[sql] Import SQLite 3.17.0.

third_party/sqlite/src/src/pcache1.c

 /*
 ** 2008 November 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.
 **
@@ skipping 261 matching lines @@
   if( pcache1.nInitPage==0 ) return 0;
   /* Do not bother with a bulk allocation if the cache size very small */
   if( pCache->nMax<3 ) return 0;
   sqlite3BeginBenignMalloc();
   if( pcache1.nInitPage>0 ){
     szBulk = pCache->szAlloc * (i64)pcache1.nInitPage;
   }else{
     szBulk = -1024 * (i64)pcache1.nInitPage;
   }
   if( szBulk > pCache->szAlloc*(i64)pCache->nMax ){
-    szBulk = pCache->szAlloc*pCache->nMax;
+    szBulk = pCache->szAlloc*(i64)pCache->nMax;
   }
   zBulk = pCache->pBulk = sqlite3Malloc( szBulk );
   sqlite3EndBenignMalloc();
   if( zBulk ){
     int nBulk = sqlite3MallocSize(zBulk)/pCache->szAlloc;
     int i;
     for(i=0; i<nBulk; i++){
       PgHdr1 *pX = (PgHdr1*)&zBulk[pCache->szPage];
       pX->page.pBuf = zBulk;
       pX->page.pExtra = &pX[1];
@@ skipping 48 matching lines @@
 #endif
     sqlite3MemdebugSetType(p, MEMTYPE_PCACHE);
   }
   return p;
 }
 
 /*
 ** Free an allocated buffer obtained from pcache1Alloc().
 */
 static void pcache1Free(void *p){
-  int nFreed = 0;
   if( p==0 ) return;
   if( SQLITE_WITHIN(p, pcache1.pStart, pcache1.pEnd) ){
     PgFreeslot *pSlot;
     sqlite3_mutex_enter(pcache1.mutex);
     sqlite3StatusDown(SQLITE_STATUS_PAGECACHE_USED, 1);
     pSlot = (PgFreeslot*)p;
     pSlot->pNext = pcache1.pFree;
     pcache1.pFree = pSlot;
     pcache1.nFreeSlot++;
     pcache1.bUnderPressure = pcache1.nFreeSlot<pcache1.nReserve;
     assert( pcache1.nFreeSlot<=pcache1.nSlot );
     sqlite3_mutex_leave(pcache1.mutex);
   }else{
     assert( sqlite3MemdebugHasType(p, MEMTYPE_PCACHE) );
     sqlite3MemdebugSetType(p, MEMTYPE_HEAP);
 #ifndef SQLITE_DISABLE_PAGECACHE_OVERFLOW_STATS
-    nFreed = sqlite3MallocSize(p);
-    sqlite3_mutex_enter(pcache1.mutex);
-    sqlite3StatusDown(SQLITE_STATUS_PAGECACHE_OVERFLOW, nFreed);
-    sqlite3_mutex_leave(pcache1.mutex);
+    {
+      int nFreed = 0;
+      nFreed = sqlite3MallocSize(p);
+      sqlite3_mutex_enter(pcache1.mutex);
+      sqlite3StatusDown(SQLITE_STATUS_PAGECACHE_OVERFLOW, nFreed);
+      sqlite3_mutex_leave(pcache1.mutex);
+    }
 #endif
     sqlite3_free(p);
   }
 }
 
