Move bundled copy of sqlite one level deeper to better separate it...

third_party/sqlite/src/pcache.c

Index: third_party/sqlite/src/pcache.c
===================================================================
--- third_party/sqlite/src/pcache.c	(revision 56608)
+++ third_party/sqlite/src/pcache.c	(working copy)
@@ -1,574 +0,0 @@
-/*
-** 2008 August 05
-**
-** 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 file implements that page cache.
-**
-** @(#) $Id: pcache.c,v 1.47 2009/07/25 11:46:49 danielk1977 Exp $
-*/
-#include "sqliteInt.h"
-
-/*
-** A complete page cache is an instance of this structure.
-*/
-struct PCache {
-  PgHdr *pDirty, *pDirtyTail;         /* List of dirty pages in LRU order */
-  PgHdr *pSynced;                     /* Last synced page in dirty page list */
-  int nRef;                           /* Number of referenced pages */
-  int nMax;                           /* Configured cache size */
-  int szPage;                         /* Size of every page in this cache */
-  int szExtra;                        /* Size of extra space for each page */
-  int bPurgeable;                     /* True if pages are on backing store */
-  int (*xStress)(void*,PgHdr*);       /* Call to try make a page clean */
-  void *pStress;                      /* Argument to xStress */
-  sqlite3_pcache *pCache;             /* Pluggable cache module */
-  PgHdr *pPage1;                      /* Reference to page 1 */
-};
-
-/*
-** Some of the assert() macros in this code are too expensive to run
-** even during normal debugging.  Use them only rarely on long-running
-** tests.  Enable the expensive asserts using the
-** -DSQLITE_ENABLE_EXPENSIVE_ASSERT=1 compile-time option.
-*/
-#ifdef SQLITE_ENABLE_EXPENSIVE_ASSERT
-# define expensive_assert(X)  assert(X)
-#else
-# define expensive_assert(X)
-#endif
-
-/********************************** Linked List Management ********************/
-
-#if !defined(NDEBUG) && defined(SQLITE_ENABLE_EXPENSIVE_ASSERT)
-/*
-** Check that the pCache->pSynced variable is set correctly. If it
-** is not, either fail an assert or return zero. Otherwise, return
-** non-zero. This is only used in debugging builds, as follows:
-**
-**   expensive_assert( pcacheCheckSynced(pCache) );
-*/
-static int pcacheCheckSynced(PCache *pCache){
-  PgHdr *p;
-  for(p=pCache->pDirtyTail; p!=pCache->pSynced; p=p->pDirtyPrev){
-    assert( p->nRef || (p->flags&PGHDR_NEED_SYNC) );
-  }
-  return (p==0 || p->nRef || (p->flags&PGHDR_NEED_SYNC)==0);
-}
-#endif /* !NDEBUG && SQLITE_ENABLE_EXPENSIVE_ASSERT */
-
-/*
-** Remove page pPage from the list of dirty pages.
-*/
-static void pcacheRemoveFromDirtyList(PgHdr *pPage){
-  PCache *p = pPage->pCache;
-
-  assert( pPage->pDirtyNext || pPage==p->pDirtyTail );
-  assert( pPage->pDirtyPrev || pPage==p->pDirty );
-
-  /* Update the PCache1.pSynced variable if necessary. */
-  if( p->pSynced==pPage ){
-    PgHdr *pSynced = pPage->pDirtyPrev;
-    while( pSynced && (pSynced->flags&PGHDR_NEED_SYNC) ){
-      pSynced = pSynced->pDirtyPrev;
-    }
-    p->pSynced = pSynced;
-  }
-
-  if( pPage->pDirtyNext ){
-    pPage->pDirtyNext->pDirtyPrev = pPage->pDirtyPrev;
-  }else{
-    assert( pPage==p->pDirtyTail );
-    p->pDirtyTail = pPage->pDirtyPrev;
-  }
-  if( pPage->pDirtyPrev ){
-    pPage->pDirtyPrev->pDirtyNext = pPage->pDirtyNext;
-  }else{
-    assert( pPage==p->pDirty );
-    p->pDirty = pPage->pDirtyNext;
-  }
-  pPage->pDirtyNext = 0;
-  pPage->pDirtyPrev = 0;
-
-  expensive_assert( pcacheCheckSynced(p) );
-}
-
-/*
-** Add page pPage to the head of the dirty list (PCache1.pDirty is set to
-** pPage).
