWN_LOCK||eLock==EXCLUSIVE_LOCK) ){
|
| + pPager->eLock = (u8)eLock;
|
| + IOTRACE(("LOCK %p %d\n", pPager, eLock))
|
| + }
|
| + }
|
| + return rc;
|
| +}
|
| +
|
| +/*
|
| +** This function determines whether or not the atomic-write optimization
|
| +** can be used with this pager. The optimization can be used if:
|
| +**
|
| +** (a) the value returned by OsDeviceCharacteristics() indicates that
|
| +** a database page may be written atomically, and
|
| +** (b) the value returned by OsSectorSize() is less than or equal
|
| +** to the page size.
|
| +**
|
| +** The optimization is also always enabled for temporary files. It is
|
| +** an error to call this function if pPager is opened on an in-memory
|
| +** database.
|
| +**
|
| +** If the optimization cannot be used, 0 is returned. If it can be used,
|
| +** then the value returned is the size of the journal file when it
|
| +** contains rollback data for exactly one page.
|
| +*/
|
| +#ifdef SQLITE_ENABLE_ATOMIC_WRITE
|
| +static int jrnlBufferSize(Pager *pPager){
|
| + assert( !MEMDB );
|
| + if( !pPager->tempFile ){
|
| + int dc; /* Device characteristics */
|
| + int nSector; /* Sector size */
|
| + int szPage; /* Page size */
|
| +
|
| + assert( isOpen(pPager->fd) );
|
| + dc = sqlite3OsDeviceCharacteristics(pPager->fd);
|
| + nSector = pPager->sectorSize;
|
| + szPage = pPager->pageSize;
|
| +
|
| + assert(SQLITE_IOCAP_ATOMIC512==(512>>8));
|
| + assert(SQLITE_IOCAP_ATOMIC64K==(65536>>8));
|
| + if( 0==(dc&(SQLITE_IOCAP_ATOMIC|(szPage>>8)) || nSector>szPage) ){
|
| + return 0;
|
| + }
|
| + }
|
| +
|
| + return JOURNAL_HDR_SZ(pPager) + JOURNAL_PG_SZ(pPager);
|
| +}
|
| +#endif
|
| +
|
| +/*
|
| +** If SQLITE_CHECK_PAGES is defined then we do some sanity checking
|
| +** on the cache using a hash function. This is used for testing
|
| +** and debugging only.
|
| +*/
|
| +#ifdef SQLITE_CHECK_PAGES
|
| +/*
|
| +** Return a 32-bit hash of the page data for pPage.
|
| +*/
|
| +static u32 pager_datahash(int nByte, unsigned char *pData){
|
| + u32 hash = 0;
|
| + int i;
|
| + for(i=0; i<nByte; i++){
|
| + hash = (hash*1039) + pData[i];
|
| + }
|
| + return hash;
|
| +}
|
| +static u32 pager_pagehash(PgHdr *pPage){
|
| + return pager_datahash(pPage->pPager->pageSize, (unsigned char *)pPage->pData);
|
| +}
|
| +static void pager_set_pagehash(PgHdr *pPage){
|
| + pPage->pageHash = pager_pagehash(pPage);
|
| +}
|
| +
|
| +/*
|
| +** The CHECK_PAGE macro takes a PgHdr* as an argument. If SQLITE_CHECK_PAGES
|
| +** is defined, and NDEBUG is not defined, an assert() statement checks
|
| +** that the page is either dirty or still matches the calculated page-hash.
|
| +*/
|
| +#define CHECK_PAGE(x) checkPage(x)
|
| +static void checkPage(PgHdr *pPg){
|
| + Pager *pPager = pPg->pPager;
|
| + assert( pPager->eState!=PAGER_ERROR );
|
| + assert( (pPg->flags&PGHDR_DIRTY) || pPg->pageHash==pager_pagehash(pPg) );
|
| +}
|
| +
|
| +#else
|
| +#define pager_datahash(X,Y) 0
|
| +#define pager_pagehash(X) 0
|
| +#define pager_set_pagehash(X)
|
| +#define CHECK_PAGE(x)
|
| +#endif /* SQLITE_CHECK_PAGES */
|
| +
|
| +/*
|
| +** When this is called the journal file for pager pPager must be open.
|
| +** This function attempts to read a master journal file name from the
|
| +** end of the file and, if successful, copies it into memory supplied
|
| +** by the caller. See comments above writeMasterJournal() for the format
|
| +** used to store a master journal file name at the end of a journal file.
|
| +**
|
| +** zMaster must point to a buffer of at least nMaster bytes allocated by
|
| +** the caller. This should be sqlite3_vfs.mxPathname+1 (to ensure there is
|
| +** enough space to write the master journal name). If the master journal
|
| +** name in the journal is longer than nMaster bytes (including a
|
| +** nul-terminator), then this is handled as if no master journal name
|
| +** were present in the journal.
|
| +**
|
| +** If a master journal file name is present at the end of the journal
|
| +** file, then it is copied into the buffer pointed to by zMaster. A
|
| +** nul-terminator byte is appended to the buffer following the master
|
| +** journal file name.
|
| +**
|
| +** If it is determined that no master journal file name is present
|
| +** zMaster[0] is set to 0 and SQLITE_OK returned.
|
| +**
|
| +** If an error occurs while reading from the journal file, an SQLite
|
| +** error code is returned.
|
| +*/
|
| +static int readMasterJournal(sqlite3_file *pJrnl, char *zMaster, u32 nMaster){
|
| + int rc; /* Return code */
|
| + u32 len; /* Length in bytes of master journal name */
|
| + i64 szJ; /* Total size in bytes of journal file pJrnl */
|
| + u32 cksum; /* MJ checksum value read from journal */
|
| + u32 u; /* Unsigned loop counter */
|
| + unsigned char aMagic[8]; /* A buffer to hold the magic header */
|
| + zMaster[0] = '\0';
|
| +
|
| + if( SQLITE_OK!=(rc = sqlite3OsFileSize(pJrnl, &szJ))
|
| + || szJ<16
|
| + || SQLITE_OK!=(rc = read32bits(pJrnl, szJ-16, &len))
|
| + || len>=nMaster
|
| + || SQLITE_OK!=(rc = read32bits(pJrnl, szJ-12, &cksum))
|
| + || SQLITE_OK!=(rc = sqlite3OsRead(pJrnl, aMagic, 8, szJ-8))
|
| + || memcmp(aMagic, aJournalMagic, 8)
|
| + || SQLITE_OK!=(rc = sqlite3OsRead(pJrnl, zMaster, len, szJ-16-len))
|
| + ){
|
| + return rc;
|
| + }
|
| +
|
| + /* See if the checksum matches the master journal name */
|
| + for(u=0; u<len; u++){
|
| + cksum -= zMaster[u];
|
| + }
|
| + if( cksum ){
|
| + /* If the checksum doesn't add up, then one or more of the disk sectors
|
| + ** containing the master journal filename is corrupted. This means
|
| + ** definitely roll back, so just return SQLITE_OK and report a (nul)
|
| + ** master-journal filename.
|
| + */
|
| + len = 0;
|
| + }
|
| + zMaster[len] = '\0';
|
| +
|
| + return SQLITE_OK;
|
| +}
|
| +
|
| +/*
|
| +** Return the offset of the sector boundary at or immediately
|
| +** following the value in pPager->journalOff, assuming a sector
|
| +** size of pPager->sectorSize bytes.
|
| +**
|
| +** i.e for a sector size of 512:
|
| +**
|
| +** Pager.journalOff Return value
|
| +** ---------------------------------------
|
| +** 0 0
|
| +** 512 512
|
| +** 100 512
|
| +** 2000 2048
|
| +**
|
| +*/
|
| +static i64 journalHdrOffset(Pager *pPager){
|
| + i64 offset = 0;
|
| + i64 c = pPager->journalOff;
|
| + if( c ){
|
| + offset = ((c-1)/JOURNAL_HDR_SZ(pPager) + 1) * JOURNAL_HDR_SZ(pPager);
|
| + }
|
| + assert( offset%JOURNAL_HDR_SZ(pPager)==0 );
|
| + assert( offset>=c );
|
| + assert( (offset-c)<JOURNAL_HDR_SZ(pPager) );
|
| + return offset;
|
| +}
|
| +
|
| +/*
|
| +** The journal file must be open when this function is called.
|
| +**
|
| +** This function is a no-op if the journal file has not been written to
|
| +** within the current transaction (i.e. if Pager.journalOff==0).
|
| +**
|
| +** If doTruncate is non-zero or the Pager.journalSizeLimit variable is
|
| +** set to 0, then truncate the journal file to zero bytes in size. Otherwise,
|
| +** zero the 28-byte header at the start of the journal file. In either case,
|
| +** if the pager is not in no-sync mode, sync the journal file immediately
|
| +** after writing or truncating it.
|
| +**
|
| +** If Pager.journalSizeLimit is set to a positive, non-zero value, and
|
| +** following the truncation or zeroing described above the size of the
|
| +** journal file in bytes is larger than this value, then truncate the
|
| +** journal file to Pager.journalSizeLimit bytes. The journal file does
|
| +** not need to be synced following this operation.
|
| +**
|
| +** If an IO error occurs, abandon processing and return the IO error code.
|
| +** Otherwise, return SQLITE_OK.
|
| +*/
|
| +static int zeroJournalHdr(Pager *pPager, int doTruncate){
|
| + int rc = SQLITE_OK; /* Return code */
|
| + assert( isOpen(pPager->jfd) );
|
| + if( pPager->journalOff ){
|
| + const i64 iLimit = pPager->journalSizeLimit; /* Local cache of jsl */
|
| +
|
| + IOTRACE(("JZEROHDR %p\n", pPager))
|
| + if( doTruncate || iLimit==0 ){
|
| + rc = sqlite3OsTruncate(pPager->jfd, 0);
|
| + }else{
|
| + static const char zeroHdr[28] = {0};
|
| + rc = sqlite3OsWrite(pPager->jfd, zeroHdr, sizeof(zeroHdr), 0);
|
| + }
|
| + if( rc==SQLITE_OK && !pPager->noSync ){
|
| + rc = sqlite3OsSync(pPager->jfd, SQLITE_SYNC_DATAONLY|pPager->syncFlags);
|
| + }
|
| +
|
| + /* At this point the transaction is committed but the write lock
|
| + ** is still held on the file. If there is a size limit configured for
|
| + ** the persistent journal and the journal file currently consumes more
|
| + ** space than that limit allows for, truncate it now. There is no need
|
| + ** to sync the file following this operation.
|
| + */
|
| + if( rc==SQLITE_OK && iLimit>0 ){
|
| + i64 sz;
|
| + rc = sqlite3OsFileSize(pPager->jfd, &sz);
|
| + if( rc==SQLITE_OK && sz>iLimit ){
|
| + rc = sqlite3OsTruncate(pPager->jfd, iLimit);
|
| + }
|
| + }
|
| + }
|
| + return rc;
|
| +}
|
| +
|
| +/*
|
| +** The journal file must be open when this routine is called. A journal
|
| +** header (JOURNAL_HDR_SZ bytes) is written into the journal file at the
|
| +** current location.
|
| +**
|
| +** The format for the journal header is as follows:
|
| +** - 8 bytes: Magic identifying journal format.
|
| +** - 4 bytes: Number of records in journal, or -1 no-sync mode is on.
|
| +** - 4 bytes: Random number used for page hash.
|
| +** - 4 bytes: Initial database page count.
|
| +** - 4 bytes: Sector size used by the process that wrote this journal.
|
| +** - 4 bytes: Database page size.
|
| +**
|
| +** Followed by (JOURNAL_HDR_SZ - 28) bytes of unused space.
|
| +*/
|
| +static int writeJournalHdr(Pager *pPager){
|
| + int rc = SQLITE_OK; /* Return code */
|
| + char *zHeader = pPager->pTmpSpace; /* Temporary space used to build header */
|
| + u32 nHeader = (u32)pPager->pageSize;/* Size of buffer pointed to by zHeader */
|
| + u32 nWrite; /* Bytes of header sector written */
|
| + int ii; /* Loop counter */
|
| +
|
| + assert( isOpen(pPager->jfd) ); /* Journal file must be open. */
|
| +
|
| + if( nHeader>JOURNAL_HDR_SZ(pPager) ){
|
| + nHeader = JOURNAL_HDR_SZ(pPager);
|
| + }
|
| +
|
| + /* If there are active savepoints and any of them were created
|
| + ** since the most recent journal header was written, update the
|
| + ** PagerSavepoint.iHdrOffset fields now.
|
| + */
|
| + for(ii=0; ii<pPager->nSavepoint; ii++){
|
| + if( pPager->aSavepoint[ii].iHdrOffset==0 ){
|
| + pPager->aSavepoint[ii].iHdrOffset = pPager->journalOff;
|
| + }
|
| + }
|
| +
|
| + pPager->journalHdr = pPager->journalOff = journalHdrOffset(pPager);
|
| +
|
| + /*
|
| + ** Write the nRec Field - the number of page records that follow this
|
| + ** journal header. Normally, zero is written to this value at this time.
|
| + ** After the records are added to the journal (and the journal synced,
|
| + ** if in full-sync mode), the zero is overwritten with the true number
|
| + ** of records (see syncJournal()).
|
| + **
|
| + ** A faster alternative is to write 0xFFFFFFFF to the nRec field. When
|
| + ** reading the journal this value tells SQLite to assume that the
|
| + ** rest of the journal file contains valid page records. This assumption
|
| + ** is dangerous, as if a failure occurred whilst writing to the journal
|
| + ** file it may contain some garbage data. There are two scenarios
|
| + ** where this risk can be ignored:
|
| + **
|
| + ** * When the pager is in no-sync mode. Corruption can follow a
|
| + ** power failure in this case anyway.
|
| + **
|
| + ** * When the SQLITE_IOCAP_SAFE_APPEND flag is set. This guarantees
|
| + ** that garbage data is never appended to the journal file.
|
| + */
|
| + assert( isOpen(pPager->fd) || pPager->noSync );
|
| + if( pPager->noSync || (pPager->journalMode==PAGER_JOURNALMODE_MEMORY)
|
| + || (sqlite3OsDeviceCharacteristics(pPager->fd)&SQLITE_IOCAP_SAFE_APPEND)
|
| + ){
|
| + memcpy(zHeader, aJournalMagic, sizeof(aJournalMagic));
|
| + put32bits(&zHeader[sizeof(aJournalMagic)], 0xffffffff);
|
| + }else{
|
| + memset(zHeader, 0, sizeof(aJournalMagic)+4);
|
| + }
|
| +
|
| + /* The random check-hash initialiser */
|
| + sqlite3_randomness(sizeof(pPager->cksumInit), &pPager->cksumInit);
|
| + put32bits(&zHeader[sizeof(aJournalMagic)+4], pPager->cksumInit);
|
| + /* The initial database size */
|
| + put32bits(&zHeader[sizeof(aJournalMagic)+8], pPager->dbOrigSize);
|
| + /* The assumed sector size for this process */
|
| + put32bits(&zHeader[sizeof(aJournalMagic)+12], pPager->sectorSize);
|
| +
|
| + /* The page size */
|
| + put32bits(&zHeader[sizeof(aJournalMagic)+16], pPager->pageSize);
|
| +
|
| + /* Initializing the tail of the buffer is not necessary. Everything
|
| + ** works find if the following memset() is omitted. But initializing
|
| + ** the memory prevents valgrind from complaining, so we are willing to
|
| + ** take the performance hit.
|
| + */
|
| + memset(&zHeader[sizeof(aJournalMagic)+20], 0,
|
| + nHeader-(sizeof(aJournalMagic)+20));
|
| +
|
| + /* In theory, it is only necessary to write the 28 bytes that the
|
| + ** journal header consumes to the journal file here. Then increment the
|
| + ** Pager.journalOff variable by JOURNAL_HDR_SZ so that the next
|
| + ** record is written to the following sector (leaving a gap in the file
|
| + ** that will be implicitly filled in by the OS).
|
| + **
|
| + ** However it has been discovered that on some systems this pattern can
|
| + ** be significantly slower than contiguously writing data to the file,
|
| + ** even if that means explicitly writing data to the block of
|
| + ** (JOURNAL_HDR_SZ - 28) bytes that will not be used. So that is what
|
| + ** is done.
|
| + **
|
| + ** The loop is required here in case the sector-size is larger than the
|
| + ** database page size. Since the zHeader buffer is only Pager.pageSize
|
| + ** bytes in size, more than one call to sqlite3OsWrite() may be required
|
| + ** to populate the entire journal header sector.
|
| + */
|
| + for(nWrite=0; rc==SQLITE_OK&&nWrite<JOURNAL_HDR_SZ(pPager); nWrite+=nHeader){
|
| + IOTRACE(("JHDR %p %lld %d\n", pPager, pPager->journalHdr, nHeader))
|
| + rc = sqlite3OsWrite(pPager->jfd, zHeader, nHeader, pPager->journalOff);
|
| + assert( pPager->journalHdr <= pPager->journalOff );
|
| + pPager->journalOff += nHeader;
|
| + }
|
| +
|
| + return rc;
|
| +}
|
| +
|
| +/*
|
| +** The journal file must be open when this is called. A journal header file
|
| +** (JOURNAL_HDR_SZ bytes) is read from the current location in the journal
|
| +** file. The current location in the journal file is given by
|
| +** pPager->journalOff. See comments above function writeJournalHdr() for
|
| +** a description of the journal header format.
|
| +**
|
| +** If the header is read successfully, *pNRec is set to the number of
|
| +** page records following this header and *pDbSize is set to the size of the
|
| +** database before the transaction began, in pages. Also, pPager->cksumInit
|
| +** is set to the value read from the journal header. SQLITE_OK is returned
|
| +** in this case.
|
| +**
|
| +** If the journal header file appears to be corrupted, SQLITE_DONE is
|
| +** returned and *pNRec and *PDbSize are undefined. If JOURNAL_HDR_SZ bytes
|
| +** cannot be read from the journal file an error code is returned.
|
| +*/
|
| +static int readJournalHdr(
|
| + Pager *pPager, /* Pager object */
|
| + int isHot,
|
| + i64 journalSize, /* Size of the open journal file in bytes */
|
| + u32 *pNRec, /* OUT: Value read from the nRec field */
|
| + u32 *pDbSize /* OUT: Value of original database size field */
|
| +){
|
| + int rc; /* Return code */
|
| + unsigned char aMagic[8]; /* A buffer to hold the magic header */
|
| + i64 iHdrOff; /* Offset of journal header being read */
|
| +
|
| + assert( isOpen(pPager->jfd) ); /* Journal file must be open. */
|
| +
|
| + /* Advance Pager.journalOff to the start of the next sector. If the
|
| + ** journal file is too small for there to be a header stored at this
|
| + ** point, return SQLITE_DONE.
|
| + */
|
| + pPager->journalOff = journalHdrOffset(pPager);
|
| + if( pPager->journalOff+JOURNAL_HDR_SZ(pPager) > journalSize ){
|
| + return SQLITE_DONE;
|
| + }
|
| + iHdrOff = pPager->journalOff;
|
| +
|
| + /* Read in the first 8 bytes of the journal header. If they do not match
|
| + ** the magic string found at the start of each journal header, return
|
| + ** SQLITE_DONE. If an IO error occurs, return an error code. Otherwise,
|
| + ** proceed.
|
| + */
|
| + if( isHot || iHdrOff!=pPager->journalHdr ){
|
| + rc = sqlite3OsRead(pPager->jfd, aMagic, sizeof(aMagic), iHdrOff);
|
| + if( rc ){
|
| + return rc;
|
| + }
|
| + if( memcmp(aMagic, aJournalMagic, sizeof(aMagic))!=0 ){
|
| + return SQLITE_DONE;
|
| + }
|
| + }
|
| +
|
| + /* Read the first three 32-bit fields of the journal header: The nRec
|
| + ** field, the checksum-initializer and the database size at the start
|
| + ** of the transaction. Return an error code if anything goes wrong.
|
| + */
|
| + if( SQLITE_OK!=(rc = read32bits(pPager->jfd, iHdrOff+8, pNRec))
|
| + || SQLITE_OK!=(rc = read32bits(pPager->jfd, iHdrOff+12, &pPager->cksumInit))
|
| + || SQLITE_OK!=(rc = read32bits(pPager->jfd, iHdrOff+16, pDbSize))
|
| + ){
|
| + return rc;
|
| + }
|
| +
|
| + if( pPager->journalOff==0 ){
|
| + u32 iPageSize; /* Page-size field of journal header */
|
| + u32 iSectorSize; /* Sector-size field of journal header */
|
| +
|
| + /* Read the page-size and sector-size journal header fields. */
|
| + if( SQLITE_OK!=(rc = read32bits(pPager->jfd, iHdrOff+20, &iSectorSize))
|
| + || SQLITE_OK!=(rc = read32bits(pPager->jfd, iHdrOff+24, &iPageSize))
|
| + ){
|
| + return rc;
|
| + }
|
| +
|
| + /* Versions of SQLite prior to 3.5.8 set the page-size field of the
|
| + ** journal header to zero. In this case, assume that the Pager.pageSize
|
| + ** variable is already set to the correct page size.
|
| + */
|
| + if( iPageSize==0 ){
|
| + iPageSize = pPager->pageSize;
|
| + }
|
| +
|
| + /* Check that the values read from the page-size and sector-size fields
|
| + ** are within range. To be 'in range', both values need to be a power
|
| + ** of two greater than or equal to 512 or 32, and not greater than their
|
| + ** respective compile time maximum limits.
|
| + */
|
| + if( iPageSize<512 || iSectorSize<32
|
| + || iPageSize>SQLITE_MAX_PAGE_SIZE || iSectorSize>MAX_SECTOR_SIZE
|
| + || ((iPageSize-1)&iPageSize)!=0 || ((iSectorSize-1)&iSectorSize)!=0
|
| + ){
|
| + /* If the either the page-size or sector-size in the journal-header is
|
| + ** invalid, then the process that wrote the journal-header must have
|
| + ** crashed before the header was synced. In this case stop reading
|
| + ** the journal file here.
|
| + */
|
| + return SQLITE_DONE;
|
| + }
|
| +
|
| + /* Update the page-size to match the value read from the journal.
|
| + ** Use a testcase() macro to make sure that malloc failure within
|
| + ** PagerSetPagesize() is tested.
|
| + */
|
| + rc = sqlite3PagerSetPagesize(pPager, &iPageSize, -1);
|
| + testcase( rc!=SQLITE_OK );
|
| +
|
| + /* Update the assumed sector-size to match the value used by
|
| + ** the process that created this journal. If this journal was
|
| + ** created by a process other than this one, then this routine
|
| + ** is being called from within pager_playback(). The local value
|
| + ** of Pager.sectorSize is restored at the end of that routine.
|
| + */
|
| + pPager->sectorSize = iSectorSize;
|
| + }
|
| +
|
| + pPager->journalOff += JOURNAL_HDR_SZ(pPager);
|
| + return rc;
|
| +}
|
| +
|
| +
|
| +/*
|
| +** Write the supplied master journal name into the journal file for pager
|
| +** pPager at the current location. The master journal name must be the last
|
| +** thing written to a journal file. If the pager is in full-sync mode, the
|
| +** journal file descriptor is advanced to the next sector boundary before
|
| +** anything is written. The format is:
|
| +**
|
| +** + 4 bytes: PAGER_MJ_PGNO.
|
| +** + N bytes: Master journal filename in utf-8.
|
| +** + 4 bytes: N (length of master journal name in bytes, no nul-terminator).
|
| +** + 4 bytes: Master journal name checksum.
|
| +** + 8 bytes: aJournalMagic[].
|
| +**
|
| +** The master journal page checksum is the sum of the bytes in the master
|
| +** journal name, where each byte is interpreted as a signed 8-bit integer.
|
| +**
|
| +** If zMaster is a NULL pointer (occurs for a single database transaction),
|
| +** this call is a no-op.
|
| +*/
|
| +static int writeMasterJournal(Pager *pPager, const char *zMaster){
|
| + int rc; /* Return code */
|
| + int nMaster; /* Length of string zMaster */
|
| + i64 iHdrOff; /* Offset of header in journal file */
|
| + i64 jrnlSize; /* Size of journal file on disk */
|
| + u32 cksum = 0; /* Checksum of string zMaster */
|
| +
|
| + assert( pPager->setMaster==0 );
|
| + assert( !pagerUseWal(pPager) );
|
| +
|
| + if( !zMaster
|
| + || pPager->journalMode==PAGER_JOURNALMODE_MEMORY
|
| + || pPager->journalMode==PAGER_JOURNALMODE_OFF
|
| + ){
|
| + return SQLITE_OK;
|
| + }
|
| + pPager->setMaster = 1;
|
| + assert( isOpen(pPager->jfd) );
|
| + assert( pPager->journalHdr <= pPager->journalOff );
|
| +
|
| + /* Calculate the length in bytes and the checksum of zMaster */
|
| + for(nMaster=0; zMaster[nMaster]; nMaster++){
|
| + cksum += zMaster[nMaster];
|
| + }
|
| +
|
| + /* If in full-sync mode, advance to the next disk sector before writing
|
| + ** the master journal name. This is in case the previous page written to
|
| + ** the journal has already been synced.
|
| + */
|
| + if( pPager->fullSync ){
|
| + pPager->journalOff = journalHdrOffset(pPager);
|
| + }
|
| + iHdrOff = pPager->journalOff;
|
| +
|
| + /* Write the master journal data to the end of the journal file. If
|
| + ** an error occurs, return the error code to the caller.
|
| + */
|
| + if( (0 != (rc = write32bits(pPager->jfd, iHdrOff, PAGER_MJ_PGNO(pPager))))
|
| + || (0 != (rc = sqlite3OsWrite(pPager->jfd, zMaster, nMaster, iHdrOff+4)))
|
| + || (0 != (rc = write32bits(pPager->jfd, iHdrOff+4+nMaster, nMaster)))
|
| + || (0 != (rc = write32bits(pPager->jfd, iHdrOff+4+nMaster+4, cksum)))
|
| + || (0 != (rc = sqlite3OsWrite(pPager->jfd, aJournalMagic, 8, iHdrOff+4+nMaster+8)))
|
| + ){
|
| + return rc;
|
| + }
|
| + pPager->journalOff += (nMaster+20);
|
| +
|
| + /* If the pager is in peristent-journal mode, then the physical
|
| + ** journal-file may extend past the end of the master-journal name
|
| + ** and 8 bytes of magic data just written to the file. This is
|
| + ** dangerous because the code to rollback a hot-journal file
|
| + ** will not be able to find the master-journal name to determine
|
| + ** whether or not the journal is hot.
|
| + **
|
| + ** Easiest thing to do in this scenario is to truncate the journal
|
| + ** file to the required size.
|
| + */
|
| + if( SQLITE_OK==(rc = sqlite3OsFileSize(pPager->jfd, &jrnlSize))
|
| + && jrnlSize>pPager->journalOff
|
| + ){
|
| + rc = sqlite3OsTruncate(pPager->jfd, pPager->journalOff);
|
| + }
|
| + return rc;
|
| +}
|
| +
|
| +/*
|
| +** Find a page in the hash table given its page number. Return
|
| +** a pointer to the page or NULL if the requested page is not
|
| +** already in memory.
|
| +*/
|
| +static PgHdr *pager_lookup(Pager *pPager, Pgno pgno){
|
| + PgHdr *p; /* Return value */
|
| +
|
| + /* It is not possible for a call to PcacheFetch() with createFlag==0 to
|
| + ** fail, since no attempt to allocate dynamic memory will be made.
|
| + */
|
| + (void)sqlite3PcacheFetch(pPager->pPCache, pgno, 0, &p);
|
| + return p;
|
| +}
|
| +
|
| +/*
|
| +** Discard the entire contents of the in-memory page-cache.
|
| +*/
|
| +static void pager_reset(Pager *pPager){
|
| + sqlite3BackupRestart(pPager->pBackup);
|
| + sqlite3PcacheClear(pPager->pPCache);
|
| +}
|
| +
|
| +/*
|
| +** Free all structures in the Pager.aSavepoint[] array and set both
|
| +** Pager.aSavepoint and Pager.nSavepoint to zero. Close the sub-journal
|
| +** if it is open and the pager is not in exclusive mode.
|
| +*/
|
| +static void releaseAllSavepoints(Pager *pPager){
|
| + int ii; /* Iterator for looping through Pager.aSavepoint */
|
| + for(ii=0; ii<pPager->nSavepoint; ii++){
|
| + sqlite3BitvecDestroy(pPager->aSavepoint[ii].pInSavepoint);
|
| + }
|
| + if( !pPager->exclusiveMode || sqlite3IsMemJournal(pPager->sjfd) ){
|
| + sqlite3OsClose(pPager->sjfd);
|
| + }
|
| + sqlite3_free(pPager->aSavepoint);
|
| + pPager->aSavepoint = 0;
|
| + pPager->nSavepoint = 0;
|
| + pPager->nSubRec = 0;
|
| +}
|
| +
|
| +/*
|
| +** Set the bit number pgno in the PagerSavepoint.pInSavepoint
|
| +** bitvecs of all open savepoints. Return SQLITE_OK if successful
|
| +** or SQLITE_NOMEM if a malloc failure occurs.
|
| +*/
|
| +static int addToSavepointBitvecs(Pager *pPager, Pgno pgno){
|
| + int ii; /* Loop counter */
|
| + int rc = SQLITE_OK; /* Result code */
|
| +
|
| + for(ii=0; ii<pPager->nSavepoint; ii++){
|
| + PagerSavepoint *p = &pPager->aSavepoint[ii];
|
| + if( pgno<=p->nOrig ){
|
| + rc |= sqlite3BitvecSet(p->pInSavepoint, pgno);
|
| + testcase( rc==SQLITE_NOMEM );
|
| + assert( rc==SQLITE_OK || rc==SQLITE_NOMEM );
|
| + }
|
| + }
|
| + return rc;
|
| +}
|
| +
|
| +/*
|
| +** This function is a no-op if the pager is in exclusive mode and not
|
| +** in the ERROR state. Otherwise, it switches the pager to PAGER_OPEN
|
| +** state.
|
| +**
|
| +** If the pager is not in exclusive-access mode, the database file is
|
| +** completely unlocked. If the file is unlocked and the file-system does
|
| +** not exhibit the UNDELETABLE_WHEN_OPEN property, the journal file is
|
| +** closed (if it is open).
|
| +**
|
| +** If the pager is in ERROR state when this function is called, the
|
| +** contents of the pager cache are discarded before switching back to
|
| +** the OPEN state. Regardless of whether the pager is in exclusive-mode
|
| +** or not, any journal file left in the file-system will be treated
|
| +** as a hot-journal and rolled back the next time a read-transaction
|
| +** is opened (by this or by any other connection).
|
| +*/
|
| +static void pager_unlock(Pager *pPager){
|
| +
|
| + assert( pPager->eState==PAGER_READER
|
| + || pPager->eState==PAGER_OPEN
|
| + || pPager->eState==PAGER_ERROR
|
| + );
|
| +
|
| + sqlite3BitvecDestroy(pPager->pInJournal);
|
| + pPager->pInJournal = 0;
|
| + releaseAllSavepoints(pPager);
|
| +
|
| + if( pagerUseWal(pPager) ){
|
| + assert( !isOpen(pPager->jfd) );
|
| + sqlite3WalEndReadTransaction(pPager->pWal);
|
| + pPager->eState = PAGER_OPEN;
|
| + }else if( !pPager->exclusiveMode ){
|
| + int rc; /* Error code returned by pagerUnlockDb() */
|
| + int iDc = isOpen(pPager->fd)?sqlite3OsDeviceCharacteristics(pPager->fd):0;
|
| +
|
| + /* If the operating system support deletion of open files, then
|
| + ** close the journal file when dropping the database lock. Otherwise
|
| + ** another connection with journal_mode=delete might delete the file
|
| + ** out from under us.
|
| + */
|
| + assert( (PAGER_JOURNALMODE_MEMORY & 5)!=1 );
|
| + assert( (PAGER_JOURNALMODE_OFF & 5)!=1 );
|
| + assert( (PAGER_JOURNALMODE_WAL & 5)!=1 );
|
| + assert( (PAGER_JOURNALMODE_DELETE & 5)!=1 );
|
| + assert( (PAGER_JOURNALMODE_TRUNCATE & 5)==1 );
|
| + assert( (PAGER_JOURNALMODE_PERSIST & 5)==1 );
|
| + if( 0==(iDc & SQLITE_IOCAP_UNDELETABLE_WHEN_OPEN)
|
| + || 1!=(pPager->journalMode & 5)
|
| + ){
|
| + sqlite3OsClose(pPager->jfd);
|
| + }
|
| +
|
| + /* If the pager is in the ERROR state and the call to unlock the database
|
| + ** file fails, set the current lock to UNKNOWN_LOCK. See the comment
|
| + ** above the #define for UNKNOWN_LOCK for an explanation of why this
|
| + ** is necessary.
|
| + */
|
| + rc = pagerUnlockDb(pPager, NO_LOCK);
|
| + if( rc!=SQLITE_OK && pPager->eState==PAGER_ERROR ){
|
| + pPager->eLock = UNKNOWN_LOCK;
|
| + }
|
| +
|
| + /* The pager state may be changed from PAGER_ERROR to PAGER_OPEN here
|
| + ** without clearing the error code. This is intentional - the error
|
| + ** code is cleared and the cache reset in the block below.
|
| + */
|
| + assert( pPager->errCode || pPager->eState!=PAGER_ERROR );
|
| + pPager->changeCountDone = 0;
|
| + pPager->eState = PAGER_OPEN;
|
| + }
|
| +
|
| + /* If Pager.errCode is set, the contents of the pager cache cannot be
|
| + ** trusted. Now that there are no outstanding references to the pager,
|
| + ** it can safely move back to PAGER_OPEN state. This happens in both
|
| + ** normal and exclusive-locking mode.
|
| + */
|
| + if( pPager->errCode ){
|
| + assert( !MEMDB );
|
| + pager_reset(pPager);
|
| + pPager->changeCountDone = pPager->tempFile;
|
| + pPager->eState = PAGER_OPEN;
|
| + pPager->errCode = SQLITE_OK;
|
| + }
|
| +
|
| + pPager->journalOff = 0;
|
| + pPager->journalHdr = 0;
|
| + pPager->setMaster = 0;
|
| +}
|
| +
|
| +/*
|
| +** This function is called whenever an IOERR or FULL error that requires
|
| +** the pager to transition into the ERROR state may ahve occurred.
