atomicPointerCompareAndExchange

fnbool atomicPointerCompareAndExchange(void * atomic, void * oldval = null, void * newval = null)

Compares atomic to oldval and, if equal, sets it to newval. If atomic was not equal to oldval then no change occurs.

This compare and exchange is done atomically.

Think of this operation as an atomic version of { if (*atomic == oldval) { *atomic = newval; return TRUE; } else return FALSE; }.

This call acts as a full compiler and hardware memory barrier.

While atomic has a volatile qualifier, this is a historical artifact and the pointer passed to it should not be volatile.

Parameters

atomica pointer to a #gpointer-sized value
oldvalthe value to compare with
newvalthe value to conditionally replace with

Returns

true if the exchange took place