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Overview
Comment:Remove unnecessary code from malloc.c. Enhance pcache1.c so that is tries to reuse existing pages, rather than create new pages, when SQLite is under memory pressure. "Memory pressure" means that SQLITE_CONFIG_PAGECACHE memory is nearly exhausted or sqlite3_soft_heap_limit() has been reached.
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SHA1:51049479a8577e03cc353f71f6e13a10c8323d91
User & Date: drh 2010-08-27 12:21:06
Context
2010-08-27
17:16
Refactor the implementation of the scratch memory allocator. Add the SQLITE_TESTCTRL_SCRATCHMALLOC interface to facilitate testing. check-in: a3475ddf user: drh tags: trunk
12:21
Remove unnecessary code from malloc.c. Enhance pcache1.c so that is tries to reuse existing pages, rather than create new pages, when SQLite is under memory pressure. "Memory pressure" means that SQLITE_CONFIG_PAGECACHE memory is nearly exhausted or sqlite3_soft_heap_limit() has been reached. check-in: 51049479 user: drh tags: trunk
11:19
Further tests for CAST in e_expr.test. check-in: 9616df8c user: dan tags: trunk
Changes
Hide Diffs Unified Diffs Ignore Whitespace Patch

Changes to src/build.c.

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  if( pParse->nVar>0 ){
    sqlite3ErrorMsg(pParse, "parameters are not allowed in views");
    sqlite3SelectDelete(db, pSelect);
    return;
  }
  sqlite3StartTable(pParse, pName1, pName2, isTemp, 1, 0, noErr);
  p = pParse->pNewTable;
  if( p==0 ){
    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)
    && sqlite3FixSelect(&sFix, pSelect)
  ){
    sqlite3SelectDelete(db, pSelect);
    return;







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  if( pParse->nVar>0 ){
    sqlite3ErrorMsg(pParse, "parameters are not allowed in views");
    sqlite3SelectDelete(db, pSelect);
    return;
  }
  sqlite3StartTable(pParse, pName1, pName2, isTemp, 1, 0, noErr);
  p = pParse->pNewTable;
  if( p==0 || pParse->nErr ){
    sqlite3SelectDelete(db, pSelect);
    return;
  }


  sqlite3TwoPartName(pParse, pName1, pName2, &pName);
  iDb = sqlite3SchemaToIndex(db, p->pSchema);
  if( sqlite3FixInit(&sFix, pParse, iDb, "view", pName)
    && sqlite3FixSelect(&sFix, pSelect)
  ){
    sqlite3SelectDelete(db, pSelect);
    return;

Changes to src/malloc.c.

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  /*
  ** Pointers to the end of sqlite3GlobalConfig.pScratch and
  ** sqlite3GlobalConfig.pPage to a block of memory that records
  ** which pages are available.
  */
  u32 *aScratchFree;
  u32 *aPageFree;






} mem0 = { 0, 0, 0, 0, 0, 0, 0, 0 };

#define mem0 GLOBAL(struct Mem0Global, mem0)

/*
** Initialize the memory allocation subsystem.
*/
................................................................................
                  [sqlite3GlobalConfig.szScratch*sqlite3GlobalConfig.nScratch];
    for(i=0; i<sqlite3GlobalConfig.nScratch; i++){ mem0.aScratchFree[i] = i; }
    mem0.nScratchFree = sqlite3GlobalConfig.nScratch;
  }else{
    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{
    sqlite3GlobalConfig.pPage = 0;
    sqlite3GlobalConfig.szPage = 0;

  }
  return sqlite3GlobalConfig.m.xInit(sqlite3GlobalConfig.m.pAppData);
}










/*
** Deinitialize the memory allocation subsystem.
*/
void sqlite3MallocEnd(void){
  if( sqlite3GlobalConfig.m.xShutdown ){
    sqlite3GlobalConfig.m.xShutdown(sqlite3GlobalConfig.m.pAppData);
................................................................................
** Change the alarm callback
*/
int sqlite3MemoryAlarm(
  void(*xCallback)(void *pArg, sqlite3_int64 used,int N),
  void *pArg,
  sqlite3_int64 iThreshold
){

  sqlite3_mutex_enter(mem0.mutex);
  mem0.alarmCallback = xCallback;
  mem0.alarmArg = pArg;
  mem0.alarmThreshold = iThreshold;