|
| +** The first argument is a pointer to the pager structure, the second
|
| +** the error-code about to be returned by a pager API function. The
|
| +** value returned is a copy of the second argument to this function.
|
| +**
|
| +** If the second argument is SQLITE_FULL, SQLITE_IOERR or one of the
|
| +** IOERR sub-codes, the pager enters the ERROR state and the error code
|
| +** is stored in Pager.errCode. While the pager remains in the ERROR state,
|
| +** all major API calls on the Pager will immediately return Pager.errCode.
|
| +**
|
| +** The ERROR state indicates that the contents of the pager-cache
|
| +** cannot be trusted. This state can be cleared by completely discarding
|
| +** the contents of the pager-cache. If a transaction was active when
|
| +** the persistent error occurred, then the rollback journal may need
|
| +** to be replayed to restore the contents of the database file (as if
|
| +** it were a hot-journal).
|
| +*/
|
| +static int pager_error(Pager *pPager, int rc){
|
| + int rc2 = rc & 0xff;
|
| + assert( rc==SQLITE_OK || !MEMDB );
|
| + assert(
|
| + pPager->errCode==SQLITE_FULL ||
|
| + pPager->errCode==SQLITE_OK ||
|
| + (pPager->errCode & 0xff)==SQLITE_IOERR
|
| + );
|
| + if( rc2==SQLITE_FULL || rc2==SQLITE_IOERR ){
|
| + pPager->errCode = rc;
|
| + pPager->eState = PAGER_ERROR;
|
| + }
|
| + return rc;
|
| +}
|
| +
|
| +/*
|
| +** This routine ends a transaction. A transaction is usually ended by
|
| +** either a COMMIT or a ROLLBACK operation. This routine may be called
|
| +** after rollback of a hot-journal, or if an error occurs while opening
|
| +** the journal file or writing the very first journal-header of a
|
| +** database transaction.
|
| +**
|
| +** This routine is never called in PAGER_ERROR state. If it is called
|
| +** in PAGER_NONE or PAGER_SHARED state and the lock held is less
|
| +** exclusive than a RESERVED lock, it is a no-op.
|
| +**
|
| +** Otherwise, any active savepoints are released.
|
| +**
|
| +** If the journal file is open, then it is "finalized". Once a journal
|
| +** file has been finalized it is not possible to use it to roll back a
|
| +** transaction. Nor will it be considered to be a hot-journal by this
|
| +** or any other database connection. Exactly how a journal is finalized
|
| +** depends on whether or not the pager is running in exclusive mode and
|
| +** the current journal-mode (Pager.journalMode value), as follows:
|
| +**
|
| +** journalMode==MEMORY
|
| +** Journal file descriptor is simply closed. This destroys an
|
| +** in-memory journal.
|
| +**
|
| +** journalMode==TRUNCATE
|
| +** Journal file is truncated to zero bytes in size.
|
| +**
|
| +** journalMode==PERSIST
|
| +** The first 28 bytes of the journal file are zeroed. This invalidates
|
| +** the first journal header in the file, and hence the entire journal
|
| +** file. An invalid journal file cannot be rolled back.
|
| +**
|
| +** journalMode==DELETE
|
| +** The journal file is closed and deleted using sqlite3OsDelete().
|
| +**
|
| +** If the pager is running in exclusive mode, this method of finalizing
|
| +** the journal file is never used. Instead, if the journalMode is
|
| +** DELETE and the pager is in exclusive mode, the method described under
|
| +** journalMode==PERSIST is used instead.
|
| +**
|
| +** After the journal is finalized, the pager moves to PAGER_READER state.
|
| +** If running in non-exclusive rollback mode, the lock on the file is
|
| +** downgraded to a SHARED_LOCK.
|
| +**
|
| +** SQLITE_OK is returned if no error occurs. If an error occurs during
|
| +** any of the IO operations to finalize the journal file or unlock the
|
| +** database then the IO error code is returned to the user. If the
|
| +** operation to finalize the journal file fails, then the code still
|
| +** tries to unlock the database file if not in exclusive mode. If the
|
| +** unlock operation fails as well, then the first error code related
|
| +** to the first error encountered (the journal finalization one) is
|
| +** returned.
|
| +*/
|
| +static int pager_end_transaction(Pager *pPager, int hasMaster){
|
| + int rc = SQLITE_OK; /* Error code from journal finalization operation */
|
| + int rc2 = SQLITE_OK; /* Error code from db file unlock operation */
|
| +
|
| + /* Do nothing if the pager does not have an open write transaction
|
| + ** or at least a RESERVED lock. This function may be called when there
|
| + ** is no write-transaction active but a RESERVED or greater lock is
|
| + ** held under two circumstances:
|
| + **
|
| + ** 1. After a successful hot-journal rollback, it is called with
|
| + ** eState==PAGER_NONE and eLock==EXCLUSIVE_LOCK.
|
| + **
|
| + ** 2. If a connection with locking_mode=exclusive holding an EXCLUSIVE
|
| + ** lock switches back to locking_mode=normal and then executes a
|
| + ** read-transaction, this function is called with eState==PAGER_READER
|
| + ** and eLock==EXCLUSIVE_LOCK when the read-transaction is closed.
|
| + */
|
| + assert( assert_pager_state(pPager) );
|
| + assert( pPager->eState!=PAGER_ERROR );
|
| + if( pPager->eState<PAGER_WRITER_LOCKED && pPager->eLock<RESERVED_LOCK ){
|
| + return SQLITE_OK;
|
| + }
|
| +
|
| + releaseAllSavepoints(pPager);
|
| + assert( isOpen(pPager->jfd) || pPager->pInJournal==0 );
|
| + if( isOpen(pPager->jfd) ){
|
| + assert( !pagerUseWal(pPager) );
|
| +
|
| + /* Finalize the journal file. */
|
| + if( sqlite3IsMemJournal(pPager->jfd) ){
|
| + assert( pPager->journalMode==PAGER_JOURNALMODE_MEMORY );
|
| + sqlite3OsClose(pPager->jfd);
|
| + }else if( pPager->journalMode==PAGER_JOURNALMODE_TRUNCATE ){
|
| + if( pPager->journalOff==0 ){
|
| + rc = SQLITE_OK;
|
| + }else{
|
| + rc = sqlite3OsTruncate(pPager->jfd, 0);
|
| + }
|
| + pPager->journalOff = 0;
|
| + }else if( pPager->journalMode==PAGER_JOURNALMODE_PERSIST
|
| + || (pPager->exclusiveMode && pPager->journalMode!=PAGER_JOURNALMODE_WAL)
|
| + ){
|
| + rc = zeroJournalHdr(pPager, hasMaster);
|
| + pPager->journalOff = 0;
|
| + }else{
|
| + /* This branch may be executed with Pager.journalMode==MEMORY if
|
| + ** a hot-journal was just rolled back. In this case the journal
|
| + ** file should be closed and deleted. If this connection writes to
|
| + ** the database file, it will do so using an in-memory journal.
|
| + */
|
| + assert( pPager->journalMode==PAGER_JOURNALMODE_DELETE
|
| + || pPager->journalMode==PAGER_JOURNALMODE_MEMORY
|
| + || pPager->journalMode==PAGER_JOURNALMODE_WAL
|
| + );
|
| + sqlite3OsClose(pPager->jfd);
|
| + if( !pPager->tempFile ){
|
| + rc = sqlite3OsDelete(pPager->pVfs, pPager->zJournal, 0);
|
| + }
|
| + }
|
| + }
|
| +
|
| +#ifdef SQLITE_CHECK_PAGES
|
| + sqlite3PcacheIterateDirty(pPager->pPCache, pager_set_pagehash);
|
| + if( pPager->dbSize==0 && sqlite3PcacheRefCount(pPager->pPCache)>0 ){
|
| + PgHdr *p = pager_lookup(pPager, 1);
|
| + if( p ){
|
| + p->pageHash = 0;
|
| + sqlite3PagerUnref(p);
|
| + }
|
| + }
|
| +#endif
|
| +
|
| + sqlite3BitvecDestroy(pPager->pInJournal);
|
| + pPager->pInJournal = 0;
|
| + pPager->nRec = 0;
|
| + sqlite3PcacheCleanAll(pPager->pPCache);
|
| + sqlite3PcacheTruncate(pPager->pPCache, pPager->dbSize);
|
| +
|
| + if( pagerUseWal(pPager) ){
|
| + /* Drop the WAL write-lock, if any. Also, if the connection was in
|
| + ** locking_mode=exclusive mode but is no longer, drop the EXCLUSIVE
|
| + ** lock held on the database file.
|
| + */
|
| + rc2 = sqlite3WalEndWriteTransaction(pPager->pWal);
|
| + assert( rc2==SQLITE_OK );
|
| + }
|
| + if( !pPager->exclusiveMode
|
| + && (!pagerUseWal(pPager) || sqlite3WalExclusiveMode(pPager->pWal, 0))
|
| + ){
|
| + rc2 = pagerUnlockDb(pPager, SHARED_LOCK);
|
| + pPager->changeCountDone = 0;
|
| + }
|
| + pPager->eState = PAGER_READER;
|
| + pPager->setMaster = 0;
|
| +
|
| + return (rc==SQLITE_OK?rc2:rc);
|
| +}
|
| +
|
| +/*
|
| +** Execute a rollback if a transaction is active and unlock the
|
| +** database file.
|
| +**
|
| +** If the pager has already entered the ERROR state, do not attempt
|
| +** the rollback at this time. Instead, pager_unlock() is called. The
|
| +** call to pager_unlock() will discard all in-memory pages, unlock
|
| +** the database file and move the pager back to OPEN state. If this
|
| +** means that there is a hot-journal left in the file-system, the next
|
| +** connection to obtain a shared lock on the pager (which may be this one)
|
| +** will roll it back.
|
| +**
|
| +** If the pager has not already entered the ERROR state, but an IO or
|
| +** malloc error occurs during a rollback, then this will itself cause
|
| +** the pager to enter the ERROR state. Which will be cleared by the
|
| +** call to pager_unlock(), as described above.
|
| +*/
|
| +static void pagerUnlockAndRollback(Pager *pPager){
|
| + if( pPager->eState!=PAGER_ERROR && pPager->eState!=PAGER_OPEN ){
|
| + assert( assert_pager_state(pPager) );
|
| + if( pPager->eState>=PAGER_WRITER_LOCKED ){
|
| + sqlite3BeginBenignMalloc();
|
| + sqlite3PagerRollback(pPager);
|
| + sqlite3EndBenignMalloc();
|
| + }else if( !pPager->exclusiveMode ){
|
| + assert( pPager->eState==PAGER_READER );
|
| + pager_end_transaction(pPager, 0);
|
| + }
|
| + }
|
| + pager_unlock(pPager);
|
| +}
|
| +
|
| +/*
|
| +** Parameter aData must point to a buffer of pPager->pageSize bytes
|
| +** of data. Compute and return a checksum based ont the contents of the
|
| +** page of data and the current value of pPager->cksumInit.
|
| +**
|
| +** This is not a real checksum. It is really just the sum of the
|
| +** random initial value (pPager->cksumInit) and every 200th byte
|
| +** of the page data, starting with byte offset (pPager->pageSize%200).
|
| +** Each byte is interpreted as an 8-bit unsigned integer.
|
| +**
|
| +** Changing the formula used to compute this checksum results in an
|
| +** incompatible journal file format.
|
| +**
|
| +** If journal corruption occurs due to a power failure, the most likely
|
| +** scenario is that one end or the other of the record will be changed.
|
| +** It is much less likely that the two ends of the journal record will be
|
| +** correct and the middle be corrupt. Thus, this "checksum" scheme,
|
| +** though fast and simple, catches the mostly likely kind of corruption.
|
| +*/
|
| +static u32 pager_cksum(Pager *pPager, const u8 *aData){
|
| + u32 cksum = pPager->cksumInit; /* Checksum value to return */
|
| + int i = pPager->pageSize-200; /* Loop counter */
|
| + while( i>0 ){
|
| + cksum += aData[i];
|
| + i -= 200;
|
| + }
|
| + return cksum;
|
| +}
|
| +
|
| +/*
|
| +** Report the current page size and number of reserved bytes back
|
| +** to the codec.
|
| +*/
|
| +#ifdef SQLITE_HAS_CODEC
|
| +static void pagerReportSize(Pager *pPager){
|
| + if( pPager->xCodecSizeChng ){
|
| + pPager->xCodecSizeChng(pPager->pCodec, pPager->pageSize,
|
| + (int)pPager->nReserve);
|
| + }
|
| +}
|
| +#else
|
| +# define pagerReportSize(X) /* No-op if we do not support a codec */
|
| +#endif
|
| +
|
| +/*
|
| +** Read a single page from either the journal file (if isMainJrnl==1) or
|
| +** from the sub-journal (if isMainJrnl==0) and playback that page.
|
| +** The page begins at offset *pOffset into the file. The *pOffset
|
| +** value is increased to the start of the next page in the journal.
|
| +**
|
| +** The main rollback journal uses checksums - the statement journal does
|
| +** not.
|
| +**
|
| +** If the page number of the page record read from the (sub-)journal file
|
| +** is greater than the current value of Pager.dbSize, then playback is
|
| +** skipped and SQLITE_OK is returned.
|
| +**
|
| +** If pDone is not NULL, then it is a record of pages that have already
|
| +** been played back. If the page at *pOffset has already been played back
|
| +** (if the corresponding pDone bit is set) then skip the playback.
|
| +** Make sure the pDone bit corresponding to the *pOffset page is set
|
| +** prior to returning.
|
| +**
|
| +** If the page record is successfully read from the (sub-)journal file
|
| +** and played back, then SQLITE_OK is returned. If an IO error occurs
|
| +** while reading the record from the (sub-)journal file or while writing
|
| +** to the database file, then the IO error code is returned. If data
|
| +** is successfully read from the (sub-)journal file but appears to be
|
| +** corrupted, SQLITE_DONE is returned. Data is considered corrupted in
|
| +** two circumstances:
|
| +**
|
| +** * If the record page-number is illegal (0 or PAGER_MJ_PGNO), or
|
| +** * If the record is being rolled back from the main journal file
|
| +** and the checksum field does not match the record content.
|
| +**
|
| +** Neither of these two scenarios are possible during a savepoint rollback.
|
| +**
|
| +** If this is a savepoint rollback, then memory may have to be dynamically
|
| +** allocated by this function. If this is the case and an allocation fails,
|
| +** SQLITE_NOMEM is returned.
|
| +*/
|
| +static int pager_playback_one_page(
|
| + Pager *pPager, /* The pager being played back */
|
| + i64 *pOffset, /* Offset of record to playback */
|
| + Bitvec *pDone, /* Bitvec of pages already played back */
|
| + int isMainJrnl, /* 1 -> main journal. 0 -> sub-journal. */
|
| + int isSavepnt /* True for a savepoint rollback */
|
| +){
|
| + int rc;
|
| + PgHdr *pPg; /* An existing page in the cache */
|
| + Pgno pgno; /* The page number of a page in journal */
|
| + u32 cksum; /* Checksum used for sanity checking */
|
| + char *aData; /* Temporary storage for the page */
|
| + sqlite3_file *jfd; /* The file descriptor for the journal file */
|
| + int isSynced; /* True if journal page is synced */
|
| +
|
| + assert( (isMainJrnl&~1)==0 ); /* isMainJrnl is 0 or 1 */
|
| + assert( (isSavepnt&~1)==0 ); /* isSavepnt is 0 or 1 */
|
| + assert( isMainJrnl || pDone ); /* pDone always used on sub-journals */
|
| + assert( isSavepnt || pDone==0 ); /* pDone never used on non-savepoint */
|
| +
|
| + aData = pPager->pTmpSpace;
|
| + assert( aData ); /* Temp storage must have already been allocated */
|
| + assert( pagerUseWal(pPager)==0 || (!isMainJrnl && isSavepnt) );
|
| +
|
| + /* Either the state is greater than PAGER_WRITER_CACHEMOD (a transaction
|
| + ** or savepoint rollback done at the request of the caller) or this is
|
| + ** a hot-journal rollback. If it is a hot-journal rollback, the pager
|
| + ** is in state OPEN and holds an EXCLUSIVE lock. Hot-journal rollback
|
| + ** only reads from the main journal, not the sub-journal.
|
| + */
|
| + assert( pPager->eState>=PAGER_WRITER_CACHEMOD
|
| + || (pPager->eState==PAGER_OPEN && pPager->eLock==EXCLUSIVE_LOCK)
|
| + );
|
| + assert( pPager->eState>=PAGER_WRITER_CACHEMOD || isMainJrnl );
|
| +
|
| + /* Read the page number and page data from the journal or sub-journal
|
| + ** file. Return an error code to the caller if an IO error occurs.
|
| + */
|
| + jfd = isMainJrnl ? pPager->jfd : pPager->sjfd;
|
| + rc = read32bits(jfd, *pOffset, &pgno);
|
| + if( rc!=SQLITE_OK ) return rc;
|
| + rc = sqlite3OsRead(jfd, (u8*)aData, pPager->pageSize, (*pOffset)+4);
|
| + if( rc!=SQLITE_OK ) return rc;
|
| + *pOffset += pPager->pageSize + 4 + isMainJrnl*4;
|
| +
|
| + /* Sanity checking on the page. This is more important that I originally
|
| + ** thought. If a power failure occurs while the journal is being written,
|
| + ** it could cause invalid data to be written into the journal. We need to
|
| + ** detect this invalid data (with high probability) and ignore it.
|
| + */
|
| + if( pgno==0 || pgno==PAGER_MJ_PGNO(pPager) ){
|
| + assert( !isSavepnt );
|
| + return SQLITE_DONE;
|
| + }
|
| + if( pgno>(Pgno)pPager->dbSize || sqlite3BitvecTest(pDone, pgno) ){
|
| + return SQLITE_OK;
|
| + }
|
| + if( isMainJrnl ){
|
| + rc = read32bits(jfd, (*pOffset)-4, &cksum);
|
| + if( rc ) return rc;
|
| + if( !isSavepnt && pager_cksum(pPager, (u8*)aData)!=cksum ){
|
| + return SQLITE_DONE;
|
| + }
|
| + }
|
| +
|
| + /* If this page has already been played by before during the current
|
| + ** rollback, then don't bother to play it back again.
|
| + */
|
| + if( pDone && (rc = sqlite3BitvecSet(pDone, pgno))!=SQLITE_OK ){
|
| + return rc;
|
| + }
|
| +
|
| + /* When playing back page 1, restore the nReserve setting
|
| + */
|
| + if( pgno==1 && pPager->nReserve!=((u8*)aData)[20] ){
|
| + pPager->nReserve = ((u8*)aData)[20];
|
| + pagerReportSize(pPager);
|
| + }
|
| +
|
| + /* If the pager is in CACHEMOD state, then there must be a copy of this
|
| + ** page in the pager cache. In this case just update the pager cache,
|
| + ** not the database file. The page is left marked dirty in this case.
|
| + **
|
| + ** An exception to the above rule: If the database is in no-sync mode
|
| + ** and a page is moved during an incremental vacuum then the page may
|
| + ** not be in the pager cache. Later: if a malloc() or IO error occurs
|
| + ** during a Movepage() call, then the page may not be in the cache
|
| + ** either. So the condition described in the above paragraph is not
|
| + ** assert()able.
|
| + **
|
| + ** If in WRITER_DBMOD, WRITER_FINISHED or OPEN state, then we update the
|
| + ** pager cache if it exists and the main file. The page is then marked
|
| + ** not dirty. Since this code is only executed in PAGER_OPEN state for
|
| + ** a hot-journal rollback, it is guaranteed that the page-cache is empty
|
| + ** if the pager is in OPEN state.
|
| + **
|
| + ** Ticket #1171: The statement journal might contain page content that is
|
| + ** different from the page content at the start of the transaction.
|
| + ** This occurs when a page is changed prior to the start of a statement
|
| + ** then changed again within the statement. When rolling back such a
|
| + ** statement we must not write to the original database unless we know
|
| + ** for certain that original page contents are synced into the main rollback
|
| + ** journal. Otherwise, a power loss might leave modified data in the
|
| + ** database file without an entry in the rollback journal that can
|
| + ** restore the database to its original form. Two conditions must be
|
| + ** met before writing to the database files. (1) the database must be
|
| + ** locked. (2) we know that the original page content is fully synced
|
| + ** in the main journal either because the page is not in cache or else
|
| + ** the page is marked as needSync==0.
|
| + **
|
| + ** 2008-04-14: When attempting to vacuum a corrupt database file, it
|
| + ** is possible to fail a statement on a database that does not yet exist.
|
| + ** Do not attempt to write if database file has never been opened.
|
| + */
|
| + if( pagerUseWal(pPager) ){
|
| + pPg = 0;
|
| + }else{
|
| + pPg = pager_lookup(pPager, pgno);
|
| + }
|
| + assert( pPg || !MEMDB );
|
| + assert( pPager->eState!=PAGER_OPEN || pPg==0 );
|
| + PAGERTRACE(("PLAYBACK %d page %d hash(%08x) %s\n",
|
| + PAGERID(pPager), pgno, pager_datahash(pPager->pageSize, (u8*)aData),
|
| + (isMainJrnl?"main-journal":"sub-journal")
|
| + ));
|
| + if( isMainJrnl ){
|
| + isSynced = pPager->noSync || (*pOffset <= pPager->journalHdr);
|
| + }else{
|
| + isSynced = (pPg==0 || 0==(pPg->flags & PGHDR_NEED_SYNC));
|
| + }
|
| + if( isOpen(pPager->fd)
|
| + && (pPager->eState>=PAGER_WRITER_DBMOD || pPager->eState==PAGER_OPEN)
|
| + && isSynced
|
| + ){
|
| + i64 ofst = (pgno-1)*(i64)pPager->pageSize;
|
| + testcase( !isSavepnt && pPg!=0 && (pPg->flags&PGHDR_NEED_SYNC)!=0 );
|
| + assert( !pagerUseWal(pPager) );
|
| + rc = sqlite3OsWrite(pPager->fd, (u8*)aData, pPager->pageSize, ofst);
|
| + if( pgno>pPager->dbFileSize ){
|
| + pPager->dbFileSize = pgno;
|
| + }
|
| + if( pPager->pBackup ){
|
| + CODEC1(pPager, aData, pgno, 3, rc=SQLITE_NOMEM);
|
| + sqlite3BackupUpdate(pPager->pBackup, pgno, (u8*)aData);
|
| + CODEC2(pPager, aData, pgno, 7, rc=SQLITE_NOMEM, aData);
|
| + }
|
| + }else if( !isMainJrnl && pPg==0 ){
|
| + /* If this is a rollback of a savepoint and data was not written to
|
| + ** the database and the page is not in-memory, there is a potential
|
| + ** problem. When the page is next fetched by the b-tree layer, it
|
| + ** will be read from the database file, which may or may not be
|
| + ** current.
|
| + **
|
| + ** There are a couple of different ways this can happen. All are quite
|
| + ** obscure. When running in synchronous mode, this can only happen
|
| + ** if the page is on the free-list at the start of the transaction, then
|
| + ** populated, then moved using sqlite3PagerMovepage().
|
| + **
|
| + ** The solution is to add an in-memory page to the cache containing
|
| + ** the data just read from the sub-journal. Mark the page as dirty
|
| + ** and if the pager requires a journal-sync, then mark the page as
|
| + ** requiring a journal-sync before it is written.
|
| + */
|
| + assert( isSavepnt );
|
| + assert( pPager->doNotSpill==0 );
|
| + pPager->doNotSpill++;
|
| + rc = sqlite3PagerAcquire(pPager, pgno, &pPg, 1);
|
| + assert( pPager->doNotSpill==1 );
|
| + pPager->doNotSpill--;
|
| + if( rc!=SQLITE_OK ) return rc;
|
| + pPg->flags &= ~PGHDR_NEED_READ;
|
| + sqlite3PcacheMakeDirty(pPg);
|
| + }
|
| + if( pPg ){
|
| + /* No page should ever be explicitly rolled back that is in use, except
|
| + ** for page 1 which is held in use in order to keep the lock on the
|
| + ** database active. However such a page may be rolled back as a result
|
| + ** of an internal error resulting in an automatic call to
|
| + ** sqlite3PagerRollback().
|
| + */
|
| + void *pData;
|
| + pData = pPg->pData;
|
| + memcpy(pData, (u8*)aData, pPager->pageSize);
|
| + pPager->xReiniter(pPg);
|
| + if( isMainJrnl && (!isSavepnt || *pOffset<=pPager->journalHdr) ){
|
| + /* If the contents of this page were just restored from the main
|
| + ** journal file, then its content must be as they were when the
|
| + ** transaction was first opened. In this case we can mark the page
|
| + ** as clean, since there will be no need to write it out to the
|
| + ** database.
|
| + **
|
| + ** There is one exception to this rule. If the page is being rolled
|
| + ** back as part of a savepoint (or statement) rollback from an
|
| + ** unsynced portion of the main journal file, then it is not safe
|
| + ** to mark the page as clean. This is because marking the page as
|
| + ** clean will clear the PGHDR_NEED_SYNC flag. Since the page is
|
| + ** already in the journal file (recorded in Pager.pInJournal) and
|
| + ** the PGHDR_NEED_SYNC flag is cleared, if the page is written to
|
| + ** again within this transaction, it will be marked as dirty but
|
| + ** the PGHDR_NEED_SYNC flag will not be set. It could then potentially
|
| + ** be written out into the database file before its journal file
|
| + ** segment is synced. If a crash occurs during or following this,
|
| + ** database corruption may ensue.
|
| + */
|
| + assert( !pagerUseWal(pPager) );
|
| + sqlite3PcacheMakeClean(pPg);
|
| + }
|
| + pager_set_pagehash(pPg);
|
| +
|
| + /* If this was page 1, then restore the value of Pager.dbFileVers.
|
| + ** Do this before any decoding. */
|
| + if( pgno==1 ){
|
| + memcpy(&pPager->dbFileVers, &((u8*)pData)[24],sizeof(pPager->dbFileVers));
|
| + }
|
| +
|
| + /* Decode the page just read from disk */
|
| + CODEC1(pPager, pData, pPg->pgno, 3, rc=SQLITE_NOMEM);
|
| + sqlite3PcacheRelease(pPg);
|
| + }
|
| + return rc;
|
| +}
|
| +
|
| +/*
|
| +** Parameter zMaster is the name of a master journal file. A single journal
|
| +** file that referred to the master journal file has just been rolled back.
|
| +** This routine checks if it is possible to delete the master journal file,
|
| +** and does so if it is.
|
| +**
|
| +** Argument zMaster may point to Pager.pTmpSpace. So that buffer is not
|
| +** available for use within this function.
|
| +**
|
| +** When a master journal file is created, it is populated with the names
|
| +** of all of its child journals, one after another, formatted as utf-8
|
| +** encoded text. The end of each child journal file is marked with a
|
| +** nul-terminator byte (0x00). i.e. the entire contents of a master journal
|
| +** file for a transaction involving two databases might be:
|
| +**
|
| +** "/home/bill/a.db-journal\x00/home/bill/b.db-journal\x00"
|
| +**
|
| +** A master journal file may only be deleted once all of its child
|
| +** journals have been rolled back.
|
| +**
|
| +** This function reads the contents of the master-journal file into
|
| +** memory and loops through each of the child journal names. For
|
| +** each child journal, it checks if:
|
| +**
|
| +** * if the child journal exists, and if so
|
| +** * if the child journal contains a reference to master journal
|
| +** file zMaster
|
| +**
|
| +** If a child journal can be found that matches both of the criteria
|
| +** above, this function returns without doing anything. Otherwise, if
|
| +** no such child journal can be found, file zMaster is deleted from
|
| +** the file-system using sqlite3OsDelete().
|
| +**
|
| +** If an IO error within this function, an error code is returned. This
|
| +** function allocates memory by calling sqlite3Malloc(). If an allocation
|
| +** fails, SQLITE_NOMEM is returned. Otherwise, if no IO or malloc errors
|
| +** occur, SQLITE_OK is returned.
|
| +**
|
| +** TODO: This function allocates a single block of memory to load
|
| +** the entire contents of the master journal file. This could be
|
| +** a couple of kilobytes or so - potentially larger than the page
|
| +** size.
|
| +*/
|
| +static int pager_delmaster(Pager *pPager, const char *zMaster){
|
| + sqlite3_vfs *pVfs = pPager->pVfs;
|
| + int rc; /* Return code */
|
| + sqlite3_file *pMaster; /* Malloc'd master-journal file descriptor */
|
| + sqlite3_file *pJournal; /* Malloc'd child-journal file descriptor */
|
| + char *zMasterJournal = 0; /* Contents of master journal file */
|
| + i64 nMasterJournal; /* Size of master journal file */
|
| + char *zJournal; /* Pointer to one journal within MJ file */
|
| + char *zMasterPtr; /* Space to hold MJ filename from a journal file */
|
| + int nMasterPtr; /* Amount of space allocated to zMasterPtr[] */
|
| +
|
| + /* Allocate space for both the pJournal and pMaster file descriptors.
|
| + ** If successful, open the master journal file for reading.
|
| + */
|
| + pMaster = (sqlite3_file *)sqlite3MallocZero(pVfs->szOsFile * 2);
|
| + pJournal = (sqlite3_file *)(((u8 *)pMaster) + pVfs->szOsFile);
|
| + if( !pMaster ){
|
| + rc = SQLITE_NOMEM;
|
| + }else{
|
| + const int flags = (SQLITE_OPEN_READONLY|SQLITE_OPEN_MASTER_JOURNAL);
|
| + rc = sqlite3OsOpen(pVfs, zMaster, pMaster, flags, 0);
|
| + }
|
| + if( rc!=SQLITE_OK ) goto delmaster_out;
|
| +
|
| + /* Load the entire master journal file into space obtained from
|
| + ** sqlite3_malloc() and pointed to by zMasterJournal. Also obtain
|
| + ** sufficient space (in zMasterPtr) to hold the names of master
|
| + ** journal files extracted from regular rollback-journals.
|
| + */
|
| + rc = sqlite3OsFileSize(pMaster, &nMasterJournal);
|
| + if( rc!=SQLITE_OK ) goto delmaster_out;
|
| + nMasterPtr = pVfs->mxPathname+1;
|
| + zMasterJournal = sqlite3Malloc((int)nMasterJournal + nMasterPtr + 1);
|
| + if( !zMasterJournal ){
|
| + rc = SQLITE_NOMEM;
|
| + goto delmaster_out;
|
| + }
|
| + zMasterPtr = &zMasterJournal[nMasterJournal+1];
|
| + rc = sqlite3OsRead(pMaster, zMasterJournal, (int)nMasterJournal, 0);
|
| + if( rc!=SQLITE_OK ) goto delmaster_out;
|
| + zMasterJournal[nMasterJournal] = 0;
|
| +
|
| + zJournal = zMasterJournal;
|
| + while( (zJournal-zMasterJournal)<nMasterJournal ){
|
| + int exists;
|
| + rc = sqlite3OsAccess(pVfs, zJournal, SQLITE_ACCESS_EXISTS, &exists);
|
| + if( rc!=SQLITE_OK ){
|
| + goto delmaster_out;
|
| + }
|
| + if( exists ){
|
| + /* One of the journals pointed to by the master journal exists.
|
| + ** Open it and check if it points at the master journal. If
|
| + ** so, return without deleting the master journal file.
|
| + */
|
| + int c;
|
| + int flags = (SQLITE_OPEN_READONLY|SQLITE_OPEN_MAIN_JOURNAL);
|
| + rc = sqlite3OsOpen(pVfs, zJournal, pJournal, flags, 0);
|
| + if( rc!=SQLITE_OK ){
|
| + goto delmaster_out;
|
| + }
|
| +
|
| + rc = readMasterJournal(pJournal, zMasterPtr, nMasterPtr);
|
| + sqlite3OsClose(pJournal);
|
| + if( rc!=SQLITE_OK ){
|
| + goto delmaster_out;
|
| + }
|
| +
|
| + c = zMasterPtr[0]!=0 && strcmp(zMasterPtr, zMaster)==0;
|
| + if( c ){
|
| + /* We have a match. Do not delete the master journal file. */
|
| + goto delmaster_out;
|
| + }
|
| + }
|
| + zJournal += (sqlite3Strlen30(zJournal)+1);
|
| + }
|
| +
|
| + sqlite3OsClose(pMaster);
|
| + rc = sqlite3OsDelete(pVfs, zMaster, 0);
|
| +
|
| +delmaster_out:
|
| + sqlite3_free(zMasterJournal);
|
| + if( pMaster ){
|
| + sqlite3OsClose(pMaster);
|
| + assert( !isOpen(pJournal) );
|
| + sqlite3_free(pMaster);
|
| + }
|
| + return rc;
|
| +}
|
| +
|
| +
|
| +/*
|
| +** This function is used to change the actual size of the database
|
| +** file in the file-system. This only happens when committing a transaction,
|
| +** or rolling back a transaction (including rolling back a hot-journal).
|
| +**
|
| +** If the main database file is not open, or the pager is not in either
|
| +** DBMOD or OPEN state, this function is a no-op. Otherwise, the size
|
| +** of the file is changed to nPage pages (nPage*pPager->pageSize bytes).
|
| +** If the file on disk is currently larger than nPage pages, then use the VFS
|
| +** xTruncate() method to truncate it.
|
| +**
|
| +** Or, it might might be the case that the file on disk is smaller than
|
| +** nPage pages. Some operating system implementations can get confused if
|
| +** you try to truncate a file to some size that is larger than it
|
| +** currently is, so detect this case and write a single zero byte to
|
| +** the end of the new file instead.
|
| +**
|
| +** If successful, return SQLITE_OK. If an IO error occurs while modifying
|
| +** the database file, return the error code to the caller.
