@ -60,15 +60,9 @@ static void MemoryContextStatsInternal(MemoryContext context, int level);
* You should not do memory allocations within a critical section , because
* an out - of - memory error will be escalated to a PANIC . To enforce that
* rule , the allocation functions Assert that .
*
* There are a two exceptions : 1 ) error recovery uses ErrorContext , which
* has some memory set aside so that you don ' t run out . And 2 ) checkpointer
* currently just hopes for the best , which is wrong and ought to be fixed ,
* but it ' s a known issue so let ' s not complain about in the meanwhile .
*/
# define AssertNotInCriticalSection(context) \
Assert ( CritSectionCount = = 0 | | ( context ) = = ErrorContext | | \
AmCheckpointerProcess ( ) )
Assert ( CritSectionCount = = 0 | | ( context ) - > allowInCritSection )
/*****************************************************************************
* EXPORTED ROUTINES *
@ -120,7 +114,10 @@ MemoryContextInit(void)
* require it to contain at least 8 K at all times . This is the only case
* where retained memory in a context is * essential * - - - we want to be
* sure ErrorContext still has some memory even if we ' ve run out
* elsewhere !
* elsewhere ! Also , allow allocations in ErrorContext within a critical
* section . Otherwise a PANIC will cause an assertion failure in the
* error reporting code , before printing out the real cause of the
* failure .
*
* This should be the last step in this function , as elog . c assumes memory
* management works once ErrorContext is non - null .
@ -130,6 +127,7 @@ MemoryContextInit(void)
8 * 1024 ,
8 * 1024 ,
8 * 1024 ) ;
MemoryContextAllowInCriticalSection ( ErrorContext , true ) ;
}
/*
@ -305,6 +303,26 @@ MemoryContextSetParent(MemoryContext context, MemoryContext new_parent)
}
}
/*
* MemoryContextAllowInCriticalSection
* Allow / disallow allocations in this memory context within a critical
* section .
*
* Normally , memory allocations are not allowed within a critical section ,
* because a failure would lead to PANIC . There are a few exceptions to
* that , like allocations related to debugging code that is not supposed to
* be enabled in production . This function can be used to exempt specific
* memory contexts from the assertion in palloc ( ) .
*/
void
MemoryContextAllowInCriticalSection ( MemoryContext context , bool allow )
{
AssertArg ( MemoryContextIsValid ( context ) ) ;
# ifdef USE_ASSERT_CHECKING
context - > allowInCritSection = allow ;
# endif
}
/*
* GetMemoryChunkSpace
* Given a currently - allocated chunk , determine the total space
@ -533,6 +551,7 @@ MemoryContextCreate(NodeTag tag, Size size,
MemoryContext node ;
Size needed = size + strlen ( name ) + 1 ;
/* creating new memory contexts is not allowed in a critical section */
Assert ( CritSectionCount = = 0 ) ;
/* Get space for node and name */
@ -570,6 +589,11 @@ MemoryContextCreate(NodeTag tag, Size size,
node - > parent = parent ;
node - > nextchild = parent - > firstchild ;
parent - > firstchild = node ;
# ifdef USE_ASSERT_CHECKING
/* inherit allowInCritSection flag from parent */
node - > allowInCritSection = parent - > allowInCritSection ;
# endif
}
VALGRIND_CREATE_MEMPOOL ( node , 0 , false ) ;
Heikki Linnakangas
11 years ago