SQLite

  if( sqlite3GlobalConfig.isMutexInit ){
    sqlite3MutexEnd();
    sqlite3GlobalConfig.isMutexInit = 0;
  }

  return SQLITE_OK;
}

/*
** If a custom memory allocator is configured using the legacy 
** SQLITE_CONFIG_MALLOC interface, this function is used as the xCalloc()
** method.
*/
static void *syntheticCalloc(int nByte){
  void *pRet = sqlite3GlobalConfig.m.xMalloc(nByte);
  if( pRet ) memset(pRet, 0, nByte);
  return pRet;
}

/*
** This API allows applications to modify the global configuration of
** the SQLite library at run-time.
**
** This routine should only be called when there are no outstanding
** database connections or memory allocations.  This routine is not

    case SQLITE_CONFIG_GETMUTEX: {
      /* Retrieve the current mutex implementation */
      *va_arg(ap, sqlite3_mutex_methods*) = sqlite3GlobalConfig.mutex;
      break;
    }
#endif

    case SQLITE_CONFIG_MALLOC: {
      /* Specify an alternative malloc implementation */
      int nCopy = offsetof(sqlite3_mem_methods, xCalloc);
      memcpy(&sqlite3GlobalConfig.m, va_arg(ap, sqlite3_mem_methods*), nCopy);
      sqlite3GlobalConfig.m.xCalloc = syntheticCalloc;
      break;
    }
    case SQLITE_CONFIG_GETMALLOC: {
      /* Retrieve the current malloc() implementation */
      int nCopy = offsetof(sqlite3_mem_methods, xCalloc);
      if( sqlite3GlobalConfig.m.xMalloc==0 ) sqlite3MemSetDefault();
      memcpy(va_arg(ap, sqlite3_mem_methods*), &sqlite3GlobalConfig.m, nCopy);
      break;
    }

    case SQLITE_CONFIG_MALLOC2: {
      /* Specify an alternative malloc implementation */
      sqlite3GlobalConfig.m = *va_arg(ap, sqlite3_mem_methods*);
      break;
    }
    case SQLITE_CONFIG_GETMALLOC2: {
      /* Retrieve the current malloc() implementation */
      if( sqlite3GlobalConfig.m.xMalloc==0 ) sqlite3MemSetDefault();
      *va_arg(ap, sqlite3_mem_methods*) = sqlite3GlobalConfig.m;
      break;
    }

    case SQLITE_CONFIG_MEMSTATUS: {
      /* Enable or disable the malloc status collection */
      sqlite3GlobalConfig.bMemstat = va_arg(ap, int);
      break;
    }
    case SQLITE_CONFIG_SCRATCH: {
      /* Designate a buffer for scratch memory space */

  mem0.alarmArg = pArg;
}

/*
** Do a memory allocation with statistics and alarms.  Assume the
** lock is already held.
*/
static int mallocWithAlarm(
  void *(*xAlloc)(int),          /* Memory allocation function */
  int n,                         /* Bytes of memory to allocate */
  void **pp                      /* OUT: Pointer to allocation */
){
  int nFull;
  void *p;

  assert( sqlite3_mutex_held(mem0.mutex) );
  assert( xAlloc==sqlite3GlobalConfig.m.xMalloc 
       || xAlloc==sqlite3GlobalConfig.m.xCalloc 
  );
  nFull = sqlite3GlobalConfig.m.xRoundup(n);
  sqlite3StatusSet(SQLITE_STATUS_MALLOC_SIZE, n);
  if( mem0.alarmCallback!=0 ){
    int nUsed = sqlite3StatusValue(SQLITE_STATUS_MEMORY_USED);
    if( nUsed >= mem0.alarmThreshold - nFull ){
      mem0.nearlyFull = 1;
      sqlite3MallocAlarm(nFull);
    }else{
      mem0.nearlyFull = 0;
    }
  }
  p = xAlloc(nFull);
#ifdef SQLITE_ENABLE_MEMORY_MANAGEMENT
  if( p==0 && mem0.alarmCallback ){
    sqlite3MallocAlarm(nFull);
    p = xAlloc(nFull);
  }
#endif
  if( p ){
    nFull = sqlite3MallocSize(p);
    sqlite3StatusAdd(SQLITE_STATUS_MEMORY_USED, nFull);
    sqlite3StatusAdd(SQLITE_STATUS_MALLOC_COUNT, 1);
  }
  *pp = p;
  return nFull;
}