|
| +*/
|
| +static int pager_truncate(Pager *pPager, Pgno nPage){
|
| + int rc = SQLITE_OK;
|
| + assert( pPager->eState!=PAGER_ERROR );
|
| + assert( pPager->eState!=PAGER_READER );
|
| +
|
| + if( isOpen(pPager->fd)
|
| + && (pPager->eState>=PAGER_WRITER_DBMOD || pPager->eState==PAGER_OPEN)
|
| + ){
|
| + i64 currentSize, newSize;
|
| + int szPage = pPager->pageSize;
|
| + assert( pPager->eLock==EXCLUSIVE_LOCK );
|
| + /* TODO: Is it safe to use Pager.dbFileSize here? */
|
| + rc = sqlite3OsFileSize(pPager->fd, ¤tSize);
|
| + newSize = szPage*(i64)nPage;
|
| + if( rc==SQLITE_OK && currentSize!=newSize ){
|
| + if( currentSize>newSize ){
|
| + rc = sqlite3OsTruncate(pPager->fd, newSize);
|
| + }else{
|
| + char *pTmp = pPager->pTmpSpace;
|
| + memset(pTmp, 0, szPage);
|
| + testcase( (newSize-szPage) < currentSize );
|
| + testcase( (newSize-szPage) == currentSize );
|
| + testcase( (newSize-szPage) > currentSize );
|
| + rc = sqlite3OsWrite(pPager->fd, pTmp, szPage, newSize-szPage);
|
| + }
|
| + if( rc==SQLITE_OK ){
|
| + pPager->dbFileSize = nPage;
|
| + }
|
| + }
|
| + }
|
| + return rc;
|
| +}
|
| +
|
| +/*
|
| +** Set the value of the Pager.sectorSize variable for the given
|
| +** pager based on the value returned by the xSectorSize method
|
| +** of the open database file. The sector size will be used used
|
| +** to determine the size and alignment of journal header and
|
| +** master journal pointers within created journal files.
|
| +**
|
| +** For temporary files the effective sector size is always 512 bytes.
|
| +**
|
| +** Otherwise, for non-temporary files, the effective sector size is
|
| +** the value returned by the xSectorSize() method rounded up to 32 if
|
| +** it is less than 32, or rounded down to MAX_SECTOR_SIZE if it
|
| +** is greater than MAX_SECTOR_SIZE.
|
| +*/
|
| +static void setSectorSize(Pager *pPager){
|
| + assert( isOpen(pPager->fd) || pPager->tempFile );
|
| +
|
| + if( !pPager->tempFile ){
|
| + /* Sector size doesn't matter for temporary files. Also, the file
|
| + ** may not have been opened yet, in which case the OsSectorSize()
|
| + ** call will segfault.
|
| + */
|
| + pPager->sectorSize = sqlite3OsSectorSize(pPager->fd);
|
| + }
|
| + if( pPager->sectorSize<32 ){
|
| + pPager->sectorSize = 512;
|
| + }
|
| + if( pPager->sectorSize>MAX_SECTOR_SIZE ){
|
| + assert( MAX_SECTOR_SIZE>=512 );
|
| + pPager->sectorSize = MAX_SECTOR_SIZE;
|
| + }
|
| +}
|
| +
|
| +/*
|
| +** Playback the journal and thus restore the database file to
|
| +** the state it was in before we started making changes.
|
| +**
|
| +** The journal file format is as follows:
|
| +**
|
| +** (1) 8 byte prefix. A copy of aJournalMagic[].
|
| +** (2) 4 byte big-endian integer which is the number of valid page records
|
| +** in the journal. If this value is 0xffffffff, then compute the
|
| +** number of page records from the journal size.
|
| +** (3) 4 byte big-endian integer which is the initial value for the
|
| +** sanity checksum.
|
| +** (4) 4 byte integer which is the number of pages to truncate the
|
| +** database to during a rollback.
|
| +** (5) 4 byte big-endian integer which is the sector size. The header
|
| +** is this many bytes in size.
|
| +** (6) 4 byte big-endian integer which is the page size.
|
| +** (7) zero padding out to the next sector size.
|
| +** (8) Zero or more pages instances, each as follows:
|
| +** + 4 byte page number.
|
| +** + pPager->pageSize bytes of data.
|
| +** + 4 byte checksum
|
| +**
|
| +** When we speak of the journal header, we mean the first 7 items above.
|
| +** Each entry in the journal is an instance of the 8th item.
|
| +**
|
| +** Call the value from the second bullet "nRec". nRec is the number of
|
| +** valid page entries in the journal. In most cases, you can compute the
|
| +** value of nRec from the size of the journal file. But if a power
|
| +** failure occurred while the journal was being written, it could be the
|
| +** case that the size of the journal file had already been increased but
|
| +** the extra entries had not yet made it safely to disk. In such a case,
|
| +** the value of nRec computed from the file size would be too large. For
|
| +** that reason, we always use the nRec value in the header.
|
| +**
|
| +** If the nRec value is 0xffffffff it means that nRec should be computed
|
| +** from the file size. This value is used when the user selects the
|
| +** no-sync option for the journal. A power failure could lead to corruption
|
| +** in this case. But for things like temporary table (which will be
|
| +** deleted when the power is restored) we don't care.
|
| +**
|
| +** If the file opened as the journal file is not a well-formed
|
| +** journal file then all pages up to the first corrupted page are rolled
|
| +** back (or no pages if the journal header is corrupted). The journal file
|
| +** is then deleted and SQLITE_OK returned, just as if no corruption had
|
| +** been encountered.
|
| +**
|
| +** If an I/O or malloc() error occurs, the journal-file is not deleted
|
| +** and an error code is returned.
|
| +**
|
| +** The isHot parameter indicates that we are trying to rollback a journal
|
| +** that might be a hot journal. Or, it could be that the journal is
|
| +** preserved because of JOURNALMODE_PERSIST or JOURNALMODE_TRUNCATE.
|
| +** If the journal really is hot, reset the pager cache prior rolling
|
| +** back any content. If the journal is merely persistent, no reset is
|
| +** needed.
|
| +*/
|
| +static int pager_playback(Pager *pPager, int isHot){
|
| + sqlite3_vfs *pVfs = pPager->pVfs;
|
| + i64 szJ; /* Size of the journal file in bytes */
|
| + u32 nRec; /* Number of Records in the journal */
|
| + u32 u; /* Unsigned loop counter */
|
| + Pgno mxPg = 0; /* Size of the original file in pages */
|
| + int rc; /* Result code of a subroutine */
|
| + int res = 1; /* Value returned by sqlite3OsAccess() */
|
| + char *zMaster = 0; /* Name of master journal file if any */
|
| + int needPagerReset; /* True to reset page prior to first page rollback */
|
| +
|
| + /* Figure out how many records are in the journal. Abort early if
|
| + ** the journal is empty.
|
| + */
|
| + assert( isOpen(pPager->jfd) );
|
| + rc = sqlite3OsFileSize(pPager->jfd, &szJ);
|
| + if( rc!=SQLITE_OK ){
|
| + goto end_playback;
|
| + }
|
| +
|
| + /* Read the master journal name from the journal, if it is present.
|
| + ** If a master journal file name is specified, but the file is not
|
| + ** present on disk, then the journal is not hot and does not need to be
|
| + ** played back.
|
| + **
|
| + ** TODO: Technically the following is an error because it assumes that
|
| + ** buffer Pager.pTmpSpace is (mxPathname+1) bytes or larger. i.e. that
|
| + ** (pPager->pageSize >= pPager->pVfs->mxPathname+1). Using os_unix.c,
|
| + ** mxPathname is 512, which is the same as the minimum allowable value
|
| + ** for pageSize.
|
| + */
|
| + zMaster = pPager->pTmpSpace;
|
| + rc = readMasterJournal(pPager->jfd, zMaster, pPager->pVfs->mxPathname+1);
|
| + if( rc==SQLITE_OK && zMaster[0] ){
|
| + rc = sqlite3OsAccess(pVfs, zMaster, SQLITE_ACCESS_EXISTS, &res);
|
| + }
|
| + zMaster = 0;
|
| + if( rc!=SQLITE_OK || !res ){
|
| + goto end_playback;
|
| + }
|
| + pPager->journalOff = 0;
|
| + needPagerReset = isHot;
|
| +
|
| + /* This loop terminates either when a readJournalHdr() or
|
| + ** pager_playback_one_page() call returns SQLITE_DONE or an IO error
|
| + ** occurs.
|
| + */
|
| + while( 1 ){
|
| + /* Read the next journal header from the journal file. If there are
|
| + ** not enough bytes left in the journal file for a complete header, or
|
| + ** it is corrupted, then a process must have failed while writing it.
|
| + ** This indicates nothing more needs to be rolled back.
|
| + */
|
| + rc = readJournalHdr(pPager, isHot, szJ, &nRec, &mxPg);
|
| + if( rc!=SQLITE_OK ){
|
| + if( rc==SQLITE_DONE ){
|
| + rc = SQLITE_OK;
|
| + }
|
| + goto end_playback;
|
| + }
|
| +
|
| + /* If nRec is 0xffffffff, then this journal was created by a process
|
| + ** working in no-sync mode. This means that the rest of the journal
|
| + ** file consists of pages, there are no more journal headers. Compute
|
| + ** the value of nRec based on this assumption.
|
| + */
|
| + if( nRec==0xffffffff ){
|
| + assert( pPager->journalOff==JOURNAL_HDR_SZ(pPager) );
|
| + nRec = (int)((szJ - JOURNAL_HDR_SZ(pPager))/JOURNAL_PG_SZ(pPager));
|
| + }
|
| +
|
| + /* If nRec is 0 and this rollback is of a transaction created by this
|
| + ** process and if this is the final header in the journal, then it means
|
| + ** that this part of the journal was being filled but has not yet been
|
| + ** synced to disk. Compute the number of pages based on the remaining
|
| + ** size of the file.
|
| + **
|
| + ** The third term of the test was added to fix ticket #2565.
|
| + ** When rolling back a hot journal, nRec==0 always means that the next
|
| + ** chunk of the journal contains zero pages to be rolled back. But
|
| + ** when doing a ROLLBACK and the nRec==0 chunk is the last chunk in
|
| + ** the journal, it means that the journal might contain additional
|
| + ** pages that need to be rolled back and that the number of pages
|
| + ** should be computed based on the journal file size.
|
| + */
|
| + if( nRec==0 && !isHot &&
|
| + pPager->journalHdr+JOURNAL_HDR_SZ(pPager)==pPager->journalOff ){
|
| + nRec = (int)((szJ - pPager->journalOff) / JOURNAL_PG_SZ(pPager));
|
| + }
|
| +
|
| + /* If this is the first header read from the journal, truncate the
|
| + ** database file back to its original size.
|
| + */
|
| + if( pPager->journalOff==JOURNAL_HDR_SZ(pPager) ){
|
| + rc = pager_truncate(pPager, mxPg);
|
| + if( rc!=SQLITE_OK ){
|
| + goto end_playback;
|
| + }
|
| + pPager->dbSize = mxPg;
|
| + }
|
| +
|
| + /* Copy original pages out of the journal and back into the
|
| + ** database file and/or page cache.
|
| + */
|
| + for(u=0; u<nRec; u++){
|
| + if( needPagerReset ){
|
| + pager_reset(pPager);
|
| + needPagerReset = 0;
|
| + }
|
| + rc = pager_playback_one_page(pPager,&pPager->journalOff,0,1,0);
|
| + if( rc!=SQLITE_OK ){
|
| + if( rc==SQLITE_DONE ){
|
| + rc = SQLITE_OK;
|
| + pPager->journalOff = szJ;
|
| + break;
|
| + }else if( rc==SQLITE_IOERR_SHORT_READ ){
|
| + /* If the journal has been truncated, simply stop reading and
|
| + ** processing the journal. This might happen if the journal was
|
| + ** not completely written and synced prior to a crash. In that
|
| + ** case, the database should have never been written in the
|
| + ** first place so it is OK to simply abandon the rollback. */
|
| + rc = SQLITE_OK;
|
| + goto end_playback;
|
| + }else{
|
| + /* If we are unable to rollback, quit and return the error
|
| + ** code. This will cause the pager to enter the error state
|
| + ** so that no further harm will be done. Perhaps the next
|
| + ** process to come along will be able to rollback the database.
|
| + */
|
| + goto end_playback;
|
| + }
|
| + }
|
| + }
|
| + }
|
| + /*NOTREACHED*/
|
| + assert( 0 );
|
| +
|
| +end_playback:
|
| + /* Following a rollback, the database file should be back in its original
|
| + ** state prior to the start of the transaction, so invoke the
|
| + ** SQLITE_FCNTL_DB_UNCHANGED file-control method to disable the
|
| + ** assertion that the transaction counter was modified.
|
| + */
|
| + assert(
|
| + pPager->fd->pMethods==0 ||
|
| + sqlite3OsFileControl(pPager->fd,SQLITE_FCNTL_DB_UNCHANGED,0)>=SQLITE_OK
|
| + );
|
| +
|
| + /* If this playback is happening automatically as a result of an IO or
|
| + ** malloc error that occurred after the change-counter was updated but
|
| + ** before the transaction was committed, then the change-counter
|
| + ** modification may just have been reverted. If this happens in exclusive
|
| + ** mode, then subsequent transactions performed by the connection will not
|
| + ** update the change-counter at all. This may lead to cache inconsistency
|
| + ** problems for other processes at some point in the future. So, just
|
| + ** in case this has happened, clear the changeCountDone flag now.
|
| + */
|
| + pPager->changeCountDone = pPager->tempFile;
|
| +
|
| + if( rc==SQLITE_OK ){
|
| + zMaster = pPager->pTmpSpace;
|
| + rc = readMasterJournal(pPager->jfd, zMaster, pPager->pVfs->mxPathname+1);
|
| + testcase( rc!=SQLITE_OK );
|
| + }
|
| + if( rc==SQLITE_OK
|
| + && (pPager->eState>=PAGER_WRITER_DBMOD || pPager->eState==PAGER_OPEN)
|
| + ){
|
| + rc = sqlite3PagerSync(pPager);
|
| + }
|
| + if( rc==SQLITE_OK ){
|
| + rc = pager_end_transaction(pPager, zMaster[0]!='\0');
|
| + testcase( rc!=SQLITE_OK );
|
| + }
|
| + if( rc==SQLITE_OK && zMaster[0] && res ){
|
| + /* If there was a master journal and this routine will return success,
|
| + ** see if it is possible to delete the master journal.
|
| + */
|
| + rc = pager_delmaster(pPager, zMaster);
|
| + testcase( rc!=SQLITE_OK );
|
| + }
|
| +
|
| + /* The Pager.sectorSize variable may have been updated while rolling
|
| + ** back a journal created by a process with a different sector size
|
| + ** value. Reset it to the correct value for this process.
|
| + */
|
| + setSectorSize(pPager);
|
| + return rc;
|
| +}
|
| +
|
| +
|
| +/*
|
| +** Read the content for page pPg out of the database file and into
|
| +** pPg->pData. A shared lock or greater must be held on the database
|
| +** file before this function is called.
|
| +**
|
| +** If page 1 is read, then the value of Pager.dbFileVers[] is set to
|
| +** the value read from the database file.
|
| +**
|
| +** If an IO error occurs, then the IO error is returned to the caller.
|
| +** Otherwise, SQLITE_OK is returned.
|
| +*/
|
| +static int readDbPage(PgHdr *pPg){
|
| + Pager *pPager = pPg->pPager; /* Pager object associated with page pPg */
|
| + Pgno pgno = pPg->pgno; /* Page number to read */
|
| + int rc = SQLITE_OK; /* Return code */
|
| + int isInWal = 0; /* True if page is in log file */
|
| + int pgsz = pPager->pageSize; /* Number of bytes to read */
|
| +
|
| + assert( pPager->eState>=PAGER_READER && !MEMDB );
|
| + assert( isOpen(pPager->fd) );
|
| +
|
| + if( NEVER(!isOpen(pPager->fd)) ){
|
| + assert( pPager->tempFile );
|
| + memset(pPg->pData, 0, pPager->pageSize);
|
| + return SQLITE_OK;
|
| + }
|
| +
|
| + if( pagerUseWal(pPager) ){
|
| + /* Try to pull the page from the write-ahead log. */
|
| + rc = sqlite3WalRead(pPager->pWal, pgno, &isInWal, pgsz, pPg->pData);
|
| + }
|
| + if( rc==SQLITE_OK && !isInWal ){
|
| + i64 iOffset = (pgno-1)*(i64)pPager->pageSize;
|
| + rc = sqlite3OsRead(pPager->fd, pPg->pData, pgsz, iOffset);
|
| + if( rc==SQLITE_IOERR_SHORT_READ ){
|
| + rc = SQLITE_OK;
|
| + }
|
| + }
|
| +
|
| + if( pgno==1 ){
|
| + if( rc ){
|
| + /* If the read is unsuccessful, set the dbFileVers[] to something
|
| + ** that will never be a valid file version. dbFileVers[] is a copy
|
| + ** of bytes 24..39 of the database. Bytes 28..31 should always be
|
| + ** zero or the size of the database in page. Bytes 32..35 and 35..39
|
| + ** should be page numbers which are never 0xffffffff. So filling
|
| + ** pPager->dbFileVers[] with all 0xff bytes should suffice.
|
| + **
|
| + ** For an encrypted database, the situation is more complex: bytes
|
| + ** 24..39 of the database are white noise. But the probability of
|
| + ** white noising equaling 16 bytes of 0xff is vanishingly small so
|
| + ** we should still be ok.
|
| + */
|
| + memset(pPager->dbFileVers, 0xff, sizeof(pPager->dbFileVers));
|
| + }else{
|
| + u8 *dbFileVers = &((u8*)pPg->pData)[24];
|
| + memcpy(&pPager->dbFileVers, dbFileVers, sizeof(pPager->dbFileVers));
|
| + }
|
| + }
|
| + CODEC1(pPager, pPg->pData, pgno, 3, rc = SQLITE_NOMEM);
|
| +
|
| + PAGER_INCR(sqlite3_pager_readdb_count);
|
| + PAGER_INCR(pPager->nRead);
|
| + IOTRACE(("PGIN %p %d\n", pPager, pgno));
|
| + PAGERTRACE(("FETCH %d page %d hash(%08x)\n",
|
| + PAGERID(pPager), pgno, pager_pagehash(pPg)));
|
| +
|
| + return rc;
|
| +}
|
| +
|
| +/*
|
| +** Update the value of the change-counter at offsets 24 and 92 in
|
| +** the header and the sqlite version number at offset 96.
|
| +**
|
| +** This is an unconditional update. See also the pager_incr_changecounter()
|
| +** routine which only updates the change-counter if the update is actually
|
| +** needed, as determined by the pPager->changeCountDone state variable.
|
| +*/
|
| +static void pager_write_changecounter(PgHdr *pPg){
|
| + u32 change_counter;
|
| +
|
| + /* Increment the value just read and write it back to byte 24. */
|
| + change_counter = sqlite3Get4byte((u8*)pPg->pPager->dbFileVers)+1;
|
| + put32bits(((char*)pPg->pData)+24, change_counter);
|
| +
|
| + /* Also store the SQLite version number in bytes 96..99 and in
|
| + ** bytes 92..95 store the change counter for which the version number
|
| + ** is valid. */
|
| + put32bits(((char*)pPg->pData)+92, change_counter);
|
| + put32bits(((char*)pPg->pData)+96, SQLITE_VERSION_NUMBER);
|
| +}
|
| +
|
| +#ifndef SQLITE_OMIT_WAL
|
| +/*
|
| +** This function is invoked once for each page that has already been
|
| +** written into the log file when a WAL transaction is rolled back.
|
| +** Parameter iPg is the page number of said page. The pCtx argument
|
| +** is actually a pointer to the Pager structure.
|
| +**
|
| +** If page iPg is present in the cache, and has no outstanding references,
|
| +** it is discarded. Otherwise, if there are one or more outstanding
|
| +** references, the page content is reloaded from the database. If the
|
| +** attempt to reload content from the database is required and fails,
|
| +** return an SQLite error code. Otherwise, SQLITE_OK.
|
| +*/
|
| +static int pagerUndoCallback(void *pCtx, Pgno iPg){
|
| + int rc = SQLITE_OK;
|
| + Pager *pPager = (Pager *)pCtx;
|
| + PgHdr *pPg;
|
| +
|
| + pPg = sqlite3PagerLookup(pPager, iPg);
|
| + if( pPg ){
|
| + if( sqlite3PcachePageRefcount(pPg)==1 ){
|
| + sqlite3PcacheDrop(pPg);
|
| + }else{
|
| + rc = readDbPage(pPg);
|
| + if( rc==SQLITE_OK ){
|
| + pPager->xReiniter(pPg);
|
| + }
|
| + sqlite3PagerUnref(pPg);
|
| + }
|
| + }
|
| +
|
| + /* Normally, if a transaction is rolled back, any backup processes are
|
| + ** updated as data is copied out of the rollback journal and into the
|
| + ** database. This is not generally possible with a WAL database, as
|
| + ** rollback involves simply truncating the log file. Therefore, if one
|
| + ** or more frames have already been written to the log (and therefore
|
| + ** also copied into the backup databases) as part of this transaction,
|
| + ** the backups must be restarted.
|
| + */
|
| + sqlite3BackupRestart(pPager->pBackup);
|
| +
|
| + return rc;
|
| +}
|
| +
|
| +/*
|
| +** This function is called to rollback a transaction on a WAL database.
|
| +*/
|
| +static int pagerRollbackWal(Pager *pPager){
|
| + int rc; /* Return Code */
|
| + PgHdr *pList; /* List of dirty pages to revert */
|
| +
|
| + /* For all pages in the cache that are currently dirty or have already
|
| + ** been written (but not committed) to the log file, do one of the
|
| + ** following:
|
| + **
|
| + ** + Discard the cached page (if refcount==0), or
|
| + ** + Reload page content from the database (if refcount>0).
|
| + */
|
| + pPager->dbSize = pPager->dbOrigSize;
|
| + rc = sqlite3WalUndo(pPager->pWal, pagerUndoCallback, (void *)pPager);
|
| + pList = sqlite3PcacheDirtyList(pPager->pPCache);
|
| + while( pList && rc==SQLITE_OK ){
|
| + PgHdr *pNext = pList->pDirty;
|
| + rc = pagerUndoCallback((void *)pPager, pList->pgno);
|
| + pList = pNext;
|
| + }
|
| +
|
| + return rc;
|
| +}
|
| +
|
| +/*
|
| +** This function is a wrapper around sqlite3WalFrames(). As well as logging
|
| +** the contents of the list of pages headed by pList (connected by pDirty),
|
| +** this function notifies any active backup processes that the pages have
|
| +** changed.
|
| +**
|
| +** The list of pages passed into this routine is always sorted by page number.
|
| +** Hence, if page 1 appears anywhere on the list, it will be the first page.
|
| +*/
|
| +static int pagerWalFrames(
|
| + Pager *pPager, /* Pager object */
|
| + PgHdr *pList, /* List of frames to log */
|
| + Pgno nTruncate, /* Database size after this commit */
|
| + int isCommit, /* True if this is a commit */
|
| + int syncFlags /* Flags to pass to OsSync() (or 0) */
|
| +){
|
| + int rc; /* Return code */
|
| +#if defined(SQLITE_DEBUG) || defined(SQLITE_CHECK_PAGES)
|
| + PgHdr *p; /* For looping over pages */
|
| +#endif
|
| +
|
| + assert( pPager->pWal );
|
| +#ifdef SQLITE_DEBUG
|
| + /* Verify that the page list is in accending order */
|
| + for(p=pList; p && p->pDirty; p=p->pDirty){
|
| + assert( p->pgno < p->pDirty->pgno );
|
| + }
|
| +#endif
|
| +
|
| + if( isCommit ){
|
| + /* If a WAL transaction is being committed, there is no point in writing
|
| + ** any pages with page numbers greater than nTruncate into the WAL file.
|
| + ** They will never be read by any client. So remove them from the pDirty
|
| + ** list here. */
|
| + PgHdr *p;
|
| + PgHdr **ppNext = &pList;
|
| + for(p=pList; (*ppNext = p); p=p->pDirty){
|
| + if( p->pgno<=nTruncate ) ppNext = &p->pDirty;
|
| + }
|
| + assert( pList );
|
| + }
|
| +
|
| + if( pList->pgno==1 ) pager_write_changecounter(pList);
|
| + rc = sqlite3WalFrames(pPager->pWal,
|
| + pPager->pageSize, pList, nTruncate, isCommit, syncFlags
|
| + );
|
| + if( rc==SQLITE_OK && pPager->pBackup ){
|
| + PgHdr *p;
|
| + for(p=pList; p; p=p->pDirty){
|
| + sqlite3BackupUpdate(pPager->pBackup, p->pgno, (u8 *)p->pData);
|
| + }
|
| + }
|
| +
|
| +#ifdef SQLITE_CHECK_PAGES
|
| + pList = sqlite3PcacheDirtyList(pPager->pPCache);
|
| + for(p=pList; p; p=p->pDirty){
|
| + pager_set_pagehash(p);
|
| + }
|
| +#endif
|
| +
|
| + return rc;
|
| +}
|
| +
|
| +/*
|
| +** Begin a read transaction on the WAL.
|
| +**
|
| +** This routine used to be called "pagerOpenSnapshot()" because it essentially
|
| +** makes a snapshot of the database at the current point in time and preserves
|
| +** that snapshot for use by the reader in spite of concurrently changes by
|
| +** other writers or checkpointers.
|
| +*/
|
| +static int pagerBeginReadTransaction(Pager *pPager){
|
| + int rc; /* Return code */
|
| + int changed = 0; /* True if cache must be reset */
|
| +
|
| + assert( pagerUseWal(pPager) );
|
| + assert( pPager->eState==PAGER_OPEN || pPager->eState==PAGER_READER );
|
| +
|
| + /* sqlite3WalEndReadTransaction() was not called for the previous
|
| + ** transaction in locking_mode=EXCLUSIVE. So call it now. If we
|
| + ** are in locking_mode=NORMAL and EndRead() was previously called,
|
| + ** the duplicate call is harmless.
|
| + */
|
| + sqlite3WalEndReadTransaction(pPager->pWal);
|
| +
|
| + rc = sqlite3WalBeginReadTransaction(pPager->pWal, &changed);
|
| + if( rc!=SQLITE_OK || changed ){
|
| + pager_reset(pPager);
|
| + }
|
| +
|
| + return rc;
|
| +}
|
| +#endif
|
| +
|
| +/*
|
| +** This function is called as part of the transition from PAGER_OPEN
|
| +** to PAGER_READER state to determine the size of the database file
|
| +** in pages (assuming the page size currently stored in Pager.pageSize).
|
| +**
|
| +** If no error occurs, SQLITE_OK is returned and the size of the database
|
| +** in pages is stored in *pnPage. Otherwise, an error code (perhaps
|
| +** SQLITE_IOERR_FSTAT) is returned and *pnPage is left unmodified.
|
| +*/
|
| +static int pagerPagecount(Pager *pPager, Pgno *pnPage){
|
| + Pgno nPage; /* Value to return via *pnPage */
|
| +
|
| + /* Query the WAL sub-system for the database size. The WalDbsize()
|
| + ** function returns zero if the WAL is not open (i.e. Pager.pWal==0), or
|
| + ** if the database size is not available. The database size is not
|
| + ** available from the WAL sub-system if the log file is empty or
|
| + ** contains no valid committed transactions.
|
| + */
|
| + assert( pPager->eState==PAGER_OPEN );
|
| + assert( pPager->eLock>=SHARED_LOCK || pPager->noReadlock );
|
| + nPage = sqlite3WalDbsize(pPager->pWal);
|
| +
|
| + /* If the database size was not available from the WAL sub-system,
|
| + ** determine it based on the size of the database file. If the size
|
| + ** of the database file is not an integer multiple of the page-size,
|
| + ** round down to the nearest page. Except, any file larger than 0
|
| + ** bytes in size is considered to contain at least one page.
|
| + */
|
| + if( nPage==0 ){
|
| + i64 n = 0; /* Size of db file in bytes */
|
| + assert( isOpen(pPager->fd) || pPager->tempFile );
|
| + if( isOpen(pPager->fd) ){
|
| + int rc = sqlite3OsFileSize(pPager->fd, &n);
|
| + if( rc!=SQLITE_OK ){
|
| + return rc;
|
| + }
|
| + }
|
| + nPage = (Pgno)(n / pPager->pageSize);
|
| + if( nPage==0 && n>0 ){
|
| + nPage = 1;
|
| + }
|
| + }
|
| +
|
| + /* If the current number of pages in the file is greater than the
|
| + ** configured maximum pager number, increase the allowed limit so
|
| + ** that the file can be read.
|
| + */
|
| + if( nPage>pPager->mxPgno ){
|
| + pPager->mxPgno = (Pgno)nPage;
|
| + }
|
| +
|
| + *pnPage = nPage;
|
| + return SQLITE_OK;
|
| +}
|
| +
|
| +#ifndef SQLITE_OMIT_WAL
|
| +/*
|
| +** Check if the *-wal file that corresponds to the database opened by pPager
|
| +** exists if the database is not empy, or verify that the *-wal file does
|
| +** not exist (by deleting it) if the database file is empty.
|
| +**
|
| +** If the database is not empty and the *-wal file exists, open the pager
|
| +** in WAL mode. If the database is empty or if no *-wal file exists and
|
| +** if no error occurs, make sure Pager.journalMode is not set to
|
| +** PAGER_JOURNALMODE_WAL.
|
| +**
|
| +** Return SQLITE_OK or an error code.
|
| +**
|
| +** The caller must hold a SHARED lock on the database file to call this
|
| +** function. Because an EXCLUSIVE lock on the db file is required to delete
|
| +** a WAL on a none-empty database, this ensures there is no race condition
|
| +** between the xAccess() below and an xDelete() being executed by some
|
| +** other connection.
|
| +*/
|
| +static int pagerOpenWalIfPresent(Pager *pPager){
|
| + int rc = SQLITE_OK;
|
| + assert( pPager->eState==PAGER_OPEN );
|
| + assert( pPager->eLock>=SHARED_LOCK || pPager->noReadlock );
|
| +
|
| + if( !pPager->tempFile ){
|
| + int isWal; /* True if WAL file exists */
|
| + Pgno nPage; /* Size of the database file */
|
| +
|
| + rc = pagerPagecount(pPager, &nPage);
|
| + if( rc ) return rc;
|
| + if( nPage==0 ){
|
| + rc = sqlite3OsDelete(pPager->pVfs, pPager->zWal, 0);
|
| + isWal = 0;
|
| + }else{
|
| + rc = sqlite3OsAccess(
|
| + pPager->pVfs, pPager->zWal, SQLITE_ACCESS_EXISTS, &isWal
|
| + );
|
| + }
|
| + if( rc==SQLITE_OK ){
|
| + if( isWal ){
|
| + testcase( sqlite3PcachePagecount(pPager->pPCache)==0 );
|
| + rc = sqlite3PagerOpenWal(pPager, 0);
|
| + }else if( pPager->journalMode==PAGER_JOURNALMODE_WAL ){
|
| + pPager->journalMode = PAGER_JOURNALMODE_DELETE;
|
| + }
|
| + }
|
| + }
|
| + return rc;
|
| +}
|
| +#endif
|
| +
|
| +/*
|
| +** Playback savepoint pSavepoint. Or, if pSavepoint==NULL, then playback
|
| +** the entire master journal file. The case pSavepoint==NULL occurs when
|
| +** a ROLLBACK TO command is invoked on a SAVEPOINT that is a transaction
|
| +** savepoint.
|
| +**
|
| +** When pSavepoint is not NULL (meaning a non-transaction savepoint is
|
| +** being rolled back), then the rollback consists of up to three stages,
|
| +** performed in the order specified:
|
| +**
|
| +** * Pages are played back from the main journal starting at byte
|
| +** offset PagerSavepoint.iOffset and continuing to
|
| +** PagerSavepoint.iHdrOffset, or to the end of the main journal
|
| +** file if PagerSavepoint.iHdrOffset is zero.
|
| +**
|
| +** * If PagerSavepoint.iHdrOffset is not zero, then pages are played
|
| +** back starting from the journal header immediately following
|
| +** PagerSavepoint.iHdrOffset to the end of the main journal file.
|
| +**
|
| +** * Pages are then played back from the sub-journal file, starting
|
| +** with the PagerSavepoint.iSubRec and continuing to the end of
|
| +** the journal file.
|
| +**
|
| +** Throughout the rollback process, each time a page is rolled back, the
|
| +** corresponding bit is set in a bitvec structure (variable pDone in the
|
| +** implementation below). This is used to ensure that a page is only
|
| +** rolled back the first time it is encountered in either journal.
|
| +**
|
| +** If pSavepoint is NULL, then pages are only played back from the main
|
| +** journal file. There is no need for a bitvec in this case.
|
| +**
|
| +** In either case, before playback commences the Pager.dbSize variable
|
| +** is reset to the value that it held at the start of the savepoint
|
| +** (or transaction). No page with a page-number greater than this value
|
| +** is played back. If one is encountered it is simply skipped.
|
| +*/
|
| +static int pagerPlaybackSavepoint(Pager *pPager, PagerSavepoint *pSavepoint){
|
| + i64 szJ; /* Effective size of the main journal */
|
| + i64 iHdrOff; /* End of first segment of main-journal records */
|
| + int rc = SQLITE_OK; /* Return code */
|
| + Bitvec *pDone = 0; /* Bitvec to ensure pages played back only once */
|
| +
|
| + assert( pPager->eState!=PAGER_ERROR );
|
| + assert( pPager->eState>=PAGER_WRITER_LOCKED );
|
| +
|
| + /* Allocate a bitvec to use to store the set of pages rolled back */
|
| + if( pSavepoint ){
|
| + pDone = sqlite3BitvecCreate(pSavepoint->nOrig);
|
| + if( !pDone ){
|
| + return SQLITE_NOMEM;
|
| + }
|
| + }
|
| +
|
| + /* Set the database size back to the value it was before the savepoint
|
| + ** being reverted was opened.
|
| + */
|
| + pPager->dbSize = pSavepoint ? pSavepoint->nOrig : pPager->dbOrigSize;
|
| + pPager->changeCountDone = pPager->tempFile;
|
| +
|
| + if( !pSavepoint && pagerUseWal(pPager) ){
|
| + return pagerRollbackWal(pPager);
|
| + }
|
| +
|
| + /* Use pPager->journalOff as the effective size of the main rollback
|
| + ** journal. The actual file might be larger than this in
|
| + ** PAGER_JOURNALMODE_TRUNCATE or PAGER_JOURNALMODE_PERSIST. But anything
|
| + ** past pPager->journalOff is off-limits to us.
|
| + */
|
| + szJ = pPager->journalOff;
|
| + assert( pagerUseWal(pPager)==0 || szJ==0 );
|
| +
|
| + /* Begin by rolling back records from the main journal starting at
|
| + ** PagerSavepoint.iOffset and continuing to the next journal header.
|
| + ** There might be records in the main journal that have a page number
|
| + ** greater than the current database size (pPager->dbSize) but those
|
| + ** will be skipped automatically. Pages are added to pDone as they
|
| + ** are played back.
