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Split pg_start_backup() and pg_stop_backup() into two pieces

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Move the actual functionality into a separate function that's
easier to call internally, and change the SQL-callable function
to be a wrapper calling this.

Also create a pg_abort_backup() function, only callable internally,
that does only the most vital parts of pg_stop_backup(), making it
safe(r) to call from error handlers.
This commit is contained in:
Magnus Hagander 2011-01-09 21:00:28 +01:00
parent ca63029eac
commit 4448917d51
2 changed files with 62 additions and 8 deletions
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66
src/backend/access/transam/xlog.c
View File

@ -8308,6 +8308,21 @@ pg_start_backup(PG_FUNCTION_ARGS)
text *backupid = PG_GETARG_TEXT_P(0);
bool fast = PG_GETARG_BOOL(1);
char *backupidstr;
XLogRecPtr startpoint;
char startxlogstr[MAXFNAMELEN];
backupidstr = text_to_cstring(backupid);
startpoint = do_pg_start_backup(backupidstr, fast);
snprintf(startxlogstr, sizeof(startxlogstr), "%X/%X",
startpoint.xlogid, startpoint.xrecoff);
PG_RETURN_TEXT_P(cstring_to_text(startxlogstr));
}
XLogRecPtr
do_pg_start_backup(const char *backupidstr, bool fast)
{
XLogRecPtr checkpointloc;
XLogRecPtr startpoint;
pg_time_t stamp_time;
@ -8335,8 +8350,6 @@ pg_start_backup(PG_FUNCTION_ARGS)
errmsg("WAL level not sufficient for making an online backup"),
errhint("wal_level must be set to \"archive\" or \"hot_standby\" at server start.")));
backupidstr = text_to_cstring(backupid);
/*
* Mark backup active in shared memory. We must do full-page WAL writes
* during an on-line backup even if not doing so at other times, because
@ -8459,9 +8472,7 @@ pg_start_backup(PG_FUNCTION_ARGS)
/*
* We're done. As a convenience, return the starting WAL location.
*/
snprintf(xlogfilename, sizeof(xlogfilename), "%X/%X",
startpoint.xlogid, startpoint.xrecoff);
PG_RETURN_TEXT_P(cstring_to_text(xlogfilename));
return startpoint;
}
/* Error cleanup callback for pg_start_backup */
@ -8489,6 +8500,19 @@ pg_start_backup_callback(int code, Datum arg)
*/
Datum
pg_stop_backup(PG_FUNCTION_ARGS)
{
XLogRecPtr stoppoint;
char stopxlogstr[MAXFNAMELEN];
stoppoint = do_pg_stop_backup();
snprintf(stopxlogstr, sizeof(stopxlogstr), "%X/%X",
stoppoint.xlogid, stoppoint.xrecoff);
PG_RETURN_TEXT_P(cstring_to_text(stopxlogstr));
}
XLogRecPtr
do_pg_stop_backup(void)
{
XLogRecPtr startpoint;
XLogRecPtr stoppoint;
@ -8699,9 +8723,35 @@ pg_stop_backup(PG_FUNCTION_ARGS)
/*
* We're done. As a convenience, return the ending WAL location.
*/
snprintf(stopxlogfilename, sizeof(stopxlogfilename), "%X/%X",
stoppoint.xlogid, stoppoint.xrecoff);
PG_RETURN_TEXT_P(cstring_to_text(stopxlogfilename));
return stoppoint;
}
/*
* do_pg_abort_backup: abort a running backup
*
* This does just the most basic steps of pg_stop_backup(), by taking the
* system out of backup mode, thus making it a lot more safe to call from
* an error handler.
*/
void
do_pg_abort_backup(void)
{
/*
* OK to clear forcePageWrites
*/
LWLockAcquire(WALInsertLock, LW_EXCLUSIVE);
XLogCtl->Insert.forcePageWrites = false;
LWLockRelease(WALInsertLock);
/*
* Remove backup label file
*/
if (unlink(BACKUP_LABEL_FILE) != 0)
ereport(ERROR,
(errcode_for_file_access(),
errmsg("could not remove file \"%s\": %m",
BACKUP_LABEL_FILE)));
}
/*

4
src/include/access/xlog.h
View File

@ -312,4 +312,8 @@ extern void HandleStartupProcInterrupts(void);
extern void StartupProcessMain(void);
extern void WakeupRecovery(void);
extern XLogRecPtr do_pg_start_backup(const char *backupidstr, bool fast);
extern XLogRecPtr do_pg_stop_backup(void);
extern void do_pg_abort_backup(void);
#endif /* XLOG_H */