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Repair two places where SIGTERM exit could leave shared memory state

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corrupted.  (Neither is very important if SIGTERM is used to shut down the
whole database cluster together, but there's a problem if someone tries to
SIGTERM individual backends.)  To do this, introduce new infrastructure
macros PG_ENSURE_ERROR_CLEANUP/PG_END_ENSURE_ERROR_CLEANUP that take care
of transiently pushing an on_shmem_exit cleanup hook.  Also use this method
for createdb cleanup --- that wasn't a shared-memory-corruption problem,
but SIGTERM abort of createdb could leave orphaned files lying around.

Backpatch as far as 8.2.  The shmem corruption cases don't exist in 8.1,
and the createdb usage doesn't seem important enough to risk backpatching
further.
This commit is contained in:
Tom Lane
2008-04-16 23:59:40 +00:00
parent 74be86847c
commit d1cbd26ded
9 changed files with 153 additions and 57 deletions
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32
src/backend/access/transam/xlog.c
View File

@ -7,7 +7,7 @@
* Portions Copyright (c) 1996-2008, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* $PostgreSQL: pgsql/src/backend/access/transam/xlog.c,v 1.296 2008/04/05 01:34:06 momjian Exp $
* $PostgreSQL: pgsql/src/backend/access/transam/xlog.c,v 1.297 2008/04/16 23:59:40 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -43,6 +43,7 @@
#include "postmaster/bgwriter.h"
#include "storage/bufpage.h"
#include "storage/fd.h"
#include "storage/ipc.h"
#include "storage/pmsignal.h"
#include "storage/procarray.h"
#include "storage/smgr.h"
@ -419,11 +420,11 @@ static void writeTimeLineHistory(TimeLineID newTLI, TimeLineID parentTLI,
static void WriteControlFile(void);
static void ReadControlFile(void);
static char *str_time(pg_time_t tnow);
static void issue_xlog_fsync(void);
#ifdef WAL_DEBUG
static void xlog_outrec(StringInfo buf, XLogRecord *record);
#endif
static void issue_xlog_fsync(void);
static void pg_start_backup_callback(int code, Datum arg);
static bool read_backup_label(XLogRecPtr *checkPointLoc,
XLogRecPtr *minRecoveryLoc);
static void rm_redo_error_callback(void *arg);
@ -6442,8 +6443,8 @@ pg_start_backup(PG_FUNCTION_ARGS)
XLogCtl->Insert.forcePageWrites = true;
LWLockRelease(WALInsertLock);
/* Use a TRY block to ensure we release forcePageWrites if fail below */
PG_TRY();
/* Ensure we release forcePageWrites if fail below */
PG_ENSURE_ERROR_CLEANUP(pg_start_backup_callback, (Datum) 0);
{
/*
* Force a CHECKPOINT. Aside from being necessary to prevent torn
@ -6515,16 +6516,7 @@ pg_start_backup(PG_FUNCTION_ARGS)
errmsg("could not write file \"%s\": %m",
BACKUP_LABEL_FILE)));
}
PG_CATCH();
{
/* Turn off forcePageWrites on failure */
LWLockAcquire(WALInsertLock, LW_EXCLUSIVE);
XLogCtl->Insert.forcePageWrites = false;
LWLockRelease(WALInsertLock);
PG_RE_THROW();
}
PG_END_TRY();
PG_END_ENSURE_ERROR_CLEANUP(pg_start_backup_callback, (Datum) 0);
/*
* We're done. As a convenience, return the starting WAL location.
@ -6534,6 +6526,16 @@ pg_start_backup(PG_FUNCTION_ARGS)
PG_RETURN_TEXT_P(cstring_to_text(xlogfilename));
}
/* Error cleanup callback for pg_start_backup */
static void
pg_start_backup_callback(int code, Datum arg)
{
/* Turn off forcePageWrites on failure */
LWLockAcquire(WALInsertLock, LW_EXCLUSIVE);
XLogCtl->Insert.forcePageWrites = false;
LWLockRelease(WALInsertLock);
}
/*
* pg_stop_backup: finish taking an on-line backup dump
*