|
| + */
|
| + if( pSavepoint && !pagerUseWal(pPager) ){
|
| + iHdrOff = pSavepoint->iHdrOffset ? pSavepoint->iHdrOffset : szJ;
|
| + pPager->journalOff = pSavepoint->iOffset;
|
| + while( rc==SQLITE_OK && pPager->journalOff<iHdrOff ){
|
| + rc = pager_playback_one_page(pPager, &pPager->journalOff, pDone, 1, 1);
|
| + }
|
| + assert( rc!=SQLITE_DONE );
|
| + }else{
|
| + pPager->journalOff = 0;
|
| + }
|
| +
|
| + /* Continue rolling back records out of the main journal starting at
|
| + ** the first journal header seen and continuing until the effective end
|
| + ** of the main journal file. Continue to skip out-of-range pages and
|
| + ** continue adding pages rolled back to pDone.
|
| + */
|
| + while( rc==SQLITE_OK && pPager->journalOff<szJ ){
|
| + u32 ii; /* Loop counter */
|
| + u32 nJRec = 0; /* Number of Journal Records */
|
| + u32 dummy;
|
| + rc = readJournalHdr(pPager, 0, szJ, &nJRec, &dummy);
|
| + assert( rc!=SQLITE_DONE );
|
| +
|
| + /*
|
| + ** The "pPager->journalHdr+JOURNAL_HDR_SZ(pPager)==pPager->journalOff"
|
| + ** test is related to ticket #2565. See the discussion in the
|
| + ** pager_playback() function for additional information.
|
| + */
|
| + if( nJRec==0
|
| + && pPager->journalHdr+JOURNAL_HDR_SZ(pPager)==pPager->journalOff
|
| + ){
|
| + nJRec = (u32)((szJ - pPager->journalOff)/JOURNAL_PG_SZ(pPager));
|
| + }
|
| + for(ii=0; rc==SQLITE_OK && ii<nJRec && pPager->journalOff<szJ; ii++){
|
| + rc = pager_playback_one_page(pPager, &pPager->journalOff, pDone, 1, 1);
|
| + }
|
| + assert( rc!=SQLITE_DONE );
|
| + }
|
| + assert( rc!=SQLITE_OK || pPager->journalOff>=szJ );
|
| +
|
| + /* Finally, rollback pages from the sub-journal. Page that were
|
| + ** previously rolled back out of the main journal (and are hence in pDone)
|
| + ** will be skipped. Out-of-range pages are also skipped.
|
| + */
|
| + if( pSavepoint ){
|
| + u32 ii; /* Loop counter */
|
| + i64 offset = pSavepoint->iSubRec*(4+pPager->pageSize);
|
| +
|
| + if( pagerUseWal(pPager) ){
|
| + rc = sqlite3WalSavepointUndo(pPager->pWal, pSavepoint->aWalData);
|
| + }
|
| + for(ii=pSavepoint->iSubRec; rc==SQLITE_OK && ii<pPager->nSubRec; ii++){
|
| + assert( offset==ii*(4+pPager->pageSize) );
|
| + rc = pager_playback_one_page(pPager, &offset, pDone, 0, 1);
|
| + }
|
| + assert( rc!=SQLITE_DONE );
|
| + }
|
| +
|
| + sqlite3BitvecDestroy(pDone);
|
| + if( rc==SQLITE_OK ){
|
| + pPager->journalOff = szJ;
|
| + }
|
| +
|
| + return rc;
|
| +}
|
| +
|
| +/*
|
| +** Change the maximum number of in-memory pages that are allowed.
|
| +*/
|
| +void sqlite3PagerSetCachesize(Pager *pPager, int mxPage){
|
| + sqlite3PcacheSetCachesize(pPager->pPCache, mxPage);
|
| +}
|
| +
|
| +/*
|
| +** Adjust the robustness of the database to damage due to OS crashes
|
| +** or power failures by changing the number of syncs()s when writing
|
| +** the rollback journal. There are three levels:
|
| +**
|
| +** OFF sqlite3OsSync() is never called. This is the default
|
| +** for temporary and transient files.
|
| +**
|
| +** NORMAL The journal is synced once before writes begin on the
|
| +** database. This is normally adequate protection, but
|
| +** it is theoretically possible, though very unlikely,
|
| +** that an inopertune power failure could leave the journal
|
| +** in a state which would cause damage to the database
|
| +** when it is rolled back.
|
| +**
|
| +** FULL The journal is synced twice before writes begin on the
|
| +** database (with some additional information - the nRec field
|
| +** of the journal header - being written in between the two
|
| +** syncs). If we assume that writing a
|
| +** single disk sector is atomic, then this mode provides
|
| +** assurance that the journal will not be corrupted to the
|
| +** point of causing damage to the database during rollback.
|
| +**
|
| +** The above is for a rollback-journal mode. For WAL mode, OFF continues
|
| +** to mean that no syncs ever occur. NORMAL means that the WAL is synced
|
| +** prior to the start of checkpoint and that the database file is synced
|
| +** at the conclusion of the checkpoint if the entire content of the WAL
|
| +** was written back into the database. But no sync operations occur for
|
| +** an ordinary commit in NORMAL mode with WAL. FULL means that the WAL
|
| +** file is synced following each commit operation, in addition to the
|
| +** syncs associated with NORMAL.
|
| +**
|
| +** Do not confuse synchronous=FULL with SQLITE_SYNC_FULL. The
|
| +** SQLITE_SYNC_FULL macro means to use the MacOSX-style full-fsync
|
| +** using fcntl(F_FULLFSYNC). SQLITE_SYNC_NORMAL means to do an
|
| +** ordinary fsync() call. There is no difference between SQLITE_SYNC_FULL
|
| +** and SQLITE_SYNC_NORMAL on platforms other than MacOSX. But the
|
| +** synchronous=FULL versus synchronous=NORMAL setting determines when
|
| +** the xSync primitive is called and is relevant to all platforms.
|
| +**
|
| +** Numeric values associated with these states are OFF==1, NORMAL=2,
|
| +** and FULL=3.
|
| +*/
|
| +#ifndef SQLITE_OMIT_PAGER_PRAGMAS
|
| +void sqlite3PagerSetSafetyLevel(
|
| + Pager *pPager, /* The pager to set safety level for */
|
| + int level, /* PRAGMA synchronous. 1=OFF, 2=NORMAL, 3=FULL */
|
| + int bFullFsync, /* PRAGMA fullfsync */
|
| + int bCkptFullFsync /* PRAGMA checkpoint_fullfsync */
|
| +){
|
| + assert( level>=1 && level<=3 );
|
| + pPager->noSync = (level==1 || pPager->tempFile) ?1:0;
|
| + pPager->fullSync = (level==3 && !pPager->tempFile) ?1:0;
|
| + if( pPager->noSync ){
|
| + pPager->syncFlags = 0;
|
| + pPager->ckptSyncFlags = 0;
|
| + }else if( bFullFsync ){
|
| + pPager->syncFlags = SQLITE_SYNC_FULL;
|
| + pPager->ckptSyncFlags = SQLITE_SYNC_FULL;
|
| + }else if( bCkptFullFsync ){
|
| + pPager->syncFlags = SQLITE_SYNC_NORMAL;
|
| + pPager->ckptSyncFlags = SQLITE_SYNC_FULL;
|
| + }else{
|
| + pPager->syncFlags = SQLITE_SYNC_NORMAL;
|
| + pPager->ckptSyncFlags = SQLITE_SYNC_NORMAL;
|
| + }
|
| +}
|
| +#endif
|
| +
|
| +/*
|
| +** The following global variable is incremented whenever the library
|
| +** attempts to open a temporary file. This information is used for
|
| +** testing and analysis only.
|
| +*/
|
| +#ifdef SQLITE_TEST
|
| +int sqlite3_opentemp_count = 0;
|
| +#endif
|
| +
|
| +/*
|
| +** Open a temporary file.
|
| +**
|
| +** Write the file descriptor into *pFile. Return SQLITE_OK on success
|
| +** or some other error code if we fail. The OS will automatically
|
| +** delete the temporary file when it is closed.
|
| +**
|
| +** The flags passed to the VFS layer xOpen() call are those specified
|
| +** by parameter vfsFlags ORed with the following:
|
| +**
|
| +** SQLITE_OPEN_READWRITE
|
| +** SQLITE_OPEN_CREATE
|
| +** SQLITE_OPEN_EXCLUSIVE
|
| +** SQLITE_OPEN_DELETEONCLOSE
|
| +*/
|
| +static int pagerOpentemp(
|
| + Pager *pPager, /* The pager object */
|
| + sqlite3_file *pFile, /* Write the file descriptor here */
|
| + int vfsFlags /* Flags passed through to the VFS */
|
| +){
|
| + int rc; /* Return code */
|
| +
|
| +#ifdef SQLITE_TEST
|
| + sqlite3_opentemp_count++; /* Used for testing and analysis only */
|
| +#endif
|
| +
|
| + vfsFlags |= SQLITE_OPEN_READWRITE | SQLITE_OPEN_CREATE |
|
| + SQLITE_OPEN_EXCLUSIVE | SQLITE_OPEN_DELETEONCLOSE;
|
| + rc = sqlite3OsOpen(pPager->pVfs, 0, pFile, vfsFlags, 0);
|
| + assert( rc!=SQLITE_OK || isOpen(pFile) );
|
| + return rc;
|
| +}
|
| +
|
| +/*
|
| +** Set the busy handler function.
|
| +**
|
| +** The pager invokes the busy-handler if sqlite3OsLock() returns
|
| +** SQLITE_BUSY when trying to upgrade from no-lock to a SHARED lock,
|
| +** or when trying to upgrade from a RESERVED lock to an EXCLUSIVE
|
| +** lock. It does *not* invoke the busy handler when upgrading from
|
| +** SHARED to RESERVED, or when upgrading from SHARED to EXCLUSIVE
|
| +** (which occurs during hot-journal rollback). Summary:
|
| +**
|
| +** Transition | Invokes xBusyHandler
|
| +** --------------------------------------------------------
|
| +** NO_LOCK -> SHARED_LOCK | Yes
|
| +** SHARED_LOCK -> RESERVED_LOCK | No
|
| +** SHARED_LOCK -> EXCLUSIVE_LOCK | No
|
| +** RESERVED_LOCK -> EXCLUSIVE_LOCK | Yes
|
| +**
|
| +** If the busy-handler callback returns non-zero, the lock is
|
| +** retried. If it returns zero, then the SQLITE_BUSY error is
|
| +** returned to the caller of the pager API function.
|
| +*/
|
| +void sqlite3PagerSetBusyhandler(
|
| + Pager *pPager, /* Pager object */
|
| + int (*xBusyHandler)(void *), /* Pointer to busy-handler function */
|
| + void *pBusyHandlerArg /* Argument to pass to xBusyHandler */
|
| +){
|
| + pPager->xBusyHandler = xBusyHandler;
|
| + pPager->pBusyHandlerArg = pBusyHandlerArg;
|
| +}
|
| +
|
| +/*
|
| +** Change the page size used by the Pager object. The new page size
|
| +** is passed in *pPageSize.
|
| +**
|
| +** If the pager is in the error state when this function is called, it
|
| +** is a no-op. The value returned is the error state error code (i.e.
|
| +** one of SQLITE_IOERR, an SQLITE_IOERR_xxx sub-code or SQLITE_FULL).
|
| +**
|
| +** Otherwise, if all of the following are true:
|
| +**
|
| +** * the new page size (value of *pPageSize) is valid (a power
|
| +** of two between 512 and SQLITE_MAX_PAGE_SIZE, inclusive), and
|
| +**
|
| +** * there are no outstanding page references, and
|
| +**
|
| +** * the database is either not an in-memory database or it is
|
| +** an in-memory database that currently consists of zero pages.
|
| +**
|
| +** then the pager object page size is set to *pPageSize.
|
| +**
|
| +** If the page size is changed, then this function uses sqlite3PagerMalloc()
|
| +** to obtain a new Pager.pTmpSpace buffer. If this allocation attempt
|
| +** fails, SQLITE_NOMEM is returned and the page size remains unchanged.
|
| +** In all other cases, SQLITE_OK is returned.
|
| +**
|
| +** If the page size is not changed, either because one of the enumerated
|
| +** conditions above is not true, the pager was in error state when this
|
| +** function was called, or because the memory allocation attempt failed,
|
| +** then *pPageSize is set to the old, retained page size before returning.
|
| +*/
|
| +int sqlite3PagerSetPagesize(Pager *pPager, u32 *pPageSize, int nReserve){
|
| + int rc = SQLITE_OK;
|
| +
|
| + /* It is not possible to do a full assert_pager_state() here, as this
|
| + ** function may be called from within PagerOpen(), before the state
|
| + ** of the Pager object is internally consistent.
|
| + **
|
| + ** At one point this function returned an error if the pager was in
|
| + ** PAGER_ERROR state. But since PAGER_ERROR state guarantees that
|
| + ** there is at least one outstanding page reference, this function
|
| + ** is a no-op for that case anyhow.
|
| + */
|
| +
|
| + u32 pageSize = *pPageSize;
|
| + assert( pageSize==0 || (pageSize>=512 && pageSize<=SQLITE_MAX_PAGE_SIZE) );
|
| + if( (pPager->memDb==0 || pPager->dbSize==0)
|
| + && sqlite3PcacheRefCount(pPager->pPCache)==0
|
| + && pageSize && pageSize!=(u32)pPager->pageSize
|
| + ){
|
| + char *pNew = NULL; /* New temp space */
|
| + i64 nByte = 0;
|
| +
|
| + if( pPager->eState>PAGER_OPEN && isOpen(pPager->fd) ){
|
| + rc = sqlite3OsFileSize(pPager->fd, &nByte);
|
| + }
|
| + if( rc==SQLITE_OK ){
|
| + pNew = (char *)sqlite3PageMalloc(pageSize);
|
| + if( !pNew ) rc = SQLITE_NOMEM;
|
| + }
|
| +
|
| + if( rc==SQLITE_OK ){
|
| + pager_reset(pPager);
|
| + pPager->dbSize = (Pgno)(nByte/pageSize);
|
| + pPager->pageSize = pageSize;
|
| + sqlite3PageFree(pPager->pTmpSpace);
|
| + pPager->pTmpSpace = pNew;
|
| + sqlite3PcacheSetPageSize(pPager->pPCache, pageSize);
|
| + }
|
| + }
|
| +
|
| + *pPageSize = pPager->pageSize;
|
| + if( rc==SQLITE_OK ){
|
| + if( nReserve<0 ) nReserve = pPager->nReserve;
|
| + assert( nReserve>=0 && nReserve<1000 );
|
| + pPager->nReserve = (i16)nReserve;
|
| + pagerReportSize(pPager);
|
| + }
|
| + return rc;
|
| +}
|
| +
|
| +/*
|
| +** Return a pointer to the "temporary page" buffer held internally
|
| +** by the pager. This is a buffer that is big enough to hold the
|
| +** entire content of a database page. This buffer is used internally
|
| +** during rollback and will be overwritten whenever a rollback
|
| +** occurs. But other modules are free to use it too, as long as
|
| +** no rollbacks are happening.
|
| +*/
|
| +void *sqlite3PagerTempSpace(Pager *pPager){
|
| + return pPager->pTmpSpace;
|
| +}
|
| +
|
| +/*
|
| +** Attempt to set the maximum database page count if mxPage is positive.
|
| +** Make no changes if mxPage is zero or negative. And never reduce the
|
| +** maximum page count below the current size of the database.
|
| +**
|
| +** Regardless of mxPage, return the current maximum page count.
|
| +*/
|
| +int sqlite3PagerMaxPageCount(Pager *pPager, int mxPage){
|
| + if( mxPage>0 ){
|
| + pPager->mxPgno = mxPage;
|
| + }
|
| + assert( pPager->eState!=PAGER_OPEN ); /* Called only by OP_MaxPgcnt */
|
| + assert( pPager->mxPgno>=pPager->dbSize ); /* OP_MaxPgcnt enforces this */
|
| + return pPager->mxPgno;
|
| +}
|
| +
|
| +/*
|
| +** The following set of routines are used to disable the simulated
|
| +** I/O error mechanism. These routines are used to avoid simulated
|
| +** errors in places where we do not care about errors.
|
| +**
|
| +** Unless -DSQLITE_TEST=1 is used, these routines are all no-ops
|
| +** and generate no code.
|
| +*/
|
| +#ifdef SQLITE_TEST
|
| +extern int sqlite3_io_error_pending;
|
| +extern int sqlite3_io_error_hit;
|
| +static int saved_cnt;
|
| +void disable_simulated_io_errors(void){
|
| + saved_cnt = sqlite3_io_error_pending;
|
| + sqlite3_io_error_pending = -1;
|
| +}
|
| +void enable_simulated_io_errors(void){
|
| + sqlite3_io_error_pending = saved_cnt;
|
| +}
|
| +#else
|
| +# define disable_simulated_io_errors()
|
| +# define enable_simulated_io_errors()
|
| +#endif
|
| +
|
| +/*
|
| +** Read the first N bytes from the beginning of the file into memory
|
| +** that pDest points to.
|
| +**
|
| +** If the pager was opened on a transient file (zFilename==""), or
|
| +** opened on a file less than N bytes in size, the output buffer is
|
| +** zeroed and SQLITE_OK returned. The rationale for this is that this
|
| +** function is used to read database headers, and a new transient or
|
| +** zero sized database has a header than consists entirely of zeroes.
|
| +**
|
| +** If any IO error apart from SQLITE_IOERR_SHORT_READ is encountered,
|
| +** the error code is returned to the caller and the contents of the
|
| +** output buffer undefined.
|
| +*/
|
| +int sqlite3PagerReadFileheader(Pager *pPager, int N, unsigned char *pDest){
|
| + int rc = SQLITE_OK;
|
| + memset(pDest, 0, N);
|
| + assert( isOpen(pPager->fd) || pPager->tempFile );
|
| +
|
| + /* This routine is only called by btree immediately after creating
|
| + ** the Pager object. There has not been an opportunity to transition
|
| + ** to WAL mode yet.
|
| + */
|
| + assert( !pagerUseWal(pPager) );
|
| +
|
| + if( isOpen(pPager->fd) ){
|
| + IOTRACE(("DBHDR %p 0 %d\n", pPager, N))
|
| + rc = sqlite3OsRead(pPager->fd, pDest, N, 0);
|
| + if( rc==SQLITE_IOERR_SHORT_READ ){
|
| + rc = SQLITE_OK;
|
| + }
|
| + }
|
| + return rc;
|
| +}
|
| +
|
| +/*
|
| +** This function may only be called when a read-transaction is open on
|
| +** the pager. It returns the total number of pages in the database.
|
| +**
|
| +** However, if the file is between 1 and <page-size> bytes in size, then
|
| +** this is considered a 1 page file.
|
| +*/
|
| +void sqlite3PagerPagecount(Pager *pPager, int *pnPage){
|
| + assert( pPager->eState>=PAGER_READER );
|
| + assert( pPager->eState!=PAGER_WRITER_FINISHED );
|
| + *pnPage = (int)pPager->dbSize;
|
| +}
|
| +
|
| +
|
| +/*
|
| +** Try to obtain a lock of type locktype on the database file. If
|
| +** a similar or greater lock is already held, this function is a no-op
|
| +** (returning SQLITE_OK immediately).
|
| +**
|
| +** Otherwise, attempt to obtain the lock using sqlite3OsLock(). Invoke
|
| +** the busy callback if the lock is currently not available. Repeat
|
| +** until the busy callback returns false or until the attempt to
|
| +** obtain the lock succeeds.
|
| +**
|
| +** Return SQLITE_OK on success and an error code if we cannot obtain
|
| +** the lock. If the lock is obtained successfully, set the Pager.state
|
| +** variable to locktype before returning.
|
| +*/
|
| +static int pager_wait_on_lock(Pager *pPager, int locktype){
|
| + int rc; /* Return code */
|
| +
|
| + /* Check that this is either a no-op (because the requested lock is
|
| + ** already held, or one of the transistions that the busy-handler
|
| + ** may be invoked during, according to the comment above
|
| + ** sqlite3PagerSetBusyhandler().
|
| + */
|
| + assert( (pPager->eLock>=locktype)
|
| + || (pPager->eLock==NO_LOCK && locktype==SHARED_LOCK)
|
| + || (pPager->eLock==RESERVED_LOCK && locktype==EXCLUSIVE_LOCK)
|
| + );
|
| +
|
| + do {
|
| + rc = pagerLockDb(pPager, locktype);
|
| + }while( rc==SQLITE_BUSY && pPager->xBusyHandler(pPager->pBusyHandlerArg) );
|
| + return rc;
|
| +}
|
| +
|
| +/*
|
| +** Function assertTruncateConstraint(pPager) checks that one of the
|
| +** following is true for all dirty pages currently in the page-cache:
|
| +**
|
| +** a) The page number is less than or equal to the size of the
|
| +** current database image, in pages, OR
|
| +**
|
| +** b) if the page content were written at this time, it would not
|
| +** be necessary to write the current content out to the sub-journal
|
| +** (as determined by function subjRequiresPage()).
|
| +**
|
| +** If the condition asserted by this function were not true, and the
|
| +** dirty page were to be discarded from the cache via the pagerStress()
|
| +** routine, pagerStress() would not write the current page content to
|
| +** the database file. If a savepoint transaction were rolled back after
|
| +** this happened, the correct behaviour would be to restore the current
|
| +** content of the page. However, since this content is not present in either
|
| +** the database file or the portion of the rollback journal and
|
| +** sub-journal rolled back the content could not be restored and the
|
| +** database image would become corrupt. It is therefore fortunate that
|
| +** this circumstance cannot arise.
|
| +*/
|
| +#if defined(SQLITE_DEBUG)
|
| +static void assertTruncateConstraintCb(PgHdr *pPg){
|
| + assert( pPg->flags&PGHDR_DIRTY );
|
| + assert( !subjRequiresPage(pPg) || pPg->pgno<=pPg->pPager->dbSize );
|
| +}
|
| +static void assertTruncateConstraint(Pager *pPager){
|
| + sqlite3PcacheIterateDirty(pPager->pPCache, assertTruncateConstraintCb);
|
| +}
|
| +#else
|
| +# define assertTruncateConstraint(pPager)
|
| +#endif
|
| +
|
| +/*
|
| +** Truncate the in-memory database file image to nPage pages. This
|
| +** function does not actually modify the database file on disk. It
|
| +** just sets the internal state of the pager object so that the
|
| +** truncation will be done when the current transaction is committed.
|
| +*/
|
| +void sqlite3PagerTruncateImage(Pager *pPager, Pgno nPage){
|
| + assert( pPager->dbSize>=nPage );
|
| + assert( pPager->eState>=PAGER_WRITER_CACHEMOD );
|
| + pPager->dbSize = nPage;
|
| + assertTruncateConstraint(pPager);
|
| +}
|
| +
|
| +
|
| +/*
|
| +** This function is called before attempting a hot-journal rollback. It
|
| +** syncs the journal file to disk, then sets pPager->journalHdr to the
|
| +** size of the journal file so that the pager_playback() routine knows
|
| +** that the entire journal file has been synced.
|
| +**
|
| +** Syncing a hot-journal to disk before attempting to roll it back ensures
|
| +** that if a power-failure occurs during the rollback, the process that
|
| +** attempts rollback following system recovery sees the same journal
|
| +** content as this process.
|
| +**
|
| +** If everything goes as planned, SQLITE_OK is returned. Otherwise,
|
| +** an SQLite error code.
|
| +*/
|
| +static int pagerSyncHotJournal(Pager *pPager){
|
| + int rc = SQLITE_OK;
|
| + if( !pPager->noSync ){
|
| + rc = sqlite3OsSync(pPager->jfd, SQLITE_SYNC_NORMAL);
|
| + }
|
| + if( rc==SQLITE_OK ){
|
| + rc = sqlite3OsFileSize(pPager->jfd, &pPager->journalHdr);
|
| + }
|
| + return rc;
|
| +}
|
| +
|
| +/*
|
| +** Shutdown the page cache. Free all memory and close all files.
|
| +**
|
| +** If a transaction was in progress when this routine is called, that
|
| +** transaction is rolled back. All outstanding pages are invalidated
|
| +** and their memory is freed. Any attempt to use a page associated
|
| +** with this page cache after this function returns will likely
|
| +** result in a coredump.
|
| +**
|
| +** This function always succeeds. If a transaction is active an attempt
|
| +** is made to roll it back. If an error occurs during the rollback
|
| +** a hot journal may be left in the filesystem but no error is returned
|
| +** to the caller.
|
| +*/
|
| +int sqlite3PagerClose(Pager *pPager){
|
| + u8 *pTmp = (u8 *)pPager->pTmpSpace;
|
| +
|
| + disable_simulated_io_errors();
|
| + sqlite3BeginBenignMalloc();
|
| + /* pPager->errCode = 0; */
|
| + pPager->exclusiveMode = 0;
|
| +#ifndef SQLITE_OMIT_WAL
|
| + sqlite3WalClose(pPager->pWal, pPager->ckptSyncFlags, pPager->pageSize, pTmp);
|
| + pPager->pWal = 0;
|
| +#endif
|
| + pager_reset(pPager);
|
| + if( MEMDB ){
|
| + pager_unlock(pPager);
|
| + }else{
|
| + /* If it is open, sync the journal file before calling UnlockAndRollback.
|
| + ** If this is not done, then an unsynced portion of the open journal
|
| + ** file may be played back into the database. If a power failure occurs
|
| + ** while this is happening, the database could become corrupt.
|
| + **
|
| + ** If an error occurs while trying to sync the journal, shift the pager
|
| + ** into the ERROR state. This causes UnlockAndRollback to unlock the
|
| + ** database and close the journal file without attempting to roll it
|
| + ** back or finalize it. The next database user will have to do hot-journal
|
| + ** rollback before accessing the database file.
|
| + */
|
| + if( isOpen(pPager->jfd) ){
|
| + pager_error(pPager, pagerSyncHotJournal(pPager));
|
| + }
|
| + pagerUnlockAndRollback(pPager);
|
| + }
|
| + sqlite3EndBenignMalloc();
|
| + enable_simulated_io_errors();
|
| + PAGERTRACE(("CLOSE %d\n", PAGERID(pPager)));
|
| + IOTRACE(("CLOSE %p\n", pPager))
|
| + sqlite3OsClose(pPager->jfd);
|
| + sqlite3OsClose(pPager->fd);
|
| + sqlite3PageFree(pTmp);
|
| + sqlite3PcacheClose(pPager->pPCache);
|
| +
|
| +#ifdef SQLITE_HAS_CODEC
|
| + if( pPager->xCodecFree ) pPager->xCodecFree(pPager->pCodec);
|
| +#endif
|
| +
|
| + assert( !pPager->aSavepoint && !pPager->pInJournal );
|
| + assert( !isOpen(pPager->jfd) && !isOpen(pPager->sjfd) );
|
| +
|
| + sqlite3_free(pPager);
|
| + return SQLITE_OK;
|
| +}
|
| +
|
| +#if !defined(NDEBUG) || defined(SQLITE_TEST)
|
| +/*
|
| +** Return the page number for page pPg.
|
| +*/
|
| +Pgno sqlite3PagerPagenumber(DbPage *pPg){
|
| + return pPg->pgno;
|
| +}
|
| +#endif
|
| +
|
| +/*
|
| +** Increment the reference count for page pPg.
|
| +*/
|
| +void sqlite3PagerRef(DbPage *pPg){
|
| + sqlite3PcacheRef(pPg);
|
| +}
|
| +
|
| +/*
|
| +** Sync the journal. In other words, make sure all the pages that have
|
| +** been written to the journal have actually reached the surface of the
|
| +** disk and can be restored in the event of a hot-journal rollback.
|
| +**
|
| +** If the Pager.noSync flag is set, then this function is a no-op.
|
| +** Otherwise, the actions required depend on the journal-mode and the
|
| +** device characteristics of the the file-system, as follows:
|
| +**
|
| +** * If the journal file is an in-memory journal file, no action need
|
| +** be taken.
|
| +**
|
| +** * Otherwise, if the device does not support the SAFE_APPEND property,
|
| +** then the nRec field of the most recently written journal header
|
| +** is updated to contain the number of journal records that have
|
| +** been written following it. If the pager is operating in full-sync
|
| +** mode, then the journal file is synced before this field is updated.
|
| +**
|
| +** * If the device does not support the SEQUENTIAL property, then
|
| +** journal file is synced.
|
| +**
|
| +** Or, in pseudo-code:
|
| +**
|
| +** if( NOT <in-memory journal> ){
|
| +** if( NOT SAFE_APPEND ){
|
| +** if( <full-sync mode> ) xSync(<journal file>);
|
| +** <update nRec field>
|
| +** }
|
| +** if( NOT SEQUENTIAL ) xSync(<journal file>);
|
| +** }
|
| +**
|
| +** If successful, this routine clears the PGHDR_NEED_SYNC flag of every
|
| +** page currently held in memory before returning SQLITE_OK. If an IO
|
| +** error is encountered, then the IO error code is returned to the caller.
|
| +*/
|
| +static int syncJournal(Pager *pPager, int newHdr){
|
| + int rc; /* Return code */
|
| +
|
| + assert( pPager->eState==PAGER_WRITER_CACHEMOD
|
| + || pPager->eState==PAGER_WRITER_DBMOD
|
| + );
|
| + assert( assert_pager_state(pPager) );
|
| + assert( !pagerUseWal(pPager) );
|
| +
|
| + rc = sqlite3PagerExclusiveLock(pPager);
|
| + if( rc!=SQLITE_OK ) return rc;
|
| +
|
| + if( !pPager->noSync ){
|
| + assert( !pPager->tempFile );
|
| + if( isOpen(pPager->jfd) && pPager->journalMode!=PAGER_JOURNALMODE_MEMORY ){
|
| + const int iDc = sqlite3OsDeviceCharacteristics(pPager->fd);
|
| + assert( isOpen(pPager->jfd) );
|
| +
|
| + if( 0==(iDc&SQLITE_IOCAP_SAFE_APPEND) ){
|
| + /* This block deals with an obscure problem. If the last connection
|
| + ** that wrote to this database was operating in persistent-journal
|
| + ** mode, then the journal file may at this point actually be larger
|
| + ** than Pager.journalOff bytes. If the next thing in the journal
|
| + ** file happens to be a journal-header (written as part of the
|
| + ** previous connection's transaction), and a crash or power-failure
|
| + ** occurs after nRec is updated but before this connection writes
|
| + ** anything else to the journal file (or commits/rolls back its
|
| + ** transaction), then SQLite may become confused when doing the
|
| + ** hot-journal rollback following recovery. It may roll back all
|
| + ** of this connections data, then proceed to rolling back the old,
|
| + ** out-of-date data that follows it. Database corruption.
|
| + **
|
| + ** To work around this, if the journal file does appear to contain
|
| + ** a valid header following Pager.journalOff, then write a 0x00
|
| + ** byte to the start of it to prevent it from being recognized.
|
| + **
|
| + ** Variable iNextHdrOffset is set to the offset at which this
|
| + ** problematic header will occur, if it exists. aMagic is used
|
| + ** as a temporary buffer to inspect the first couple of bytes of
|
| + ** the potential journal header.
|
| + */
|
| + i64 iNextHdrOffset;
|
| + u8 aMagic[8];
|
| + u8 zHeader[sizeof(aJournalMagic)+4];
|
| +
|
| + memcpy(zHeader, aJournalMagic, sizeof(aJournalMagic));
|
| + put32bits(&zHeader[sizeof(aJournalMagic)], pPager->nRec);
|
| +
|
| + iNextHdrOffset = journalHdrOffset(pPager);
|
| + rc = sqlite3OsRead(pPager->jfd, aMagic, 8, iNextHdrOffset);
|
| + if( rc==SQLITE_OK && 0==memcmp(aMagic, aJournalMagic, 8) ){
|
| + static const u8 zerobyte = 0;
|
| + rc = sqlite3OsWrite(pPager->jfd, &zerobyte, 1, iNextHdrOffset);
|
| + }
|
| + if( rc!=SQLITE_OK && rc!=SQLITE_IOERR_SHORT_READ ){
|
| + return rc;
|
| + }
|
| +
|
| + /* Write the nRec value into the journal file header. If in
|
| + ** full-synchronous mode, sync the journal first. This ensures that
|
| + ** all data has really hit the disk before nRec is updated to mark
|
| + ** it as a candidate for rollback.
|
| + **
|
| + ** This is not required if the persistent media supports the
|
| + ** SAFE_APPEND property. Because in this case it is not possible
|
| + ** for garbage data to be appended to the file, the nRec field
|
| + ** is populated with 0xFFFFFFFF when the journal header is written
|
| + ** and never needs to be updated.
|
| + */
|
| + if( pPager->fullSync && 0==(iDc&SQLITE_IOCAP_SEQUENTIAL) ){
|
| + PAGERTRACE(("SYNC journal of %d\n", PAGERID(pPager)));
|
| + IOTRACE(("JSYNC %p\n", pPager))
|
| + rc = sqlite3OsSync(pPager->jfd, pPager->syncFlags);
|
| + if( rc!=SQLITE_OK ) return rc;
|
| + }
|
| + IOTRACE(("JHDR %p %lld\n", pPager, pPager->journalHdr));
|
| + rc = sqlite3OsWrite(
|
| + pPager->jfd, zHeader, sizeof(zHeader), pPager->journalHdr
|
| + );
|
| + if( rc!=SQLITE_OK ) return rc;
|
| + }
|
| + if( 0==(iDc&SQLITE_IOCAP_SEQUENTIAL) ){
|
| + PAGERTRACE(("SYNC journal of %d\n", PAGERID(pPager)));
|
| + IOTRACE(("JSYNC %p\n", pPager))
|
| + rc = sqlite3OsSync(pPager->jfd, pPager->syncFlags|
|
| + (pPager->syncFlags==SQLITE_SYNC_FULL?SQLITE_SYNC_DATAONLY:0)
|
| + );
|
| + if( rc!=SQLITE_OK ) return rc;
|
| + }
|
| +
|
| + pPager->journalHdr = pPager->journalOff;
|
| + if( newHdr && 0==(iDc&SQLITE_IOCAP_SAFE_APPEND) ){
|
| + pPager->nRec = 0;
|
| + rc = writeJournalHdr(pPager);
|
| + if( rc!=SQLITE_OK ) return rc;
|
| + }
|
| + }else{
|
| + pPager->journalHdr = pPager->journalOff;
|
| + }
|
| + }
|
| +
|
| + /* Unless the pager is in noSync mode, the journal file was just
|
| + ** successfully synced. Either way, clear the PGHDR_NEED_SYNC flag on
|
| + ** all pages.
