Index: app/sql/connection.h |
diff --git a/app/sql/connection.h b/app/sql/connection.h |
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-// Copyright (c) 2011 The Chromium Authors. All rights reserved. |
-// Use of this source code is governed by a BSD-style license that can be |
-// found in the LICENSE file. |
- |
-#ifndef APP_SQL_CONNECTION_H_ |
-#define APP_SQL_CONNECTION_H_ |
-#pragma once |
- |
-#include <map> |
-#include <set> |
-#include <string> |
- |
-#include "base/basictypes.h" |
-#include "base/memory/ref_counted.h" |
-#include "base/time.h" |
- |
-class FilePath; |
-struct sqlite3; |
-struct sqlite3_stmt; |
- |
-namespace sql { |
- |
-class Statement; |
- |
-// Uniquely identifies a statement. There are two modes of operation: |
-// |
-// - In the most common mode, you will use the source file and line number to |
-// identify your statement. This is a convienient way to get uniqueness for |
-// a statement that is only used in one place. Use the SQL_FROM_HERE macro |
-// to generate a StatementID. |
-// |
-// - In the "custom" mode you may use the statement from different places or |
-// need to manage it yourself for whatever reason. In this case, you should |
-// make up your own unique name and pass it to the StatementID. This name |
-// must be a static string, since this object only deals with pointers and |
-// assumes the underlying string doesn't change or get deleted. |
-// |
-// This object is copyable and assignable using the compiler-generated |
-// operator= and copy constructor. |
-class StatementID { |
- public: |
- // Creates a uniquely named statement with the given file ane line number. |
- // Normally you will use SQL_FROM_HERE instead of calling yourself. |
- StatementID(const char* file, int line) |
- : number_(line), |
- str_(file) { |
- } |
- |
- // Creates a uniquely named statement with the given user-defined name. |
- explicit StatementID(const char* unique_name) |
- : number_(-1), |
- str_(unique_name) { |
- } |
- |
- // This constructor is unimplemented and will generate a linker error if |
- // called. It is intended to try to catch people dynamically generating |
- // a statement name that will be deallocated and will cause a crash later. |
- // All strings must be static and unchanging! |
- explicit StatementID(const std::string& dont_ever_do_this); |
- |
- // We need this to insert into our map. |
- bool operator<(const StatementID& other) const; |
- |
- private: |
- int number_; |
- const char* str_; |
-}; |
- |
-#define SQL_FROM_HERE sql::StatementID(__FILE__, __LINE__) |
- |
-class Connection; |
- |
-// ErrorDelegate defines the interface to implement error handling and recovery |
-// for sqlite operations. This allows the rest of the classes to return true or |
-// false while the actual error code and causing statement are delivered using |
-// the OnError() callback. |
-// The tipical usage is to centralize the code designed to handle database |
-// corruption, low-level IO errors or locking violations. |
-class ErrorDelegate : public base::RefCounted<ErrorDelegate> { |
- public: |
- ErrorDelegate(); |
- |
- // |error| is an sqlite result code as seen in sqlite\preprocessed\sqlite3.h |
- // |connection| is db connection where the error happened and |stmt| is |
- // our best guess at the statement that triggered the error. Do not store |
- // these pointers. |
- // |
- // |stmt| MAY BE NULL if there is no statement causing the problem (i.e. on |
- // initialization). |
- // |
- // If the error condition has been fixed an the original statement succesfuly |
- // re-tried then returning SQLITE_OK is appropiate; otherwise is recomended |
- // that you return the original |error| or the appropiae error code. |
- virtual int OnError(int error, Connection* connection, Statement* stmt) = 0; |
- |
- protected: |
- friend class base::RefCounted<ErrorDelegate>; |
- |
- virtual ~ErrorDelegate(); |
-}; |
- |
-class Connection { |
- private: |
- class StatementRef; // Forward declaration, see real one below. |
- |
- public: |
- // The database is opened by calling Open[InMemory](). Any uncommitted |
- // transactions will be rolled back when this object is deleted. |
- Connection(); |
- ~Connection(); |
- |
- // Pre-init configuration ---------------------------------------------------- |
- |
- // Sets the page size that will be used when creating a new database. This |
- // must be called before Init(), and will only have an effect on new |
- // databases. |
- // |
- // From sqlite.org: "The page size must be a power of two greater than or |
- // equal to 512 and less than or equal to SQLITE_MAX_PAGE_SIZE. The maximum |
- // value for SQLITE_MAX_PAGE_SIZE is 32768." |
- void set_page_size(int page_size) { page_size_ = page_size; } |
- |
- // Sets the number of pages that will be cached in memory by sqlite. The |
- // total cache size in bytes will be page_size * cache_size. This must be |
- // called before Open() to have an effect. |
- void set_cache_size(int cache_size) { cache_size_ = cache_size; } |
- |
- // Call to put the database in exclusive locking mode. There is no "back to |
- // normal" flag because of some additional requirements sqlite puts on this |
- // transaition (requires another access to the DB) and because we don't |
- // actually need it. |
- // |
- // Exclusive mode means that the database is not unlocked at the end of each |
- // transaction, which means there may be less time spent initializing the |