/*

** Use allocator function xAlloc to allocate n bytes of memory.
*/
static void *memAllocate(
  void *(*xAlloc)(int),           /* Memory allocation function */
  int n                           /* Bytes of space to allocate */
){
  void *p;
  if( n<=0               /* IMP: R-65312-04917 */ 
   || n>=0x7fffff00
  ){
    /* A memory allocation of a number of bytes which is near the maximum
    ** signed integer value might cause an integer overflow inside of the
    ** xMalloc().  Hence we limit the maximum size to 0x7fffff00, giving
    ** 255 bytes of overhead.  SQLite itself will never use anything near
    ** this amount.  The only way to reach the limit is with sqlite3_malloc() */
    p = 0;
  }else if( sqlite3GlobalConfig.bMemstat ){
    sqlite3_mutex_enter(mem0.mutex);
    mallocWithAlarm(xAlloc, n, &p);
    sqlite3_mutex_leave(mem0.mutex);
  }else{
    p = xAlloc(n);
  }
  assert( EIGHT_BYTE_ALIGNMENT(p) );  /* IMP: R-04675-44850 */
  return p;
}


/*
** Allocate memory.  This routine is like sqlite3_malloc() except that it
** assumes the memory subsystem has already been initialized.
*/
void *sqlite3Malloc(int n){
  return memAllocate(sqlite3GlobalConfig.m.xMalloc, n);
}

/*
** Allocate and zero memory.
*/ 
void *sqlite3MallocZero(int n){
  return memAllocate(sqlite3GlobalConfig.m.xCalloc, n);
}

/*
** This version of the memory allocation is for use by the application.
** First make sure the memory subsystem is initialized, then do the
** allocation.
*/
void *sqlite3_malloc(int n){
#ifndef SQLITE_OMIT_AUTOINIT

    mem0.nScratchFree--;
    sqlite3StatusAdd(SQLITE_STATUS_SCRATCH_USED, 1);
    sqlite3StatusSet(SQLITE_STATUS_SCRATCH_SIZE, n);
    sqlite3_mutex_leave(mem0.mutex);
  }else{
    if( sqlite3GlobalConfig.bMemstat ){
      sqlite3StatusSet(SQLITE_STATUS_SCRATCH_SIZE, n);
      n = mallocWithAlarm(sqlite3GlobalConfig.m.xMalloc, n, &p);
      if( p ) sqlite3StatusAdd(SQLITE_STATUS_SCRATCH_OVERFLOW, n);
      sqlite3_mutex_leave(mem0.mutex);
    }else{
      sqlite3_mutex_leave(mem0.mutex);
      p = sqlite3GlobalConfig.m.xMalloc(n);
    }
    sqlite3MemdebugSetType(p, MEMTYPE_SCRATCH);

void *sqlite3_realloc(void *pOld, int n){
#ifndef SQLITE_OMIT_AUTOINIT
  if( sqlite3_initialize() ) return 0;
#endif
  return sqlite3Realloc(pOld, n);
}


/*
** Allocate and, if bZero is true, zero memory. If the allocation 











** fails, set the mallocFailed flag in the connection pointer.












**
** If db!=0 and db->mallocFailed is true (indicating a prior malloc
** failure on the same database connection) then always return 0.
** Hence for a particular database connection, once malloc starts
** failing, it fails consistently until mallocFailed is reset.
** This is an important assumption.  There are many places in the
** code that do things like this:
**
**         int *a = (int*)sqlite3DbMallocRaw(db, 100);
**         int *b = (int*)sqlite3DbMallocRaw(db, 200);
**         if( b ) a[10] = 9;
**
** In other words, if a subsequent malloc (ex: "b") worked, it is assumed
** that all prior mallocs (ex: "a") worked too.
*/
static void *dbMalloc(sqlite3 *db, int n, int bZero){
  void *p;
  assert( db==0 || sqlite3_mutex_held(db->mutex) );
  assert( db==0 || db->pnBytesFreed==0 );
#ifndef SQLITE_OMIT_LOOKASIDE
  if( db ){
    LookasideSlot *pBuf;
    if( db->mallocFailed ){

