Have pg_stop_backup() wait for all archive files to be sent, rather than

returing right away.  This guarantees that when pg_stop_backup()
returns, you have a valid backup.

Simon Riggs

1 files changed, 43 insertions, 6 deletions

diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index 1b6a58f661..b059e49bc3 100644
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -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 1.295 2008/03/25 22:42:42 tgl Exp $
+ * $PostgreSQL: pgsql/src/backend/access/transam/xlog.c,v 1.296 2008/04/05 01:34:06 momjian Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -382,7 +382,7 @@ static bool InRedo = false;
 
 static void XLogArchiveNotify(const char *xlog);
 static void XLogArchiveNotifySeg(uint32 log, uint32 seg);
-static bool XLogArchiveCheckDone(const char *xlog);
+static bool XLogArchiveCheckDone(const char *xlog, bool create_if_missing);
 static void XLogArchiveCleanup(const char *xlog);
 static void readRecoveryCommandFile(void);
 static void exitArchiveRecovery(TimeLineID endTLI,
@@ -1128,7 +1128,7 @@ XLogArchiveNotifySeg(uint32 log, uint32 seg)
  * create <XLOG>.ready fails, we'll retry during subsequent checkpoints.
  */
 static bool
-XLogArchiveCheckDone(const char *xlog)
+XLogArchiveCheckDone(const char *xlog, bool create_if_missing)
 {
 	char		archiveStatusPath[MAXPGPATH];
 	struct stat stat_buf;
@@ -1153,7 +1153,9 @@ XLogArchiveCheckDone(const char *xlog)
 		return true;
 
 	/* Retry creation of the .ready file */
-	XLogArchiveNotify(xlog);
+	if (create_if_missing)
+		XLogArchiveNotify(xlog);
+
 	return false;
 }
 
@@ -2704,7 +2706,7 @@ RemoveOldXlogFiles(uint32 log, uint32 seg, XLogRecPtr endptr)
 			strspn(xlde->d_name, "0123456789ABCDEF") == 24 &&
 			strcmp(xlde->d_name + 8, lastoff + 8) <= 0)
 		{
-			if (XLogArchiveCheckDone(xlde->d_name))
+			if (XLogArchiveCheckDone(xlde->d_name, true))
 			{
 				snprintf(path, MAXPGPATH, XLOGDIR "/%s", xlde->d_name);
 
@@ -2771,7 +2773,7 @@ CleanupBackupHistory(void)
 			strcmp(xlde->d_name + strlen(xlde->d_name) - strlen(".backup"),
 				   ".backup") == 0)
 		{
-			if (XLogArchiveCheckDone(xlde->d_name))
+			if (XLogArchiveCheckDone(xlde->d_name, true))
 			{
 				ereport(DEBUG2,
 				(errmsg("removing transaction log backup history file \"%s\"",
@@ -6556,6 +6558,8 @@ pg_stop_backup(PG_FUNCTION_ARGS)
 	FILE	   *fp;
 	char		ch;
 	int			ich;
+	int			seconds_before_warning;
+	int			waits = 0;
 
 	if (!superuser())
 		ereport(ERROR,
@@ -6660,6 +6664,39 @@ pg_stop_backup(PG_FUNCTION_ARGS)
 	CleanupBackupHistory();
 
 	/*
+	 * Wait until the history file has been archived. We assume that the 
+	 * alphabetic sorting property of the WAL files ensures the last WAL
+	 * file is guaranteed archived by the time the history file is archived.
+	 *
+	 * We wait forever, since archive_command is supposed to work and
+	 * we assume the admin wanted his backup to work completely. If you 
+	 * don't wish to wait, you can SET statement_timeout = xx;
+	 *
+	 * If the status file is missing, we assume that is because it was
+	 * set to .ready before we slept, then while asleep it has been set
+	 * to .done and then removed by a concurrent checkpoint.
+	 */
+	BackupHistoryFileName(histfilepath, ThisTimeLineID, _logId, _logSeg,
+						  startpoint.xrecoff % XLogSegSize);
+
+	seconds_before_warning = 60;
+	waits = 0;
+
+	while (!XLogArchiveCheckDone(histfilepath, false))
+	{
+		CHECK_FOR_INTERRUPTS();
+
+		pg_usleep(1000000L);
+
+		if (++waits >= seconds_before_warning)
+		{
+			seconds_before_warning *= 2;     /* This wraps in >10 years... */
+			elog(WARNING, "pg_stop_backup() waiting for archive to complete " 
+							"(%d seconds delay)", waits);
+		}
+	}
+
+	/*
 	 * We're done.  As a convenience, return the ending WAL location.
 	 */
 	snprintf(stopxlogfilename, sizeof(stopxlogfilename), "%X/%X",