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-rw-r--r--src/build.c4
-rw-r--r--src/malloc.c40
-rw-r--r--src/pcache1.c51
-rw-r--r--src/sqliteInt.h1
4 files changed, 75 insertions, 21 deletions
diff --git a/src/build.c b/src/build.c
index 636b8a694..5d3af6c38 100644
--- a/src/build.c
+++ b/src/build.c
@@ -1648,12 +1648,10 @@ void sqlite3CreateView(
}
sqlite3StartTable(pParse, pName1, pName2, isTemp, 1, 0, noErr);
p = pParse->pNewTable;
- if( p==0 ){
+ if( p==0 || pParse->nErr ){
sqlite3SelectDelete(db, pSelect);
return;
}
- assert( pParse->nErr==0 ); /* If sqlite3StartTable return non-NULL then
- ** there could not have been an error */
sqlite3TwoPartName(pParse, pName1, pName2, &pName);
iDb = sqlite3SchemaToIndex(db, p->pSchema);
if( sqlite3FixInit(&sFix, pParse, iDb, "view", pName)
diff --git a/src/malloc.c b/src/malloc.c
index b36b44f7f..751d9b174 100644
--- a/src/malloc.c
+++ b/src/malloc.c
@@ -97,7 +97,12 @@ static SQLITE_WSD struct Mem0Global {
** which pages are available.
*/
u32 *aScratchFree;
- u32 *aPageFree;
+
+ /*
+ ** True if heap is nearly "full" where "full" is defined by the
+ ** sqlite3_soft_heap_limit() setting.
+ */
+ int nearlyFull;
} mem0 = { 0, 0, 0, 0, 0, 0, 0, 0 };
#define mem0 GLOBAL(struct Mem0Global, mem0)
@@ -125,26 +130,25 @@ int sqlite3MallocInit(void){
sqlite3GlobalConfig.pScratch = 0;
sqlite3GlobalConfig.szScratch = 0;
}
- if( sqlite3GlobalConfig.pPage && sqlite3GlobalConfig.szPage>=512
- && sqlite3GlobalConfig.nPage>=1 ){
- int i;
- int overhead;
- int sz = ROUNDDOWN8(sqlite3GlobalConfig.szPage);
- int n = sqlite3GlobalConfig.nPage;
- overhead = (4*n + sz - 1)/sz;
- sqlite3GlobalConfig.nPage -= overhead;
- mem0.aPageFree = (u32*)&((char*)sqlite3GlobalConfig.pPage)
- [sqlite3GlobalConfig.szPage*sqlite3GlobalConfig.nPage];
- for(i=0; i<sqlite3GlobalConfig.nPage; i++){ mem0.aPageFree[i] = i; }
- mem0.nPageFree = sqlite3GlobalConfig.nPage;
- }else{
+ if( sqlite3GlobalConfig.pPage==0 || sqlite3GlobalConfig.szPage<512
+ || sqlite3GlobalConfig.nPage<1 ){
sqlite3GlobalConfig.pPage = 0;
sqlite3GlobalConfig.szPage = 0;
+ sqlite3GlobalConfig.nPage = 0;
}
return sqlite3GlobalConfig.m.xInit(sqlite3GlobalConfig.m.pAppData);
}
/*
+** Return true if the heap is currently under memory pressure - in other
+** words if the amount of heap used is close to the limit set by
+** sqlite3_soft_heap_limit().
+*/
+int sqlite3HeapNearlyFull(void){
+ return mem0.nearlyFull;
+}
+
+/*
** Deinitialize the memory allocation subsystem.
*/
void sqlite3MallocEnd(void){
@@ -186,10 +190,13 @@ int sqlite3MemoryAlarm(
void *pArg,
sqlite3_int64 iThreshold
){
+ int nUsed;
sqlite3_mutex_enter(mem0.mutex);
mem0.alarmCallback = xCallback;
mem0.alarmArg = pArg;
mem0.alarmThreshold = iThreshold;
+ nUsed = sqlite3StatusValue(SQLITE_STATUS_MEMORY_USED);
+ mem0.nearlyFull = (iThreshold>0 && iThreshold<=nUsed);
sqlite3_mutex_leave(mem0.mutex);
return SQLITE_OK;
}
@@ -240,14 +247,19 @@ static int mallocWithAlarm(int n, void **pp){
if( mem0.alarmCallback!=0 ){
int nUsed = sqlite3StatusValue(SQLITE_STATUS_MEMORY_USED);
if( nUsed+nFull >= mem0.alarmThreshold ){
+ mem0.nearlyFull = 1;
sqlite3MallocAlarm(nFull);
+ }else{
+ mem0.nearlyFull = 0;
}
}
p = sqlite3GlobalConfig.m.xMalloc(nFull);
+#ifdef SQLITE_ENABLE_MEMORY_MANAGEMENT
if( p==0 && mem0.alarmCallback ){
sqlite3MallocAlarm(nFull);
p = sqlite3GlobalConfig.m.xMalloc(nFull);
}
+#endif
if( p ){
nFull = sqlite3MallocSize(p);
sqlite3StatusAdd(SQLITE_STATUS_MEMORY_USED, nFull);
diff --git a/src/pcache1.c b/src/pcache1.c
index 75c9be72c..eb2e2982d 100644
--- a/src/pcache1.c
+++ b/src/pcache1.c
@@ -89,6 +89,9 @@ static SQLITE_WSD struct PCacheGlobal {
/* Variables related to SQLITE_CONFIG_PAGECACHE settings. */
int szSlot; /* Size of each free slot */
+ int nSlot; /* The number of pcache slots */
+ int nFreeSlot; /* Number of unused pcache slots */
+ int nReserve; /* Try to keep nFreeSlot above this */
void *pStart, *pEnd; /* Bounds of pagecache malloc range */
PgFreeslot *pFree; /* Free page blocks */
int isInit; /* True if initialized */
@@ -136,6 +139,8 @@ void sqlite3PCacheBufferSetup(void *pBuf, int sz, int n){
PgFreeslot *p;
sz = ROUNDDOWN8(sz);
pcache1.szSlot = sz;
+ pcache1.nSlot = pcache1.nFreeSlot = n;
+ pcache1.nReserve = n>90 ? 10 : (n/10 + 1);
pcache1.pStart = pBuf;
pcache1.pFree = 0;
while( n-- ){
@@ -162,6 +167,8 @@ static void *pcache1Alloc(int nByte){
assert( pcache1.isInit );
p = (PgHdr1 *)pcache1.pFree;
pcache1.pFree = pcache1.pFree->pNext;
+ pcache1.nFreeSlot--;
+ assert( pcache1.nFreeSlot>=0 );
sqlite3StatusAdd(SQLITE_STATUS_PAGECACHE_USED, 1);
}else{
@@ -195,6 +202,8 @@ static void pcache1Free(void *p){
pSlot = (PgFreeslot*)p;
pSlot->pNext = pcache1.pFree;
pcache1.pFree = pSlot;
+ pcache1.nFreeSlot++;
+ assert( pcache1.nFreeSlot<=pcache1.nSlot );
}else{
int iSize;
assert( sqlite3MemdebugHasType(p, MEMTYPE_PCACHE) );
@@ -280,6 +289,32 @@ void sqlite3PageFree(void *p){
pcache1LeaveMutex();
}
+
+/*
+** Return true if it desirable to avoid allocating a new page cache
+** entry.