|
| + */
|
| + sqlite3PcacheClearSyncFlags(pPager->pPCache);
|
| + pPager->eState = PAGER_WRITER_DBMOD;
|
| + assert( assert_pager_state(pPager) );
|
| + return SQLITE_OK;
|
| +}
|
| +
|
| +/*
|
| +** The argument is the first in a linked list of dirty pages connected
|
| +** by the PgHdr.pDirty pointer. This function writes each one of the
|
| +** in-memory pages in the list to the database file. The argument may
|
| +** be NULL, representing an empty list. In this case this function is
|
| +** a no-op.
|
| +**
|
| +** The pager must hold at least a RESERVED lock when this function
|
| +** is called. Before writing anything to the database file, this lock
|
| +** is upgraded to an EXCLUSIVE lock. If the lock cannot be obtained,
|
| +** SQLITE_BUSY is returned and no data is written to the database file.
|
| +**
|
| +** If the pager is a temp-file pager and the actual file-system file
|
| +** is not yet open, it is created and opened before any data is
|
| +** written out.
|
| +**
|
| +** Once the lock has been upgraded and, if necessary, the file opened,
|
| +** the pages are written out to the database file in list order. Writing
|
| +** a page is skipped if it meets either of the following criteria:
|
| +**
|
| +** * The page number is greater than Pager.dbSize, or
|
| +** * The PGHDR_DONT_WRITE flag is set on the page.
|
| +**
|
| +** If writing out a page causes the database file to grow, Pager.dbFileSize
|
| +** is updated accordingly. If page 1 is written out, then the value cached
|
| +** in Pager.dbFileVers[] is updated to match the new value stored in
|
| +** the database file.
|
| +**
|
| +** If everything is successful, SQLITE_OK is returned. If an IO error
|
| +** occurs, an IO error code is returned. Or, if the EXCLUSIVE lock cannot
|
| +** be obtained, SQLITE_BUSY is returned.
|
| +*/
|
| +static int pager_write_pagelist(Pager *pPager, PgHdr *pList){
|
| + int rc = SQLITE_OK; /* Return code */
|
| +
|
| + /* This function is only called for rollback pagers in WRITER_DBMOD state. */
|
| + assert( !pagerUseWal(pPager) );
|
| + assert( pPager->eState==PAGER_WRITER_DBMOD );
|
| + assert( pPager->eLock==EXCLUSIVE_LOCK );
|
| +
|
| + /* If the file is a temp-file has not yet been opened, open it now. It
|
| + ** is not possible for rc to be other than SQLITE_OK if this branch
|
| + ** is taken, as pager_wait_on_lock() is a no-op for temp-files.
|
| + */
|
| + if( !isOpen(pPager->fd) ){
|
| + assert( pPager->tempFile && rc==SQLITE_OK );
|
| + rc = pagerOpentemp(pPager, pPager->fd, pPager->vfsFlags);
|
| + }
|
| +
|
| + /* Before the first write, give the VFS a hint of what the final
|
| + ** file size will be.
|
| + */
|
| + assert( rc!=SQLITE_OK || isOpen(pPager->fd) );
|
| + if( rc==SQLITE_OK && pPager->dbSize>pPager->dbHintSize ){
|
| + sqlite3_int64 szFile = pPager->pageSize * (sqlite3_int64)pPager->dbSize;
|
| + sqlite3OsFileControl(pPager->fd, SQLITE_FCNTL_SIZE_HINT, &szFile);
|
| + pPager->dbHintSize = pPager->dbSize;
|
| + }
|
| +
|
| + while( rc==SQLITE_OK && pList ){
|
| + Pgno pgno = pList->pgno;
|
| +
|
| + /* If there are dirty pages in the page cache with page numbers greater
|
| + ** than Pager.dbSize, this means sqlite3PagerTruncateImage() was called to
|
| + ** make the file smaller (presumably by auto-vacuum code). Do not write
|
| + ** any such pages to the file.
|
| + **
|
| + ** Also, do not write out any page that has the PGHDR_DONT_WRITE flag
|
| + ** set (set by sqlite3PagerDontWrite()).
|
| + */
|
| + if( pgno<=pPager->dbSize && 0==(pList->flags&PGHDR_DONT_WRITE) ){
|
| + i64 offset = (pgno-1)*(i64)pPager->pageSize; /* Offset to write */
|
| + char *pData; /* Data to write */
|
| +
|
| + assert( (pList->flags&PGHDR_NEED_SYNC)==0 );
|
| + if( pList->pgno==1 ) pager_write_changecounter(pList);
|
| +
|
| + /* Encode the database */
|
| + CODEC2(pPager, pList->pData, pgno, 6, return SQLITE_NOMEM, pData);
|
| +
|
| + /* Write out the page data. */
|
| + rc = sqlite3OsWrite(pPager->fd, pData, pPager->pageSize, offset);
|
| +
|
| + /* If page 1 was just written, update Pager.dbFileVers to match
|
| + ** the value now stored in the database file. If writing this
|
| + ** page caused the database file to grow, update dbFileSize.
|
| + */
|
| + if( pgno==1 ){
|
| + memcpy(&pPager->dbFileVers, &pData[24], sizeof(pPager->dbFileVers));
|
| + }
|
| + if( pgno>pPager->dbFileSize ){
|
| + pPager->dbFileSize = pgno;
|
| + }
|
| +
|
| + /* Update any backup objects copying the contents of this pager. */
|
| + sqlite3BackupUpdate(pPager->pBackup, pgno, (u8*)pList->pData);
|
| +
|
| + PAGERTRACE(("STORE %d page %d hash(%08x)\n",
|
| + PAGERID(pPager), pgno, pager_pagehash(pList)));
|
| + IOTRACE(("PGOUT %p %d\n", pPager, pgno));
|
| + PAGER_INCR(sqlite3_pager_writedb_count);
|
| + PAGER_INCR(pPager->nWrite);
|
| + }else{
|
| + PAGERTRACE(("NOSTORE %d page %d\n", PAGERID(pPager), pgno));
|
| + }
|
| + pager_set_pagehash(pList);
|
| + pList = pList->pDirty;
|
| + }
|
| +
|
| + return rc;
|
| +}
|
| +
|
| +/*
|
| +** Ensure that the sub-journal file is open. If it is already open, this
|
| +** function is a no-op.
|
| +**
|
| +** SQLITE_OK is returned if everything goes according to plan. An
|
| +** SQLITE_IOERR_XXX error code is returned if a call to sqlite3OsOpen()
|
| +** fails.
|
| +*/
|
| +static int openSubJournal(Pager *pPager){
|
| + int rc = SQLITE_OK;
|
| + if( !isOpen(pPager->sjfd) ){
|
| + if( pPager->journalMode==PAGER_JOURNALMODE_MEMORY || pPager->subjInMemory ){
|
| + sqlite3MemJournalOpen(pPager->sjfd);
|
| + }else{
|
| + rc = pagerOpentemp(pPager, pPager->sjfd, SQLITE_OPEN_SUBJOURNAL);
|
| + }
|
| + }
|
| + return rc;
|
| +}
|
| +
|
| +/*
|
| +** Append a record of the current state of page pPg to the sub-journal.
|
| +** It is the callers responsibility to use subjRequiresPage() to check
|
| +** that it is really required before calling this function.
|
| +**
|
| +** If successful, set the bit corresponding to pPg->pgno in the bitvecs
|
| +** for all open savepoints before returning.
|
| +**
|
| +** This function returns SQLITE_OK if everything is successful, an IO
|
| +** error code if the attempt to write to the sub-journal fails, or
|
| +** SQLITE_NOMEM if a malloc fails while setting a bit in a savepoint
|
| +** bitvec.
|
| +*/
|
| +static int subjournalPage(PgHdr *pPg){
|
| + int rc = SQLITE_OK;
|
| + Pager *pPager = pPg->pPager;
|
| + if( pPager->journalMode!=PAGER_JOURNALMODE_OFF ){
|
| +
|
| + /* Open the sub-journal, if it has not already been opened */
|
| + assert( pPager->useJournal );
|
| + assert( isOpen(pPager->jfd) || pagerUseWal(pPager) );
|
| + assert( isOpen(pPager->sjfd) || pPager->nSubRec==0 );
|
| + assert( pagerUseWal(pPager)
|
| + || pageInJournal(pPg)
|
| + || pPg->pgno>pPager->dbOrigSize
|
| + );
|
| + rc = openSubJournal(pPager);
|
| +
|
| + /* If the sub-journal was opened successfully (or was already open),
|
| + ** write the journal record into the file. */
|
| + if( rc==SQLITE_OK ){
|
| + void *pData = pPg->pData;
|
| + i64 offset = pPager->nSubRec*(4+pPager->pageSize);
|
| + char *pData2;
|
| +
|
| + CODEC2(pPager, pData, pPg->pgno, 7, return SQLITE_NOMEM, pData2);
|
| + PAGERTRACE(("STMT-JOURNAL %d page %d\n", PAGERID(pPager), pPg->pgno));
|
| + rc = write32bits(pPager->sjfd, offset, pPg->pgno);
|
| + if( rc==SQLITE_OK ){
|
| + rc = sqlite3OsWrite(pPager->sjfd, pData2, pPager->pageSize, offset+4);
|
| + }
|
| + }
|
| + }
|
| + if( rc==SQLITE_OK ){
|
| + pPager->nSubRec++;
|
| + assert( pPager->nSavepoint>0 );
|
| + rc = addToSavepointBitvecs(pPager, pPg->pgno);
|
| + }
|
| + return rc;
|
| +}
|
| +
|
| +/*
|
| +** This function is called by the pcache layer when it has reached some
|
| +** soft memory limit. The first argument is a pointer to a Pager object
|
| +** (cast as a void*). The pager is always 'purgeable' (not an in-memory
|
| +** database). The second argument is a reference to a page that is
|
| +** currently dirty but has no outstanding references. The page
|
| +** is always associated with the Pager object passed as the first
|
| +** argument.
|
| +**
|
| +** The job of this function is to make pPg clean by writing its contents
|
| +** out to the database file, if possible. This may involve syncing the
|
| +** journal file.
|
| +**
|
| +** If successful, sqlite3PcacheMakeClean() is called on the page and
|
| +** SQLITE_OK returned. If an IO error occurs while trying to make the
|
| +** page clean, the IO error code is returned. If the page cannot be
|
| +** made clean for some other reason, but no error occurs, then SQLITE_OK
|
| +** is returned by sqlite3PcacheMakeClean() is not called.
|
| +*/
|
| +static int pagerStress(void *p, PgHdr *pPg){
|
| + Pager *pPager = (Pager *)p;
|
| + int rc = SQLITE_OK;
|
| +
|
| + assert( pPg->pPager==pPager );
|
| + assert( pPg->flags&PGHDR_DIRTY );
|
| +
|
| + /* The doNotSyncSpill flag is set during times when doing a sync of
|
| + ** journal (and adding a new header) is not allowed. This occurs
|
| + ** during calls to sqlite3PagerWrite() while trying to journal multiple
|
| + ** pages belonging to the same sector.
|
| + **
|
| + ** The doNotSpill flag inhibits all cache spilling regardless of whether
|
| + ** or not a sync is required. This is set during a rollback.
|
| + **
|
| + ** Spilling is also prohibited when in an error state since that could
|
| + ** lead to database corruption. In the current implementaton it
|
| + ** is impossible for sqlite3PCacheFetch() to be called with createFlag==1
|
| + ** while in the error state, hence it is impossible for this routine to
|
| + ** be called in the error state. Nevertheless, we include a NEVER()
|
| + ** test for the error state as a safeguard against future changes.
|
| + */
|
| + if( NEVER(pPager->errCode) ) return SQLITE_OK;
|
| + if( pPager->doNotSpill ) return SQLITE_OK;
|
| + if( pPager->doNotSyncSpill && (pPg->flags & PGHDR_NEED_SYNC)!=0 ){
|
| + return SQLITE_OK;
|
| + }
|
| +
|
| + pPg->pDirty = 0;
|
| + if( pagerUseWal(pPager) ){
|
| + /* Write a single frame for this page to the log. */
|
| + if( subjRequiresPage(pPg) ){
|
| + rc = subjournalPage(pPg);
|
| + }
|
| + if( rc==SQLITE_OK ){
|
| + rc = pagerWalFrames(pPager, pPg, 0, 0, 0);
|
| + }
|
| + }else{
|
| +
|
| + /* Sync the journal file if required. */
|
| + if( pPg->flags&PGHDR_NEED_SYNC
|
| + || pPager->eState==PAGER_WRITER_CACHEMOD
|
| + ){
|
| + rc = syncJournal(pPager, 1);
|
| + }
|
| +
|
| + /* If the page number of this page is larger than the current size of
|
| + ** the database image, it may need to be written to the sub-journal.
|
| + ** This is because the call to pager_write_pagelist() below will not
|
| + ** actually write data to the file in this case.
|
| + **
|
| + ** Consider the following sequence of events:
|
| + **
|
| + ** BEGIN;
|
| + ** <journal page X>
|
| + ** <modify page X>
|
| + ** SAVEPOINT sp;
|
| + ** <shrink database file to Y pages>
|
| + ** pagerStress(page X)
|
| + ** ROLLBACK TO sp;
|
| + **
|
| + ** If (X>Y), then when pagerStress is called page X will not be written
|
| + ** out to the database file, but will be dropped from the cache. Then,
|
| + ** following the "ROLLBACK TO sp" statement, reading page X will read
|
| + ** data from the database file. This will be the copy of page X as it
|
| + ** was when the transaction started, not as it was when "SAVEPOINT sp"
|
| + ** was executed.
|
| + **
|
| + ** The solution is to write the current data for page X into the
|
| + ** sub-journal file now (if it is not already there), so that it will
|
| + ** be restored to its current value when the "ROLLBACK TO sp" is
|
| + ** executed.
|
| + */
|
| + if( NEVER(
|
| + rc==SQLITE_OK && pPg->pgno>pPager->dbSize && subjRequiresPage(pPg)
|
| + ) ){
|
| + rc = subjournalPage(pPg);
|
| + }
|
| +
|
| + /* Write the contents of the page out to the database file. */
|
| + if( rc==SQLITE_OK ){
|
| + assert( (pPg->flags&PGHDR_NEED_SYNC)==0 );
|
| + rc = pager_write_pagelist(pPager, pPg);
|
| + }
|
| + }
|
| +
|
| + /* Mark the page as clean. */
|
| + if( rc==SQLITE_OK ){
|
| + PAGERTRACE(("STRESS %d page %d\n", PAGERID(pPager), pPg->pgno));
|
| + sqlite3PcacheMakeClean(pPg);
|
| + }
|
| +
|
| + return pager_error(pPager, rc);
|
| +}
|
| +
|
| +
|
| +/*
|
| +** Allocate and initialize a new Pager object and put a pointer to it
|
| +** in *ppPager. The pager should eventually be freed by passing it
|
| +** to sqlite3PagerClose().
|
| +**
|
| +** The zFilename argument is the path to the database file to open.
|
| +** If zFilename is NULL then a randomly-named temporary file is created
|
| +** and used as the file to be cached. Temporary files are be deleted
|
| +** automatically when they are closed. If zFilename is ":memory:" then
|
| +** all information is held in cache. It is never written to disk.
|
| +** This can be used to implement an in-memory database.
|
| +**
|
| +** The nExtra parameter specifies the number of bytes of space allocated
|
| +** along with each page reference. This space is available to the user
|
| +** via the sqlite3PagerGetExtra() API.
|
| +**
|
| +** The flags argument is used to specify properties that affect the
|
| +** operation of the pager. It should be passed some bitwise combination
|
| +** of the PAGER_OMIT_JOURNAL and PAGER_NO_READLOCK flags.
|
| +**
|
| +** The vfsFlags parameter is a bitmask to pass to the flags parameter
|
| +** of the xOpen() method of the supplied VFS when opening files.
|
| +**
|
| +** If the pager object is allocated and the specified file opened
|
| +** successfully, SQLITE_OK is returned and *ppPager set to point to
|
| +** the new pager object. If an error occurs, *ppPager is set to NULL
|
| +** and error code returned. This function may return SQLITE_NOMEM
|
| +** (sqlite3Malloc() is used to allocate memory), SQLITE_CANTOPEN or
|
| +** various SQLITE_IO_XXX errors.
|
| +*/
|
| +int sqlite3PagerOpen(
|
| + sqlite3_vfs *pVfs, /* The virtual file system to use */
|
| + Pager **ppPager, /* OUT: Return the Pager structure here */
|
| + const char *zFilename, /* Name of the database file to open */
|
| + int nExtra, /* Extra bytes append to each in-memory page */
|
| + int flags, /* flags controlling this file */
|
| + int vfsFlags, /* flags passed through to sqlite3_vfs.xOpen() */
|
| + void (*xReinit)(DbPage*) /* Function to reinitialize pages */
|
| +){
|
| + u8 *pPtr;
|
| + Pager *pPager = 0; /* Pager object to allocate and return */
|
| + int rc = SQLITE_OK; /* Return code */
|
| + int tempFile = 0; /* True for temp files (incl. in-memory files) */
|
| + int memDb = 0; /* True if this is an in-memory file */
|
| + int readOnly = 0; /* True if this is a read-only file */
|
| + int journalFileSize; /* Bytes to allocate for each journal fd */
|
| + char *zPathname = 0; /* Full path to database file */
|
| + int nPathname = 0; /* Number of bytes in zPathname */
|
| + int useJournal = (flags & PAGER_OMIT_JOURNAL)==0; /* False to omit journal */
|
| + int noReadlock = (flags & PAGER_NO_READLOCK)!=0; /* True to omit read-lock */
|
| + int pcacheSize = sqlite3PcacheSize(); /* Bytes to allocate for PCache */
|
| + u32 szPageDflt = SQLITE_DEFAULT_PAGE_SIZE; /* Default page size */
|
| +
|
| + /* Figure out how much space is required for each journal file-handle
|
| + ** (there are two of them, the main journal and the sub-journal). This
|
| + ** is the maximum space required for an in-memory journal file handle
|
| + ** and a regular journal file-handle. Note that a "regular journal-handle"
|
| + ** may be a wrapper capable of caching the first portion of the journal
|
| + ** file in memory to implement the atomic-write optimization (see
|
| + ** source file journal.c).
|
| + */
|
| + if( sqlite3JournalSize(pVfs)>sqlite3MemJournalSize() ){
|
| + journalFileSize = ROUND8(sqlite3JournalSize(pVfs));
|
| + }else{
|
| + journalFileSize = ROUND8(sqlite3MemJournalSize());
|
| + }
|
| +
|
| + /* Set the output variable to NULL in case an error occurs. */
|
| + *ppPager = 0;
|
| +
|
| +#ifndef SQLITE_OMIT_MEMORYDB
|
| + if( flags & PAGER_MEMORY ){
|
| + memDb = 1;
|
| + zFilename = 0;
|
| + }
|
| +#endif
|
| +
|
| + /* Compute and store the full pathname in an allocated buffer pointed
|
| + ** to by zPathname, length nPathname. Or, if this is a temporary file,
|
| + ** leave both nPathname and zPathname set to 0.
|
| + */
|
| + if( zFilename && zFilename[0] ){
|
| + nPathname = pVfs->mxPathname+1;
|
| + zPathname = sqlite3Malloc(nPathname*2);
|
| + if( zPathname==0 ){
|
| + return SQLITE_NOMEM;
|
| + }
|
| + zPathname[0] = 0; /* Make sure initialized even if FullPathname() fails */
|
| + rc = sqlite3OsFullPathname(pVfs, zFilename, nPathname, zPathname);
|
| + nPathname = sqlite3Strlen30(zPathname);
|
| + if( rc==SQLITE_OK && nPathname+8>pVfs->mxPathname ){
|
| + /* This branch is taken when the journal path required by
|
| + ** the database being opened will be more than pVfs->mxPathname
|
| + ** bytes in length. This means the database cannot be opened,
|
| + ** as it will not be possible to open the journal file or even
|
| + ** check for a hot-journal before reading.
|
| + */
|
| + rc = SQLITE_CANTOPEN_BKPT;
|
| + }
|
| + if( rc!=SQLITE_OK ){
|
| + sqlite3_free(zPathname);
|
| + return rc;
|
| + }
|
| + }
|
| +
|
| + /* Allocate memory for the Pager structure, PCache object, the
|
| + ** three file descriptors, the database file name and the journal
|
| + ** file name. The layout in memory is as follows:
|
| + **
|
| + ** Pager object (sizeof(Pager) bytes)
|
| + ** PCache object (sqlite3PcacheSize() bytes)
|
| + ** Database file handle (pVfs->szOsFile bytes)
|
| + ** Sub-journal file handle (journalFileSize bytes)
|
| + ** Main journal file handle (journalFileSize bytes)
|
| + ** Database file name (nPathname+1 bytes)
|
| + ** Journal file name (nPathname+8+1 bytes)
|
| + */
|
| + pPtr = (u8 *)sqlite3MallocZero(
|
| + ROUND8(sizeof(*pPager)) + /* Pager structure */
|
| + ROUND8(pcacheSize) + /* PCache object */
|
| + ROUND8(pVfs->szOsFile) + /* The main db file */
|
| + journalFileSize * 2 + /* The two journal files */
|
| + nPathname + 1 + /* zFilename */
|
| + nPathname + 8 + 1 /* zJournal */
|
| +#ifndef SQLITE_OMIT_WAL
|
| + + nPathname + 4 + 1 /* zWal */
|
| +#endif
|
| + );
|
| + assert( EIGHT_BYTE_ALIGNMENT(SQLITE_INT_TO_PTR(journalFileSize)) );
|
| + if( !pPtr ){
|
| + sqlite3_free(zPathname);
|
| + return SQLITE_NOMEM;
|
| + }
|
| + pPager = (Pager*)(pPtr);
|
| + pPager->pPCache = (PCache*)(pPtr += ROUND8(sizeof(*pPager)));
|
| + pPager->fd = (sqlite3_file*)(pPtr += ROUND8(pcacheSize));
|
| + pPager->sjfd = (sqlite3_file*)(pPtr += ROUND8(pVfs->szOsFile));
|
| + pPager->jfd = (sqlite3_file*)(pPtr += journalFileSize);
|
| + pPager->zFilename = (char*)(pPtr += journalFileSize);
|
| + assert( EIGHT_BYTE_ALIGNMENT(pPager->jfd) );
|
| +
|
| + /* Fill in the Pager.zFilename and Pager.zJournal buffers, if required. */
|
| + if( zPathname ){
|
| + assert( nPathname>0 );
|
| + pPager->zJournal = (char*)(pPtr += nPathname + 1);
|
| + memcpy(pPager->zFilename, zPathname, nPathname);
|
| + memcpy(pPager->zJournal, zPathname, nPathname);
|
| + memcpy(&pPager->zJournal[nPathname], "-journal", 8);
|
| +#ifndef SQLITE_OMIT_WAL
|
| + pPager->zWal = &pPager->zJournal[nPathname+8+1];
|
| + memcpy(pPager->zWal, zPathname, nPathname);
|
| + memcpy(&pPager->zWal[nPathname], "-wal", 4);
|
| +#endif
|
| + sqlite3_free(zPathname);
|
| + }
|
| + pPager->pVfs = pVfs;
|
| + pPager->vfsFlags = vfsFlags;
|
| +
|
| + /* Open the pager file.
|
| + */
|
| + if( zFilename && zFilename[0] ){
|
| + int fout = 0; /* VFS flags returned by xOpen() */
|
| + rc = sqlite3OsOpen(pVfs, pPager->zFilename, pPager->fd, vfsFlags, &fout);
|
| + assert( !memDb );
|
| + readOnly = (fout&SQLITE_OPEN_READONLY);
|
| +
|
| + /* If the file was successfully opened for read/write access,
|
| + ** choose a default page size in case we have to create the
|
| + ** database file. The default page size is the maximum of:
|
| + **
|
| + ** + SQLITE_DEFAULT_PAGE_SIZE,
|
| + ** + The value returned by sqlite3OsSectorSize()
|
| + ** + The largest page size that can be written atomically.
|
| + */
|
| + if( rc==SQLITE_OK && !readOnly ){
|
| + setSectorSize(pPager);
|
| + assert(SQLITE_DEFAULT_PAGE_SIZE<=SQLITE_MAX_DEFAULT_PAGE_SIZE);
|
| + if( szPageDflt<pPager->sectorSize ){
|
| + if( pPager->sectorSize>SQLITE_MAX_DEFAULT_PAGE_SIZE ){
|
| + szPageDflt = SQLITE_MAX_DEFAULT_PAGE_SIZE;
|
| + }else{
|
| + szPageDflt = (u32)pPager->sectorSize;
|
| + }
|
| + }
|
| +#ifdef SQLITE_ENABLE_ATOMIC_WRITE
|
| + {
|
| + int iDc = sqlite3OsDeviceCharacteristics(pPager->fd);
|
| + int ii;
|
| + assert(SQLITE_IOCAP_ATOMIC512==(512>>8));
|
| + assert(SQLITE_IOCAP_ATOMIC64K==(65536>>8));
|
| + assert(SQLITE_MAX_DEFAULT_PAGE_SIZE<=65536);
|
| + for(ii=szPageDflt; ii<=SQLITE_MAX_DEFAULT_PAGE_SIZE; ii=ii*2){
|
| + if( iDc&(SQLITE_IOCAP_ATOMIC|(ii>>8)) ){
|
| + szPageDflt = ii;
|
| + }
|
| + }
|
| + }
|
| +#endif
|
| + }
|
| + }else{
|
| + /* If a temporary file is requested, it is not opened immediately.
|
| + ** In this case we accept the default page size and delay actually
|
| + ** opening the file until the first call to OsWrite().
|
| + **
|
| + ** This branch is also run for an in-memory database. An in-memory
|
| + ** database is the same as a temp-file that is never written out to
|
| + ** disk and uses an in-memory rollback journal.
|
| + */
|
| + tempFile = 1;
|
| + pPager->eState = PAGER_READER;
|
| + pPager->eLock = EXCLUSIVE_LOCK;
|
| + readOnly = (vfsFlags&SQLITE_OPEN_READONLY);
|
| + }
|
| +
|
| + /* The following call to PagerSetPagesize() serves to set the value of
|
| + ** Pager.pageSize and to allocate the Pager.pTmpSpace buffer.
|
| + */
|
| + if( rc==SQLITE_OK ){
|
| + assert( pPager->memDb==0 );
|
| + rc = sqlite3PagerSetPagesize(pPager, &szPageDflt, -1);
|
| + testcase( rc!=SQLITE_OK );
|
| + }
|
| +
|
| + /* If an error occurred in either of the blocks above, free the
|
| + ** Pager structure and close the file.
|
| + */
|
| + if( rc!=SQLITE_OK ){
|
| + assert( !pPager->pTmpSpace );
|
| + sqlite3OsClose(pPager->fd);
|
| + sqlite3_free(pPager);
|
| + return rc;
|
| + }
|
| +
|
| + /* Initialize the PCache object. */
|
| + assert( nExtra<1000 );
|
| + nExtra = ROUND8(nExtra);
|
| + sqlite3PcacheOpen(szPageDflt, nExtra, !memDb,
|
| + !memDb?pagerStress:0, (void *)pPager, pPager->pPCache);
|
| +
|
| + PAGERTRACE(("OPEN %d %s\n", FILEHANDLEID(pPager->fd), pPager->zFilename));
|
| + IOTRACE(("OPEN %p %s\n", pPager, pPager->zFilename))
|
| +
|
| + pPager->useJournal = (u8)useJournal;
|
| + pPager->noReadlock = (noReadlock && readOnly) ?1:0;
|
| + /* pPager->stmtOpen = 0; */
|
| + /* pPager->stmtInUse = 0; */
|
| + /* pPager->nRef = 0; */
|
| + /* pPager->stmtSize = 0; */
|
| + /* pPager->stmtJSize = 0; */
|
| + /* pPager->nPage = 0; */
|
| + pPager->mxPgno = SQLITE_MAX_PAGE_COUNT;
|
| + /* pPager->state = PAGER_UNLOCK; */
|
| +#if 0
|
| + assert( pPager->state == (tempFile ? PAGER_EXCLUSIVE : PAGER_UNLOCK) );
|
| +#endif
|
| + /* pPager->errMask = 0; */
|
| + pPager->tempFile = (u8)tempFile;
|
| + assert( tempFile==PAGER_LOCKINGMODE_NORMAL
|
| + || tempFile==PAGER_LOCKINGMODE_EXCLUSIVE );
|
| + assert( PAGER_LOCKINGMODE_EXCLUSIVE==1 );
|
| + pPager->exclusiveMode = (u8)tempFile;
|
| + pPager->changeCountDone = pPager->tempFile;
|
| + pPager->memDb = (u8)memDb;
|
| + pPager->readOnly = (u8)readOnly;
|
| + assert( useJournal || pPager->tempFile );
|
| + pPager->noSync = pPager->tempFile;
|
| + pPager->fullSync = pPager->noSync ?0:1;
|
| + pPager->syncFlags = pPager->noSync ? 0 : SQLITE_SYNC_NORMAL;
|
| + pPager->ckptSyncFlags = pPager->syncFlags;
|
| + /* pPager->pFirst = 0; */
|
| + /* pPager->pFirstSynced = 0; */
|
| + /* pPager->pLast = 0; */
|
| + pPager->nExtra = (u16)nExtra;
|
| + pPager->journalSizeLimit = SQLITE_DEFAULT_JOURNAL_SIZE_LIMIT;
|
| + assert( isOpen(pPager->fd) || tempFile );
|
| + setSectorSize(pPager);
|
| + if( !useJournal ){
|
| + pPager->journalMode = PAGER_JOURNALMODE_OFF;
|
| + }else if( memDb ){
|
| + pPager->journalMode = PAGER_JOURNALMODE_MEMORY;
|
| + }
|
| + /* pPager->xBusyHandler = 0; */
|
| + /* pPager->pBusyHandlerArg = 0; */
|
| + pPager->xReiniter = xReinit;
|
| + /* memset(pPager->aHash, 0, sizeof(pPager->aHash)); */
|
| +
|
| + *ppPager = pPager;
|
| + return SQLITE_OK;
|
| +}
|
| +
|
| +
|
| +
|
| +/*
|
| +** This function is called after transitioning from PAGER_UNLOCK to
|
| +** PAGER_SHARED state. It tests if there is a hot journal present in
|
| +** the file-system for the given pager. A hot journal is one that
|
| +** needs to be played back. According to this function, a hot-journal
|
| +** file exists if the following criteria are met:
|
| +**
|
| +** * The journal file exists in the file system, and
|
| +** * No process holds a RESERVED or greater lock on the database file, and
|
| +** * The database file itself is greater than 0 bytes in size, and
|
| +** * The first byte of the journal file exists and is not 0x00.
|
| +**
|
| +** If the current size of the database file is 0 but a journal file
|
| +** exists, that is probably an old journal left over from a prior
|
| +** database with the same name. In this case the journal file is
|
| +** just deleted using OsDelete, *pExists is set to 0 and SQLITE_OK
|
| +** is returned.
|
| +**
|
| +** This routine does not check if there is a master journal filename
|
| +** at the end of the file. If there is, and that master journal file
|
| +** does not exist, then the journal file is not really hot. In this
|
| +** case this routine will return a false-positive. The pager_playback()
|
| +** routine will discover that the journal file is not really hot and
|
| +** will not roll it back.
|
| +**
|
| +** If a hot-journal file is found to exist, *pExists is set to 1 and
|
| +** SQLITE_OK returned. If no hot-journal file is present, *pExists is
|
| +** set to 0 and SQLITE_OK returned. If an IO error occurs while trying
|
| +** to determine whether or not a hot-journal file exists, the IO error
|
| +** code is returned and the value of *pExists is undefined.
|
| +*/
|
| +static int hasHotJournal(Pager *pPager, int *pExists){
|
| + sqlite3_vfs * const pVfs = pPager->pVfs;
|
| + int rc = SQLITE_OK; /* Return code */
|
| + int exists = 1; /* True if a journal file is present */
|
| + int jrnlOpen = !!isOpen(pPager->jfd);
|
| +
|
| + assert( pPager->useJournal );
|
| + assert( isOpen(pPager->fd) );
|
| + assert( pPager->eState==PAGER_OPEN );
|
| +
|
| + assert( jrnlOpen==0 || ( sqlite3OsDeviceCharacteristics(pPager->jfd) &
|
| + SQLITE_IOCAP_UNDELETABLE_WHEN_OPEN
|
| + ));
|
| +
|
| + *pExists = 0;
|
| + if( !jrnlOpen ){
|
| + rc = sqlite3OsAccess(pVfs, pPager->zJournal, SQLITE_ACCESS_EXISTS, &exists);
|
| + }
|
| + if( rc==SQLITE_OK && exists ){
|
| + int locked = 0; /* True if some process holds a RESERVED lock */
|
| +
|
| + /* Race condition here: Another process might have been holding the
|
| + ** the RESERVED lock and have a journal open at the sqlite3OsAccess()
|
| + ** call above, but then delete the journal and drop the lock before
|
| + ** we get to the following sqlite3OsCheckReservedLock() call. If that
|
| + ** is the case, this routine might think there is a hot journal when
|
| + ** in fact there is none. This results in a false-positive which will
|
| + ** be dealt with by the playback routine. Ticket #3883.
|
| + */
|
| + rc = sqlite3OsCheckReservedLock(pPager->fd, &locked);
|
| + if( rc==SQLITE_OK && !locked ){
|
| + Pgno nPage; /* Number of pages in database file */
|
| +
|
| + /* Check the size of the database file. If it consists of 0 pages,
|
| + ** then delete the journal file. See the header comment above for
|
| + ** the reasoning here. Delete the obsolete journal file under
|
| + ** a RESERVED lock to avoid race conditions and to avoid violating
|
| + ** [H33020].
|
| + */
|
| + rc = pagerPagecount(pPager, &nPage);
|
| + if( rc==SQLITE_OK ){
|
| + if( nPage==0 ){
|
| + sqlite3BeginBenignMalloc();
|
| + if( pagerLockDb(pPager, RESERVED_LOCK)==SQLITE_OK ){
|
| + sqlite3OsDelete(pVfs, pPager->zJournal, 0);
|
| + if( !pPager->exclusiveMode ) pagerUnlockDb(pPager, SHARED_LOCK);
|
| + }
|
| + sqlite3EndBenignMalloc();
|
| + }else{
|
| + /* The journal file exists and no other connection has a reserved
|
| + ** or greater lock on the database file. Now check that there is
|
| + ** at least one non-zero bytes at the start of the journal file.
