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Comment:Only do the specialized MacOS single-core zone_malloc initialization if compiled with the SQLITE_MIGHT_BE_SINGLE_CORE flag. This avoids a (harmless) warning about OSAtomicCompareAndSwapPtrBarrier() being deprecated.
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SHA3-256: 4e6a03d9e12b120d15946b025f97a97697cb8e8af543c238ffda220c9e3f28f4
User & Date: drh 2017-03-18 13:59:46
Context
2017-03-20
13:03
Documentation fix: SQLITE_SOURCE_ID is a now a SHA3-256 hash. check-in: 2aa22509 user: drh tags: trunk
2017-03-18
13:59
Only do the specialized MacOS single-core zone_malloc initialization if compiled with the SQLITE_MIGHT_BE_SINGLE_CORE flag. This avoids a (harmless) warning about OSAtomicCompareAndSwapPtrBarrier() being deprecated. check-in: 4e6a03d9 user: drh tags: trunk
2017-03-17
23:08
Fix an error in the newly revised documentation for SQLITE_LIMIT_VDBE_OP. No changes to code. check-in: f4cf8635 user: drh tags: trunk
Changes
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Changes to src/mem1.c.

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/*
** Use the zone allocator available on apple products unless the
** 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_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))

................................................................................
}

/*
** Initialize this module.
*/
static int sqlite3MemInit(void *NotUsed){
#if defined(__APPLE__) && !defined(SQLITE_WITHOUT_ZONEMALLOC)
  int cpuCount;
  size_t len;
  if( _sqliteZone_ ){
    return SQLITE_OK;
  }













  len = sizeof(cpuCount);
  /* One usually wants to use hw.acctivecpu for MT decisions, but not here */
  sysctlbyname("hw.ncpu", &cpuCount, &len, NULL, 0);
  if( cpuCount>1 ){
    /* defer MT decisions to system malloc */
    _sqliteZone_ = malloc_default_zone();
  }else{
    /* only 1 core, use our own zone to contention over global locks, 
    ** e.g. we have our own dedicated locks */
    bool success;
    malloc_zone_t* newzone = malloc_create_zone(4096, 0);
    malloc_set_zone_name(newzone, "Sqlite_Heap");
    do{
      success = OSAtomicCompareAndSwapPtrBarrier(NULL, newzone, 
                                 (void * volatile *)&_sqliteZone_);
    }while(!_sqliteZone_);
    if( !success ){
      /* somebody registered a zone first */
      malloc_destroy_zone(newzone);
    }
  }
#endif



  UNUSED_PARAMETER(NotUsed);
  return SQLITE_OK;
}

/*
** Deinitialize this module.
*/







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/*
** Use the zone allocator available on apple products unless the
** SQLITE_WITHOUT_ZONEMALLOC symbol is defined.
*/
#include <sys/sysctl.h>
#include <malloc/malloc.h>
#ifdef SQLITE_MIGHT_BE_SINGLE_CORE
#include <libkern/OSAtomic.h>
#endif /* SQLITE_MIGHT_BE_SINGLE_CORE */
static malloc_zone_t* _sqliteZone_;
#define SQLITE_MALLOC(x) malloc_zone_malloc(_sqliteZone_, (x))
#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))

................................................................................
}

/*
** Initialize this module.
*/
static int sqlite3MemInit(void *NotUsed){
#if defined(__APPLE__) && !defined(SQLITE_WITHOUT_ZONEMALLOC)


  if( _sqliteZone_ ){
    return SQLITE_OK;
  }
#ifndef SQLITE_MIGHT_BE_SINGLE_CORE
  /* If not compiled with the SQLITE_MIGHT_BE_SINGLE_CORE flag, assume
  ** that multiple cores are always available.  This is the default case.
  */
  _sqliteZone_ = malloc_default_zone();
#else
  /* With the SQLITE_MIGHT_BE_SINGLE_CORE compile-time option, check the
  ** number of cores.  Different malloc() strategies are used for single-core and
  ** multi-core machines.
  */
  {
    int cpuCount;
    size_t len;
    len = sizeof(cpuCount);
    /* One usually wants to use hw.acctivecpu for MT decisions, but not here */
    sysctlbyname("hw.ncpu", &cpuCount, &len, NULL, 0);
    if( cpuCount>1 ){
      /* defer MT decisions to system malloc */
      _sqliteZone_ = malloc_default_zone();
    }else{
      /* only 1 core, use our own zone to contention over global locks, 
      ** e.g. we have our own dedicated locks */
      bool success;
      malloc_zone_t* newzone = malloc_create_zone(4096, 0);
      malloc_set_zone_name(newzone, "Sqlite_Heap");
      do{
        success = OSAtomicCompareAndSwapPtrBarrier(NULL, newzone, 
                                   (void * volatile *)&_sqliteZone_);
      }while(!_sqliteZone_);
      if( !success ){
        /* somebody registered a zone first */
        malloc_destroy_zone(newzone);
      }
    }

  }
#endif /* SQLITE_MIGHT_BE_SINGLE_CORE */
#endif /*  defined(__APPLE__) && !defined(SQLITE_WITHOUT_ZONEMALLOC) */
  UNUSED_PARAMETER(NotUsed);
  return SQLITE_OK;
}

/*
** Deinitialize this module.
*/