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Make some minor improvements in memory-context infrastructure. 

We lack a version of repalloc() that supports MCXT_ALLOC_NO_OOM
semantics, so invent repalloc_extended() with the usual set of
flags.  repalloc_huge() becomes a legacy wrapper for that.

Also, fix dynahash.c so that it can support HASH_ENTER_NULL
requests when using the default palloc-based allocator.
The only reason it didn't do that already was the lack of the
MCXT_ALLOC_NO_OOM option when that code was written, ages ago.

While here, simplify a few overcomplicated tests in mcxt.c.

Discussion: https://postgr.es/m/2982579.1662416866@sss.pgh.pa.us
This commit is contained in:
Tom Lane 2022-10-14 11:55:56 -04:00
parent 1b11561cc1
commit 9c911ec065
3 changed files with 56 additions and 42 deletions
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13
src/backend/utils/hash/dynahash.c
View File

@ -289,7 +289,8 @@ static void *
DynaHashAlloc(Size size)
{
Assert(MemoryContextIsValid(CurrentDynaHashCxt));
return MemoryContextAlloc(CurrentDynaHashCxt, size);
return MemoryContextAllocExtended(CurrentDynaHashCxt, size,
MCXT_ALLOC_NO_OOM);
}
@ -939,9 +940,7 @@ calc_bucket(HASHHDR *hctl, uint32 hash_val)
*
* HASH_ENTER will normally ereport a generic "out of memory" error if
* it is unable to create a new entry. The HASH_ENTER_NULL operation is
* the same except it will return NULL if out of memory. Note that
* HASH_ENTER_NULL cannot be used with the default palloc-based allocator,
* since palloc internally ereports on out-of-memory.
* the same except it will return NULL if out of memory.
*
* If foundPtr isn't NULL, then *foundPtr is set true if we found an
* existing entry in the table, false otherwise. This is needed in the
@ -1084,12 +1083,8 @@ hash_search_with_hash_value(HTAB *hashp,
}
return NULL;
case HASH_ENTER_NULL:
/* ENTER_NULL does not work with palloc-based allocator */
Assert(hashp->alloc != DynaHashAlloc);
/* FALL THRU */
case HASH_ENTER:
case HASH_ENTER_NULL:
/* Return existing element if found, else create one */
if (currBucket != NULL)
return (void *) ELEMENTKEY(currBucket);

83
src/backend/utils/mmgr/mcxt.c
View File

@ -1114,8 +1114,8 @@ MemoryContextAllocExtended(MemoryContext context, Size size, int flags)
AssertArg(MemoryContextIsValid(context));
AssertNotInCriticalSection(context);
if (((flags & MCXT_ALLOC_HUGE) != 0 && !AllocHugeSizeIsValid(size)) ||
((flags & MCXT_ALLOC_HUGE) == 0 && !AllocSizeIsValid(size)))
if (!((flags & MCXT_ALLOC_HUGE) != 0 ? AllocHugeSizeIsValid(size) :
AllocSizeIsValid(size)))
elog(ERROR, "invalid memory alloc request size %zu", size);
context->isReset = false;
@ -1269,8 +1269,8 @@ palloc_extended(Size size, int flags)
AssertArg(MemoryContextIsValid(context));
AssertNotInCriticalSection(context);
if (((flags & MCXT_ALLOC_HUGE) != 0 && !AllocHugeSizeIsValid(size)) ||
((flags & MCXT_ALLOC_HUGE) == 0 && !AllocSizeIsValid(size)))
if (!((flags & MCXT_ALLOC_HUGE) != 0 ? AllocHugeSizeIsValid(size) :
AllocSizeIsValid(size)))
elog(ERROR, "invalid memory alloc request size %zu", size);
context->isReset = false;
@ -1351,6 +1351,50 @@ repalloc(void *pointer, Size size)
return ret;
}
/*
* repalloc_extended
* Adjust the size of a previously allocated chunk,
* with HUGE and NO_OOM options.
*/
void *
repalloc_extended(void *pointer, Size size, int flags)
{
#if defined(USE_ASSERT_CHECKING) || defined(USE_VALGRIND)
MemoryContext context = GetMemoryChunkContext(pointer);
#endif
void *ret;
if (!((flags & MCXT_ALLOC_HUGE) != 0 ? AllocHugeSizeIsValid(size) :
AllocSizeIsValid(size)))
elog(ERROR, "invalid memory alloc request size %zu", size);
AssertNotInCriticalSection(context);
/* isReset must be false already */
Assert(!context->isReset);
ret = MCXT_METHOD(pointer, realloc) (pointer, size);
if (unlikely(ret == NULL))
{
if ((flags & MCXT_ALLOC_NO_OOM) == 0)
{
MemoryContext cxt = GetMemoryChunkContext(pointer);
MemoryContextStats(TopMemoryContext);
ereport(ERROR,
(errcode(ERRCODE_OUT_OF_MEMORY),
errmsg("out of memory"),
errdetail("Failed on request of size %zu in memory context \"%s\".",
size, cxt->name)));
}
return NULL;
}
VALGRIND_MEMPOOL_CHANGE(context, pointer, ret, size);
return ret;
}
/*
* MemoryContextAllocHuge
* Allocate (possibly-expansive) space within the specified context.
@ -1394,35 +1438,8 @@ MemoryContextAllocHuge(MemoryContext context, Size size)
void *
repalloc_huge(void *pointer, Size size)
{
#if defined(USE_ASSERT_CHECKING) || defined(USE_VALGRIND)
MemoryContext context = GetMemoryChunkContext(pointer);
#endif
void *ret;
if (!AllocHugeSizeIsValid(size))
elog(ERROR, "invalid memory alloc request size %zu", size);
AssertNotInCriticalSection(context);
/* isReset must be false already */
Assert(!context->isReset);
ret = MCXT_METHOD(pointer, realloc) (pointer, size);
if (unlikely(ret == NULL))
{
MemoryContext cxt = GetMemoryChunkContext(pointer);
MemoryContextStats(TopMemoryContext);
ereport(ERROR,
(errcode(ERRCODE_OUT_OF_MEMORY),
errmsg("out of memory"),
errdetail("Failed on request of size %zu in memory context \"%s\".",
size, cxt->name)));
}
VALGRIND_MEMPOOL_CHANGE(context, pointer, ret, size);
return ret;
/* this one seems not worth its own implementation */
return repalloc_extended(pointer, size, MCXT_ALLOC_HUGE);
}
/*

2
src/include/utils/palloc.h
View File

@ -78,6 +78,8 @@ extern void *palloc(Size size);
extern void *palloc0(Size size);
extern void *palloc_extended(Size size, int flags);
extern pg_nodiscard void *repalloc(void *pointer, Size size);
extern pg_nodiscard void *repalloc_extended(void *pointer,
Size size, int flags);
extern void pfree(void *pointer);
/*