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Provide a way to supress the "out of memory" error when allocating.

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Using the new interface MemoryContextAllocExtended, callers can
specify MCXT_ALLOC_NO_OOM if they are prepared to handle a NULL
return value.

Michael Paquier, reviewed and somewhat revised by me.
This commit is contained in:
Robert Haas 2015-01-30 12:56:48 -05:00
parent 3d660d33aa
commit bd4e2fd97d
2 changed files with 49 additions and 0 deletions
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40
src/backend/utils/mmgr/mcxt.c
View File

@ -711,6 +711,46 @@ MemoryContextAllocZeroAligned(MemoryContext context, Size size)
return ret;
}
/*
* MemoryContextAllocExtended
* Allocate space within the specified context using the given flags.
*/
void *
MemoryContextAllocExtended(MemoryContext context, Size size, int flags)
{
void *ret;
AssertArg(MemoryContextIsValid(context));
AssertNotInCriticalSection(context);
if (((flags & MCXT_ALLOC_HUGE) != 0 && !AllocHugeSizeIsValid(size)) ||
((flags & MCXT_ALLOC_HUGE) == 0 && !AllocSizeIsValid(size)))
elog(ERROR, "invalid memory alloc request size %zu", size);
context->isReset = false;
ret = (*context->methods->alloc) (context, size);
if (ret == NULL)
{
if ((flags & MCXT_ALLOC_NO_OOM) == 0)
{
MemoryContextStats(TopMemoryContext);
ereport(ERROR,
(errcode(ERRCODE_OUT_OF_MEMORY),
errmsg("out of memory"),
errdetail("Failed on request of size %zu.", size)));
}
return NULL;
}
VALGRIND_MEMPOOL_ALLOC(context, ret, size);
if ((flags & MCXT_ALLOC_ZERO) != 0)
MemSetAligned(ret, 0, size);
return ret;
}
void *
palloc(Size size)
{

9
src/include/utils/palloc.h
View File

@ -42,12 +42,21 @@ typedef struct MemoryContextData *MemoryContext;
*/
extern PGDLLIMPORT MemoryContext CurrentMemoryContext;
/*
* Flags for MemoryContextAllocExtended.
*/
#define MCXT_ALLOC_HUGE 0x01 /* allow huge allocation (> 1 GB) */
#define MCXT_ALLOC_NO_OOM 0x02 /* no failure if out-of-memory */
#define MCXT_ALLOC_ZERO 0x04 /* zero allocated memory */
/*
* Fundamental memory-allocation operations (more are in utils/memutils.h)
*/
extern void *MemoryContextAlloc(MemoryContext context, Size size);
extern void *MemoryContextAllocZero(MemoryContext context, Size size);
extern void *MemoryContextAllocZeroAligned(MemoryContext context, Size size);
extern void *MemoryContextAllocExtended(MemoryContext context,
Size size, int flags);
extern void *palloc(Size size);
extern void *palloc0(Size size);