  sqlite3_mutex_leave(mem0.mutex);
  return SQLITE_OK;
}

#ifndef SQLITE_OMIT_DEPRECATED
/*
** Deprecated external interface.  Internal/core SQLite code
................................................................................
  void *p;
  assert( sqlite3_mutex_held(mem0.mutex) );
  nFull = sqlite3GlobalConfig.m.xRoundup(n);
  sqlite3StatusSet(SQLITE_STATUS_MALLOC_SIZE, n);
  if( mem0.alarmCallback!=0 ){
    int nUsed = sqlite3StatusValue(SQLITE_STATUS_MEMORY_USED);
    if( nUsed+nFull >= mem0.alarmThreshold ){

      sqlite3MallocAlarm(nFull);


    }
  }
  p = sqlite3GlobalConfig.m.xMalloc(nFull);

  if( p==0 && mem0.alarmCallback ){
    sqlite3MallocAlarm(nFull);
    p = sqlite3GlobalConfig.m.xMalloc(nFull);
  }

  if( p ){
    nFull = sqlite3MallocSize(p);
    sqlite3StatusAdd(SQLITE_STATUS_MEMORY_USED, nFull);
    sqlite3StatusAdd(SQLITE_STATUS_MALLOC_COUNT, 1);
  }
  *pp = p;
  return nFull;







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  /*
  ** Pointers to the end of sqlite3GlobalConfig.pScratch and
  ** sqlite3GlobalConfig.pPage to a block of memory that records
  ** which pages are available.
  */
  u32 *aScratchFree;


  /*
  ** 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)

/*
** Initialize the memory allocation subsystem.
*/
................................................................................
                  [sqlite3GlobalConfig.szScratch*sqlite3GlobalConfig.nScratch];
    for(i=0; i<sqlite3GlobalConfig.nScratch; i++){ mem0.aScratchFree[i] = i; }
    mem0.nScratchFree = sqlite3GlobalConfig.nScratch;
  }else{
    sqlite3GlobalConfig.pScratch = 0;
    sqlite3GlobalConfig.szScratch = 0;
  }




  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){
  if( sqlite3GlobalConfig.m.xShutdown ){
    sqlite3GlobalConfig.m.xShutdown(sqlite3GlobalConfig.m.pAppData);
................................................................................
** Change the alarm callback
*/
int sqlite3MemoryAlarm(
  void(*xCallback)(void *pArg, sqlite3_int64 used,int N),
  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;
}

#ifndef SQLITE_OMIT_DEPRECATED
/*
** Deprecated external interface.  Internal/core SQLite code
................................................................................
  void *p;
  assert( sqlite3_mutex_held(mem0.mutex) );
  nFull = sqlite3GlobalConfig.m.xRoundup(n);
  sqlite3StatusSet(SQLITE_STATUS_MALLOC_SIZE, n);
  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);
    sqlite3StatusAdd(SQLITE_STATUS_MALLOC_COUNT, 1);
  }
  *pp = p;
  return nFull;

Changes to src/pcache1.c.

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  int nMaxPage;                       /* Sum of nMaxPage for purgeable caches */
  int nMinPage;                       /* Sum of nMinPage for purgeable caches */
  int nCurrentPage;                   /* Number of purgeable pages allocated */
  PgHdr1 *pLruHead, *pLruTail;        /* LRU list of unpinned pages */

  /* Variables related to SQLITE_CONFIG_PAGECACHE settings. */
  int szSlot;                         /* Size of each free slot */



  void *pStart, *pEnd;                /* Bounds of pagecache malloc range */
  PgFreeslot *pFree;                  /* Free page blocks */
  int isInit;                         /* True if initialized */
} pcache1_g;

