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Convert the arithmetic for shared memory size calculation from 'int'

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to 'Size' (that is, size_t), and install overflow detection checks in it.
This allows us to remove the former arbitrary restrictions on NBuffers
etc.  It won't make any difference in a 32-bit machine, but in a 64-bit
machine you could theoretically have terabytes of shared buffers.
(How efficiently we could manage 'em remains to be seen.)  Similarly,
num_temp_buffers, work_mem, and maintenance_work_mem can be set above
2Gb on a 64-bit machine.  Original patch from Koichi Suzuki, additional
work by moi.
This commit is contained in:
Tom Lane
2005-08-20 23:26:37 +00:00
parent 2299ceab1c
commit 0007490e09
50 changed files with 774 additions and 275 deletions
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43
src/backend/storage/ipc/shmem.c
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@@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/storage/ipc/shmem.c,v 1.84 2005/05/29 04:23:04 tgl Exp $
* $PostgreSQL: pgsql/src/backend/storage/ipc/shmem.c,v 1.85 2005/08/20 23:26:20 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -141,8 +141,8 @@ InitShmemAllocation(void *seghdr, bool init)
void *
ShmemAlloc(Size size)
{
uint32 newStart;
uint32 newFree;
Size newStart;
Size newFree;
void *newSpace;
/* use volatile pointer to prevent code rearrangement */
@@ -415,3 +415,40 @@ ShmemInitStruct(const char *name, Size size, bool *foundPtr)
SpinLockRelease(ShmemIndexLock);
return structPtr;
}
/*
* Add two Size values, checking for overflow
*/
Size
add_size(Size s1, Size s2)
{
Size result;
result = s1 + s2;
/* We are assuming Size is an unsigned type here... */
if (result < s1 || result < s2)
ereport(ERROR,
(errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED),
errmsg("requested shared memory size overflows size_t")));
return result;
}
/*
* Multiply two Size values, checking for overflow
*/
Size
mul_size(Size s1, Size s2)
{
Size result;
if (s1 == 0 || s2 == 0)
return 0;
result = s1 * s2;
/* We are assuming Size is an unsigned type here... */
if (result / s2 != s1)
ereport(ERROR,
(errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED),
errmsg("requested shared memory size overflows size_t")));
return result;
}