Movatterモバイル変換

[0]ホーム
URL:

Skip to content

Navigation Menu

Sign in
Appearance settings

Search code, repositories, users, issues, pull requests...

Provide feedback

We read every piece of feedback, and take your input very seriously.

Saved searches

Use saved searches to filter your results more quickly

 Sign up
Appearance settings

Commit789a5b3

Browse files
committed
Move attached to shared memory out into a separate function for clarity.
1 parent075a007 commit789a5b3

File tree

1 file changed

+75
-68
lines changed

1 file changed

+75
-68
lines changed

‎src/backend/port/sysv_shmem.c‎

Lines changed: 75 additions & 68 deletions
Original file line numberDiff line numberDiff line change
@@ -10,7 +10,7 @@
1010
* Portions Copyright (c) 1994, Regents of the University of California
1111
*
1212
* IDENTIFICATION
13-
* $Header: /cvsroot/pgsql/src/backend/port/sysv_shmem.c,v 1.9 2003/05/0814:49:03 momjian Exp $
13+
* $Header: /cvsroot/pgsql/src/backend/port/sysv_shmem.c,v 1.10 2003/05/0819:17:07 momjian Exp $
1414
*
1515
*-------------------------------------------------------------------------
1616
*/
@@ -47,6 +47,8 @@ static void IpcMemoryDetach(int status, Datum shmaddr);
4747
staticvoidIpcMemoryDelete(intstatus,DatumshmId);
4848
staticvoid*PrivateMemoryCreate(uint32size);
4949
staticvoidPrivateMemoryDelete(intstatus,Datummemaddr);
50+
staticPGShmemHeader*PGSharedMemoryAttach(IpcMemoryKeykey,
51+
IpcMemoryId*shmid,void*addr);
5052

5153

5254
/*
@@ -297,72 +299,48 @@ PGSharedMemoryCreate(uint32 size, bool makePrivate, int port)
297299
IpcMemoryKeyNextShmemSegID;
298300
void*memAddress;
299301
PGShmemHeader*hdr;
302+
IpcMemoryIdshmid;
300303

301304
/* Room for a header? */
302305
Assert(size>MAXALIGN(sizeof(PGShmemHeader)));
303306

304-
if (ExecBackend&&UsedShmemSegID!=0)
305-
NextShmemSegID=UsedShmemSegID;
306-
else
307-
NextShmemSegID=port*1000+1;
308-
309-
for (;;NextShmemSegID++)
307+
/* Just attach and return the pointer */
308+
if (ExecBackend&&UsedShmemSegAddr!=NULL&& !makePrivate)
310309
{
311-
IpcMemoryIdshmid;
312-
313-
/* Special case if creating a private segment --- just malloc() it */
314-
if (makePrivate)
315-
{
316-
memAddress=PrivateMemoryCreate(size);
317-
break;
318-
}
319-
320-
/* If attach to fixed address, only try once */
321-
if (ExecBackend&&UsedShmemSegAddr!=NULL&&NextShmemSegID!=UsedShmemSegID)
310+
if ((hdr= (PGShmemHeader*)memAddress=PGSharedMemoryAttach(
311+
UsedShmemSegID,&shmid,UsedShmemSegAddr))==NULL)
322312
{
323-
fprintf(stderr,"Unable to attach to memory at fixed address: shmget(key=%d, addr=%p) failed: %s\n",
313+
fprintf(stderr,"Unable to attach topropermemory at fixed address: shmget(key=%d, addr=%p) failed: %s\n",
324314
(int)UsedShmemSegID,UsedShmemSegAddr,strerror(errno));
325315
proc_exit(1);
326316
}
317+
returnhdr;
318+
}
327319

328-
if (!ExecBackend||UsedShmemSegAddr==NULL)
329-
{
330-
/* Try to create new segment */
331-
memAddress=InternalIpcMemoryCreate(NextShmemSegID,size);
332-
if (memAddress)
333-
break;/* successful create and attach */
334-
}
335-
336-
/* See if it looks to be leftover from a dead Postgres process */
337-
shmid=shmget(NextShmemSegID,sizeof(PGShmemHeader),0);
338-
if (shmid<0)
339-
continue;/* failed: must be some other app's */
340-
341-
/* use intimate shared memory on SPARC Solaris */
342-
memAddress=shmat(shmid,UsedShmemSegAddr,
343-
#if defined(solaris)&&defined(__sparc__)
344-
SHM_SHARE_MMU
345-
#else
346-
0
347-
#endif
348-
);
349-
350-
if (memAddress== (void*)-1)
351-
continue;/* failed: must be some other app's */
320+
/* Create shared memory */
321+
322+
NextShmemSegID=port*1000+1;
352323

