Joe Mistachkin wrote:
bool success;
malloc_zone_t* newzone = malloc_create_zone(4096, 0);
malloc_set_zone_name(newzone, "Sqlite_Heap");
do{
+#if MAC_OS_X_VERSION_MIN_REQUIRED >= MAC_OS_X_VERSION_10_5
success = OSAtomicCompareAndSwapPtrBarrier(NULL, newzone,
(void * volatile *)&_sqliteZone_);
+#else
+ success = OSAtomicCompareAndSwapPtr(NULL, newzone,
+ (void * volatile *)&_sqliteZone_);
+ OSMemoryBarrier();
+#endif
}while(!_sqliteZone_);
if( !success ){
/* somebody registered a zone first */
malloc_destroy_zone(newzone);
}
With this algorithm, where there are not multiple memory objects having
some defined, coordinated meaning with respect to each other, the
barrier not necessary. So this code could be simplified to simply use
the non-barrier pointer swap, always.
Cheers,
--
Larry Brasfield
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