 #ifdef SQLITE_ENABLE_MEMORY_MANAGEMENT
 /*
 ** Return the size of a pcache allocation
 */
 static int pcache1MemSize(void *p){
@@ skipping 241 matching lines @@
 ** Discard all pages from cache pCache with a page number (key value) 
 ** greater than or equal to iLimit. Any pinned pages that meet this 
 ** criteria are unpinned before they are discarded.
 **
 ** The PCache mutex must be held when this function is called.
 */
 static void pcache1TruncateUnsafe(
   PCache1 *pCache,             /* The cache to truncate */
   unsigned int iLimit          /* Drop pages with this pgno or larger */
 ){
-  TESTONLY( unsigned int nPage = 0; )  /* To assert pCache->nPage is correct */
-  unsigned int h;
+  TESTONLY( int nPage = 0; )  /* To assert pCache->nPage is correct */
+  unsigned int h, iStop;
   assert( sqlite3_mutex_held(pCache->pGroup->mutex) );
-  for(h=0; h<pCache->nHash; h++){
-    PgHdr1 **pp = &pCache->apHash[h]; 
+  assert( pCache->iMaxKey >= iLimit );
+  assert( pCache->nHash > 0 );
+  if( pCache->iMaxKey - iLimit < pCache->nHash ){
+    /* If we are just shaving the last few pages off the end of the
+    ** cache, then there is no point in scanning the entire hash table.
+    ** Only scan those hash slots that might contain pages that need to
+    ** be removed. */
+    h = iLimit % pCache->nHash;
+    iStop = pCache->iMaxKey % pCache->nHash;
+    TESTONLY( nPage = -10; )  /* Disable the pCache->nPage validity check */
+  }else{
+    /* This is the general case where many pages are being removed.
+    ** It is necessary to scan the entire hash table */
+    h = pCache->nHash/2;
+    iStop = h - 1;
+  }
+  for(;;){
+    PgHdr1 **pp;
     PgHdr1 *pPage;
+    assert( h<pCache->nHash );
+    pp = &pCache->apHash[h]; 
     while( (pPage = *pp)!=0 ){
       if( pPage->iKey>=iLimit ){
         pCache->nPage--;
         *pp = pPage->pNext;
         if( !pPage->isPinned ) pcache1PinPage(pPage);
         pcache1FreePage(pPage);
       }else{
         pp = &pPage->pNext;
-        TESTONLY( nPage++; )
+        TESTONLY( if( nPage>=0 ) nPage++; )
       }
     }
+    if( h==iStop ) break;
+    h = (h+1) % pCache->nHash;
   }
-  assert( pCache->nPage==nPage );
+  assert( nPage<0 || pCache->nPage==(unsigned)nPage );
 }
 
 /******************************************************************************/
 /******** sqlite3_pcache Methods **********************************************/
 
 /*
 ** Implementation of the sqlite3_pcache.xInit method.
 */
 static int pcache1Init(void *NotUsed){
   UNUSED_PARAMETER(NotUsed);
@@ skipping 23 matching lines @@
   pcache1.separateCache = 0;
 #elif SQLITE_THREADSAFE
   pcache1.separateCache = sqlite3GlobalConfig.pPage==0
                           || sqlite3GlobalConfig.bCoreMutex>0;
 #else
   pcache1.separateCache = sqlite3GlobalConfig.pPage==0;
 #endif
 
 #if SQLITE_THREADSAFE
   if( sqlite3GlobalConfig.bCoreMutex ){
-    pcache1.grp.mutex = sqlite3_mutex_alloc(SQLITE_MUTEX_STATIC_LRU);
-    pcache1.mutex = sqlite3_mutex_alloc(SQLITE_MUTEX_STATIC_PMEM);
+    pcache1.grp.mutex = sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_LRU);
+    pcache1.mutex = sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_PMEM);
   }
 #endif
   if( pcache1.separateCache
    && sqlite3GlobalConfig.nPage!=0
    && sqlite3GlobalConfig.pPage==0
   ){
     pcache1.nInitPage = sqlite3GlobalConfig.nPage;
   }else{
     pcache1.nInitPage = 0;
   }
@@ skipping 415 matching lines @@
 /*
 ** Implementation of the sqlite3_pcache.xDestroy method. 
 **
 ** Destroy a cache allocated using pcache1Create().
 */
 static void pcache1Destroy(sqlite3_pcache *p){
   PCache1 *pCache = (PCache1 *)p;
   PGroup *pGroup = pCache->pGroup;
   assert( pCache->bPurgeable || (pCache->nMax==0 && pCache->nMin==0) );
   pcache1EnterMutex(pGroup);
-  pcache1TruncateUnsafe(pCache, 0);
+  if( pCache->nPage ) pcache1TruncateUnsafe(pCache, 0);
   assert( pGroup->nMaxPage >= pCache->nMax );
   pGroup->nMaxPage -= pCache->nMax;
   assert( pGroup->nMinPage >= pCache->nMin );
   pGroup->nMinPage -= pCache->nMin;
   pGroup->mxPinned = pGroup->nMaxPage + 10 - pGroup->nMinPage;
   pcache1EnforceMaxPage(pCache);
   pcache1LeaveMutex(pGroup);
   sqlite3_free(pCache->pBulk);
   sqlite3_free(pCache->apHash);
   sqlite3_free(pCache);
@@ skipping 87 matching lines @@
   for(p=pcache1.grp.lru.pLruNext; p && !p->isAnchor; p=p->pLruNext){
     assert( p->isPinned==0 );
     nRecyclable++;
   }
   *pnCurrent = pcache1.grp.nCurrentPage;
   *pnMax = (int)pcache1.grp.nMaxPage;
   *pnMin = (int)pcache1.grp.nMinPage;
   *pnRecyclable = nRecyclable;
 }
 #endif