+**
+** If memory was allocated specifically to the page cache using
+** SQLITE_CONFIG_PAGECACHE but that memory has all been used, then
+** it is desirable to avoid allocating a new page cache entry because
+** presumably SQLITE_CONFIG_PAGECACHE was suppose to be sufficient
+** for all page cache needs and we should not need to spill the
+** allocation onto the heap.
+**
+** Or, the heap is used for all page cache memory put the heap is
+** under memory pressure, then again it is desirable to avoid
+** allocating a new page cache entry in order to avoid stressing
+** the heap even further.
+*/
+static int pcache1UnderMemoryPressure(PCache1 *pCache){
+ assert( sqlite3_mutex_held(pcache1.mutex) );
+ if( pcache1.nSlot && pCache->szPage<=pcache1.szSlot ){
+ return pcache1.nFreeSlot<pcache1.nReserve;
+ }else{
+ return sqlite3HeapNearlyFull();
+ }
+}
+
/******************************************************************************/
/******** General Implementation Functions ************************************/
@@ -521,14 +556,16 @@ static int pcache1Pagecount(sqlite3_pcache *p){
** 2. If createFlag==0 and the page is not already in the cache, NULL is
** returned.
**
-** 3. If createFlag is 1, and the page is not already in the cache,
-** and if either of the following are true, return NULL:
+** 3. If createFlag is 1, and the page is not already in the cache, then
+** return NULL (do not allocate a new page) if any of the following
+** conditions are true:
**
** (a) the number of pages pinned by the cache is greater than
** PCache1.nMax, or
+**
** (b) the number of pages pinned by the cache is greater than
** the sum of nMax for all purgeable caches, less the sum of
-** nMin for all other purgeable caches.
+** nMin for all other purgeable caches, or
**
** 4. If none of the first three conditions apply and the cache is marked
** as purgeable, and if one of the following is true:
@@ -540,6 +577,9 @@ static int pcache1Pagecount(sqlite3_pcache *p){
** already equal to or greater than the sum of nMax for all
** purgeable caches,
**
+** (c) The system is under memory pressure and wants to avoid
+** unnecessary pages cache entry allocations
+**
** then attempt to recycle a page from the LRU list. If it is the right
** size, return the recycled buffer. Otherwise, free the buffer and
** proceed to step 5.
@@ -571,6 +611,7 @@ static void *pcache1Fetch(sqlite3_pcache *p, unsigned int iKey, int createFlag){
if( createFlag==1 && (
nPinned>=(pcache1.nMaxPage+pCache->nMin-pcache1.nMinPage)
|| nPinned>=(pCache->nMax * 9 / 10)
+ || pcache1UnderMemoryPressure(pCache)
)){
goto fetch_out;
}
@@ -581,7 +622,9 @@ static void *pcache1Fetch(sqlite3_pcache *p, unsigned int iKey, int createFlag){
/* Step 4. Try to recycle a page buffer if appropriate. */
if( pCache->bPurgeable && pcache1.pLruTail && (
- (pCache->nPage+1>=pCache->nMax) || pcache1.nCurrentPage>=pcache1.nMaxPage
+ (pCache->nPage+1>=pCache->nMax)
+ || pcache1.nCurrentPage>=pcache1.nMaxPage
+ || pcache1UnderMemoryPressure(pCache)
)){
pPage = pcache1.pLruTail;
pcache1RemoveFromHash(pPage);
diff --git a/src/sqliteInt.h b/src/sqliteInt.h
index c44c25fa5..6c41315f8 100644
--- a/src/sqliteInt.h
+++ b/src/sqliteInt.h
@@ -2503,6 +2503,7 @@ void sqlite3PageFree(void*);
void sqlite3MemSetDefault(void);
void sqlite3BenignMallocHooks(void (*)(void), void (*)(void));
int sqlite3MemoryAlarm(void (*)(void*, sqlite3_int64, int), void*, sqlite3_int64);
+int sqlite3HeapNearlyFull(void);
/*
** On systems with ample stack space and that support alloca(), make
generated by cgit v1.2.3 (git 2.25.1) at 2025-07-18 21:17:50 +0000