- // next transaction because it doesn't have to re-aquire locks. |
- // |
- // This must be called before Open() to have an effect. |
- void set_exclusive_locking() { exclusive_locking_ = true; } |
- |
- // Sets the object that will handle errors. Recomended that it should be set |
- // before calling Open(). If not set, the default is to ignore errors on |
- // release and assert on debug builds. |
- void set_error_delegate(ErrorDelegate* delegate) { |
- error_delegate_ = delegate; |
- } |
- |
- // Initialization ------------------------------------------------------------ |
- |
- // Initializes the SQL connection for the given file, returning true if the |
- // file could be opened. You can call this or OpenInMemory. |
- bool Open(const FilePath& path); |
- |
- // Initializes the SQL connection for a temporary in-memory database. There |
- // will be no associated file on disk, and the initial database will be |
- // empty. You can call this or Open. |
- bool OpenInMemory(); |
- |
- // Returns trie if the database has been successfully opened. |
- bool is_open() const { return !!db_; } |
- |
- // Closes the database. This is automatically performed on destruction for |
- // you, but this allows you to close the database early. You must not call |
- // any other functions after closing it. It is permissable to call Close on |
- // an uninitialized or already-closed database. |
- void Close(); |
- |
- // Pre-loads the first <cache-size> pages into the cache from the file. |
- // If you expect to soon use a substantial portion of the database, this |
- // is much more efficient than allowing the pages to be populated organically |
- // since there is no per-page hard drive seeking. If the file is larger than |
- // the cache, the last part that doesn't fit in the cache will be brought in |
- // organically. |
- // |
- // This function assumes your class is using a meta table on the current |
- // database, as it openes a transaction on the meta table to force the |
- // database to be initialized. You should feel free to initialize the meta |
- // table after calling preload since the meta table will already be in the |
- // database if it exists, and if it doesn't exist, the database won't |
- // generally exist either. |
- void Preload(); |
- |
- // Transactions -------------------------------------------------------------- |
- |
- // Transaction management. We maintain a virtual transaction stack to emulate |
- // nested transactions since sqlite can't do nested transactions. The |
- // limitation is you can't roll back a sub transaction: if any transaction |
- // fails, all transactions open will also be rolled back. Any nested |
- // transactions after one has rolled back will return fail for Begin(). If |
- // Begin() fails, you must not call Commit or Rollback(). |
- // |
- // Normally you should use sql::Transaction to manage a transaction, which |
- // will scope it to a C++ context. |
- bool BeginTransaction(); |
- void RollbackTransaction(); |
- bool CommitTransaction(); |
- |
- // Returns the current transaction nesting, which will be 0 if there are |
- // no open transactions. |
- int transaction_nesting() const { return transaction_nesting_; } |
- |
- // Statements ---------------------------------------------------------------- |
- |
- // Executes the given SQL string, returning true on success. This is |
- // normally used for simple, 1-off statements that don't take any bound |
- // parameters and don't return any data (e.g. CREATE TABLE). |
- bool Execute(const char* sql); |
- |
- // Returns true if we have a statement with the given identifier already |
- // cached. This is normally not necessary to call, but can be useful if the |
- // caller has to dynamically build up SQL to avoid doing so if it's already |
- // cached. |
- bool HasCachedStatement(const StatementID& id) const; |
- |
- // Returns a statement for the given SQL using the statement cache. It can |
- // take a nontrivial amount of work to parse and compile a statement, so |
- // keeping commonly-used ones around for future use is important for |
- // performance. |
- // |
- // The SQL may have an error, so the caller must check validity of the |
- // statement before using it. |
- // |
- // The StatementID and the SQL must always correspond to one-another. The |
- // ID is the lookup into the cache, so crazy things will happen if you use |
- // different SQL with the same ID. |
- // |
- // You will normally use the SQL_FROM_HERE macro to generate a statement |
- // ID associated with the current line of code. This gives uniqueness without |
- // you having to manage unique names. See StatementID above for more. |
- // |
- // Example: |
- // sql::Statement stmt(connection_.GetCachedStatement( |
- // SQL_FROM_HERE, "SELECT * FROM foo")); |
- // if (!stmt) |
- // return false; // Error creating statement. |
- scoped_refptr<StatementRef> GetCachedStatement(const StatementID& id, |
- const char* sql); |
- |
- // Returns a non-cached statement for the given SQL. Use this for SQL that |
- // is only executed once or only rarely (there is overhead associated with |
- // keeping a statement cached). |
- // |
- // See GetCachedStatement above for examples and error information. |
- scoped_refptr<StatementRef> GetUniqueStatement(const char* sql); |
- |
- // Info querying ------------------------------------------------------------- |
- |
- // Returns true if the given table exists. |