|
| + ** If there is, then we consider this journal to be hot. If not,
|
| + ** it can be ignored.
|
| + */
|
| + if( !jrnlOpen ){
|
| + int f = SQLITE_OPEN_READONLY|SQLITE_OPEN_MAIN_JOURNAL;
|
| + rc = sqlite3OsOpen(pVfs, pPager->zJournal, pPager->jfd, f, &f);
|
| + }
|
| + if( rc==SQLITE_OK ){
|
| + u8 first = 0;
|
| + rc = sqlite3OsRead(pPager->jfd, (void *)&first, 1, 0);
|
| + if( rc==SQLITE_IOERR_SHORT_READ ){
|
| + rc = SQLITE_OK;
|
| + }
|
| + if( !jrnlOpen ){
|
| + sqlite3OsClose(pPager->jfd);
|
| + }
|
| + *pExists = (first!=0);
|
| + }else if( rc==SQLITE_CANTOPEN ){
|
| + /* If we cannot open the rollback journal file in order to see if
|
| + ** its has a zero header, that might be due to an I/O error, or
|
| + ** it might be due to the race condition described above and in
|
| + ** ticket #3883. Either way, assume that the journal is hot.
|
| + ** This might be a false positive. But if it is, then the
|
| + ** automatic journal playback and recovery mechanism will deal
|
| + ** with it under an EXCLUSIVE lock where we do not need to
|
| + ** worry so much with race conditions.
|
| + */
|
| + *pExists = 1;
|
| + rc = SQLITE_OK;
|
| + }
|
| + }
|
| + }
|
| + }
|
| + }
|
| +
|
| + return rc;
|
| +}
|
| +
|
| +/*
|
| +** This function is called to obtain a shared lock on the database file.
|
| +** It is illegal to call sqlite3PagerAcquire() until after this function
|
| +** has been successfully called. If a shared-lock is already held when
|
| +** this function is called, it is a no-op.
|
| +**
|
| +** The following operations are also performed by this function.
|
| +**
|
| +** 1) If the pager is currently in PAGER_OPEN state (no lock held
|
| +** on the database file), then an attempt is made to obtain a
|
| +** SHARED lock on the database file. Immediately after obtaining
|
| +** the SHARED lock, the file-system is checked for a hot-journal,
|
| +** which is played back if present. Following any hot-journal
|
| +** rollback, the contents of the cache are validated by checking
|
| +** the 'change-counter' field of the database file header and
|
| +** discarded if they are found to be invalid.
|
| +**
|
| +** 2) If the pager is running in exclusive-mode, and there are currently
|
| +** no outstanding references to any pages, and is in the error state,
|
| +** then an attempt is made to clear the error state by discarding
|
| +** the contents of the page cache and rolling back any open journal
|
| +** file.
|
| +**
|
| +** If everything is successful, SQLITE_OK is returned. If an IO error
|
| +** occurs while locking the database, checking for a hot-journal file or
|
| +** rolling back a journal file, the IO error code is returned.
|
| +*/
|
| +int sqlite3PagerSharedLock(Pager *pPager){
|
| + int rc = SQLITE_OK; /* Return code */
|
| +
|
| + /* This routine is only called from b-tree and only when there are no
|
| + ** outstanding pages. This implies that the pager state should either
|
| + ** be OPEN or READER. READER is only possible if the pager is or was in
|
| + ** exclusive access mode.
|
| + */
|
| + assert( sqlite3PcacheRefCount(pPager->pPCache)==0 );
|
| + assert( assert_pager_state(pPager) );
|
| + assert( pPager->eState==PAGER_OPEN || pPager->eState==PAGER_READER );
|
| + if( NEVER(MEMDB && pPager->errCode) ){ return pPager->errCode; }
|
| +
|
| + if( !pagerUseWal(pPager) && pPager->eState==PAGER_OPEN ){
|
| + int bHotJournal = 1; /* True if there exists a hot journal-file */
|
| +
|
| + assert( !MEMDB );
|
| + assert( pPager->noReadlock==0 || pPager->readOnly );
|
| +
|
| + if( pPager->noReadlock==0 ){
|
| + rc = pager_wait_on_lock(pPager, SHARED_LOCK);
|
| + if( rc!=SQLITE_OK ){
|
| + assert( pPager->eLock==NO_LOCK || pPager->eLock==UNKNOWN_LOCK );
|
| + goto failed;
|
| + }
|
| + }
|
| +
|
| + /* If a journal file exists, and there is no RESERVED lock on the
|
| + ** database file, then it either needs to be played back or deleted.
|
| + */
|
| + if( pPager->eLock<=SHARED_LOCK ){
|
| + rc = hasHotJournal(pPager, &bHotJournal);
|
| + }
|
| + if( rc!=SQLITE_OK ){
|
| + goto failed;
|
| + }
|
| + if( bHotJournal ){
|
| + /* Get an EXCLUSIVE lock on the database file. At this point it is
|
| + ** important that a RESERVED lock is not obtained on the way to the
|
| + ** EXCLUSIVE lock. If it were, another process might open the
|
| + ** database file, detect the RESERVED lock, and conclude that the
|
| + ** database is safe to read while this process is still rolling the
|
| + ** hot-journal back.
|
| + **
|
| + ** Because the intermediate RESERVED lock is not requested, any
|
| + ** other process attempting to access the database file will get to
|
| + ** this point in the code and fail to obtain its own EXCLUSIVE lock
|
| + ** on the database file.
|
| + **
|
| + ** Unless the pager is in locking_mode=exclusive mode, the lock is
|
| + ** downgraded to SHARED_LOCK before this function returns.
|
| + */
|
| + rc = pagerLockDb(pPager, EXCLUSIVE_LOCK);
|
| + if( rc!=SQLITE_OK ){
|
| + goto failed;
|
| + }
|
| +
|
| + /* If it is not already open and the file exists on disk, open the
|
| + ** journal for read/write access. Write access is required because
|
| + ** in exclusive-access mode the file descriptor will be kept open
|
| + ** and possibly used for a transaction later on. Also, write-access
|
| + ** is usually required to finalize the journal in journal_mode=persist
|
| + ** mode (and also for journal_mode=truncate on some systems).
|
| + **
|
| + ** If the journal does not exist, it usually means that some
|
| + ** other connection managed to get in and roll it back before
|
| + ** this connection obtained the exclusive lock above. Or, it
|
| + ** may mean that the pager was in the error-state when this
|
| + ** function was called and the journal file does not exist.
|
| + */
|
| + if( !isOpen(pPager->jfd) ){
|
| + sqlite3_vfs * const pVfs = pPager->pVfs;
|
| + int bExists; /* True if journal file exists */
|
| + rc = sqlite3OsAccess(
|
| + pVfs, pPager->zJournal, SQLITE_ACCESS_EXISTS, &bExists);
|
| + if( rc==SQLITE_OK && bExists ){
|
| + int fout = 0;
|
| + int f = SQLITE_OPEN_READWRITE|SQLITE_OPEN_MAIN_JOURNAL;
|
| + assert( !pPager->tempFile );
|
| + rc = sqlite3OsOpen(pVfs, pPager->zJournal, pPager->jfd, f, &fout);
|
| + assert( rc!=SQLITE_OK || isOpen(pPager->jfd) );
|
| + if( rc==SQLITE_OK && fout&SQLITE_OPEN_READONLY ){
|
| + rc = SQLITE_CANTOPEN_BKPT;
|
| + sqlite3OsClose(pPager->jfd);
|
| + }
|
| + }
|
| + }
|
| +
|
| + /* Playback and delete the journal. Drop the database write
|
| + ** lock and reacquire the read lock. Purge the cache before
|
| + ** playing back the hot-journal so that we don't end up with
|
| + ** an inconsistent cache. Sync the hot journal before playing
|
| + ** it back since the process that crashed and left the hot journal
|
| + ** probably did not sync it and we are required to always sync
|
| + ** the journal before playing it back.
|
| + */
|
| + if( isOpen(pPager->jfd) ){
|
| + assert( rc==SQLITE_OK );
|
| + rc = pagerSyncHotJournal(pPager);
|
| + if( rc==SQLITE_OK ){
|
| + rc = pager_playback(pPager, 1);
|
| + pPager->eState = PAGER_OPEN;
|
| + }
|
| + }else if( !pPager->exclusiveMode ){
|
| + pagerUnlockDb(pPager, SHARED_LOCK);
|
| + }
|
| +
|
| + if( rc!=SQLITE_OK ){
|
| + /* This branch is taken if an error occurs while trying to open
|
| + ** or roll back a hot-journal while holding an EXCLUSIVE lock. The
|
| + ** pager_unlock() routine will be called before returning to unlock
|
| + ** the file. If the unlock attempt fails, then Pager.eLock must be
|
| + ** set to UNKNOWN_LOCK (see the comment above the #define for
|
| + ** UNKNOWN_LOCK above for an explanation).
|
| + **
|
| + ** In order to get pager_unlock() to do this, set Pager.eState to
|
| + ** PAGER_ERROR now. This is not actually counted as a transition
|
| + ** to ERROR state in the state diagram at the top of this file,
|
| + ** since we know that the same call to pager_unlock() will very
|
| + ** shortly transition the pager object to the OPEN state. Calling
|
| + ** assert_pager_state() would fail now, as it should not be possible
|
| + ** to be in ERROR state when there are zero outstanding page
|
| + ** references.
|
| + */
|
| + pager_error(pPager, rc);
|
| + goto failed;
|
| + }
|
| +
|
| + assert( pPager->eState==PAGER_OPEN );
|
| + assert( (pPager->eLock==SHARED_LOCK)
|
| + || (pPager->exclusiveMode && pPager->eLock>SHARED_LOCK)
|
| + );
|
| + }
|
| +
|
| + if( !pPager->tempFile
|
| + && (pPager->pBackup || sqlite3PcachePagecount(pPager->pPCache)>0)
|
| + ){
|
| + /* The shared-lock has just been acquired on the database file
|
| + ** and there are already pages in the cache (from a previous
|
| + ** read or write transaction). Check to see if the database
|
| + ** has been modified. If the database has changed, flush the
|
| + ** cache.
|
| + **
|
| + ** Database changes is detected by looking at 15 bytes beginning
|
| + ** at offset 24 into the file. The first 4 of these 16 bytes are
|
| + ** a 32-bit counter that is incremented with each change. The
|
| + ** other bytes change randomly with each file change when
|
| + ** a codec is in use.
|
| + **
|
| + ** There is a vanishingly small chance that a change will not be
|
| + ** detected. The chance of an undetected change is so small that
|
| + ** it can be neglected.
|
| + */
|
| + Pgno nPage = 0;
|
| + char dbFileVers[sizeof(pPager->dbFileVers)];
|
| +
|
| + rc = pagerPagecount(pPager, &nPage);
|
| + if( rc ) goto failed;
|
| +
|
| + if( nPage>0 ){
|
| + IOTRACE(("CKVERS %p %d\n", pPager, sizeof(dbFileVers)));
|
| + rc = sqlite3OsRead(pPager->fd, &dbFileVers, sizeof(dbFileVers), 24);
|
| + if( rc!=SQLITE_OK ){
|
| + goto failed;
|
| + }
|
| + }else{
|
| + memset(dbFileVers, 0, sizeof(dbFileVers));
|
| + }
|
| +
|
| + if( memcmp(pPager->dbFileVers, dbFileVers, sizeof(dbFileVers))!=0 ){
|
| + pager_reset(pPager);
|
| + }
|
| + }
|
| +
|
| + /* If there is a WAL file in the file-system, open this database in WAL
|
| + ** mode. Otherwise, the following function call is a no-op.
|
| + */
|
| + rc = pagerOpenWalIfPresent(pPager);
|
| +#ifndef SQLITE_OMIT_WAL
|
| + assert( pPager->pWal==0 || rc==SQLITE_OK );
|
| +#endif
|
| + }
|
| +
|
| + if( pagerUseWal(pPager) ){
|
| + assert( rc==SQLITE_OK );
|
| + rc = pagerBeginReadTransaction(pPager);
|
| + }
|
| +
|
| + if( pPager->eState==PAGER_OPEN && rc==SQLITE_OK ){
|
| + rc = pagerPagecount(pPager, &pPager->dbSize);
|
| + }
|
| +
|
| + failed:
|
| + if( rc!=SQLITE_OK ){
|
| + assert( !MEMDB );
|
| + pager_unlock(pPager);
|
| + assert( pPager->eState==PAGER_OPEN );
|
| + }else{
|
| + pPager->eState = PAGER_READER;
|
| + }
|
| + return rc;
|
| +}
|
| +
|
| +/*
|
| +** If the reference count has reached zero, rollback any active
|
| +** transaction and unlock the pager.
|
| +**
|
| +** Except, in locking_mode=EXCLUSIVE when there is nothing to in
|
| +** the rollback journal, the unlock is not performed and there is
|
| +** nothing to rollback, so this routine is a no-op.
|
| +*/
|
| +static void pagerUnlockIfUnused(Pager *pPager){
|
| + if( (sqlite3PcacheRefCount(pPager->pPCache)==0) ){
|
| + pagerUnlockAndRollback(pPager);
|
| + }
|
| +}
|
| +
|
| +/*
|
| +** Acquire a reference to page number pgno in pager pPager (a page
|
| +** reference has type DbPage*). If the requested reference is
|
| +** successfully obtained, it is copied to *ppPage and SQLITE_OK returned.
|
| +**
|
| +** If the requested page is already in the cache, it is returned.
|
| +** Otherwise, a new page object is allocated and populated with data
|
| +** read from the database file. In some cases, the pcache module may
|
| +** choose not to allocate a new page object and may reuse an existing
|
| +** object with no outstanding references.
|
| +**
|
| +** The extra data appended to a page is always initialized to zeros the
|
| +** first time a page is loaded into memory. If the page requested is
|
| +** already in the cache when this function is called, then the extra
|
| +** data is left as it was when the page object was last used.
|
| +**
|
| +** If the database image is smaller than the requested page or if a
|
| +** non-zero value is passed as the noContent parameter and the
|
| +** requested page is not already stored in the cache, then no
|
| +** actual disk read occurs. In this case the memory image of the
|
| +** page is initialized to all zeros.
|
| +**
|
| +** If noContent is true, it means that we do not care about the contents
|
| +** of the page. This occurs in two seperate scenarios:
|
| +**
|
| +** a) When reading a free-list leaf page from the database, and
|
| +**
|
| +** b) When a savepoint is being rolled back and we need to load
|
| +** a new page into the cache to be filled with the data read
|
| +** from the savepoint journal.
|
| +**
|
| +** If noContent is true, then the data returned is zeroed instead of
|
| +** being read from the database. Additionally, the bits corresponding
|
| +** to pgno in Pager.pInJournal (bitvec of pages already written to the
|
| +** journal file) and the PagerSavepoint.pInSavepoint bitvecs of any open
|
| +** savepoints are set. This means if the page is made writable at any
|
| +** point in the future, using a call to sqlite3PagerWrite(), its contents
|
| +** will not be journaled. This saves IO.
|
| +**
|
| +** The acquisition might fail for several reasons. In all cases,
|
| +** an appropriate error code is returned and *ppPage is set to NULL.
|
| +**
|
| +** See also sqlite3PagerLookup(). Both this routine and Lookup() attempt
|
| +** to find a page in the in-memory cache first. If the page is not already
|
| +** in memory, this routine goes to disk to read it in whereas Lookup()
|
| +** just returns 0. This routine acquires a read-lock the first time it
|
| +** has to go to disk, and could also playback an old journal if necessary.
|
| +** Since Lookup() never goes to disk, it never has to deal with locks
|
| +** or journal files.
|
| +*/
|
| +int sqlite3PagerAcquire(
|
| + Pager *pPager, /* The pager open on the database file */
|
| + Pgno pgno, /* Page number to fetch */
|
| + DbPage **ppPage, /* Write a pointer to the page here */
|
| + int noContent /* Do not bother reading content from disk if true */
|
| +){
|
| + int rc;
|
| + PgHdr *pPg;
|
| +
|
| + assert( pPager->eState>=PAGER_READER );
|
| + assert( assert_pager_state(pPager) );
|
| +
|
| + if( pgno==0 ){
|
| + return SQLITE_CORRUPT_BKPT;
|
| + }
|
| +
|
| + /* If the pager is in the error state, return an error immediately.
|
| + ** Otherwise, request the page from the PCache layer. */
|
| + if( pPager->errCode!=SQLITE_OK ){
|
| + rc = pPager->errCode;
|
| + }else{
|
| + rc = sqlite3PcacheFetch(pPager->pPCache, pgno, 1, ppPage);
|
| + }
|
| +
|
| + if( rc!=SQLITE_OK ){
|
| + /* Either the call to sqlite3PcacheFetch() returned an error or the
|
| + ** pager was already in the error-state when this function was called.
|
| + ** Set pPg to 0 and jump to the exception handler. */
|
| + pPg = 0;
|
| + goto pager_acquire_err;
|
| + }
|
| + assert( (*ppPage)->pgno==pgno );
|
| + assert( (*ppPage)->pPager==pPager || (*ppPage)->pPager==0 );
|
| +
|
| + if( (*ppPage)->pPager && !noContent ){
|
| + /* In this case the pcache already contains an initialized copy of
|
| + ** the page. Return without further ado. */
|
| + assert( pgno<=PAGER_MAX_PGNO && pgno!=PAGER_MJ_PGNO(pPager) );
|
| + PAGER_INCR(pPager->nHit);
|
| + return SQLITE_OK;
|
| +
|
| + }else{
|
| + /* The pager cache has created a new page. Its content needs to
|
| + ** be initialized. */
|
| +
|
| + PAGER_INCR(pPager->nMiss);
|
| + pPg = *ppPage;
|
| + pPg->pPager = pPager;
|
| +
|
| + /* The maximum page number is 2^31. Return SQLITE_CORRUPT if a page
|
| + ** number greater than this, or the unused locking-page, is requested. */
|
| + if( pgno>PAGER_MAX_PGNO || pgno==PAGER_MJ_PGNO(pPager) ){
|
| + rc = SQLITE_CORRUPT_BKPT;
|
| + goto pager_acquire_err;
|
| + }
|
| +
|
| + if( MEMDB || pPager->dbSize<pgno || noContent || !isOpen(pPager->fd) ){
|
| + if( pgno>pPager->mxPgno ){
|
| + rc = SQLITE_FULL;
|
| + goto pager_acquire_err;
|
| + }
|
| + if( noContent ){
|
| + /* Failure to set the bits in the InJournal bit-vectors is benign.
|
| + ** It merely means that we might do some extra work to journal a
|
| + ** page that does not need to be journaled. Nevertheless, be sure
|
| + ** to test the case where a malloc error occurs while trying to set
|
| + ** a bit in a bit vector.
|
| + */
|
| + sqlite3BeginBenignMalloc();
|
| + if( pgno<=pPager->dbOrigSize ){
|
| + TESTONLY( rc = ) sqlite3BitvecSet(pPager->pInJournal, pgno);
|
| + testcase( rc==SQLITE_NOMEM );
|
| + }
|
| + TESTONLY( rc = ) addToSavepointBitvecs(pPager, pgno);
|
| + testcase( rc==SQLITE_NOMEM );
|
| + sqlite3EndBenignMalloc();
|
| + }
|
| + memset(pPg->pData, 0, pPager->pageSize);
|
| + IOTRACE(("ZERO %p %d\n", pPager, pgno));
|
| + }else{
|
| + assert( pPg->pPager==pPager );
|
| + rc = readDbPage(pPg);
|
| + if( rc!=SQLITE_OK ){
|
| + goto pager_acquire_err;
|
| + }
|
| + }
|
| + pager_set_pagehash(pPg);
|
| + }
|
| +
|
| + return SQLITE_OK;
|
| +
|
| +pager_acquire_err:
|
| + assert( rc!=SQLITE_OK );
|
| + if( pPg ){
|
| + sqlite3PcacheDrop(pPg);
|
| + }
|
| + pagerUnlockIfUnused(pPager);
|
| +
|
| + *ppPage = 0;
|
| + return rc;
|
| +}
|
| +
|
| +/*
|
| +** Acquire a page if it is already in the in-memory cache. Do
|
| +** not read the page from disk. Return a pointer to the page,
|
| +** or 0 if the page is not in cache.
|
| +**
|
| +** See also sqlite3PagerGet(). The difference between this routine
|
| +** and sqlite3PagerGet() is that _get() will go to the disk and read
|
| +** in the page if the page is not already in cache. This routine
|
| +** returns NULL if the page is not in cache or if a disk I/O error
|
| +** has ever happened.
|
| +*/
|
| +DbPage *sqlite3PagerLookup(Pager *pPager, Pgno pgno){
|
| + PgHdr *pPg = 0;
|
| + assert( pPager!=0 );
|
| + assert( pgno!=0 );
|
| + assert( pPager->pPCache!=0 );
|
| + assert( pPager->eState>=PAGER_READER && pPager->eState!=PAGER_ERROR );
|
| + sqlite3PcacheFetch(pPager->pPCache, pgno, 0, &pPg);
|
| + return pPg;
|
| +}
|
| +
|
| +/*
|
| +** Release a page reference.
|
| +**
|
| +** If the number of references to the page drop to zero, then the
|
| +** page is added to the LRU list. When all references to all pages
|
| +** are released, a rollback occurs and the lock on the database is
|
| +** removed.
|
| +*/
|
| +void sqlite3PagerUnref(DbPage *pPg){
|
| + if( pPg ){
|
| + Pager *pPager = pPg->pPager;
|
| + sqlite3PcacheRelease(pPg);
|
| + pagerUnlockIfUnused(pPager);
|
| + }
|
| +}
|
| +
|
| +/*
|
| +** This function is called at the start of every write transaction.
|
| +** There must already be a RESERVED or EXCLUSIVE lock on the database
|
| +** file when this routine is called.
|
| +**
|
| +** Open the journal file for pager pPager and write a journal header
|
| +** to the start of it. If there are active savepoints, open the sub-journal
|
| +** as well. This function is only used when the journal file is being
|
| +** opened to write a rollback log for a transaction. It is not used
|
| +** when opening a hot journal file to roll it back.
|
| +**
|
| +** If the journal file is already open (as it may be in exclusive mode),
|
| +** then this function just writes a journal header to the start of the
|
| +** already open file.
|
| +**
|
| +** Whether or not the journal file is opened by this function, the
|
| +** Pager.pInJournal bitvec structure is allocated.
|
| +**
|
| +** Return SQLITE_OK if everything is successful. Otherwise, return
|
| +** SQLITE_NOMEM if the attempt to allocate Pager.pInJournal fails, or
|
| +** an IO error code if opening or writing the journal file fails.
|
| +*/
|
| +static int pager_open_journal(Pager *pPager){
|
| + int rc = SQLITE_OK; /* Return code */
|
| + sqlite3_vfs * const pVfs = pPager->pVfs; /* Local cache of vfs pointer */
|
| +
|
| + assert( pPager->eState==PAGER_WRITER_LOCKED );
|
| + assert( assert_pager_state(pPager) );
|
| + assert( pPager->pInJournal==0 );
|
| +
|
| + /* If already in the error state, this function is a no-op. But on
|
| + ** the other hand, this routine is never called if we are already in
|
| + ** an error state. */
|
| + if( NEVER(pPager->errCode) ) return pPager->errCode;
|
| +
|
| + if( !pagerUseWal(pPager) && pPager->journalMode!=PAGER_JOURNALMODE_OFF ){
|
| + pPager->pInJournal = sqlite3BitvecCreate(pPager->dbSize);
|
| + if( pPager->pInJournal==0 ){
|
| + return SQLITE_NOMEM;
|
| + }
|
| +
|
| + /* Open the journal file if it is not already open. */
|
| + if( !isOpen(pPager->jfd) ){
|
| + if( pPager->journalMode==PAGER_JOURNALMODE_MEMORY ){
|
| + sqlite3MemJournalOpen(pPager->jfd);
|
| + }else{
|
| + const int flags = /* VFS flags to open journal file */
|
| + SQLITE_OPEN_READWRITE|SQLITE_OPEN_CREATE|
|
| + (pPager->tempFile ?
|
| + (SQLITE_OPEN_DELETEONCLOSE|SQLITE_OPEN_TEMP_JOURNAL):
|
| + (SQLITE_OPEN_MAIN_JOURNAL)
|
| + );
|
| + #ifdef SQLITE_ENABLE_ATOMIC_WRITE
|
| + rc = sqlite3JournalOpen(
|
| + pVfs, pPager->zJournal, pPager->jfd, flags, jrnlBufferSize(pPager)
|
| + );
|
| + #else
|
| + rc = sqlite3OsOpen(pVfs, pPager->zJournal, pPager->jfd, flags, 0);
|
| + #endif
|
| + }
|
| + assert( rc!=SQLITE_OK || isOpen(pPager->jfd) );
|
| + }
|
| +
|
| +
|
| + /* Write the first journal header to the journal file and open
|
| + ** the sub-journal if necessary.
|
| + */
|
| + if( rc==SQLITE_OK ){
|
| + /* TODO: Check if all of these are really required. */
|
| + pPager->nRec = 0;
|
| + pPager->journalOff = 0;
|
| + pPager->setMaster = 0;
|
| + pPager->journalHdr = 0;
|
| + rc = writeJournalHdr(pPager);
|
| + }
|
| + }
|
| +
|
| + if( rc!=SQLITE_OK ){
|
| + sqlite3BitvecDestroy(pPager->pInJournal);
|
| + pPager->pInJournal = 0;
|
| + }else{
|
| + assert( pPager->eState==PAGER_WRITER_LOCKED );
|
| + pPager->eState = PAGER_WRITER_CACHEMOD;
|
| + }
|
| +
|
| + return rc;
|
| +}
|
| +
|
| +/*
|
| +** Begin a write-transaction on the specified pager object. If a
|
| +** write-transaction has already been opened, this function is a no-op.
|
| +**
|
| +** If the exFlag argument is false, then acquire at least a RESERVED
|
| +** lock on the database file. If exFlag is true, then acquire at least
|
| +** an EXCLUSIVE lock. If such a lock is already held, no locking
|
| +** functions need be called.
|
| +**
|
| +** If the subjInMemory argument is non-zero, then any sub-journal opened
|
| +** within this transaction will be opened as an in-memory file. This
|
| +** has no effect if the sub-journal is already opened (as it may be when
|
| +** running in exclusive mode) or if the transaction does not require a
|
| +** sub-journal. If the subjInMemory argument is zero, then any required
|
| +** sub-journal is implemented in-memory if pPager is an in-memory database,
|
| +** or using a temporary file otherwise.
|
| +*/
|
| +int sqlite3PagerBegin(Pager *pPager, int exFlag, int subjInMemory){
|
| + int rc = SQLITE_OK;
|
| +
|
| + if( pPager->errCode ) return pPager->errCode;
|
| + assert( pPager->eState>=PAGER_READER && pPager->eState<PAGER_ERROR );
|
| + pPager->subjInMemory = (u8)subjInMemory;
|
| +
|
| + if( ALWAYS(pPager->eState==PAGER_READER) ){
|
| + assert( pPager->pInJournal==0 );
|
| +
|
| + if( pagerUseWal(pPager) ){
|
| + /* If the pager is configured to use locking_mode=exclusive, and an
|
| + ** exclusive lock on the database is not already held, obtain it now.
|
| + */
|
| + if( pPager->exclusiveMode && sqlite3WalExclusiveMode(pPager->pWal, -1) ){
|
| + rc = pagerLockDb(pPager, EXCLUSIVE_LOCK);
|
| + if( rc!=SQLITE_OK ){
|
| + return rc;
|
| + }
|
| + sqlite3WalExclusiveMode(pPager->pWal, 1);
|
| + }
|
| +
|
| + /* Grab the write lock on the log file. If successful, upgrade to
|
| + ** PAGER_RESERVED state. Otherwise, return an error code to the caller.
|
| + ** The busy-handler is not invoked if another connection already
|
| + ** holds the write-lock. If possible, the upper layer will call it.
|
| + */
|
| + rc = sqlite3WalBeginWriteTransaction(pPager->pWal);
|
| + }else{
|
| + /* Obtain a RESERVED lock on the database file. If the exFlag parameter
|
| + ** is true, then immediately upgrade this to an EXCLUSIVE lock. The
|
| + ** busy-handler callback can be used when upgrading to the EXCLUSIVE
|
| + ** lock, but not when obtaining the RESERVED lock.
|
| + */
|
| + rc = pagerLockDb(pPager, RESERVED_LOCK);
|
| + if( rc==SQLITE_OK && exFlag ){
|
| + rc = pager_wait_on_lock(pPager, EXCLUSIVE_LOCK);
|
| + }
|
| + }
|
| +
|
| + if( rc==SQLITE_OK ){
|
| + /* Change to WRITER_LOCKED state.
|
| + **
|
| + ** WAL mode sets Pager.eState to PAGER_WRITER_LOCKED or CACHEMOD
|
| + ** when it has an open transaction, but never to DBMOD or FINISHED.
|
| + ** This is because in those states the code to roll back savepoint
|
| + ** transactions may copy data from the sub-journal into the database
|
| + ** file as well as into the page cache. Which would be incorrect in
|
| + ** WAL mode.
|
| + */
|
| + pPager->eState = PAGER_WRITER_LOCKED;
|
| + pPager->dbHintSize = pPager->dbSize;
|
| + pPager->dbFileSize = pPager->dbSize;
|
| + pPager->dbOrigSize = pPager->dbSize;
|
| + pPager->journalOff = 0;
|
| + }
|
| +
|
| + assert( rc==SQLITE_OK || pPager->eState==PAGER_READER );
|
| + assert( rc!=SQLITE_OK || pPager->eState==PAGER_WRITER_LOCKED );
|
| + assert( assert_pager_state(pPager) );
|
| + }
|
| +
|
| + PAGERTRACE(("TRANSACTION %d\n", PAGERID(pPager)));
|
| + return rc;
|
| +}
|
| +
|
| +/*
|
| +** Mark a single data page as writeable. The page is written into the
|
| +** main journal or sub-journal as required. If the page is written into
|
| +** one of the journals, the corresponding bit is set in the
|
| +** Pager.pInJournal bitvec and the PagerSavepoint.pInSavepoint bitvecs
|
| +** of any open savepoints as appropriate.
|
| +*/
|
| +static int pager_write(PgHdr *pPg){
|
| + void *pData = pPg->pData;
|
| + Pager *pPager = pPg->pPager;
|
| + int rc = SQLITE_OK;
|
| +
|
| + /* This routine is not called unless a write-transaction has already
|
| + ** been started. The journal file may or may not be open at this point.
|
| + ** It is never called in the ERROR state.
|
| + */
|
| + assert( pPager->eState==PAGER_WRITER_LOCKED
|
| + || pPager->eState==PAGER_WRITER_CACHEMOD
|
| + || pPager->eState==PAGER_WRITER_DBMOD
|
| + );
|
| + assert( assert_pager_state(pPager) );
|
| +
|
| + /* If an error has been previously detected, report the same error
|
| + ** again. This should not happen, but the check provides robustness. */
|
| + if( NEVER(pPager->errCode) ) return pPager->errCode;
|
| +
|
| + /* Higher-level routines never call this function if database is not
|
| + ** writable. But check anyway, just for robustness. */
|
| + if( NEVER(pPager->readOnly) ) return SQLITE_PERM;
|
| +
|
| + CHECK_PAGE(pPg);
|
| +
|
| + /* The journal file needs to be opened. Higher level routines have already
|
| + ** obtained the necessary locks to begin the write-transaction, but the
|
| + ** rollback journal might not yet be open. Open it now if this is the case.
|
| + **
|
| + ** This is done before calling sqlite3PcacheMakeDirty() on the page.
|
| + ** Otherwise, if it were done after calling sqlite3PcacheMakeDirty(), then
|
| + ** an error might occur and the pager would end up in WRITER_LOCKED state
|
| + ** with pages marked as dirty in the cache.
|
| + */
|
| + if( pPager->eState==PAGER_WRITER_LOCKED ){
|
| + rc = pager_open_journal(pPager);
|
| + if( rc!=SQLITE_OK ) return rc;
|
| + }
|
| + assert( pPager->eState>=PAGER_WRITER_CACHEMOD );
|
| + assert( assert_pager_state(pPager) );
|
| +
|
| + /* Mark the page as dirty. If the page has already been written
|
| + ** to the journal then we can return right away.
|
| + */
|
| + sqlite3PcacheMakeDirty(pPg);
|
| + if( pageInJournal(pPg) && !subjRequiresPage(pPg) ){
|
| + assert( !pagerUseWal(pPager) );
|
| + }else{
|
| +
|
| + /* The transaction journal now exists and we have a RESERVED or an
|
| + ** EXCLUSIVE lock on the main database file. Write the current page to
|
| + ** the transaction journal if it is not there already.
|
| + */
|
| + if( !pageInJournal(pPg) && !pagerUseWal(pPager) ){
|
| + assert( pagerUseWal(pPager)==0 );
|
| + if( pPg->pgno<=pPager->dbOrigSize && isOpen(pPager->jfd) ){
|
| + u32 cksum;
|
| + char *pData2;
|
| + i64 iOff = pPager->journalOff;
|
| +
|
| + /* We should never write to the journal file the page that
|
| + ** contains the database locks. The following assert verifies
|
| + ** that we do not. */
|
| + assert( pPg->pgno!=PAGER_MJ_PGNO(pPager) );
|
| +
|
| + assert( pPager->journalHdr<=pPager->journalOff );
|
| + CODEC2(pPager, pData, pPg->pgno, 7, return SQLITE_NOMEM, pData2);
|
| + cksum = pager_cksum(pPager, (u8*)pData2);
|
| +
|
| + /* Even if an IO or diskfull error occurs while journalling the
|
| + ** page in the block above, set the need-sync flag for the page.
|
| + ** Otherwise, when the transaction is rolled back, the logic in
|
| + ** playback_one_page() will think that the page needs to be restored
|
| + ** in the database file. And if an IO error occurs while doing so,
|
| + ** then corruption may follow.