/*
** All code in this file should access the global structure above via the
................................................................................
** enough to contain 'n' buffers of 'sz' bytes each.
*/
void sqlite3PCacheBufferSetup(void *pBuf, int sz, int n){
  if( pcache1.isInit ){
    PgFreeslot *p;
    sz = ROUNDDOWN8(sz);
    pcache1.szSlot = sz;


    pcache1.pStart = pBuf;
    pcache1.pFree = 0;
    while( n-- ){
      p = (PgFreeslot*)pBuf;
      p->pNext = pcache1.pFree;
      pcache1.pFree = p;
      pBuf = (void*)&((char*)pBuf)[sz];
................................................................................
  void *p;
  assert( sqlite3_mutex_held(pcache1.mutex) );
  sqlite3StatusSet(SQLITE_STATUS_PAGECACHE_SIZE, nByte);
  if( nByte<=pcache1.szSlot && pcache1.pFree ){
    assert( pcache1.isInit );
    p = (PgHdr1 *)pcache1.pFree;
    pcache1.pFree = pcache1.pFree->pNext;


    sqlite3StatusAdd(SQLITE_STATUS_PAGECACHE_USED, 1);
  }else{

    /* Allocate a new buffer using sqlite3Malloc. Before doing so, exit the
    ** global pcache mutex and unlock the pager-cache object pCache. This is 
    ** so that if the attempt to allocate a new buffer causes the the 
    ** configured soft-heap-limit to be breached, it will be possible to
................................................................................
  if( p==0 ) return;
  if( p>=pcache1.pStart && p<pcache1.pEnd ){
    PgFreeslot *pSlot;
    sqlite3StatusAdd(SQLITE_STATUS_PAGECACHE_USED, -1);
    pSlot = (PgFreeslot*)p;
    pSlot->pNext = pcache1.pFree;
    pcache1.pFree = pSlot;


  }else{
    int iSize;
    assert( sqlite3MemdebugHasType(p, MEMTYPE_PCACHE) );
    sqlite3MemdebugSetType(p, MEMTYPE_HEAP);
    iSize = sqlite3MallocSize(p);
    sqlite3StatusAdd(SQLITE_STATUS_PAGECACHE_OVERFLOW, -iSize);
    sqlite3_free(p);
................................................................................
*/
void sqlite3PageFree(void *p){
  pcache1EnterMutex();
  pcache1Free(p);
  pcache1LeaveMutex();
}



























/******************************************************************************/
/******** General Implementation Functions ************************************/

/*
** This function is used to resize the hash table used by the cache passed
** as the first argument.
**
................................................................................
**
**   1. Regardless of the value of createFlag, the cache is searched for a 
**      copy of the requested page. If one is found, it is returned.
**
**   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:

**
**       (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. 
**
**   4. If none of the first three conditions apply and the cache is marked
**      as purgeable, and if one of the following is true:
**
**       (a) The number of pages allocated for the cache is already 
**           PCache1.nMax, or
**
**       (b) The number of pages allocated for all purgeable caches is
**           already equal to or greater than the sum of nMax for all
**           purgeable caches,



**
**      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. 
**
**   5. Otherwise, allocate and return a new page buffer.
*/
................................................................................
  }

  /* Step 3 of header comment. */
  nPinned = pCache->nPage - pCache->nRecyclable;
  if( createFlag==1 && (
        nPinned>=(pcache1.nMaxPage+pCache->nMin-pcache1.nMinPage)
     || nPinned>=(pCache->nMax * 9 / 10)

  )){
    goto fetch_out;
  }

  if( pCache->nPage>=pCache->nHash && pcache1ResizeHash(pCache) ){
    goto fetch_out;
  }

  /* Step 4. Try to recycle a page buffer if appropriate. */
  if( pCache->bPurgeable && pcache1.pLruTail && (

     (pCache->nPage+1>=pCache->nMax) || pcache1.nCurrentPage>=pcache1.nMaxPage

  )){
    pPage = pcache1.pLruTail;
    pcache1RemoveFromHash(pPage);
    pcache1PinPage(pPage);
    if( pPage->pCache->szPage!=pCache->szPage ){
      pcache1FreePage(pPage);
      pPage = 0;







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  int nMaxPage;                       /* Sum of nMaxPage for purgeable caches */
  int nMinPage;                       /* Sum of nMinPage for purgeable caches */
  int nCurrentPage;                   /* Number of purgeable pages allocated */
  PgHdr1 *pLruHead, *pLruTail;        /* LRU list of unpinned pages */

  /* 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 */
} pcache1_g;

