SQLite

} ScratchFreeslot;

/*
** State information local to the memory allocation subsystem.
*/
static SQLITE_WSD struct Mem0Global {
  sqlite3_mutex *mutex;         /* Mutex to serialize access */

  /*
  ** The alarm callback and its arguments.  The mem0.mutex lock will
  ** be held while the callback is running.  Recursive calls into
  ** the memory subsystem are allowed, but no new callbacks will be
  ** issued.
  */
  sqlite3_int64 alarmThreshold;
  void (*alarmCallback)(void*, sqlite3_int64,int);
  void *alarmArg;

  /*
  ** Pointers to the end of sqlite3GlobalConfig.pScratch memory
  ** (so that a range test can be used to determine if an allocation
  ** being freed came from pScratch) and a pointer to the list of
  ** unused scratch allocations.
  */
  void *pScratchEnd;
  ScratchFreeslot *pScratchFree;
  u32 nScratchFree;

  /*
  ** 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)

/*
** Return the memory allocator mutex. sqlite3_status() needs it.
*/
sqlite3_mutex *sqlite3MallocMutex(void){
  return mem0.mutex;
}

/*
** This routine runs when the memory allocator sees that the
** total memory allocation is about to exceed the soft heap
** limit.
*/
static void softHeapLimitEnforcer(
  void *NotUsed, 
  sqlite3_int64 NotUsed2,
  int allocSize
){
  UNUSED_PARAMETER2(NotUsed, NotUsed2);
  sqlite3_release_memory(allocSize);

}

/*

** Change the alarm callback
*/
static int sqlite3MemoryAlarm(
  void(*xCallback)(void *pArg, sqlite3_int64 used,int N),
  void *pArg,
  sqlite3_int64 iThreshold
){
  sqlite3_int64 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
** should call sqlite3MemoryAlarm.

*/
int sqlite3_memory_alarm(
  void(*xCallback)(void *pArg, sqlite3_int64 used,int N),
  void *pArg,
  sqlite3_int64 iThreshold
){
  return sqlite3MemoryAlarm(xCallback, pArg, iThreshold);
}
#endif

/*
** Set the soft heap-size limit for the library. Passing a zero or 
** negative value indicates no limit.
*/
sqlite3_int64 sqlite3_soft_heap_limit64(sqlite3_int64 n){
  sqlite3_int64 priorLimit;
  sqlite3_int64 excess;
#ifndef SQLITE_OMIT_AUTOINIT
  int rc = sqlite3_initialize();
  if( rc ) return -1;
#endif
  sqlite3_mutex_enter(mem0.mutex);
  priorLimit = mem0.alarmThreshold;
  sqlite3_mutex_leave(mem0.mutex);
  if( n<0 ) return priorLimit;
  if( n>0 ){

    sqlite3MemoryAlarm(softHeapLimitEnforcer, 0, n);
  }else{
    sqlite3MemoryAlarm(0, 0, 0);

  }
  excess = sqlite3_memory_used() - n;
  if( excess>0 ) sqlite3_release_memory((int)(excess & 0x7fffffff));
  return priorLimit;
}
void sqlite3_soft_heap_limit(int n){
  if( n<0 ) n = 0;
  sqlite3_soft_heap_limit64(n);
}

*/
sqlite3_int64 sqlite3_memory_highwater(int resetFlag){
  sqlite3_int64 res, mx;
  sqlite3_status64(SQLITE_STATUS_MEMORY_USED, &res, &mx, resetFlag);
  return mx;
}

/*
** Trigger the alarm 
*/
static void sqlite3MallocAlarm(int nByte){
  void (*xCallback)(void*,sqlite3_int64,int);
  sqlite3_int64 nowUsed;
  void *pArg;
  if( mem0.alarmCallback==0 ) return;
  xCallback = mem0.alarmCallback;
  nowUsed = sqlite3StatusValue(SQLITE_STATUS_MEMORY_USED);
  pArg = mem0.alarmArg;
  mem0.alarmCallback = 0;
  sqlite3_mutex_leave(mem0.mutex);
  xCallback(pArg, nowUsed, nByte);
  sqlite3_mutex_enter(mem0.mutex);
  mem0.alarmCallback = xCallback;
  mem0.alarmArg = pArg;
}

/*
** Do a memory allocation with statistics and alarms.  Assume the
** lock is already held.
*/
static int mallocWithAlarm(int n, void **pp){
  int nFull;
  void *p;
  assert( sqlite3_mutex_held(mem0.mutex) );
  nFull = sqlite3GlobalConfig.m.xRoundup(n);
  sqlite3StatusSet(SQLITE_STATUS_MALLOC_SIZE, n);
  if( mem0.alarmCallback!=0 ){
    sqlite3_int64 nUsed = sqlite3StatusValue(SQLITE_STATUS_MEMORY_USED);
    if( nUsed >= mem0.alarmThreshold - nFull ){
      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);
    sqlite3StatusUp(SQLITE_STATUS_MEMORY_USED, nFull);
    sqlite3StatusUp(SQLITE_STATUS_MALLOC_COUNT, 1);

  nNew = sqlite3GlobalConfig.m.xRoundup((int)nBytes);
  if( nOld==nNew ){
    pNew = pOld;
  }else if( sqlite3GlobalConfig.bMemstat ){
    sqlite3_mutex_enter(mem0.mutex);
    sqlite3StatusSet(SQLITE_STATUS_MALLOC_SIZE, (int)nBytes);
    nDiff = nNew - nOld;
    if( sqlite3StatusValue(SQLITE_STATUS_MEMORY_USED) >= 
          mem0.alarmThreshold-nDiff ){
      sqlite3MallocAlarm(nDiff);
    }
    pNew = sqlite3GlobalConfig.m.xRealloc(pOld, nNew);

    if( pNew==0 && mem0.alarmCallback ){
      sqlite3MallocAlarm((int)nBytes);
      pNew = sqlite3GlobalConfig.m.xRealloc(pOld, nNew);
    }

    if( pNew ){
      nNew = sqlite3MallocSize(pNew);
      sqlite3StatusUp(SQLITE_STATUS_MEMORY_USED, nNew-nOld);
    }
    sqlite3_mutex_leave(mem0.mutex);
  }else{
    pNew = sqlite3GlobalConfig.m.xRealloc(pOld, nNew);