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Commit11a65ee

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Get rid of the dynamic shared memory state file.
Instead of storing the ID of the dynamic shared memory controlsegment in a file within the data directory, store it in the maincontrol segment. This avoids a number of nasty corner cases,most seriously that doing an online backup and then using it onthe same machine (e.g. to fire up a standby) would result in thestandby clobbering all of the master's dynamic shared memorysegments.Per complaints from Heikki Linnakangas, Fujii Masao, and TomLane.
1 parent0886fc6 commit11a65ee

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6 files changed

+71
-166
lines changed

6 files changed

+71
-166
lines changed

‎src/backend/port/sysv_shmem.c

Lines changed: 10 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -30,6 +30,7 @@
3030

3131
#include"miscadmin.h"
3232
#include"portability/mem.h"
33+
#include"storage/dsm.h"
3334
#include"storage/ipc.h"
3435
#include"storage/pg_shmem.h"
3536
#include"utils/guc.h"
@@ -421,7 +422,8 @@ CreateAnonymousSegment(Size *size)
421422
* zero will be passed.
422423
*/
423424
PGShmemHeader*
424-
PGSharedMemoryCreate(Sizesize,boolmakePrivate,intport)
425+
PGSharedMemoryCreate(Sizesize,boolmakePrivate,intport,
426+
PGShmemHeader**shim)
425427
{
426428
IpcMemoryKeyNextShmemSegID;
427429
void*memAddress;
@@ -509,10 +511,13 @@ PGSharedMemoryCreate(Size size, bool makePrivate, int port)
509511

510512
/*
511513
* The segment appears to be from a dead Postgres process, or from a
512-
* previous cycle of life in this same process. Zap it, if possible.
514+
* previous cycle of life in this same process. Zap it, if possible,
515+
* and any associated dynamic shared memory segments, as well.
513516
* This probably shouldn't fail, but if it does, assume the segment
514517
* belongs to someone else after all, and continue quietly.
515518
*/
519+
if (hdr->dsm_control!=0)
520+
dsm_cleanup_using_control_segment(hdr->dsm_control);
516521
shmdt(memAddress);
517522
if (shmctl(shmid,IPC_RMID,NULL)<0)
518523
continue;
@@ -539,6 +544,7 @@ PGSharedMemoryCreate(Size size, bool makePrivate, int port)
539544
hdr= (PGShmemHeader*)memAddress;
540545
hdr->creatorPID=getpid();
541546
hdr->magic=PGShmemMagic;
547+
hdr->dsm_control=0;
542548

543549
/* Fill in the data directory ID info, too */
544550
if (stat(DataDir,&statbuf)<0)
@@ -554,6 +560,7 @@ PGSharedMemoryCreate(Size size, bool makePrivate, int port)
554560
*/
555561
hdr->totalsize=size;
556562
hdr->freeoffset=MAXALIGN(sizeof(PGShmemHeader));
563+
*shim=hdr;
557564

558565
/* Save info for possible future use */
559566
UsedShmemSegAddr=memAddress;
@@ -608,6 +615,7 @@ PGSharedMemoryReAttach(void)
608615
if (hdr!=origUsedShmemSegAddr)
609616
elog(FATAL,"reattaching to shared memory returned unexpected address (got %p, expected %p)",
610617
hdr,origUsedShmemSegAddr);
618+
dsm_set_control_handle(((PGShmemHeader*)hdr)->dsm_control);
611619

612620
UsedShmemSegAddr=hdr;/* probably redundant */
613621
}

‎src/backend/port/win32_shmem.c

Lines changed: 5 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -117,7 +117,8 @@ PGSharedMemoryIsInUse(unsigned long id1, unsigned long id2)
117117
*
118118
*/
119119
PGShmemHeader*
120-
PGSharedMemoryCreate(Sizesize,boolmakePrivate,intport)
120+
PGSharedMemoryCreate(Sizesize,boolmakePrivate,intport,
121+
PGShmemHeader**shim)
121122
{
122123
void*memAddress;
123124
PGShmemHeader*hdr;
@@ -245,12 +246,14 @@ PGSharedMemoryCreate(Size size, bool makePrivate, int port)
245246
*/
246247
hdr->totalsize=size;
247248
hdr->freeoffset=MAXALIGN(sizeof(PGShmemHeader));
249+
hdr->dsm_control=0;
248250

249251
/* Save info for possible future use */
250252
UsedShmemSegAddr=memAddress;
251253
UsedShmemSegSize=size;
252254
UsedShmemSegID=hmap2;
253255

256+
*shim=NULL;
254257
returnhdr;
255258
}
256259

@@ -289,6 +292,7 @@ PGSharedMemoryReAttach(void)
289292
hdr,origUsedShmemSegAddr);
290293
if (hdr->magic!=PGShmemMagic)
291294
elog(FATAL,"reattaching to shared memory returned non-PostgreSQL memory");
295+
dsm_set_control_handle(hdr->dsm_control);
292296

293297
UsedShmemSegAddr=hdr;/* probably redundant */
294298
}

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