353-
hdr= (PGShmemHeader*)memAddress;
354-
if (hdr->magic!=PGShmemMagic)
324+
for (;;NextShmemSegID++)
325+
{
326+
/* Special case if creating a private segment --- just malloc() it */
327+
if (makePrivate)
355328
{
356-
shmdt(memAddress);
357-
continue;/* segment belongs to a non-Postgres app */
329+
memAddress=PrivateMemoryCreate(size);
330+
break;
358331
}
359332

360-
/* Successfully attached to shared memory, which is all we wanted */
361-
if (ExecBackend&&UsedShmemSegAddr!=NULL)
362-
break;
333+
/* Try to create new segment */
334+
memAddress=InternalIpcMemoryCreate(NextShmemSegID,size);
335+
if (memAddress)
336+
break;/* successful create and attach */
363337

364338
/* Check shared memory and possibly remove and recreate */
365339

340+
if ((hdr= (PGShmemHeader*)memAddress=PGSharedMemoryAttach(
341+
NextShmemSegID,&shmid,UsedShmemSegAddr))==NULL)
342+
continue;/* can't attach, not one of mine */
343+
366344
/*
367345
* If I am not the creator and it belongs to an extant process,
368346
* continue.
@@ -401,31 +379,60 @@ PGSharedMemoryCreate(uint32 size, bool makePrivate, int port)
401379
*/
402380
}
403381

382+
/*
383+
* OK, we created a new segment. Mark it as created by this process.
384+
* The order of assignments here is critical so that another Postgres
385+
* process can't see the header as valid but belonging to an invalid
386+
* PID!
387+
*/
404388
hdr= (PGShmemHeader*)memAddress;
389+
hdr->creatorPID=getpid();
390+
hdr->magic=PGShmemMagic;
405391

406-
if (!ExecBackend||makePrivate||UsedShmemSegAddr==NULL)
407-
{
408-
/*
409-
* OK, we created a new segment. Mark it as created by this process.
410-
* The order of assignments here is critical so that another Postgres
411-
* process can't see the header as valid but belonging to an invalid
412-
* PID!
413-
*/
414-
hdr->creatorPID=getpid();
415-
hdr->magic=PGShmemMagic;
416-
417-
/*
418-
* Initialize space allocation status for segment.
419-
*/
420-
hdr->totalsize=size;
421-
hdr->freeoffset=MAXALIGN(sizeof(PGShmemHeader));
422-
}
392+
/*
393+
* Initialize space allocation status for segment.
394+
*/
395+
hdr->totalsize=size;
396+
hdr->freeoffset=MAXALIGN(sizeof(PGShmemHeader));
423397

424-
if (ExecBackend&& !makePrivate&&UsedShmemSegAddr==NULL)
398+
399+
if (ExecBackend&&UsedShmemSegAddr==NULL&& !makePrivate)
425400
{
426401
UsedShmemSegAddr=memAddress;
427402
UsedShmemSegID=NextShmemSegID;
428403
}
404+
405+
returnhdr;
406+
}
407+
408+
409+
/*
410+
*Attach to shared memory and make sure it has a Postgres header
411+
*/
412+
staticPGShmemHeader*
413+
PGSharedMemoryAttach(IpcMemoryKeykey,IpcMemoryId*shmid,void*addr)
414+
{
415+
PGShmemHeader*hdr;
416+
417+
if ((*shmid=shmget(key,sizeof(PGShmemHeader),0))<0)
418+
returnNULL;
429419

420+
hdr= (PGShmemHeader*)shmat(*shmid,UsedShmemSegAddr,
421+
#if defined(solaris)&&defined(__sparc__)
422+
/* use intimate shared memory on SPARC Solaris */
423+
SHM_SHARE_MMU
424+
#else
425+
0
426+
#endif
427+
);
428+
429+
if (hdr== (PGShmemHeader*)-1)
430+
returnNULL;/* failed: must be some other app's */
431+
432+
if (hdr->magic!=PGShmemMagic)
433+
{
434+
shmdt(hdr);
435+
returnNULL;/* segment belongs to a non-Postgres app */
436+
}
430437
returnhdr;
431438
}

0 commit comments

Comments
 (0)
[8]ページ先頭
©2009-2025 Movatter.jp