      }else{
        db->lookaside.pFree = pBuf->pNext;
        db->lookaside.nOut++;
        db->lookaside.anStat[0]++;
        if( db->lookaside.nOut>db->lookaside.mxOut ){
          db->lookaside.mxOut = db->lookaside.nOut;
        }
        if( bZero ) memset(pBuf, 0, n);
        return (void*)pBuf;
      }
    }
  }
#else
  if( db && db->mallocFailed ){
    return 0;
  }
#endif
  if( bZero ){
    p = sqlite3MallocZero(n);
  }else{
    p = sqlite3Malloc(n);
  }
  if( !p && db ){
    db->mallocFailed = 1;
  }
  sqlite3MemdebugSetType(p, MEMTYPE_DB |
         ((db && db->lookaside.bEnabled) ? MEMTYPE_LOOKASIDE : MEMTYPE_HEAP));
  return p;
} 

/*
** Allocate and zero memory. If the allocation fails, set the 
** mallocFailed flag in the connection pointer.
*/
void *sqlite3DbMallocZero(sqlite3 *db, int n){
  return dbMalloc(db, n, 1);
}

/*
** Allocate memory. If the allocation fails, make the mallocFailed 
** flag in the connection pointer.
*/
void *sqlite3DbMallocRaw(sqlite3 *db, int n){
  return dbMalloc(db, n, 0);
}

/*
** Resize the block of memory pointed to by p to n bytes. If the
** resize fails, set the mallocFailed flag in the connection object.
*/
void *sqlite3DbRealloc(sqlite3 *db, void *p, int n){

** SQLITE_WITHOUT_ZONEMALLOC symbol is defined.
*/
#include <sys/sysctl.h>
#include <malloc/malloc.h>
#include <libkern/OSAtomic.h>
static malloc_zone_t* _sqliteZone_;
#define SQLITE_MALLOC(x) malloc_zone_malloc(_sqliteZone_, (x))
#define SQLITE_CALLOC(x) malloc_zone_calloc(_sqliteZone_, (x), 1)
#define SQLITE_FREE(x) malloc_zone_free(_sqliteZone_, (x));
#define SQLITE_REALLOC(x,y) malloc_zone_realloc(_sqliteZone_, (x), (y))
#define SQLITE_MALLOCSIZE(x) \
        (_sqliteZone_ ? _sqliteZone_->size(_sqliteZone_,x) : malloc_size(x))

#else /* if not __APPLE__ */

/*
** Use standard C library malloc and free on non-Apple systems.  
** Also used by Apple systems if SQLITE_WITHOUT_ZONEMALLOC is defined.
*/
#define SQLITE_MALLOC(x)    malloc(x)
#define SQLITE_CALLOC(x)    calloc((x), 1)
#define SQLITE_FREE(x)      free(x)
#define SQLITE_REALLOC(x,y) realloc((x),(y))

#if (defined(_MSC_VER) && !defined(SQLITE_WITHOUT_MSIZE)) \
      || (defined(HAVE_MALLOC_H) && defined(HAVE_MALLOC_USABLE_SIZE))
# include <malloc.h>    /* Needed for malloc_usable_size on linux */
#endif
#ifdef HAVE_MALLOC_USABLE_SIZE
# ifndef SQLITE_MALLOCSIZE
#  define SQLITE_MALLOCSIZE(x) malloc_usable_size(x)
# endif
#else
# undef SQLITE_MALLOCSIZE
#endif

