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Get rid of the dynamic shared memory state file.

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Instead of storing the ID of the dynamic shared memory control
segment in a file within the data directory, store it in the main
control segment.  This avoids a number of nasty corner cases,
most seriously that doing an online backup and then using it on
the same machine (e.g. to fire up a standby) would result in the
standby clobbering all of the master's dynamic shared memory
segments.

Per complaints from Heikki Linnakangas, Fujii Masao, and Tom
Lane.
This commit is contained in:
Robert Haas
2014-04-08 11:39:55 -04:00
parent 0886fc6a5c
commit 11a65eed16
6 changed files with 71 additions and 166 deletions
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6
src/backend/port/win32_shmem.c
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@ -117,7 +117,8 @@ PGSharedMemoryIsInUse(unsigned long id1, unsigned long id2)
*
*/
PGShmemHeader *
PGSharedMemoryCreate(Size size, bool makePrivate, int port)
PGSharedMemoryCreate(Size size, bool makePrivate, int port,
PGShmemHeader **shim)
{
void *memAddress;
PGShmemHeader *hdr;
@ -245,12 +246,14 @@ PGSharedMemoryCreate(Size size, bool makePrivate, int port)
*/
hdr->totalsize = size;
hdr->freeoffset = MAXALIGN(sizeof(PGShmemHeader));
hdr->dsm_control = 0;
/* Save info for possible future use */
UsedShmemSegAddr = memAddress;
UsedShmemSegSize = size;
UsedShmemSegID = hmap2;
*shim = NULL;
return hdr;
}
@ -289,6 +292,7 @@ PGSharedMemoryReAttach(void)
hdr, origUsedShmemSegAddr);
if (hdr->magic != PGShmemMagic)
elog(FATAL, "reattaching to shared memory returned non-PostgreSQL memory");
dsm_set_control_handle(hdr->dsm_control);
UsedShmemSegAddr = hdr; /* probably redundant */
}