-*/
-static void pcacheAddToDirtyList(PgHdr *pPage){
-  PCache *p = pPage->pCache;
-
-  assert( pPage->pDirtyNext==0 && pPage->pDirtyPrev==0 && p->pDirty!=pPage );
-
-  pPage->pDirtyNext = p->pDirty;
-  if( pPage->pDirtyNext ){
-    assert( pPage->pDirtyNext->pDirtyPrev==0 );
-    pPage->pDirtyNext->pDirtyPrev = pPage;
-  }
-  p->pDirty = pPage;
-  if( !p->pDirtyTail ){
-    p->pDirtyTail = pPage;
-  }
-  if( !p->pSynced && 0==(pPage->flags&PGHDR_NEED_SYNC) ){
-    p->pSynced = pPage;
-  }
-  expensive_assert( pcacheCheckSynced(p) );
-}
-
-/*
-** Wrapper around the pluggable caches xUnpin method. If the cache is
-** being used for an in-memory database, this function is a no-op.
-*/
-static void pcacheUnpin(PgHdr *p){
-  PCache *pCache = p->pCache;
-  if( pCache->bPurgeable ){
-    if( p->pgno==1 ){
-      pCache->pPage1 = 0;
-    }
-    sqlite3GlobalConfig.pcache.xUnpin(pCache->pCache, p, 0);
-  }
-}
-
-/*************************************************** General Interfaces ******
-**
-** Initialize and shutdown the page cache subsystem. Neither of these 
-** functions are threadsafe.
-*/
-int sqlite3PcacheInitialize(void){
-  if( sqlite3GlobalConfig.pcache.xInit==0 ){
-    sqlite3PCacheSetDefault();
-  }
-  return sqlite3GlobalConfig.pcache.xInit(sqlite3GlobalConfig.pcache.pArg);
-}
-void sqlite3PcacheShutdown(void){
-  if( sqlite3GlobalConfig.pcache.xShutdown ){
-    sqlite3GlobalConfig.pcache.xShutdown(sqlite3GlobalConfig.pcache.pArg);
-  }
-}
-
-/*
-** Return the size in bytes of a PCache object.
-*/
-int sqlite3PcacheSize(void){ return sizeof(PCache); }
-
-/*
-** Create a new PCache object. Storage space to hold the object
-** has already been allocated and is passed in as the p pointer. 
-** The caller discovers how much space needs to be allocated by 
-** calling sqlite3PcacheSize().
-*/
-void sqlite3PcacheOpen(
-  int szPage,                  /* Size of every page */
-  int szExtra,                 /* Extra space associated with each page */
-  int bPurgeable,              /* True if pages are on backing store */
-  int (*xStress)(void*,PgHdr*),/* Call to try to make pages clean */
-  void *pStress,               /* Argument to xStress */
-  PCache *p                    /* Preallocated space for the PCache */
-){
-  memset(p, 0, sizeof(PCache));
-  p->szPage = szPage;
-  p->szExtra = szExtra;
-  p->bPurgeable = bPurgeable;
-  p->xStress = xStress;
-  p->pStress = pStress;
-  p->nMax = 100;
-}
-
-/*
-** Change the page size for PCache object. The caller must ensure that there
-** are no outstanding page references when this function is called.
-*/
-void sqlite3PcacheSetPageSize(PCache *pCache, int szPage){
-  assert( pCache->nRef==0 && pCache->pDirty==0 );
-  if( pCache->pCache ){
-    sqlite3GlobalConfig.pcache.xDestroy(pCache->pCache);
-    pCache->pCache = 0;
-  }
-  pCache->szPage = szPage;
-}
-
-/*
-** Try to obtain a page from the cache.
-*/
-int sqlite3PcacheFetch(
-  PCache *pCache,       /* Obtain the page from this cache */
-  Pgno pgno,            /* Page number to obtain */
-  int createFlag,       /* If true, create page if it does not exist already */
-  PgHdr **ppPage        /* Write the page here */
-){
-  PgHdr *pPage = 0;
-  int eCreate;
-
-  assert( pCache!=0 );
-  assert( createFlag==1 || createFlag==0 );
-  assert( pgno>0 );
-
-  /* If the pluggable cache (sqlite3_pcache*) has not been allocated,
-  ** allocate it now.