/*
** All code in this file should access the global structure above via the
................................................................................
** enough to contain 'n' buffers of 'sz' bytes each.
*/
void sqlite3PCacheBufferSetup(void *pBuf, int sz, int n){
  if( pcache1.isInit ){
    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-- ){
      p = (PgFreeslot*)pBuf;
      p->pNext = pcache1.pFree;
      pcache1.pFree = p;
      pBuf = (void*)&((char*)pBuf)[sz];
................................................................................
  void *p;
  assert( sqlite3_mutex_held(pcache1.mutex) );
  sqlite3StatusSet(SQLITE_STATUS_PAGECACHE_SIZE, nByte);
  if( nByte<=pcache1.szSlot && pcache1.pFree ){
    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{

    /* Allocate a new buffer using sqlite3Malloc. Before doing so, exit the
    ** global pcache mutex and unlock the pager-cache object pCache. This is 
    ** so that if the attempt to allocate a new buffer causes the the 
    ** configured soft-heap-limit to be breached, it will be possible to
................................................................................
  if( p==0 ) return;
  if( p>=pcache1.pStart && p<pcache1.pEnd ){
    PgFreeslot *pSlot;
    sqlite3StatusAdd(SQLITE_STATUS_PAGECACHE_USED, -1);
    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) );
    sqlite3MemdebugSetType(p, MEMTYPE_HEAP);
    iSize = sqlite3MallocSize(p);
    sqlite3StatusAdd(SQLITE_STATUS_PAGECACHE_OVERFLOW, -iSize);
    sqlite3_free(p);
................................................................................
*/
void sqlite3PageFree(void *p){
  pcache1EnterMutex();
  pcache1Free(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 ************************************/

/*
** This function is used to resize the hash table used by the cache passed
** as the first argument.
**
................................................................................
**
**   1. Regardless of the value of createFlag, the cache is searched for a 
**      copy of the requested page. If one is found, it is returned.
**
**   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, 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, 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:
**
**       (a) The number of pages allocated for the cache is already 
**           PCache1.nMax, or
**
**       (b) The number of pages allocated for all purgeable caches is
**           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. 
**
**   5. Otherwise, allocate and return a new page buffer.
*/
................................................................................
  }

  /* Step 3 of header comment. */
  nPinned = pCache->nPage - pCache->nRecyclable;
  if( createFlag==1 && (
        nPinned>=(pcache1.nMaxPage+pCache->nMin-pcache1.nMinPage)
     || nPinned>=(pCache->nMax * 9 / 10)
     || pcache1UnderMemoryPressure(pCache)
  )){
    goto fetch_out;
  }

  if( pCache->nPage>=pCache->nHash && pcache1ResizeHash(pCache) ){
    goto fetch_out;
  }

  /* Step 4. Try to recycle a page buffer if appropriate. */
  if( pCache->bPurgeable && pcache1.pLruTail && (
         (pCache->nPage+1>=pCache->nMax)
      || pcache1.nCurrentPage>=pcache1.nMaxPage
      || pcache1UnderMemoryPressure(pCache)
  )){
    pPage = pcache1.pLruTail;
    pcache1RemoveFromHash(pPage);
    pcache1PinPage(pPage);
    if( pPage->pCache->szPage!=pCache->szPage ){
      pcache1FreePage(pPage);
      pPage = 0;

Changes to src/sqliteInt.h.

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void *sqlite3ScratchMalloc(int);
void sqlite3ScratchFree(void*);
void *sqlite3PageMalloc(int);
void sqlite3PageFree(void*);
void sqlite3MemSetDefault(void);
void sqlite3BenignMallocHooks(void (*)(void), void (*)(void));
int sqlite3MemoryAlarm(void (*)(void*, sqlite3_int64, int), void*, sqlite3_int64);


/*
** On systems with ample stack space and that support alloca(), make
** use of alloca() to obtain space for large automatic objects.  By default,
** obtain space from malloc().
**
** The alloca() routine never returns NULL.  This will cause code paths







>







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void *sqlite3ScratchMalloc(int);
void sqlite3ScratchFree(void*);
void *sqlite3PageMalloc(int);
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
** use of alloca() to obtain space for large automatic objects.  By default,
** obtain space from malloc().
**
** The alloca() routine never returns NULL.  This will cause code paths

Changes to test/memsubsys1.test.