|
| + */
|
| + pPg->flags |= PGHDR_NEED_SYNC;
|
| +
|
| + rc = write32bits(pPager->jfd, iOff, pPg->pgno);
|
| + if( rc!=SQLITE_OK ) return rc;
|
| + rc = sqlite3OsWrite(pPager->jfd, pData2, pPager->pageSize, iOff+4);
|
| + if( rc!=SQLITE_OK ) return rc;
|
| + rc = write32bits(pPager->jfd, iOff+pPager->pageSize+4, cksum);
|
| + if( rc!=SQLITE_OK ) return rc;
|
| +
|
| + IOTRACE(("JOUT %p %d %lld %d\n", pPager, pPg->pgno,
|
| + pPager->journalOff, pPager->pageSize));
|
| + PAGER_INCR(sqlite3_pager_writej_count);
|
| + PAGERTRACE(("JOURNAL %d page %d needSync=%d hash(%08x)\n",
|
| + PAGERID(pPager), pPg->pgno,
|
| + ((pPg->flags&PGHDR_NEED_SYNC)?1:0), pager_pagehash(pPg)));
|
| +
|
| + pPager->journalOff += 8 + pPager->pageSize;
|
| + pPager->nRec++;
|
| + assert( pPager->pInJournal!=0 );
|
| + rc = sqlite3BitvecSet(pPager->pInJournal, pPg->pgno);
|
| + testcase( rc==SQLITE_NOMEM );
|
| + assert( rc==SQLITE_OK || rc==SQLITE_NOMEM );
|
| + rc |= addToSavepointBitvecs(pPager, pPg->pgno);
|
| + if( rc!=SQLITE_OK ){
|
| + assert( rc==SQLITE_NOMEM );
|
| + return rc;
|
| + }
|
| + }else{
|
| + if( pPager->eState!=PAGER_WRITER_DBMOD ){
|
| + pPg->flags |= PGHDR_NEED_SYNC;
|
| + }
|
| + PAGERTRACE(("APPEND %d page %d needSync=%d\n",
|
| + PAGERID(pPager), pPg->pgno,
|
| + ((pPg->flags&PGHDR_NEED_SYNC)?1:0)));
|
| + }
|
| + }
|
| +
|
| + /* If the statement journal is open and the page is not in it,
|
| + ** then write the current page to the statement journal. Note that
|
| + ** the statement journal format differs from the standard journal format
|
| + ** in that it omits the checksums and the header.
|
| + */
|
| + if( subjRequiresPage(pPg) ){
|
| + rc = subjournalPage(pPg);
|
| + }
|
| + }
|
| +
|
| + /* Update the database size and return.
|
| + */
|
| + if( pPager->dbSize<pPg->pgno ){
|
| + pPager->dbSize = pPg->pgno;
|
| + }
|
| + return rc;
|
| +}
|
| +
|
| +/*
|
| +** Mark a data page as writeable. This routine must be called before
|
| +** making changes to a page. The caller must check the return value
|
| +** of this function and be careful not to change any page data unless
|
| +** this routine returns SQLITE_OK.
|
| +**
|
| +** The difference between this function and pager_write() is that this
|
| +** function also deals with the special case where 2 or more pages
|
| +** fit on a single disk sector. In this case all co-resident pages
|
| +** must have been written to the journal file before returning.
|
| +**
|
| +** If an error occurs, SQLITE_NOMEM or an IO error code is returned
|
| +** as appropriate. Otherwise, SQLITE_OK.
|
| +*/
|
| +int sqlite3PagerWrite(DbPage *pDbPage){
|
| + int rc = SQLITE_OK;
|
| +
|
| + PgHdr *pPg = pDbPage;
|
| + Pager *pPager = pPg->pPager;
|
| + Pgno nPagePerSector = (pPager->sectorSize/pPager->pageSize);
|
| +
|
| + assert( pPager->eState>=PAGER_WRITER_LOCKED );
|
| + assert( pPager->eState!=PAGER_ERROR );
|
| + assert( assert_pager_state(pPager) );
|
| +
|
| + if( nPagePerSector>1 ){
|
| + Pgno nPageCount; /* Total number of pages in database file */
|
| + Pgno pg1; /* First page of the sector pPg is located on. */
|
| + int nPage = 0; /* Number of pages starting at pg1 to journal */
|
| + int ii; /* Loop counter */
|
| + int needSync = 0; /* True if any page has PGHDR_NEED_SYNC */
|
| +
|
| + /* Set the doNotSyncSpill flag to 1. This is because we cannot allow
|
| + ** a journal header to be written between the pages journaled by
|
| + ** this function.
|
| + */
|
| + assert( !MEMDB );
|
| + assert( pPager->doNotSyncSpill==0 );
|
| + pPager->doNotSyncSpill++;
|
| +
|
| + /* This trick assumes that both the page-size and sector-size are
|
| + ** an integer power of 2. It sets variable pg1 to the identifier
|
| + ** of the first page of the sector pPg is located on.
|
| + */
|
| + pg1 = ((pPg->pgno-1) & ~(nPagePerSector-1)) + 1;
|
| +
|
| + nPageCount = pPager->dbSize;
|
| + if( pPg->pgno>nPageCount ){
|
| + nPage = (pPg->pgno - pg1)+1;
|
| + }else if( (pg1+nPagePerSector-1)>nPageCount ){
|
| + nPage = nPageCount+1-pg1;
|
| + }else{
|
| + nPage = nPagePerSector;
|
| + }
|
| + assert(nPage>0);
|
| + assert(pg1<=pPg->pgno);
|
| + assert((pg1+nPage)>pPg->pgno);
|
| +
|
| + for(ii=0; ii<nPage && rc==SQLITE_OK; ii++){
|
| + Pgno pg = pg1+ii;
|
| + PgHdr *pPage;
|
| + if( pg==pPg->pgno || !sqlite3BitvecTest(pPager->pInJournal, pg) ){
|
| + if( pg!=PAGER_MJ_PGNO(pPager) ){
|
| + rc = sqlite3PagerGet(pPager, pg, &pPage);
|
| + if( rc==SQLITE_OK ){
|
| + rc = pager_write(pPage);
|
| + if( pPage->flags&PGHDR_NEED_SYNC ){
|
| + needSync = 1;
|
| + }
|
| + sqlite3PagerUnref(pPage);
|
| + }
|
| + }
|
| + }else if( (pPage = pager_lookup(pPager, pg))!=0 ){
|
| + if( pPage->flags&PGHDR_NEED_SYNC ){
|
| + needSync = 1;
|
| + }
|
| + sqlite3PagerUnref(pPage);
|
| + }
|
| + }
|
| +
|
| + /* If the PGHDR_NEED_SYNC flag is set for any of the nPage pages
|
| + ** starting at pg1, then it needs to be set for all of them. Because
|
| + ** writing to any of these nPage pages may damage the others, the
|
| + ** journal file must contain sync()ed copies of all of them
|
| + ** before any of them can be written out to the database file.
|
| + */
|
| + if( rc==SQLITE_OK && needSync ){
|
| + assert( !MEMDB );
|
| + for(ii=0; ii<nPage; ii++){
|
| + PgHdr *pPage = pager_lookup(pPager, pg1+ii);
|
| + if( pPage ){
|
| + pPage->flags |= PGHDR_NEED_SYNC;
|
| + sqlite3PagerUnref(pPage);
|
| + }
|
| + }
|
| + }
|
| +
|
| + assert( pPager->doNotSyncSpill==1 );
|
| + pPager->doNotSyncSpill--;
|
| + }else{
|
| + rc = pager_write(pDbPage);
|
| + }
|
| + return rc;
|
| +}
|
| +
|
| +/*
|
| +** Return TRUE if the page given in the argument was previously passed
|
| +** to sqlite3PagerWrite(). In other words, return TRUE if it is ok
|
| +** to change the content of the page.
|
| +*/
|
| +#ifndef NDEBUG
|
| +int sqlite3PagerIswriteable(DbPage *pPg){
|
| + return pPg->flags&PGHDR_DIRTY;
|
| +}
|
| +#endif
|
| +
|
| +/*
|
| +** A call to this routine tells the pager that it is not necessary to
|
| +** write the information on page pPg back to the disk, even though
|
| +** that page might be marked as dirty. This happens, for example, when
|
| +** the page has been added as a leaf of the freelist and so its
|
| +** content no longer matters.
|
| +**
|
| +** The overlying software layer calls this routine when all of the data
|
| +** on the given page is unused. The pager marks the page as clean so
|
| +** that it does not get written to disk.
|
| +**
|
| +** Tests show that this optimization can quadruple the speed of large
|
| +** DELETE operations.
|
| +*/
|
| +void sqlite3PagerDontWrite(PgHdr *pPg){
|
| + Pager *pPager = pPg->pPager;
|
| + if( (pPg->flags&PGHDR_DIRTY) && pPager->nSavepoint==0 ){
|
| + PAGERTRACE(("DONT_WRITE page %d of %d\n", pPg->pgno, PAGERID(pPager)));
|
| + IOTRACE(("CLEAN %p %d\n", pPager, pPg->pgno))
|
| + pPg->flags |= PGHDR_DONT_WRITE;
|
| + pager_set_pagehash(pPg);
|
| + }
|
| +}
|
| +
|
| +/*
|
| +** This routine is called to increment the value of the database file
|
| +** change-counter, stored as a 4-byte big-endian integer starting at
|
| +** byte offset 24 of the pager file. The secondary change counter at
|
| +** 92 is also updated, as is the SQLite version number at offset 96.
|
| +**
|
| +** But this only happens if the pPager->changeCountDone flag is false.
|
| +** To avoid excess churning of page 1, the update only happens once.
|
| +** See also the pager_write_changecounter() routine that does an
|
| +** unconditional update of the change counters.
|
| +**
|
| +** If the isDirectMode flag is zero, then this is done by calling
|
| +** sqlite3PagerWrite() on page 1, then modifying the contents of the
|
| +** page data. In this case the file will be updated when the current
|
| +** transaction is committed.
|
| +**
|
| +** The isDirectMode flag may only be non-zero if the library was compiled
|
| +** with the SQLITE_ENABLE_ATOMIC_WRITE macro defined. In this case,
|
| +** if isDirect is non-zero, then the database file is updated directly
|
| +** by writing an updated version of page 1 using a call to the
|
| +** sqlite3OsWrite() function.
|
| +*/
|
| +static int pager_incr_changecounter(Pager *pPager, int isDirectMode){
|
| + int rc = SQLITE_OK;
|
| +
|
| + assert( pPager->eState==PAGER_WRITER_CACHEMOD
|
| + || pPager->eState==PAGER_WRITER_DBMOD
|
| + );
|
| + assert( assert_pager_state(pPager) );
|
| +
|
| + /* Declare and initialize constant integer 'isDirect'. If the
|
| + ** atomic-write optimization is enabled in this build, then isDirect
|
| + ** is initialized to the value passed as the isDirectMode parameter
|
| + ** to this function. Otherwise, it is always set to zero.
|
| + **
|
| + ** The idea is that if the atomic-write optimization is not
|
| + ** enabled at compile time, the compiler can omit the tests of
|
| + ** 'isDirect' below, as well as the block enclosed in the
|
| + ** "if( isDirect )" condition.
|
| + */
|
| +#ifndef SQLITE_ENABLE_ATOMIC_WRITE
|
| +# define DIRECT_MODE 0
|
| + assert( isDirectMode==0 );
|
| + UNUSED_PARAMETER(isDirectMode);
|
| +#else
|
| +# define DIRECT_MODE isDirectMode
|
| +#endif
|
| +
|
| + if( !pPager->changeCountDone && pPager->dbSize>0 ){
|
| + PgHdr *pPgHdr; /* Reference to page 1 */
|
| +
|
| + assert( !pPager->tempFile && isOpen(pPager->fd) );
|
| +
|
| + /* Open page 1 of the file for writing. */
|
| + rc = sqlite3PagerGet(pPager, 1, &pPgHdr);
|
| + assert( pPgHdr==0 || rc==SQLITE_OK );
|
| +
|
| + /* If page one was fetched successfully, and this function is not
|
| + ** operating in direct-mode, make page 1 writable. When not in
|
| + ** direct mode, page 1 is always held in cache and hence the PagerGet()
|
| + ** above is always successful - hence the ALWAYS on rc==SQLITE_OK.
|
| + */
|
| + if( !DIRECT_MODE && ALWAYS(rc==SQLITE_OK) ){
|
| + rc = sqlite3PagerWrite(pPgHdr);
|
| + }
|
| +
|
| + if( rc==SQLITE_OK ){
|
| + /* Actually do the update of the change counter */
|
| + pager_write_changecounter(pPgHdr);
|
| +
|
| + /* If running in direct mode, write the contents of page 1 to the file. */
|
| + if( DIRECT_MODE ){
|
| + const void *zBuf;
|
| + assert( pPager->dbFileSize>0 );
|
| + CODEC2(pPager, pPgHdr->pData, 1, 6, rc=SQLITE_NOMEM, zBuf);
|
| + if( rc==SQLITE_OK ){
|
| + rc = sqlite3OsWrite(pPager->fd, zBuf, pPager->pageSize, 0);
|
| + }
|
| + if( rc==SQLITE_OK ){
|
| + pPager->changeCountDone = 1;
|
| + }
|
| + }else{
|
| + pPager->changeCountDone = 1;
|
| + }
|
| + }
|
| +
|
| + /* Release the page reference. */
|
| + sqlite3PagerUnref(pPgHdr);
|
| + }
|
| + return rc;
|
| +}
|
| +
|
| +/*
|
| +** Sync the database file to disk. This is a no-op for in-memory databases
|
| +** or pages with the Pager.noSync flag set.
|
| +**
|
| +** If successful, or if called on a pager for which it is a no-op, this
|
| +** function returns SQLITE_OK. Otherwise, an IO error code is returned.
|
| +*/
|
| +int sqlite3PagerSync(Pager *pPager){
|
| + int rc = SQLITE_OK;
|
| + if( !pPager->noSync ){
|
| + assert( !MEMDB );
|
| + rc = sqlite3OsSync(pPager->fd, pPager->syncFlags);
|
| + }else if( isOpen(pPager->fd) ){
|
| + assert( !MEMDB );
|
| + sqlite3OsFileControl(pPager->fd, SQLITE_FCNTL_SYNC_OMITTED, (void *)&rc);
|
| + }
|
| + return rc;
|
| +}
|
| +
|
| +/*
|
| +** This function may only be called while a write-transaction is active in
|
| +** rollback. If the connection is in WAL mode, this call is a no-op.
|
| +** Otherwise, if the connection does not already have an EXCLUSIVE lock on
|
| +** the database file, an attempt is made to obtain one.
|
| +**
|
| +** If the EXCLUSIVE lock is already held or the attempt to obtain it is
|
| +** successful, or the connection is in WAL mode, SQLITE_OK is returned.
|
| +** Otherwise, either SQLITE_BUSY or an SQLITE_IOERR_XXX error code is
|
| +** returned.
|
| +*/
|
| +int sqlite3PagerExclusiveLock(Pager *pPager){
|
| + int rc = SQLITE_OK;
|
| + assert( pPager->eState==PAGER_WRITER_CACHEMOD
|
| + || pPager->eState==PAGER_WRITER_DBMOD
|
| + || pPager->eState==PAGER_WRITER_LOCKED
|
| + );
|
| + assert( assert_pager_state(pPager) );
|
| + if( 0==pagerUseWal(pPager) ){
|
| + rc = pager_wait_on_lock(pPager, EXCLUSIVE_LOCK);
|
| + }
|
| + return rc;
|
| +}
|
| +
|
| +/*
|
| +** Sync the database file for the pager pPager. zMaster points to the name
|
| +** of a master journal file that should be written into the individual
|
| +** journal file. zMaster may be NULL, which is interpreted as no master
|
| +** journal (a single database transaction).
|
| +**
|
| +** This routine ensures that:
|
| +**
|
| +** * The database file change-counter is updated,
|
| +** * the journal is synced (unless the atomic-write optimization is used),
|
| +** * all dirty pages are written to the database file,
|
| +** * the database file is truncated (if required), and
|
| +** * the database file synced.
|
| +**
|
| +** The only thing that remains to commit the transaction is to finalize
|
| +** (delete, truncate or zero the first part of) the journal file (or
|
| +** delete the master journal file if specified).
|
| +**
|
| +** Note that if zMaster==NULL, this does not overwrite a previous value
|
| +** passed to an sqlite3PagerCommitPhaseOne() call.
|
| +**
|
| +** If the final parameter - noSync - is true, then the database file itself
|
| +** is not synced. The caller must call sqlite3PagerSync() directly to
|
| +** sync the database file before calling CommitPhaseTwo() to delete the
|
| +** journal file in this case.
|
| +*/
|
| +int sqlite3PagerCommitPhaseOne(
|
| + Pager *pPager, /* Pager object */
|
| + const char *zMaster, /* If not NULL, the master journal name */
|
| + int noSync /* True to omit the xSync on the db file */
|
| +){
|
| + int rc = SQLITE_OK; /* Return code */
|
| +
|
| + assert( pPager->eState==PAGER_WRITER_LOCKED
|
| + || pPager->eState==PAGER_WRITER_CACHEMOD
|
| + || pPager->eState==PAGER_WRITER_DBMOD
|
| + || pPager->eState==PAGER_ERROR
|
| + );
|
| + assert( assert_pager_state(pPager) );
|
| +
|
| + /* If a prior error occurred, report that error again. */
|
| + if( NEVER(pPager->errCode) ) return pPager->errCode;
|
| +
|
| + PAGERTRACE(("DATABASE SYNC: File=%s zMaster=%s nSize=%d\n",
|
| + pPager->zFilename, zMaster, pPager->dbSize));
|
| +
|
| + /* If no database changes have been made, return early. */
|
| + if( pPager->eState<PAGER_WRITER_CACHEMOD ) return SQLITE_OK;
|
| +
|
| + if( MEMDB ){
|
| + /* If this is an in-memory db, or no pages have been written to, or this
|
| + ** function has already been called, it is mostly a no-op. However, any
|
| + ** backup in progress needs to be restarted.
|
| + */
|
| + sqlite3BackupRestart(pPager->pBackup);
|
| + }else{
|
| + if( pagerUseWal(pPager) ){
|
| + PgHdr *pList = sqlite3PcacheDirtyList(pPager->pPCache);
|
| + PgHdr *pPageOne = 0;
|
| + if( pList==0 ){
|
| + /* Must have at least one page for the WAL commit flag.
|
| + ** Ticket [2d1a5c67dfc2363e44f29d9bbd57f] 2011-05-18 */
|
| + rc = sqlite3PagerGet(pPager, 1, &pPageOne);
|
| + pList = pPageOne;
|
| + pList->pDirty = 0;
|
| + }
|
| + assert( pList!=0 || rc!=SQLITE_OK );
|
| + if( pList ){
|
| + rc = pagerWalFrames(pPager, pList, pPager->dbSize, 1,
|
| + (pPager->fullSync ? pPager->syncFlags : 0)
|
| + );
|
| + }
|
| + sqlite3PagerUnref(pPageOne);
|
| + if( rc==SQLITE_OK ){
|
| + sqlite3PcacheCleanAll(pPager->pPCache);
|
| + }
|
| + }else{
|
| + /* The following block updates the change-counter. Exactly how it
|
| + ** does this depends on whether or not the atomic-update optimization
|
| + ** was enabled at compile time, and if this transaction meets the
|
| + ** runtime criteria to use the operation:
|
| + **
|
| + ** * The file-system supports the atomic-write property for
|
| + ** blocks of size page-size, and
|
| + ** * This commit is not part of a multi-file transaction, and
|
| + ** * Exactly one page has been modified and store in the journal file.
|
| + **
|
| + ** If the optimization was not enabled at compile time, then the
|
| + ** pager_incr_changecounter() function is called to update the change
|
| + ** counter in 'indirect-mode'. If the optimization is compiled in but
|
| + ** is not applicable to this transaction, call sqlite3JournalCreate()
|
| + ** to make sure the journal file has actually been created, then call
|
| + ** pager_incr_changecounter() to update the change-counter in indirect
|
| + ** mode.
|
| + **
|
| + ** Otherwise, if the optimization is both enabled and applicable,
|
| + ** then call pager_incr_changecounter() to update the change-counter
|
| + ** in 'direct' mode. In this case the journal file will never be
|
| + ** created for this transaction.
|
| + */
|
| + #ifdef SQLITE_ENABLE_ATOMIC_WRITE
|
| + PgHdr *pPg;
|
| + assert( isOpen(pPager->jfd)
|
| + || pPager->journalMode==PAGER_JOURNALMODE_OFF
|
| + || pPager->journalMode==PAGER_JOURNALMODE_WAL
|
| + );
|
| + if( !zMaster && isOpen(pPager->jfd)
|
| + && pPager->journalOff==jrnlBufferSize(pPager)
|
| + && pPager->dbSize>=pPager->dbOrigSize
|
| + && (0==(pPg = sqlite3PcacheDirtyList(pPager->pPCache)) || 0==pPg->pDirty)
|
| + ){
|
| + /* Update the db file change counter via the direct-write method. The
|
| + ** following call will modify the in-memory representation of page 1
|
| + ** to include the updated change counter and then write page 1
|
| + ** directly to the database file. Because of the atomic-write
|
| + ** property of the host file-system, this is safe.
|
| + */
|
| + rc = pager_incr_changecounter(pPager, 1);
|
| + }else{
|
| + rc = sqlite3JournalCreate(pPager->jfd);
|
| + if( rc==SQLITE_OK ){
|
| + rc = pager_incr_changecounter(pPager, 0);
|
| + }
|
| + }
|
| + #else
|
| + rc = pager_incr_changecounter(pPager, 0);
|
| + #endif
|
| + if( rc!=SQLITE_OK ) goto commit_phase_one_exit;
|
| +
|
| + /* If this transaction has made the database smaller, then all pages
|
| + ** being discarded by the truncation must be written to the journal
|
| + ** file. This can only happen in auto-vacuum mode.
|
| + **
|
| + ** Before reading the pages with page numbers larger than the
|
| + ** current value of Pager.dbSize, set dbSize back to the value
|
| + ** that it took at the start of the transaction. Otherwise, the
|
| + ** calls to sqlite3PagerGet() return zeroed pages instead of
|
| + ** reading data from the database file.
|
| + */
|
| + #ifndef SQLITE_OMIT_AUTOVACUUM
|
| + if( pPager->dbSize<pPager->dbOrigSize
|
| + && pPager->journalMode!=PAGER_JOURNALMODE_OFF
|
| + ){
|
| + Pgno i; /* Iterator variable */
|
| + const Pgno iSkip = PAGER_MJ_PGNO(pPager); /* Pending lock page */
|
| + const Pgno dbSize = pPager->dbSize; /* Database image size */
|
| + pPager->dbSize = pPager->dbOrigSize;
|
| + for( i=dbSize+1; i<=pPager->dbOrigSize; i++ ){
|
| + if( !sqlite3BitvecTest(pPager->pInJournal, i) && i!=iSkip ){
|
| + PgHdr *pPage; /* Page to journal */
|
| + rc = sqlite3PagerGet(pPager, i, &pPage);
|
| + if( rc!=SQLITE_OK ) goto commit_phase_one_exit;
|
| + rc = sqlite3PagerWrite(pPage);
|
| + sqlite3PagerUnref(pPage);
|
| + if( rc!=SQLITE_OK ) goto commit_phase_one_exit;
|
| + }
|
| + }
|
| + pPager->dbSize = dbSize;
|
| + }
|
| + #endif
|
| +
|
| + /* Write the master journal name into the journal file. If a master
|
| + ** journal file name has already been written to the journal file,
|
| + ** or if zMaster is NULL (no master journal), then this call is a no-op.
|
| + */
|
| + rc = writeMasterJournal(pPager, zMaster);
|
| + if( rc!=SQLITE_OK ) goto commit_phase_one_exit;
|
| +
|
| + /* Sync the journal file and write all dirty pages to the database.
|
| + ** If the atomic-update optimization is being used, this sync will not
|
| + ** create the journal file or perform any real IO.
|
| + **
|
| + ** Because the change-counter page was just modified, unless the
|
| + ** atomic-update optimization is used it is almost certain that the
|
| + ** journal requires a sync here. However, in locking_mode=exclusive
|
| + ** on a system under memory pressure it is just possible that this is
|
| + ** not the case. In this case it is likely enough that the redundant
|
| + ** xSync() call will be changed to a no-op by the OS anyhow.
|
| + */
|
| + rc = syncJournal(pPager, 0);
|
| + if( rc!=SQLITE_OK ) goto commit_phase_one_exit;
|
| +
|
| + rc = pager_write_pagelist(pPager,sqlite3PcacheDirtyList(pPager->pPCache));
|
| + if( rc!=SQLITE_OK ){
|
| + assert( rc!=SQLITE_IOERR_BLOCKED );
|
| + goto commit_phase_one_exit;
|
| + }
|
| + sqlite3PcacheCleanAll(pPager->pPCache);
|
| +
|
| + /* If the file on disk is not the same size as the database image,
|
| + ** then use pager_truncate to grow or shrink the file here.
|
| + */
|
| + if( pPager->dbSize!=pPager->dbFileSize ){
|
| + Pgno nNew = pPager->dbSize - (pPager->dbSize==PAGER_MJ_PGNO(pPager));
|
| + assert( pPager->eState==PAGER_WRITER_DBMOD );
|
| + rc = pager_truncate(pPager, nNew);
|
| + if( rc!=SQLITE_OK ) goto commit_phase_one_exit;
|
| + }
|
| +
|
| + /* Finally, sync the database file. */
|
| + if( !noSync ){
|
| + rc = sqlite3PagerSync(pPager);
|
| + }
|
| + IOTRACE(("DBSYNC %p\n", pPager))
|
| + }
|
| + }
|
| +
|
| +commit_phase_one_exit:
|
| + if( rc==SQLITE_OK && !pagerUseWal(pPager) ){
|
| + pPager->eState = PAGER_WRITER_FINISHED;
|
| + }
|
| + return rc;
|
| +}
|
| +
|
| +
|
| +/*
|
| +** When this function is called, the database file has been completely
|
| +** updated to reflect the changes made by the current transaction and
|
| +** synced to disk. The journal file still exists in the file-system
|
| +** though, and if a failure occurs at this point it will eventually
|
| +** be used as a hot-journal and the current transaction rolled back.
|
| +**
|
| +** This function finalizes the journal file, either by deleting,
|
| +** truncating or partially zeroing it, so that it cannot be used
|
| +** for hot-journal rollback. Once this is done the transaction is
|
| +** irrevocably committed.
|
| +**
|
| +** If an error occurs, an IO error code is returned and the pager
|
| +** moves into the error state. Otherwise, SQLITE_OK is returned.
|
| +*/
|
| +int sqlite3PagerCommitPhaseTwo(Pager *pPager){
|
| + int rc = SQLITE_OK; /* Return code */
|
| +
|
| + /* This routine should not be called if a prior error has occurred.
|
| + ** But if (due to a coding error elsewhere in the system) it does get
|
| + ** called, just return the same error code without doing anything. */
|
| + if( NEVER(pPager->errCode) ) return pPager->errCode;
|
| +
|
| + assert( pPager->eState==PAGER_WRITER_LOCKED
|
| + || pPager->eState==PAGER_WRITER_FINISHED
|
| + || (pagerUseWal(pPager) && pPager->eState==PAGER_WRITER_CACHEMOD)
|
| + );
|
| + assert( assert_pager_state(pPager) );
|
| +
|
| + /* An optimization. If the database was not actually modified during
|
| + ** this transaction, the pager is running in exclusive-mode and is
|
| + ** using persistent journals, then this function is a no-op.
|
| + **
|
| + ** The start of the journal file currently contains a single journal
|
| + ** header with the nRec field set to 0. If such a journal is used as
|
| + ** a hot-journal during hot-journal rollback, 0 changes will be made
|
| + ** to the database file. So there is no need to zero the journal
|
| + ** header. Since the pager is in exclusive mode, there is no need
|
| + ** to drop any locks either.
|
| + */
|
| + if( pPager->eState==PAGER_WRITER_LOCKED
|
| + && pPager->exclusiveMode
|
| + && pPager->journalMode==PAGER_JOURNALMODE_PERSIST
|
| + ){
|
| + assert( pPager->journalOff==JOURNAL_HDR_SZ(pPager) || !pPager->journalOff );
|
| + pPager->eState = PAGER_READER;
|
| + return SQLITE_OK;
|
| + }
|
| +
|
| + PAGERTRACE(("COMMIT %d\n", PAGERID(pPager)));
|
| + rc = pager_end_transaction(pPager, pPager->setMaster);
|
| + return pager_error(pPager, rc);
|
| +}
|
| +
|
| +/*
|
| +** If a write transaction is open, then all changes made within the
|
| +** transaction are reverted and the current write-transaction is closed.
|
| +** The pager falls back to PAGER_READER state if successful, or PAGER_ERROR
|
| +** state if an error occurs.
|
| +**
|
| +** If the pager is already in PAGER_ERROR state when this function is called,
|
| +** it returns Pager.errCode immediately. No work is performed in this case.
|
| +**
|
| +** Otherwise, in rollback mode, this function performs two functions:
|
| +**
|
| +** 1) It rolls back the journal file, restoring all database file and
|
| +** in-memory cache pages to the state they were in when the transaction
|
| +** was opened, and
|
| +**
|
| +** 2) It finalizes the journal file, so that it is not used for hot
|
| +** rollback at any point in the future.
|
| +**
|
| +** Finalization of the journal file (task 2) is only performed if the
|
| +** rollback is successful.
|
| +**
|
| +** In WAL mode, all cache-entries containing data modified within the
|
| +** current transaction are either expelled from the cache or reverted to
|
| +** their pre-transaction state by re-reading data from the database or
|
| +** WAL files. The WAL transaction is then closed.
|
| +*/
|
| +int sqlite3PagerRollback(Pager *pPager){
|
| + int rc = SQLITE_OK; /* Return code */
|
| + PAGERTRACE(("ROLLBACK %d\n", PAGERID(pPager)));
|
| +
|
| + /* PagerRollback() is a no-op if called in READER or OPEN state. If
|
| + ** the pager is already in the ERROR state, the rollback is not
|
| + ** attempted here. Instead, the error code is returned to the caller.
|
| + */
|
| + assert( assert_pager_state(pPager) );
|
| + if( pPager->eState==PAGER_ERROR ) return pPager->errCode;
|
| + if( pPager->eState<=PAGER_READER ) return SQLITE_OK;
|
| +
|
| + if( pagerUseWal(pPager) ){
|
| + int rc2;
|
| + rc = sqlite3PagerSavepoint(pPager, SAVEPOINT_ROLLBACK, -1);
|
| + rc2 = pager_end_transaction(pPager, pPager->setMaster);
|
| + if( rc==SQLITE_OK ) rc = rc2;
|
| + }else if( !isOpen(pPager->jfd) || pPager->eState==PAGER_WRITER_LOCKED ){
|
| + int eState = pPager->eState;
|
| + rc = pager_end_transaction(pPager, 0);
|
| + if( !MEMDB && eState>PAGER_WRITER_LOCKED ){
|
| + /* This can happen using journal_mode=off. Move the pager to the error
|
| + ** state to indicate that the contents of the cache may not be trusted.
|
| + ** Any active readers will get SQLITE_ABORT.
|
| + */
|
| + pPager->errCode = SQLITE_ABORT;
|
| + pPager->eState = PAGER_ERROR;
|
| + return rc;
|
| + }
|
| + }else{
|
| + rc = pager_playback(pPager, 0);
|
| + }
|
| +
|
| + assert( pPager->eState==PAGER_READER || rc!=SQLITE_OK );
|
| + assert( rc==SQLITE_OK || rc==SQLITE_FULL || (rc&0xFF)==SQLITE_IOERR );
|
| +
|
| + /* If an error occurs during a ROLLBACK, we can no longer trust the pager
|
| + ** cache. So call pager_error() on the way out to make any error persistent.
|
| + */
|
| + return pager_error(pPager, rc);
|
| +}
|
| +
|
| +/*
|
| +** Return TRUE if the database file is opened read-only. Return FALSE
|
| +** if the database is (in theory) writable.
|
| +*/
|
| +u8 sqlite3PagerIsreadonly(Pager *pPager){
|
| + return pPager->readOnly;
|
| +}
|
| +
|
| +/*
|
| +** Return the number of references to the pager.
|
| +*/
|
| +int sqlite3PagerRefcount(Pager *pPager){
|
| + return sqlite3PcacheRefCount(pPager->pPCache);
|
| +}
|
| +
|
| +/*
|
| +** Return the approximate number of bytes of memory currently
|
| +** used by the pager and its associated cache.
|
| +*/
|
| +int sqlite3PagerMemUsed(Pager *pPager){
|
| + int perPageSize = pPager->pageSize + pPager->nExtra + sizeof(PgHdr)
|
| + + 5*sizeof(void*);
|
| + return perPageSize*sqlite3PcachePagecount(pPager->pPCache)
|
| + + sqlite3MallocSize(pPager)
|
| + + pPager->pageSize;
|
| +}
|
| +
|
| +/*
|
| +** Return the number of references to the specified page.
|
| +*/
|
| +int sqlite3PagerPageRefcount(DbPage *pPage){
|
| + return sqlite3PcachePageRefcount(pPage);
|
| +}
|
| +
|
| +#ifdef SQLITE_TEST
|
| +/*
|
| +** This routine is used for testing and analysis only.
|
| +*/
|
| +int *sqlite3PagerStats(Pager *pPager){
|
| + static int a[11];
|
| + a[0] = sqlite3PcacheRefCount(pPager->pPCache);
|
| + a[1] = sqlite3PcachePagecount(pPager->pPCache);
|
| + a[2] = sqlite3PcacheGetCachesize(pPager->pPCache);
|
| + a[3] = pPager->eState==PAGER_OPEN ? -1 : (int) pPager->dbSize;
|
| + a[4] = pPager->eState;
|
| + a[5] = pPager->errCode;
|
| + a[6] = pPager->nHit;
|
| + a[7] = pPager->nMiss;
|
| + a[8] = 0; /* Used to be pPager->nOvfl */
|
| + a[9] = pPager->nRead;
|
| + a[10] = pPager->nWrite;
|
| + return a;
|
| +}
|
| +#endif
|
| +
|
| +/*
|
| +** Return true if this is an in-memory pager.
|
| +*/
|
| +int sqlite3PagerIsMemdb(Pager *pPager){
|
| + return MEMDB;
|
| +}
|
| +
|
| +/*
|
| +** Check that there are at least nSavepoint savepoints open. If there are
|
| +** currently less than nSavepoints open, then open one or more savepoints
|
| +** to make up the difference. If the number of savepoints is already
|
| +** equal to nSavepoint, then this function is a no-op.
|
| +**
|
| +** If a memory allocation fails, SQLITE_NOMEM is returned. If an error
|
| +** occurs while opening the sub-journal file, then an IO error code is
|
| +** returned. Otherwise, SQLITE_OK.