-  */
-  if( !pCache->pCache && createFlag ){
-    sqlite3_pcache *p;
-    int nByte;
-    nByte = pCache->szPage + pCache->szExtra + sizeof(PgHdr);
-    p = sqlite3GlobalConfig.pcache.xCreate(nByte, pCache->bPurgeable);
-    if( !p ){
-      return SQLITE_NOMEM;
-    }
-    sqlite3GlobalConfig.pcache.xCachesize(p, pCache->nMax);
-    pCache->pCache = p;
-  }
-
-  eCreate = createFlag * (1 + (!pCache->bPurgeable || !pCache->pDirty));
-  if( pCache->pCache ){
-    pPage = sqlite3GlobalConfig.pcache.xFetch(pCache->pCache, pgno, eCreate);
-  }
-
-  if( !pPage && eCreate==1 ){
-    PgHdr *pPg;
-
-    /* Find a dirty page to write-out and recycle. First try to find a 
-    ** page that does not require a journal-sync (one with PGHDR_NEED_SYNC
-    ** cleared), but if that is not possible settle for any other 
-    ** unreferenced dirty page.
-    */
-    expensive_assert( pcacheCheckSynced(pCache) );
-    for(pPg=pCache->pSynced; 
-        pPg && (pPg->nRef || (pPg->flags&PGHDR_NEED_SYNC)); 
-        pPg=pPg->pDirtyPrev
-    );
-    if( !pPg ){
-      for(pPg=pCache->pDirtyTail; pPg && pPg->nRef; pPg=pPg->pDirtyPrev);
-    }
-    if( pPg ){
-      int rc;
-      rc = pCache->xStress(pCache->pStress, pPg);
-      if( rc!=SQLITE_OK && rc!=SQLITE_BUSY ){
-        return rc;
-      }
-    }
-
-    pPage = sqlite3GlobalConfig.pcache.xFetch(pCache->pCache, pgno, 2);
-  }
-
-  if( pPage ){
-    if( !pPage->pData ){
-      memset(pPage, 0, sizeof(PgHdr) + pCache->szExtra);
-      pPage->pExtra = (void*)&pPage[1];
-      pPage->pData = (void *)&((char *)pPage)[sizeof(PgHdr) + pCache->szExtra];
-      pPage->pCache = pCache;
-      pPage->pgno = pgno;
-    }
-    assert( pPage->pCache==pCache );
-    assert( pPage->pgno==pgno );
-    assert( pPage->pExtra==(void *)&pPage[1] );
-
-    if( 0==pPage->nRef ){
-      pCache->nRef++;
-    }
-    pPage->nRef++;
-    if( pgno==1 ){
-      pCache->pPage1 = pPage;
-    }
-  }
-  *ppPage = pPage;
-  return (pPage==0 && eCreate) ? SQLITE_NOMEM : SQLITE_OK;
-}
-
-/*
-** Decrement the reference count on a page. If the page is clean and the
-** reference count drops to 0, then it is made elible for recycling.
-*/
-void sqlite3PcacheRelease(PgHdr *p){
-  assert( p->nRef>0 );
-  p->nRef--;
-  if( p->nRef==0 ){
-    PCache *pCache = p->pCache;
-    pCache->nRef--;
-    if( (p->flags&PGHDR_DIRTY)==0 ){
-      pcacheUnpin(p);
-    }else{
-      /* Move the page to the head of the dirty list. */
-      pcacheRemoveFromDirtyList(p);
-      pcacheAddToDirtyList(p);
-    }
-  }
-}
-
-/*
-** Increase the reference count of a supplied page by 1.
-*/
-void sqlite3PcacheRef(PgHdr *p){
-  assert(p->nRef>0);
-  p->nRef++;
-}
-
-/*
-** Drop a page from the cache. There must be exactly one reference to the
-** page. This function deletes that reference, so after it returns the
-** page pointed to by p is invalid.
-*/
-void sqlite3PcacheDrop(PgHdr *p){
-  PCache *pCache;
-  assert( p->nRef==1 );
-  if( p->flags&PGHDR_DIRTY ){
-    pcacheRemoveFromDirtyList(p);
-  }
-  pCache = p->pCache;
-  pCache->nRef--;
-  if( p->pgno==1 ){
-    pCache->pPage1 = 0;
-  }
-  sqlite3GlobalConfig.pcache.xUnpin(pCache->pCache, p, 1);
-}
-
-/*
-** Make sure the page is marked as dirty. If it isn't dirty already,
-** make it so.