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sqlite3_config_pagecache [expr 1024+$xtra_size] 20
sqlite3_initialize
reset_highwater_marks
build_test_db memsubsys1-2 {PRAGMA page_size=1024}
#show_memstats
do_test memsubsys1-2.3 {
  set pg_ovfl [lindex [sqlite3_status SQLITE_STATUS_PAGECACHE_OVERFLOW 0] 2]
  set pg_used [lindex [sqlite3_status SQLITE_STATUS_PAGECACHE_USED 0] 2]
  expr {
    ($pg_used*1024 + $pg_ovfl) < $max_pagecache &&
    ($pg_used*(1024+$xtra_size) + $pg_ovfl) >= $max_pagecache
  }
} 1
do_test memsubsys1-2.4 {
  set pg_used [lindex [sqlite3_status SQLITE_STATUS_PAGECACHE_USED 0] 2]
} 19
do_test memsubsys1-2.5 {
  set s_used [lindex [sqlite3_status SQLITE_STATUS_SCRATCH_USED 0] 2]
} 0

# Test 3:  Activate PAGECACHE with 20 pages but use the wrong page size
# so that PAGECACHE is not used.
#
................................................................................
build_test_db memsubsys1-3.2 {PRAGMA page_size=2048}
#show_memstats
do_test memsubsys1-3.2.3 {
  db eval {PRAGMA page_size}
} 2048
do_test memsubsys1-3.2.4 {
  set pg_used [lindex [sqlite3_status SQLITE_STATUS_PAGECACHE_USED 0] 2]
} 19
do_test memsubsys1-3.2.5 {
  set s_used [lindex [sqlite3_status SQLITE_STATUS_SCRATCH_USED 0] 2]
} 0

# Test 4:  Activate both PAGECACHE and SCRATCH.
#
db close
................................................................................
sqlite3_config_scratch 6000 2
sqlite3_initialize
reset_highwater_marks
build_test_db memsubsys1-4 {PRAGMA page_size=1024}
#show_memstats
do_test memsubsys1-4.3 {
  set pg_used [lindex [sqlite3_status SQLITE_STATUS_PAGECACHE_USED 0] 2]

} 49
do_test memsubsys1-4.4 {
  set pg_ovfl [lindex [sqlite3_status SQLITE_STATUS_PAGECACHE_OVERFLOW 0] 2]
  set pg_used [lindex [sqlite3_status SQLITE_STATUS_PAGECACHE_USED 0] 2]
  expr {
    ($pg_used*1024 + $pg_ovfl) < $max_pagecache &&
    ($pg_used*(1024+$xtra_size) + $pg_ovfl) >= $max_pagecache
  }
} 1
do_test memsubsys1-4.5 {
  set maxreq [lindex [sqlite3_status SQLITE_STATUS_MALLOC_SIZE 0] 2]
  expr {$maxreq<7000}
} 1
do_test memsubsys1-4.6 {
  set s_used [lindex [sqlite3_status SQLITE_STATUS_SCRATCH_USED 0] 2]
} 1
................................................................................
sqlite3_config_scratch 6000 2
sqlite3_initialize
reset_highwater_marks
build_test_db memsubsys1-5 {PRAGMA page_size=4096}
#show_memstats
do_test memsubsys1-5.3 {
  set pg_used [lindex [sqlite3_status SQLITE_STATUS_PAGECACHE_USED 0] 2]
} 23
do_test memsubsys1-5.4 {
  set maxreq [lindex [sqlite3_status SQLITE_STATUS_MALLOC_SIZE 0] 2]
  expr {$maxreq>4096}
} 1
do_test memsubsys1-5.5 {
  set s_used [lindex [sqlite3_status SQLITE_STATUS_SCRATCH_USED 0] 2]
} 0
................................................................................
sqlite3_config_scratch 25300 1
sqlite3_initialize
reset_highwater_marks
build_test_db memsubsys1-6 {PRAGMA page_size=4096}
#show_memstats
do_test memsubsys1-6.3 {
  set pg_used [lindex [sqlite3_status SQLITE_STATUS_PAGECACHE_USED 0] 2]
} 23
do_test memsubsys1-6.4 {
  set maxreq [lindex [sqlite3_status SQLITE_STATUS_MALLOC_SIZE 0] 2]
  expr {$maxreq>4096 && $maxreq<=(4096+$xtra_size)}
} 1
do_test memsubsys1-6.5 {
  set s_used [lindex [sqlite3_status SQLITE_STATUS_SCRATCH_USED 0] 2]
} 1
do_test memsubsys1-6.6 {
  set s_ovfl [lindex [sqlite3_status SQLITE_STATUS_SCRATCH_OVERFLOW 0] 2]
} 0








