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Pass shared memory address on command line to exec'ed backend.

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Allow backends to attached to specified shared memory address.
This commit is contained in:
Bruce Momjian
2003-05-08 14:49:04 +00:00
parent 4e08d35e7d
commit 5e7a5c9511
5 changed files with 78 additions and 47 deletions
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89
src/backend/port/sysv_shmem.c
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@@ -10,7 +10,7 @@
* Portions Copyright (c) 1994, Regents of the University of California
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/port/sysv_shmem.c,v 1.8 2003/05/06 23:34:55 momjian Exp $
* $Header: /cvsroot/pgsql/src/backend/port/sysv_shmem.c,v 1.9 2003/05/08 14:49:03 momjian Exp $
*
*-------------------------------------------------------------------------
*/
@@ -39,9 +39,8 @@ typedef int IpcMemoryId; /* shared memory ID returned by shmget(2) */
#define IPCProtection (0600) /* access/modify by user only */
#ifdef EXEC_BACKEND
IpcMemoryKey UsedShmemSegID = 0;
#endif
void *UsedShmemSegAddr = NULL;
static void *InternalIpcMemoryCreate(IpcMemoryKey memKey, uint32 size);
static void IpcMemoryDetach(int status, Datum shmaddr);
@@ -282,7 +281,7 @@ PrivateMemoryDelete(int status, Datum memaddr)
*
* Create a shared memory segment of the given size and initialize its
* standard header. Also, register an on_shmem_exit callback to release
* the storage.
* the storage. For an exec'ed backend, it just attaches.
*
* Dead Postgres segments are recycled if found, but we do not fail upon
* collision with non-Postgres shmem segments. The idea here is to detect and
@@ -302,11 +301,9 @@ PGSharedMemoryCreate(uint32 size, bool makePrivate, int port)
/* Room for a header? */
Assert(size > MAXALIGN(sizeof(PGShmemHeader)));
#ifdef EXEC_BACKEND
if (UsedShmemSegID != 0)
if (ExecBackend && UsedShmemSegID != 0)
NextShmemSegID = UsedShmemSegID;
else
#endif
NextShmemSegID = port * 1000 + 1;
for (;;NextShmemSegID++)
@@ -320,25 +317,39 @@ PGSharedMemoryCreate(uint32 size, bool makePrivate, int port)
break;
}
/* Try to create new segment */
memAddress = InternalIpcMemoryCreate(NextShmemSegID, size);
if (memAddress)
break; /* successful create and attach */
/* If attach to fixed address, only try once */
if (ExecBackend && UsedShmemSegAddr != NULL && NextShmemSegID != UsedShmemSegID)
{
fprintf(stderr, "Unable to attach to memory at fixed address: shmget(key=%d, addr=%p) failed: %s\n",
(int) UsedShmemSegID, UsedShmemSegAddr, strerror(errno));
proc_exit(1);
}
if (!ExecBackend || UsedShmemSegAddr == NULL)
{
/* Try to create new segment */
memAddress = InternalIpcMemoryCreate(NextShmemSegID, size);
if (memAddress)
break; /* successful create and attach */
}
/* See if it looks to be leftover from a dead Postgres process */
shmid = shmget(NextShmemSegID, sizeof(PGShmemHeader), 0);
if (shmid < 0)
continue; /* failed: must be some other app's */
#if defined(solaris) && defined(__sparc__)
/* use intimate shared memory on SPARC Solaris */
memAddress = shmat(shmid, 0, SHM_SHARE_MMU);
memAddress = shmat(shmid, UsedShmemSegAddr,
#if defined(solaris) && defined(__sparc__)
SHM_SHARE_MMU
#else
memAddress = shmat(shmid, 0, 0);
0
#endif
);
if (memAddress == (void *) -1)
continue; /* failed: must be some other app's */
hdr = (PGShmemHeader *) memAddress;
if (hdr->magic != PGShmemMagic)
{
@@ -346,14 +357,19 @@ PGSharedMemoryCreate(uint32 size, bool makePrivate, int port)
continue; /* segment belongs to a non-Postgres app */
}
/* Successfully attached to shared memory, which is all we wanted */
if (ExecBackend && UsedShmemSegAddr != NULL)
break;
/* Check shared memory and possibly remove and recreate */
/*
* If the creator PID is my own PID or does not belong to any
* extant process, it's safe to zap it.
* If I am not the creator and it belongs to an extant process,
* continue.
*/
if (hdr->creatorPID != getpid())
{
if (kill(hdr->creatorPID, 0) == 0 ||
errno != ESRCH)
if (kill(hdr->creatorPID, 0) == 0 || errno != ESRCH)
{
shmdt(memAddress);
continue; /* segment belongs to a live process */
@@ -385,26 +401,31 @@ PGSharedMemoryCreate(uint32 size, bool makePrivate, int port)
*/
}
/*
* OK, we created a new segment. Mark it as created by this process.
* The order of assignments here is critical so that another Postgres
* process can't see the header as valid but belonging to an invalid
* PID!
*/
hdr = (PGShmemHeader *) memAddress;
hdr->creatorPID = getpid();
hdr->magic = PGShmemMagic;
/*
* Initialize space allocation status for segment.
*/
hdr->totalsize = size;
hdr->freeoffset = MAXALIGN(sizeof(PGShmemHeader));
if (!ExecBackend || makePrivate || UsedShmemSegAddr == NULL)
{
/*
* OK, we created a new segment. Mark it as created by this process.
* The order of assignments here is critical so that another Postgres
* process can't see the header as valid but belonging to an invalid
* PID!
*/
hdr->creatorPID = getpid();
hdr->magic = PGShmemMagic;
/*
* Initialize space allocation status for segment.
*/
hdr->totalsize = size;
hdr->freeoffset = MAXALIGN(sizeof(PGShmemHeader));
}
#ifdef EXEC_BACKEND
if (!makePrivate && UsedShmemSegID == 0)
if (ExecBackend && !makePrivate && UsedShmemSegAddr == NULL)
{
UsedShmemSegAddr = memAddress;
UsedShmemSegID = NextShmemSegID;
#endif
}
return hdr;
}