|
| +*/
|
| +int sqlite3PagerOpenSavepoint(Pager *pPager, int nSavepoint){
|
| + int rc = SQLITE_OK; /* Return code */
|
| + int nCurrent = pPager->nSavepoint; /* Current number of savepoints */
|
| +
|
| + assert( pPager->eState>=PAGER_WRITER_LOCKED );
|
| + assert( assert_pager_state(pPager) );
|
| +
|
| + if( nSavepoint>nCurrent && pPager->useJournal ){
|
| + int ii; /* Iterator variable */
|
| + PagerSavepoint *aNew; /* New Pager.aSavepoint array */
|
| +
|
| + /* Grow the Pager.aSavepoint array using realloc(). Return SQLITE_NOMEM
|
| + ** if the allocation fails. Otherwise, zero the new portion in case a
|
| + ** malloc failure occurs while populating it in the for(...) loop below.
|
| + */
|
| + aNew = (PagerSavepoint *)sqlite3Realloc(
|
| + pPager->aSavepoint, sizeof(PagerSavepoint)*nSavepoint
|
| + );
|
| + if( !aNew ){
|
| + return SQLITE_NOMEM;
|
| + }
|
| + memset(&aNew[nCurrent], 0, (nSavepoint-nCurrent) * sizeof(PagerSavepoint));
|
| + pPager->aSavepoint = aNew;
|
| +
|
| + /* Populate the PagerSavepoint structures just allocated. */
|
| + for(ii=nCurrent; ii<nSavepoint; ii++){
|
| + aNew[ii].nOrig = pPager->dbSize;
|
| + if( isOpen(pPager->jfd) && pPager->journalOff>0 ){
|
| + aNew[ii].iOffset = pPager->journalOff;
|
| + }else{
|
| + aNew[ii].iOffset = JOURNAL_HDR_SZ(pPager);
|
| + }
|
| + aNew[ii].iSubRec = pPager->nSubRec;
|
| + aNew[ii].pInSavepoint = sqlite3BitvecCreate(pPager->dbSize);
|
| + if( !aNew[ii].pInSavepoint ){
|
| + return SQLITE_NOMEM;
|
| + }
|
| + if( pagerUseWal(pPager) ){
|
| + sqlite3WalSavepoint(pPager->pWal, aNew[ii].aWalData);
|
| + }
|
| + pPager->nSavepoint = ii+1;
|
| + }
|
| + assert( pPager->nSavepoint==nSavepoint );
|
| + assertTruncateConstraint(pPager);
|
| + }
|
| +
|
| + return rc;
|
| +}
|
| +
|
| +/*
|
| +** This function is called to rollback or release (commit) a savepoint.
|
| +** The savepoint to release or rollback need not be the most recently
|
| +** created savepoint.
|
| +**
|
| +** Parameter op is always either SAVEPOINT_ROLLBACK or SAVEPOINT_RELEASE.
|
| +** If it is SAVEPOINT_RELEASE, then release and destroy the savepoint with
|
| +** index iSavepoint. If it is SAVEPOINT_ROLLBACK, then rollback all changes
|
| +** that have occurred since the specified savepoint was created.
|
| +**
|
| +** The savepoint to rollback or release is identified by parameter
|
| +** iSavepoint. A value of 0 means to operate on the outermost savepoint
|
| +** (the first created). A value of (Pager.nSavepoint-1) means operate
|
| +** on the most recently created savepoint. If iSavepoint is greater than
|
| +** (Pager.nSavepoint-1), then this function is a no-op.
|
| +**
|
| +** If a negative value is passed to this function, then the current
|
| +** transaction is rolled back. This is different to calling
|
| +** sqlite3PagerRollback() because this function does not terminate
|
| +** the transaction or unlock the database, it just restores the
|
| +** contents of the database to its original state.
|
| +**
|
| +** In any case, all savepoints with an index greater than iSavepoint
|
| +** are destroyed. If this is a release operation (op==SAVEPOINT_RELEASE),
|
| +** then savepoint iSavepoint is also destroyed.
|
| +**
|
| +** This function may return SQLITE_NOMEM if a memory allocation fails,
|
| +** or an IO error code if an IO error occurs while rolling back a
|
| +** savepoint. If no errors occur, SQLITE_OK is returned.
|
| +*/
|
| +int sqlite3PagerSavepoint(Pager *pPager, int op, int iSavepoint){
|
| + int rc = pPager->errCode; /* Return code */
|
| +
|
| + assert( op==SAVEPOINT_RELEASE || op==SAVEPOINT_ROLLBACK );
|
| + assert( iSavepoint>=0 || op==SAVEPOINT_ROLLBACK );
|
| +
|
| + if( rc==SQLITE_OK && iSavepoint<pPager->nSavepoint ){
|
| + int ii; /* Iterator variable */
|
| + int nNew; /* Number of remaining savepoints after this op. */
|
| +
|
| + /* Figure out how many savepoints will still be active after this
|
| + ** operation. Store this value in nNew. Then free resources associated
|
| + ** with any savepoints that are destroyed by this operation.
|
| + */
|
| + nNew = iSavepoint + (( op==SAVEPOINT_RELEASE ) ? 0 : 1);
|
| + for(ii=nNew; ii<pPager->nSavepoint; ii++){
|
| + sqlite3BitvecDestroy(pPager->aSavepoint[ii].pInSavepoint);
|
| + }
|
| + pPager->nSavepoint = nNew;
|
| +
|
| + /* If this is a release of the outermost savepoint, truncate
|
| + ** the sub-journal to zero bytes in size. */
|
| + if( op==SAVEPOINT_RELEASE ){
|
| + if( nNew==0 && isOpen(pPager->sjfd) ){
|
| + /* Only truncate if it is an in-memory sub-journal. */
|
| + if( sqlite3IsMemJournal(pPager->sjfd) ){
|
| + rc = sqlite3OsTruncate(pPager->sjfd, 0);
|
| + assert( rc==SQLITE_OK );
|
| + }
|
| + pPager->nSubRec = 0;
|
| + }
|
| + }
|
| + /* Else this is a rollback operation, playback the specified savepoint.
|
| + ** If this is a temp-file, it is possible that the journal file has
|
| + ** not yet been opened. In this case there have been no changes to
|
| + ** the database file, so the playback operation can be skipped.
|
| + */
|
| + else if( pagerUseWal(pPager) || isOpen(pPager->jfd) ){
|
| + PagerSavepoint *pSavepoint = (nNew==0)?0:&pPager->aSavepoint[nNew-1];
|
| + rc = pagerPlaybackSavepoint(pPager, pSavepoint);
|
| + assert(rc!=SQLITE_DONE);
|
| + }
|
| + }
|
| +
|
| + return rc;
|
| +}
|
| +
|
| +/*
|
| +** Return the full pathname of the database file.
|
| +*/
|
| +const char *sqlite3PagerFilename(Pager *pPager){
|
| + return pPager->zFilename;
|
| +}
|
| +
|
| +/*
|
| +** Return the VFS structure for the pager.
|
| +*/
|
| +const sqlite3_vfs *sqlite3PagerVfs(Pager *pPager){
|
| + return pPager->pVfs;
|
| +}
|
| +
|
| +/*
|
| +** Return the file handle for the database file associated
|
| +** with the pager. This might return NULL if the file has
|
| +** not yet been opened.
|
| +*/
|
| +sqlite3_file *sqlite3PagerFile(Pager *pPager){
|
| + return pPager->fd;
|
| +}
|
| +
|
| +/*
|
| +** Return the full pathname of the journal file.
|
| +*/
|
| +const char *sqlite3PagerJournalname(Pager *pPager){
|
| + return pPager->zJournal;
|
| +}
|
| +
|
| +/*
|
| +** Return true if fsync() calls are disabled for this pager. Return FALSE
|
| +** if fsync()s are executed normally.
|
| +*/
|
| +int sqlite3PagerNosync(Pager *pPager){
|
| + return pPager->noSync;
|
| +}
|
| +
|
| +#ifdef SQLITE_HAS_CODEC
|
| +/*
|
| +** Set or retrieve the codec for this pager
|
| +*/
|
| +void sqlite3PagerSetCodec(
|
| + Pager *pPager,
|
| + void *(*xCodec)(void*,void*,Pgno,int),
|
| + void (*xCodecSizeChng)(void*,int,int),
|
| + void (*xCodecFree)(void*),
|
| + void *pCodec
|
| +){
|
| + if( pPager->xCodecFree ) pPager->xCodecFree(pPager->pCodec);
|
| + pPager->xCodec = pPager->memDb ? 0 : xCodec;
|
| + pPager->xCodecSizeChng = xCodecSizeChng;
|
| + pPager->xCodecFree = xCodecFree;
|
| + pPager->pCodec = pCodec;
|
| + pagerReportSize(pPager);
|
| +}
|
| +void *sqlite3PagerGetCodec(Pager *pPager){
|
| + return pPager->pCodec;
|
| +}
|
| +#endif
|
| +
|
| +#ifndef SQLITE_OMIT_AUTOVACUUM
|
| +/*
|
| +** Move the page pPg to location pgno in the file.
|
| +**
|
| +** There must be no references to the page previously located at
|
| +** pgno (which we call pPgOld) though that page is allowed to be
|
| +** in cache. If the page previously located at pgno is not already
|
| +** in the rollback journal, it is not put there by by this routine.
|
| +**
|
| +** References to the page pPg remain valid. Updating any
|
| +** meta-data associated with pPg (i.e. data stored in the nExtra bytes
|
| +** allocated along with the page) is the responsibility of the caller.
|
| +**
|
| +** A transaction must be active when this routine is called. It used to be
|
| +** required that a statement transaction was not active, but this restriction
|
| +** has been removed (CREATE INDEX needs to move a page when a statement
|
| +** transaction is active).
|
| +**
|
| +** If the fourth argument, isCommit, is non-zero, then this page is being
|
| +** moved as part of a database reorganization just before the transaction
|
| +** is being committed. In this case, it is guaranteed that the database page
|
| +** pPg refers to will not be written to again within this transaction.
|
| +**
|
| +** This function may return SQLITE_NOMEM or an IO error code if an error
|
| +** occurs. Otherwise, it returns SQLITE_OK.
|
| +*/
|
| +int sqlite3PagerMovepage(Pager *pPager, DbPage *pPg, Pgno pgno, int isCommit){
|
| + PgHdr *pPgOld; /* The page being overwritten. */
|
| + Pgno needSyncPgno = 0; /* Old value of pPg->pgno, if sync is required */
|
| + int rc; /* Return code */
|
| + Pgno origPgno; /* The original page number */
|
| +
|
| + assert( pPg->nRef>0 );
|
| + assert( pPager->eState==PAGER_WRITER_CACHEMOD
|
| + || pPager->eState==PAGER_WRITER_DBMOD
|
| + );
|
| + assert( assert_pager_state(pPager) );
|
| +
|
| + /* In order to be able to rollback, an in-memory database must journal
|
| + ** the page we are moving from.
|
| + */
|
| + if( MEMDB ){
|
| + rc = sqlite3PagerWrite(pPg);
|
| + if( rc ) return rc;
|
| + }
|
| +
|
| + /* If the page being moved is dirty and has not been saved by the latest
|
| + ** savepoint, then save the current contents of the page into the
|
| + ** sub-journal now. This is required to handle the following scenario:
|
| + **
|
| + ** BEGIN;
|
| + ** <journal page X, then modify it in memory>
|
| + ** SAVEPOINT one;
|
| + ** <Move page X to location Y>
|
| + ** ROLLBACK TO one;
|
| + **
|
| + ** If page X were not written to the sub-journal here, it would not
|
| + ** be possible to restore its contents when the "ROLLBACK TO one"
|
| + ** statement were is processed.
|
| + **
|
| + ** subjournalPage() may need to allocate space to store pPg->pgno into
|
| + ** one or more savepoint bitvecs. This is the reason this function
|
| + ** may return SQLITE_NOMEM.
|
| + */
|
| + if( pPg->flags&PGHDR_DIRTY
|
| + && subjRequiresPage(pPg)
|
| + && SQLITE_OK!=(rc = subjournalPage(pPg))
|
| + ){
|
| + return rc;
|
| + }
|
| +
|
| + PAGERTRACE(("MOVE %d page %d (needSync=%d) moves to %d\n",
|
| + PAGERID(pPager), pPg->pgno, (pPg->flags&PGHDR_NEED_SYNC)?1:0, pgno));
|
| + IOTRACE(("MOVE %p %d %d\n", pPager, pPg->pgno, pgno))
|
| +
|
| + /* If the journal needs to be sync()ed before page pPg->pgno can
|
| + ** be written to, store pPg->pgno in local variable needSyncPgno.
|
| + **
|
| + ** If the isCommit flag is set, there is no need to remember that
|
| + ** the journal needs to be sync()ed before database page pPg->pgno
|
| + ** can be written to. The caller has already promised not to write to it.
|
| + */
|
| + if( (pPg->flags&PGHDR_NEED_SYNC) && !isCommit ){
|
| + needSyncPgno = pPg->pgno;
|
| + assert( pageInJournal(pPg) || pPg->pgno>pPager->dbOrigSize );
|
| + assert( pPg->flags&PGHDR_DIRTY );
|
| + }
|
| +
|
| + /* If the cache contains a page with page-number pgno, remove it
|
| + ** from its hash chain. Also, if the PGHDR_NEED_SYNC flag was set for
|
| + ** page pgno before the 'move' operation, it needs to be retained
|
| + ** for the page moved there.
|
| + */
|
| + pPg->flags &= ~PGHDR_NEED_SYNC;
|
| + pPgOld = pager_lookup(pPager, pgno);
|
| + assert( !pPgOld || pPgOld->nRef==1 );
|
| + if( pPgOld ){
|
| + pPg->flags |= (pPgOld->flags&PGHDR_NEED_SYNC);
|
| + if( MEMDB ){
|
| + /* Do not discard pages from an in-memory database since we might
|
| + ** need to rollback later. Just move the page out of the way. */
|
| + sqlite3PcacheMove(pPgOld, pPager->dbSize+1);
|
| + }else{
|
| + sqlite3PcacheDrop(pPgOld);
|
| + }
|
| + }
|
| +
|
| + origPgno = pPg->pgno;
|
| + sqlite3PcacheMove(pPg, pgno);
|
| + sqlite3PcacheMakeDirty(pPg);
|
| +
|
| + /* For an in-memory database, make sure the original page continues
|
| + ** to exist, in case the transaction needs to roll back. Use pPgOld
|
| + ** as the original page since it has already been allocated.
|
| + */
|
| + if( MEMDB ){
|
| + assert( pPgOld );
|
| + sqlite3PcacheMove(pPgOld, origPgno);
|
| + sqlite3PagerUnref(pPgOld);
|
| + }
|
| +
|
| + if( needSyncPgno ){
|
| + /* If needSyncPgno is non-zero, then the journal file needs to be
|
| + ** sync()ed before any data is written to database file page needSyncPgno.
|
| + ** Currently, no such page exists in the page-cache and the
|
| + ** "is journaled" bitvec flag has been set. This needs to be remedied by
|
| + ** loading the page into the pager-cache and setting the PGHDR_NEED_SYNC
|
| + ** flag.
|
| + **
|
| + ** If the attempt to load the page into the page-cache fails, (due
|
| + ** to a malloc() or IO failure), clear the bit in the pInJournal[]
|
| + ** array. Otherwise, if the page is loaded and written again in
|
| + ** this transaction, it may be written to the database file before
|
| + ** it is synced into the journal file. This way, it may end up in
|
| + ** the journal file twice, but that is not a problem.
|
| + */
|
| + PgHdr *pPgHdr;
|
| + rc = sqlite3PagerGet(pPager, needSyncPgno, &pPgHdr);
|
| + if( rc!=SQLITE_OK ){
|
| + if( needSyncPgno<=pPager->dbOrigSize ){
|
| + assert( pPager->pTmpSpace!=0 );
|
| + sqlite3BitvecClear(pPager->pInJournal, needSyncPgno, pPager->pTmpSpace);
|
| + }
|
| + return rc;
|
| + }
|
| + pPgHdr->flags |= PGHDR_NEED_SYNC;
|
| + sqlite3PcacheMakeDirty(pPgHdr);
|
| + sqlite3PagerUnref(pPgHdr);
|
| + }
|
| +
|
| + return SQLITE_OK;
|
| +}
|
| +#endif
|
| +
|
| +/*
|
| +** Return a pointer to the data for the specified page.
|
| +*/
|
| +void *sqlite3PagerGetData(DbPage *pPg){
|
| + assert( pPg->nRef>0 || pPg->pPager->memDb );
|
| + return pPg->pData;
|
| +}
|
| +
|
| +/*
|
| +** Return a pointer to the Pager.nExtra bytes of "extra" space
|
| +** allocated along with the specified page.
|
| +*/
|
| +void *sqlite3PagerGetExtra(DbPage *pPg){
|
| + return pPg->pExtra;
|
| +}
|
| +
|
| +/*
|
| +** Get/set the locking-mode for this pager. Parameter eMode must be one
|
| +** of PAGER_LOCKINGMODE_QUERY, PAGER_LOCKINGMODE_NORMAL or
|
| +** PAGER_LOCKINGMODE_EXCLUSIVE. If the parameter is not _QUERY, then
|
| +** the locking-mode is set to the value specified.
|
| +**
|
| +** The returned value is either PAGER_LOCKINGMODE_NORMAL or
|
| +** PAGER_LOCKINGMODE_EXCLUSIVE, indicating the current (possibly updated)
|
| +** locking-mode.
|
| +*/
|
| +int sqlite3PagerLockingMode(Pager *pPager, int eMode){
|
| + assert( eMode==PAGER_LOCKINGMODE_QUERY
|
| + || eMode==PAGER_LOCKINGMODE_NORMAL
|
| + || eMode==PAGER_LOCKINGMODE_EXCLUSIVE );
|
| + assert( PAGER_LOCKINGMODE_QUERY<0 );
|
| + assert( PAGER_LOCKINGMODE_NORMAL>=0 && PAGER_LOCKINGMODE_EXCLUSIVE>=0 );
|
| + assert( pPager->exclusiveMode || 0==sqlite3WalHeapMemory(pPager->pWal) );
|
| + if( eMode>=0 && !pPager->tempFile && !sqlite3WalHeapMemory(pPager->pWal) ){
|
| + pPager->exclusiveMode = (u8)eMode;
|
| + }
|
| + return (int)pPager->exclusiveMode;
|
| +}
|
| +
|
| +/*
|
| +** Set the journal-mode for this pager. Parameter eMode must be one of:
|
| +**
|
| +** PAGER_JOURNALMODE_DELETE
|
| +** PAGER_JOURNALMODE_TRUNCATE
|
| +** PAGER_JOURNALMODE_PERSIST
|
| +** PAGER_JOURNALMODE_OFF
|
| +** PAGER_JOURNALMODE_MEMORY
|
| +** PAGER_JOURNALMODE_WAL
|
| +**
|
| +** The journalmode is set to the value specified if the change is allowed.
|
| +** The change may be disallowed for the following reasons:
|
| +**
|
| +** * An in-memory database can only have its journal_mode set to _OFF
|
| +** or _MEMORY.
|
| +**
|
| +** * Temporary databases cannot have _WAL journalmode.
|
| +**
|
| +** The returned indicate the current (possibly updated) journal-mode.
|
| +*/
|
| +int sqlite3PagerSetJournalMode(Pager *pPager, int eMode){
|
| + u8 eOld = pPager->journalMode; /* Prior journalmode */
|
| +
|
| +#ifdef SQLITE_DEBUG
|
| + /* The print_pager_state() routine is intended to be used by the debugger
|
| + ** only. We invoke it once here to suppress a compiler warning. */
|
| + print_pager_state(pPager);
|
| +#endif
|
| +
|
| +
|
| + /* The eMode parameter is always valid */
|
| + assert( eMode==PAGER_JOURNALMODE_DELETE
|
| + || eMode==PAGER_JOURNALMODE_TRUNCATE
|
| + || eMode==PAGER_JOURNALMODE_PERSIST
|
| + || eMode==PAGER_JOURNALMODE_OFF
|
| + || eMode==PAGER_JOURNALMODE_WAL
|
| + || eMode==PAGER_JOURNALMODE_MEMORY );
|
| +
|
| + /* This routine is only called from the OP_JournalMode opcode, and
|
| + ** the logic there will never allow a temporary file to be changed
|
| + ** to WAL mode.
|
| + */
|
| + assert( pPager->tempFile==0 || eMode!=PAGER_JOURNALMODE_WAL );
|
| +
|
| + /* Do allow the journalmode of an in-memory database to be set to
|
| + ** anything other than MEMORY or OFF
|
| + */
|
| + if( MEMDB ){
|
| + assert( eOld==PAGER_JOURNALMODE_MEMORY || eOld==PAGER_JOURNALMODE_OFF );
|
| + if( eMode!=PAGER_JOURNALMODE_MEMORY && eMode!=PAGER_JOURNALMODE_OFF ){
|
| + eMode = eOld;
|
| + }
|
| + }
|
| +
|
| + if( eMode!=eOld ){
|
| +
|
| + /* Change the journal mode. */
|
| + assert( pPager->eState!=PAGER_ERROR );
|
| + pPager->journalMode = (u8)eMode;
|
| +
|
| + /* When transistioning from TRUNCATE or PERSIST to any other journal
|
| + ** mode except WAL, unless the pager is in locking_mode=exclusive mode,
|
| + ** delete the journal file.
|
| + */
|
| + assert( (PAGER_JOURNALMODE_TRUNCATE & 5)==1 );
|
| + assert( (PAGER_JOURNALMODE_PERSIST & 5)==1 );
|
| + assert( (PAGER_JOURNALMODE_DELETE & 5)==0 );
|
| + assert( (PAGER_JOURNALMODE_MEMORY & 5)==4 );
|
| + assert( (PAGER_JOURNALMODE_OFF & 5)==0 );
|
| + assert( (PAGER_JOURNALMODE_WAL & 5)==5 );
|
| +
|
| + assert( isOpen(pPager->fd) || pPager->exclusiveMode );
|
| + if( !pPager->exclusiveMode && (eOld & 5)==1 && (eMode & 1)==0 ){
|
| +
|
| + /* In this case we would like to delete the journal file. If it is
|
| + ** not possible, then that is not a problem. Deleting the journal file
|
| + ** here is an optimization only.
|
| + **
|
| + ** Before deleting the journal file, obtain a RESERVED lock on the
|
| + ** database file. This ensures that the journal file is not deleted
|
| + ** while it is in use by some other client.
|
| + */
|
| + sqlite3OsClose(pPager->jfd);
|
| + if( pPager->eLock>=RESERVED_LOCK ){
|
| + sqlite3OsDelete(pPager->pVfs, pPager->zJournal, 0);
|
| + }else{
|
| + int rc = SQLITE_OK;
|
| + int state = pPager->eState;
|
| + assert( state==PAGER_OPEN || state==PAGER_READER );
|
| + if( state==PAGER_OPEN ){
|
| + rc = sqlite3PagerSharedLock(pPager);
|
| + }
|
| + if( pPager->eState==PAGER_READER ){
|
| + assert( rc==SQLITE_OK );
|
| + rc = pagerLockDb(pPager, RESERVED_LOCK);
|
| + }
|
| + if( rc==SQLITE_OK ){
|
| + sqlite3OsDelete(pPager->pVfs, pPager->zJournal, 0);
|
| + }
|
| + if( rc==SQLITE_OK && state==PAGER_READER ){
|
| + pagerUnlockDb(pPager, SHARED_LOCK);
|
| + }else if( state==PAGER_OPEN ){
|
| + pager_unlock(pPager);
|
| + }
|
| + assert( state==pPager->eState );
|
| + }
|
| + }
|
| + }
|
| +
|
| + /* Return the new journal mode */
|
| + return (int)pPager->journalMode;
|
| +}
|
| +
|
| +/*
|
| +** Return the current journal mode.
|
| +*/
|
| +int sqlite3PagerGetJournalMode(Pager *pPager){
|
| + return (int)pPager->journalMode;
|
| +}
|
| +
|
| +/*
|
| +** Return TRUE if the pager is in a state where it is OK to change the
|
| +** journalmode. Journalmode changes can only happen when the database
|
| +** is unmodified.
|
| +*/
|
| +int sqlite3PagerOkToChangeJournalMode(Pager *pPager){
|
| + assert( assert_pager_state(pPager) );
|
| + if( pPager->eState>=PAGER_WRITER_CACHEMOD ) return 0;
|
| + if( NEVER(isOpen(pPager->jfd) && pPager->journalOff>0) ) return 0;
|
| + return 1;
|
| +}
|
| +
|
| +/*
|
| +** Get/set the size-limit used for persistent journal files.
|
| +**
|
| +** Setting the size limit to -1 means no limit is enforced.
|
| +** An attempt to set a limit smaller than -1 is a no-op.
|
| +*/
|
| +i64 sqlite3PagerJournalSizeLimit(Pager *pPager, i64 iLimit){
|
| + if( iLimit>=-1 ){
|
| + pPager->journalSizeLimit = iLimit;
|
| + }
|
| + return pPager->journalSizeLimit;
|
| +}
|
| +
|
| +/*
|
| +** Return a pointer to the pPager->pBackup variable. The backup module
|
| +** in backup.c maintains the content of this variable. This module
|
| +** uses it opaquely as an argument to sqlite3BackupRestart() and
|
| +** sqlite3BackupUpdate() only.
|
| +*/
|
| +sqlite3_backup **sqlite3PagerBackupPtr(Pager *pPager){
|
| + return &pPager->pBackup;
|
| +}
|
| +
|
| +#ifndef SQLITE_OMIT_WAL
|
| +/*
|
| +** This function is called when the user invokes "PRAGMA wal_checkpoint",
|
| +** "PRAGMA wal_blocking_checkpoint" or calls the sqlite3_wal_checkpoint()
|
| +** or wal_blocking_checkpoint() API functions.
|
| +**
|
| +** Parameter eMode is one of SQLITE_CHECKPOINT_PASSIVE, FULL or RESTART.
|
| +*/
|
| +int sqlite3PagerCheckpoint(Pager *pPager, int eMode, int *pnLog, int *pnCkpt){
|
| + int rc = SQLITE_OK;
|
| + if( pPager->pWal ){
|
| + rc = sqlite3WalCheckpoint(pPager->pWal, eMode,
|
| + pPager->xBusyHandler, pPager->pBusyHandlerArg,
|
| + pPager->ckptSyncFlags, pPager->pageSize, (u8 *)pPager->pTmpSpace,
|
| + pnLog, pnCkpt
|
| + );
|
| + }
|
| + return rc;
|
| +}
|
| +
|
| +int sqlite3PagerWalCallback(Pager *pPager){
|
| + return sqlite3WalCallback(pPager->pWal);
|
| +}
|
| +
|
| +/*
|
| +** Return true if the underlying VFS for the given pager supports the
|
| +** primitives necessary for write-ahead logging.
|
| +*/
|
| +int sqlite3PagerWalSupported(Pager *pPager){
|
| + const sqlite3_io_methods *pMethods = pPager->fd->pMethods;
|
| + return pPager->exclusiveMode || (pMethods->iVersion>=2 && pMethods->xShmMap);
|
| +}
|
| +
|
| +/*
|
| +** Attempt to take an exclusive lock on the database file. If a PENDING lock
|
| +** is obtained instead, immediately release it.
|
| +*/
|
| +static int pagerExclusiveLock(Pager *pPager){
|
| + int rc; /* Return code */
|
| +
|
| + assert( pPager->eLock==SHARED_LOCK || pPager->eLock==EXCLUSIVE_LOCK );
|
| + rc = pagerLockDb(pPager, EXCLUSIVE_LOCK);
|
| + if( rc!=SQLITE_OK ){
|
| + /* If the attempt to grab the exclusive lock failed, release the
|
| + ** pending lock that may have been obtained instead. */
|
| + pagerUnlockDb(pPager, SHARED_LOCK);
|
| + }
|
| +
|
| + return rc;
|
| +}
|
| +
|
| +/*
|
| +** Call sqlite3WalOpen() to open the WAL handle. If the pager is in
|
| +** exclusive-locking mode when this function is called, take an EXCLUSIVE
|
| +** lock on the database file and use heap-memory to store the wal-index
|
| +** in. Otherwise, use the normal shared-memory.
|
| +*/
|
| +static int pagerOpenWal(Pager *pPager){
|
| + int rc = SQLITE_OK;
|
| +
|
| + assert( pPager->pWal==0 && pPager->tempFile==0 );
|
| + assert( pPager->eLock==SHARED_LOCK || pPager->eLock==EXCLUSIVE_LOCK || pPager->noReadlock);
|
| +
|
| + /* If the pager is already in exclusive-mode, the WAL module will use
|
| + ** heap-memory for the wal-index instead of the VFS shared-memory
|
| + ** implementation. Take the exclusive lock now, before opening the WAL
|
| + ** file, to make sure this is safe.
|
| + */
|
| + if( pPager->exclusiveMode ){
|
| + rc = pagerExclusiveLock(pPager);
|
| + }
|
| +
|
| + /* Open the connection to the log file. If this operation fails,
|
| + ** (e.g. due to malloc() failure), return an error code.
|
| + */
|
| + if( rc==SQLITE_OK ){
|
| + rc = sqlite3WalOpen(pPager->pVfs,
|
| + pPager->fd, pPager->zWal, pPager->exclusiveMode, &pPager->pWal
|
| + );
|
| + }
|
| +
|
| + return rc;
|
| +}
|
| +
|
| +
|
| +/*
|
| +** The caller must be holding a SHARED lock on the database file to call
|
| +** this function.
|
| +**
|
| +** If the pager passed as the first argument is open on a real database
|
| +** file (not a temp file or an in-memory database), and the WAL file
|
| +** is not already open, make an attempt to open it now. If successful,
|
| +** return SQLITE_OK. If an error occurs or the VFS used by the pager does
|
| +** not support the xShmXXX() methods, return an error code. *pbOpen is
|
| +** not modified in either case.
|
| +**
|
| +** If the pager is open on a temp-file (or in-memory database), or if
|
| +** the WAL file is already open, set *pbOpen to 1 and return SQLITE_OK
|
| +** without doing anything.
|
| +*/
|
| +int sqlite3PagerOpenWal(
|
| + Pager *pPager, /* Pager object */
|
| + int *pbOpen /* OUT: Set to true if call is a no-op */
|
| +){
|
| + int rc = SQLITE_OK; /* Return code */
|
| +
|
| + assert( assert_pager_state(pPager) );
|
| + assert( pPager->eState==PAGER_OPEN || pbOpen );
|
| + assert( pPager->eState==PAGER_READER || !pbOpen );
|
| + assert( pbOpen==0 || *pbOpen==0 );
|
| + assert( pbOpen!=0 || (!pPager->tempFile && !pPager->pWal) );
|
| +
|
| + if( !pPager->tempFile && !pPager->pWal ){
|
| + if( !sqlite3PagerWalSupported(pPager) ) return SQLITE_CANTOPEN;
|
| +
|
| + /* Close any rollback journal previously open */
|
| + sqlite3OsClose(pPager->jfd);
|
| +
|
| + rc = pagerOpenWal(pPager);
|
| + if( rc==SQLITE_OK ){
|
| + pPager->journalMode = PAGER_JOURNALMODE_WAL;
|
| + pPager->eState = PAGER_OPEN;
|
| + }
|
| + }else{
|
| + *pbOpen = 1;
|
| + }
|
| +
|
| + return rc;
|
| +}
|
| +
|
| +/*
|
| +** This function is called to close the connection to the log file prior
|
| +** to switching from WAL to rollback mode.
|
| +**
|
| +** Before closing the log file, this function attempts to take an
|
| +** EXCLUSIVE lock on the database file. If this cannot be obtained, an
|
| +** error (SQLITE_BUSY) is returned and the log connection is not closed.
|
| +** If successful, the EXCLUSIVE lock is not released before returning.
|
| +*/
|
| +int sqlite3PagerCloseWal(Pager *pPager){
|
| + int rc = SQLITE_OK;
|
| +
|
| + assert( pPager->journalMode==PAGER_JOURNALMODE_WAL );
|
| +
|
| + /* If the log file is not already open, but does exist in the file-system,
|
| + ** it may need to be checkpointed before the connection can switch to
|
| + ** rollback mode. Open it now so this can happen.
|
| + */
|
| + if( !pPager->pWal ){
|
| + int logexists = 0;
|
| + rc = pagerLockDb(pPager, SHARED_LOCK);
|
| + if( rc==SQLITE_OK ){
|
| + rc = sqlite3OsAccess(
|
| + pPager->pVfs, pPager->zWal, SQLITE_ACCESS_EXISTS, &logexists
|
| + );
|
| + }
|
| + if( rc==SQLITE_OK && logexists ){
|
| + rc = pagerOpenWal(pPager);
|
| + }
|
| + }
|
| +
|
| + /* Checkpoint and close the log. Because an EXCLUSIVE lock is held on
|
| + ** the database file, the log and log-summary files will be deleted.
|
| + */
|
| + if( rc==SQLITE_OK && pPager->pWal ){
|
| + rc = pagerExclusiveLock(pPager);
|
| + if( rc==SQLITE_OK ){
|
| + rc = sqlite3WalClose(pPager->pWal, pPager->ckptSyncFlags,
|
| + pPager->pageSize, (u8*)pPager->pTmpSpace);
|
| + pPager->pWal = 0;
|
| + }
|
| + }
|
| + return rc;
|
| +}
|
| +
|
| +#ifdef SQLITE_HAS_CODEC
|
| +/*
|
| +** This function is called by the wal module when writing page content
|
| +** into the log file.
|
| +**
|
| +** This function returns a pointer to a buffer containing the encrypted
|
| +** page content. If a malloc fails, this function may return NULL.
|
| +*/
|
| +void *sqlite3PagerCodec(PgHdr *pPg){
|
| + void *aData = 0;
|
| + CODEC2(pPg->pPager, pPg->pData, pPg->pgno, 6, return 0, aData);
|
| + return aData;
|
| +}
|
| +#endif /* SQLITE_HAS_CODEC */
|
| +
|
| +#endif /* !SQLITE_OMIT_WAL */
|
| +
|
| +#endif /* SQLITE_OMIT_DISKIO */
|
|
|
Chromium Code Reviews
Issue 949043002:
Add //third_party/sqlite to dirs_to_snapshot, remove net_sql.patch (Closed)
Base URL: git@github.com:domokit/mojo.git@master