- bool DoesTableExist(const char* table_name) const; |
- |
- // Returns true if a column with the given name exists in the given table. |
- bool DoesColumnExist(const char* table_name, const char* column_name) const; |
- |
- // Returns sqlite's internal ID for the last inserted row. Valid only |
- // immediately after an insert. |
- int64 GetLastInsertRowId() const; |
- |
- // Returns sqlite's count of the number of rows modified by the last |
- // statement executed. Will be 0 if no statement has executed or the database |
- // is closed. |
- int GetLastChangeCount() const; |
- |
- // Errors -------------------------------------------------------------------- |
- |
- // Returns the error code associated with the last sqlite operation. |
- int GetErrorCode() const; |
- |
- // Returns the errno associated with GetErrorCode(). See |
- // SQLITE_LAST_ERRNO in SQLite documentation. |
- int GetLastErrno() const; |
- |
- // Returns a pointer to a statically allocated string associated with the |
- // last sqlite operation. |
- const char* GetErrorMessage() const; |
- |
- private: |
- // Statement access StatementRef which we don't want to expose to erverybody |
- // (they should go through Statement). |
- friend class Statement; |
- |
- // Internal initialize function used by both Init and InitInMemory. The file |
- // name is always 8 bits since we want to use the 8-bit version of |
- // sqlite3_open. The string can also be sqlite's special ":memory:" string. |
- bool OpenInternal(const std::string& file_name); |
- |
- // A StatementRef is a refcounted wrapper around a sqlite statement pointer. |
- // Refcounting allows us to give these statements out to sql::Statement |
- // objects while also optionally maintaining a cache of compiled statements |
- // by just keeping a refptr to these objects. |
- // |
- // A statement ref can be valid, in which case it can be used, or invalid to |
- // indicate that the statement hasn't been created yet, has an error, or has |
- // been destroyed. |
- // |
- // The Connection may revoke a StatementRef in some error cases, so callers |
- // should always check validity before using. |
- class StatementRef : public base::RefCounted<StatementRef> { |
- public: |
- // Default constructor initializes to an invalid statement. |
- StatementRef(); |
- StatementRef(Connection* connection, sqlite3_stmt* stmt); |
- |
- // When true, the statement can be used. |
- bool is_valid() const { return !!stmt_; } |
- |
- // If we've not been linked to a connection, this will be NULL. Guaranteed |
- // non-NULL when is_valid(). |
- Connection* connection() const { return connection_; } |
- |
- // Returns the sqlite statement if any. If the statement is not active, |
- // this will return NULL. |
- sqlite3_stmt* stmt() const { return stmt_; } |
- |
- // Destroys the compiled statement and marks it NULL. The statement will |
- // no longer be active. |
- void Close(); |
- |
- private: |
- friend class base::RefCounted<StatementRef>; |
- |
- ~StatementRef(); |
- |
- Connection* connection_; |
- sqlite3_stmt* stmt_; |
- |
- DISALLOW_COPY_AND_ASSIGN(StatementRef); |
- }; |
- friend class StatementRef; |
- |
- // Executes a rollback statement, ignoring all transaction state. Used |
- // internally in the transaction management code. |
- void DoRollback(); |
- |
- // Called by a StatementRef when it's being created or destroyed. See |
- // open_statements_ below. |
- void StatementRefCreated(StatementRef* ref); |
- void StatementRefDeleted(StatementRef* ref); |
- |
- // Frees all cached statements from statement_cache_. |
- void ClearCache(); |
- |
- // Called by Statement objects when an sqlite function returns an error. |
- // The return value is the error code reflected back to client code. |
- int OnSqliteError(int err, Statement* stmt); |
- |
- // Like |Execute()|, but retries if the database is locked. |
- bool ExecuteWithTimeout(const char* sql, base::TimeDelta ms_timeout); |
- |
- // The actual sqlite database. Will be NULL before Init has been called or if |
- // Init resulted in an error. |
- sqlite3* db_; |
- |
- // Parameters we'll configure in sqlite before doing anything else. Zero means |
- // use the default value. |
- int page_size_; |
- int cache_size_; |
- bool exclusive_locking_; |
- |
- // All cached statements. Keeping a reference to these statements means that |
- // they'll remain active. |
- typedef std::map<StatementID, scoped_refptr<StatementRef> > |
- CachedStatementMap; |
- CachedStatementMap statement_cache_; |
- |
- // A list of all StatementRefs we've given out. Each ref must register with |
- // us when it's created or destroyed. This allows us to potentially close |
- // any open statements when we encounter an error. |
- typedef std::set<StatementRef*> StatementRefSet; |
- StatementRefSet open_statements_; |
- |
- // Number of currently-nested transactions. |
- int transaction_nesting_; |
- |
- // True if any of the currently nested transactions have been rolled back. |
- // When we get to the outermost transaction, this will determine if we do |
- // a rollback instead of a commit. |
- bool needs_rollback_; |
- |
- // This object handles errors resulting from all forms of executing sqlite |
- // commands or statements. It can be null which means default handling. |
- scoped_refptr<ErrorDelegate> error_delegate_; |
- |
- DISALLOW_COPY_AND_ASSIGN(Connection); |
-}; |
- |
-} // namespace sql |
- |
-#endif // APP_SQL_CONNECTION_H_ |