-*/
-void sqlite3PcacheMakeDirty(PgHdr *p){
-  p->flags &= ~PGHDR_DONT_WRITE;
-  assert( p->nRef>0 );
-  if( 0==(p->flags & PGHDR_DIRTY) ){
-    p->flags |= PGHDR_DIRTY;
-    pcacheAddToDirtyList( p);
-  }
-}
-
-/*
-** Make sure the page is marked as clean. If it isn't clean already,
-** make it so.
-*/
-void sqlite3PcacheMakeClean(PgHdr *p){
-  if( (p->flags & PGHDR_DIRTY) ){
-    pcacheRemoveFromDirtyList(p);
-    p->flags &= ~(PGHDR_DIRTY|PGHDR_NEED_SYNC);
-    if( p->nRef==0 ){
-      pcacheUnpin(p);
-    }
-  }
-}
-
-/*
-** Make every page in the cache clean.
-*/
-void sqlite3PcacheCleanAll(PCache *pCache){
-  PgHdr *p;
-  while( (p = pCache->pDirty)!=0 ){
-    sqlite3PcacheMakeClean(p);
-  }
-}
-
-/*
-** Clear the PGHDR_NEED_SYNC flag from all dirty pages.
-*/
-void sqlite3PcacheClearSyncFlags(PCache *pCache){
-  PgHdr *p;
-  for(p=pCache->pDirty; p; p=p->pDirtyNext){
-    p->flags &= ~PGHDR_NEED_SYNC;
-  }
-  pCache->pSynced = pCache->pDirtyTail;
-}
-
-/*
-** Change the page number of page p to newPgno. 
-*/
-void sqlite3PcacheMove(PgHdr *p, Pgno newPgno){
-  PCache *pCache = p->pCache;
-  assert( p->nRef>0 );
-  assert( newPgno>0 );
-  sqlite3GlobalConfig.pcache.xRekey(pCache->pCache, p, p->pgno, newPgno);
-  p->pgno = newPgno;
-  if( (p->flags&PGHDR_DIRTY) && (p->flags&PGHDR_NEED_SYNC) ){
-    pcacheRemoveFromDirtyList(p);
-    pcacheAddToDirtyList(p);
-  }
-}
-
-/*
-** Drop every cache entry whose page number is greater than "pgno". The
-** caller must ensure that there are no outstanding references to any pages
-** other than page 1 with a page number greater than pgno.
-**
-** If there is a reference to page 1 and the pgno parameter passed to this
-** function is 0, then the data area associated with page 1 is zeroed, but
-** the page object is not dropped.
-*/
-void sqlite3PcacheTruncate(PCache *pCache, Pgno pgno){
-  if( pCache->pCache ){
-    PgHdr *p;
-    PgHdr *pNext;
-    for(p=pCache->pDirty; p; p=pNext){
-      pNext = p->pDirtyNext;
-      if( p->pgno>pgno ){
-        assert( p->flags&PGHDR_DIRTY );
-        sqlite3PcacheMakeClean(p);
-      }
-    }
-    if( pgno==0 && pCache->pPage1 ){
-      memset(pCache->pPage1->pData, 0, pCache->szPage);
-      pgno = 1;
-    }
-    sqlite3GlobalConfig.pcache.xTruncate(pCache->pCache, pgno+1);
-  }
-}
-
-/*
-** Close a cache.
-*/
-void sqlite3PcacheClose(PCache *pCache){
-  if( pCache->pCache ){
-    sqlite3GlobalConfig.pcache.xDestroy(pCache->pCache);
-  }
-}
-
-/* 
-** Discard the contents of the cache.
-*/
-void sqlite3PcacheClear(PCache *pCache){
-  sqlite3PcacheTruncate(pCache, 0);
-}
-
-/*
-** Merge two lists of pages connected by pDirty and in pgno order.
-** Do not both fixing the pDirtyPrev pointers.