#endif /* __APPLE__ or not __APPLE__ */

/*
** Like malloc() (if bZero==0) or calloc() (if bZero!=0), except remember 
** the size of the allocation so that we can find it later using 
** sqlite3MemSize().
**
** For this low-level routine, we are guaranteed that nByte>0 because
** cases of nByte<=0 will be intercepted and dealt with by higher level
** routines.
*/
static void *memMalloc(int nByte, int bZero){
#ifdef SQLITE_MALLOCSIZE
  void *p = (bZero ? SQLITE_CALLOC( nByte ) : SQLITE_MALLOC( nByte ));
  if( p==0 ){
    testcase( sqlite3GlobalConfig.xLog!=0 );
    sqlite3_log(SQLITE_NOMEM, "failed to allocate %u bytes of memory", nByte);
  }
  return p;
#else
  sqlite3_int64 *p;
  assert( nByte>0 );
  nByte = ROUND8(nByte);
  p = (bZero ? SQLITE_CALLOC( nByte+8 ) : SQLITE_MALLOC( nByte+8 ));
  if( p ){
    p[0] = nByte;
    p++;
  }else{
    testcase( sqlite3GlobalConfig.xLog!=0 );
    sqlite3_log(SQLITE_NOMEM, "failed to allocate %u bytes of memory", nByte);
  }
  return (void *)p;
#endif
}

static void *sqlite3MemMalloc(int nByte){
  return memMalloc(nByte, 0);
}
static void *sqlite3MemCalloc(int nByte){
  return memMalloc(nByte, 1);
}

/*
** Like free() but works for allocations obtained from sqlite3MemMalloc()
** or sqlite3MemRealloc().
**
** For this low-level routine, we already know that pPrior!=0 since
** cases where pPrior==0 will have been intecepted and dealt with

     sqlite3MemMalloc,
     sqlite3MemFree,
     sqlite3MemRealloc,
     sqlite3MemSize,
     sqlite3MemRoundup,
     sqlite3MemInit,
     sqlite3MemShutdown,
     0,
     sqlite3MemCalloc
  };
  sqlite3_config(SQLITE_CONFIG_MALLOC2, &defaultMethods);
}

#endif /* SQLITE_SYSTEM_MALLOC */

  void (*xFree)(void*);          /* Free a prior allocation */
  void *(*xRealloc)(void*,int);  /* Resize an allocation */
  int (*xSize)(void*);           /* Return the size of an allocation */
  int (*xRoundup)(int);          /* Round up request size to allocation size */
  int (*xInit)(void*);           /* Initialize the memory allocator */
  void (*xShutdown)(void*);      /* Deinitialize the memory allocator */
  void *pAppData;                /* Argument to xInit() and xShutdown() */
  void *(*xCalloc)(int);         /* Zeroed memory allocation function */
};

/*
** CAPI3REF: Configuration Options
** KEYWORDS: {configuration option}
**
** These constants are the available integer configuration options that

#define SQLITE_CONFIG_SERIALIZED    3  /* nil */
#define SQLITE_CONFIG_MALLOC        4  /* sqlite3_mem_methods* */
#define SQLITE_CONFIG_GETMALLOC     5  /* sqlite3_mem_methods* */
#define SQLITE_CONFIG_SCRATCH       6  /* void*, int sz, int N */
#define SQLITE_CONFIG_PAGECACHE     7  /* void*, int sz, int N */
#define SQLITE_CONFIG_HEAP          8  /* void*, int nByte, int min */
#define SQLITE_CONFIG_MEMSTATUS     9  /* boolean */
#define SQLITE_CONFIG_MUTEX        10  /* sqlite3_mutex_methods* no xCalloc() */
#define SQLITE_CONFIG_GETMUTEX     11  /* sqlite3_mutex_methods* no xCalloc() */
/* previously SQLITE_CONFIG_CHUNKALLOC 12 which is now unused. */ 
#define SQLITE_CONFIG_LOOKASIDE    13  /* int int */
#define SQLITE_CONFIG_PCACHE       14  /* no-op */
#define SQLITE_CONFIG_GETPCACHE    15  /* no-op */
#define SQLITE_CONFIG_LOG          16  /* xFunc, void* */
#define SQLITE_CONFIG_URI          17  /* int */
#define SQLITE_CONFIG_PCACHE2      18  /* sqlite3_pcache_methods2* */
#define SQLITE_CONFIG_GETPCACHE2   19  /* sqlite3_pcache_methods2* */
#define SQLITE_CONFIG_MALLOC2      20  /* sqlite3_mem_methods* incl xCalloc() */
#define SQLITE_CONFIG_GETMALLOC2   21  /* sqlite3_mem_methods* incl xCalloc() */

/*
** CAPI3REF: Database Connection Configuration Options
**
** These constants are the available integer configuration options that
** can be passed as the second argument to the [sqlite3_db_config()] interface.
**