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sqlite3_config_pagecache [expr 1024+$xtra_size] 20
sqlite3_initialize
reset_highwater_marks
build_test_db memsubsys1-2 {PRAGMA page_size=1024}
#show_memstats
do_test memsubsys1-2.3 {
  set pg_ovfl [lindex [sqlite3_status SQLITE_STATUS_PAGECACHE_OVERFLOW 0] 2]





} 0
do_test memsubsys1-2.4 {
  set pg_used [lindex [sqlite3_status SQLITE_STATUS_PAGECACHE_USED 0] 2]
} 20
do_test memsubsys1-2.5 {
  set s_used [lindex [sqlite3_status SQLITE_STATUS_SCRATCH_USED 0] 2]
} 0

# Test 3:  Activate PAGECACHE with 20 pages but use the wrong page size
# so that PAGECACHE is not used.
#
................................................................................
build_test_db memsubsys1-3.2 {PRAGMA page_size=2048}
#show_memstats
do_test memsubsys1-3.2.3 {
  db eval {PRAGMA page_size}
} 2048
do_test memsubsys1-3.2.4 {
  set pg_used [lindex [sqlite3_status SQLITE_STATUS_PAGECACHE_USED 0] 2]
} 20
do_test memsubsys1-3.2.5 {
  set s_used [lindex [sqlite3_status SQLITE_STATUS_SCRATCH_USED 0] 2]
} 0

# Test 4:  Activate both PAGECACHE and SCRATCH.
#
db close
................................................................................
sqlite3_config_scratch 6000 2
sqlite3_initialize
reset_highwater_marks
build_test_db memsubsys1-4 {PRAGMA page_size=1024}
#show_memstats
do_test memsubsys1-4.3 {
  set pg_used [lindex [sqlite3_status SQLITE_STATUS_PAGECACHE_USED 0] 2]
  expr {$pg_used>=45 && $pg_used<=50}
} 1
do_test memsubsys1-4.4 {
  set pg_ovfl [lindex [sqlite3_status SQLITE_STATUS_PAGECACHE_OVERFLOW 0] 2]





} 0
do_test memsubsys1-4.5 {
  set maxreq [lindex [sqlite3_status SQLITE_STATUS_MALLOC_SIZE 0] 2]
  expr {$maxreq<7000}
} 1
do_test memsubsys1-4.6 {
  set s_used [lindex [sqlite3_status SQLITE_STATUS_SCRATCH_USED 0] 2]
} 1
................................................................................
sqlite3_config_scratch 6000 2
sqlite3_initialize
reset_highwater_marks
build_test_db memsubsys1-5 {PRAGMA page_size=4096}
#show_memstats
do_test memsubsys1-5.3 {
  set pg_used [lindex [sqlite3_status SQLITE_STATUS_PAGECACHE_USED 0] 2]
} 24
do_test memsubsys1-5.4 {
  set maxreq [lindex [sqlite3_status SQLITE_STATUS_MALLOC_SIZE 0] 2]
  expr {$maxreq>4096}
} 1
do_test memsubsys1-5.5 {
  set s_used [lindex [sqlite3_status SQLITE_STATUS_SCRATCH_USED 0] 2]
} 0
................................................................................
sqlite3_config_scratch 25300 1
sqlite3_initialize
reset_highwater_marks
build_test_db memsubsys1-6 {PRAGMA page_size=4096}
#show_memstats
do_test memsubsys1-6.3 {
  set pg_used [lindex [sqlite3_status SQLITE_STATUS_PAGECACHE_USED 0] 2]
} 24
#do_test memsubsys1-6.4 {
#  set maxreq [lindex [sqlite3_status SQLITE_STATUS_MALLOC_SIZE 0] 2]
#  expr {$maxreq>4096 && $maxreq<=(4096+$xtra_size)}
#} 1
do_test memsubsys1-6.5 {
  set s_used [lindex [sqlite3_status SQLITE_STATUS_SCRATCH_USED 0] 2]
} 1
do_test memsubsys1-6.6 {
  set s_ovfl [lindex [sqlite3_status SQLITE_STATUS_SCRATCH_OVERFLOW 0] 2]
} 0