-*/
-static PgHdr *pcacheMergeDirtyList(PgHdr *pA, PgHdr *pB){
-  PgHdr result, *pTail;
-  pTail = &result;
-  while( pA && pB ){
-    if( pA->pgno<pB->pgno ){
-      pTail->pDirty = pA;
-      pTail = pA;
-      pA = pA->pDirty;
-    }else{
-      pTail->pDirty = pB;
-      pTail = pB;
-      pB = pB->pDirty;
-    }
-  }
-  if( pA ){
-    pTail->pDirty = pA;
-  }else if( pB ){
-    pTail->pDirty = pB;
-  }else{
-    pTail->pDirty = 0;
-  }
-  return result.pDirty;
-}
-
-/*
-** Sort the list of pages in accending order by pgno.  Pages are
-** connected by pDirty pointers.  The pDirtyPrev pointers are
-** corrupted by this sort.
-**
-** Since there cannot be more than 2^31 distinct pages in a database,
-** there cannot be more than 31 buckets required by the merge sorter.
-** One extra bucket is added to catch overflow in case something
-** ever changes to make the previous sentence incorrect.
-*/
-#define N_SORT_BUCKET  32
-static PgHdr *pcacheSortDirtyList(PgHdr *pIn){
-  PgHdr *a[N_SORT_BUCKET], *p;
-  int i;
-  memset(a, 0, sizeof(a));
-  while( pIn ){
-    p = pIn;
-    pIn = p->pDirty;
-    p->pDirty = 0;
-    for(i=0; ALWAYS(i<N_SORT_BUCKET-1); i++){
-      if( a[i]==0 ){
-        a[i] = p;
-        break;
-      }else{
-        p = pcacheMergeDirtyList(a[i], p);
-        a[i] = 0;
-      }
-    }
-    if( NEVER(i==N_SORT_BUCKET-1) ){
-      /* To get here, there need to be 2^(N_SORT_BUCKET) elements in
-      ** the input list.  But that is impossible.
-      */
-      a[i] = pcacheMergeDirtyList(a[i], p);
-    }
-  }
-  p = a[0];
-  for(i=1; i<N_SORT_BUCKET; i++){
-    p = pcacheMergeDirtyList(p, a[i]);
-  }
-  return p;
-}
-
-/*
-** Return a list of all dirty pages in the cache, sorted by page number.
-*/
-PgHdr *sqlite3PcacheDirtyList(PCache *pCache){
-  PgHdr *p;
-  for(p=pCache->pDirty; p; p=p->pDirtyNext){
-    p->pDirty = p->pDirtyNext;
-  }
-  return pcacheSortDirtyList(pCache->pDirty);
-}
-
-/* 
-** Return the total number of referenced pages held by the cache.
-*/
-int sqlite3PcacheRefCount(PCache *pCache){
-  return pCache->nRef;
-}
-
-/*
-** Return the number of references to the page supplied as an argument.
-*/
-int sqlite3PcachePageRefcount(PgHdr *p){
-  return p->nRef;
-}
-
-/* 
-** Return the total number of pages in the cache.
-*/
-int sqlite3PcachePagecount(PCache *pCache){
-  int nPage = 0;
-  if( pCache->pCache ){
-    nPage = sqlite3GlobalConfig.pcache.xPagecount(pCache->pCache);
-  }
-  return nPage;
-}
-
-/*
-** Get the suggested cache-size value.
-*/
-int sqlite3PcacheGetCachesize(PCache *pCache){
-  return pCache->nMax;
-}
-
-/*
-** Set the suggested cache-size value.
-*/
-void sqlite3PcacheSetCachesize(PCache *pCache, int mxPage){
-  pCache->nMax = mxPage;
-  if( pCache->pCache ){
-    sqlite3GlobalConfig.pcache.xCachesize(pCache->pCache, mxPage);
-  }
-}
-
-#if defined(SQLITE_CHECK_PAGES) || defined(SQLITE_DEBUG)
-/*
-** For all dirty pages currently in the cache, invoke the specified
-** callback. This is only used if the SQLITE_CHECK_PAGES macro is
-** defined.
-*/
-void sqlite3PcacheIterateDirty(PCache *pCache, void (*xIter)(PgHdr *)){
-  PgHdr *pDirty;
-  for(pDirty=pCache->pDirty; pDirty; pDirty=pDirty->pDirtyNext){
-    xIter(pDirty);
-  }
-}
-#endif