Issue #32: Wait for LSN in archived dir for PAGE backup

Author: za-arthur

src/backup.c

@@ -104,7 +104,8 @@ static int checkpoint_timeout(void);
 
 //static void backup_list_file(parray *files, const char *root, )
 static void parse_backup_filelist_filenames(parray *files, const char *root);
-static void wait_wal_lsn(XLogRecPtr lsn, bool wait_prev_segment);
+static void wait_wal_lsn(XLogRecPtr lsn, bool is_start_lsn,
+						 bool wait_prev_segment);
 static void wait_replica_wal_lsn(XLogRecPtr lsn, bool is_start_backup);
 static void make_pagemap_from_ptrack(parray *files);
 static void *StreamLog(void *arg);
@@ -1112,20 +1113,17 @@ pg_start_backup(const char *label, bool smooth, pgBackup *backup)
 		 */
 		pg_switch_wal(conn);
 
-	if (!stream_wal)
-	{
-		/*
-		 * Do not wait start_lsn for stream backup.
-		 * Because WAL streaming will start after pg_start_backup() in stream
-		 * mode.
-		 */
+	if (current.backup_mode == BACKUP_MODE_DIFF_PAGE)
 		/* In PAGE mode wait for current segment... */
-		if (current.backup_mode == BACKUP_MODE_DIFF_PAGE)
-			wait_wal_lsn(backup->start_lsn, false);
+		wait_wal_lsn(backup->start_lsn, true, false);
+	/*
+	 * Do not wait start_lsn for stream backup.
+	 * Because WAL streaming will start after pg_start_backup() in stream
+	 * mode.
+	 */
+	else if (!stream_wal)
 		/* ...for others wait for previous segment */
-		else
-			wait_wal_lsn(backup->start_lsn, true);
-	}
+		wait_wal_lsn(backup->start_lsn, true, true);
 
 	/* Wait for start_lsn to be replayed by replica */
 	if (backup->from_replica)
@@ -1443,16 +1441,20 @@ pg_ptrack_get_and_clear(Oid tablespace_oid, Oid db_oid, Oid rel_filenode,
  * If current backup started in stream mode wait for 'lsn' to be streamed in
  * 'pg_wal' directory.
  *
+ * If 'is_start_lsn' is true and backup mode is PAGE then we wait for 'lsn' to
+ * be archived in archive 'wal' directory regardless stream mode.
+ *
  * If 'wait_prev_segment' wait for previous segment.
  */
 static void
-wait_wal_lsn(XLogRecPtr lsn, bool wait_prev_segment)
+wait_wal_lsn(XLogRecPtr lsn, bool is_start_lsn, bool wait_prev_segment)
 {
 	TimeLineID	tli;
 	XLogSegNo	targetSegNo;
-	char		wal_dir[MAXPGPATH],
-				wal_segment_path[MAXPGPATH];
-	char		wal_segment[MAXFNAMELEN];
+	char		pg_wal_dir[MAXPGPATH];
+	char		wal_segment_path[MAXPGPATH],
+			   *wal_segment_dir,
+				wal_segment[MAXFNAMELEN];
 	bool		file_exists = false;
 	uint32		try_count = 0,
 				timeout;
@@ -1469,18 +1471,28 @@ wait_wal_lsn(XLogRecPtr lsn, bool wait_prev_segment)
 		targetSegNo--;
 	XLogFileName(wal_segment, tli, targetSegNo);
 
-	if (stream_wal)
+	/*
+	 * In pg_start_backup we wait for 'lsn' in 'pg_wal' directory iff it is
+	 * stream and non-page backup. Page backup needs archived WAL files, so we
+	 * wait for 'lsn' in archive 'wal' directory for page backups.
+	 *
+	 * In pg_stop_backup it depends only on stream_wal.
+	 */
+	if (stream_wal &&
+		(current.backup_mode != BACKUP_MODE_DIFF_PAGE || !is_start_lsn))
 	{
-		pgBackupGetPath2(&current, wal_dir, lengthof(wal_dir),
+		pgBackupGetPath2(&current, pg_wal_dir, lengthof(pg_wal_dir),
 						 DATABASE_DIR, PG_XLOG_DIR);
-		join_path_components(wal_segment_path, wal_dir, wal_segment);
+		join_path_components(wal_segment_path, pg_wal_dir, wal_segment);
+		wal_segment_dir = pg_wal_dir;
 
 		timeout = (uint32) checkpoint_timeout();
 		timeout = timeout + timeout * 0.1;
 	}
 	else
 	{
 		join_path_components(wal_segment_path, arclog_path, wal_segment);
+		wal_segment_dir = arclog_path;
 		timeout = archive_timeout;
 	}
 
@@ -1523,8 +1535,7 @@ wait_wal_lsn(XLogRecPtr lsn, bool wait_prev_segment)
 			/*
 			 * A WAL segment found. Check LSN on it.
 			 */
-			if ((stream_wal && wal_contains_lsn(wal_dir, lsn, tli)) ||
-				(!stream_wal && wal_contains_lsn(arclog_path, lsn, tli)))
+			if (wal_contains_lsn(wal_segment_dir, lsn, tli))
 				/* Target LSN was found */
 			{
 				elog(LOG, "Found LSN: %X/%X", (uint32) (lsn >> 32), (uint32) lsn);
@@ -1912,7 +1923,7 @@ pg_stop_backup(pgBackup *backup)
 		 * Wait for stop_lsn to be archived or streamed.
 		 * We wait for stop_lsn in stream mode just in case.
 		 */
-		wait_wal_lsn(stop_backup_lsn, false);
+		wait_wal_lsn(stop_backup_lsn, false, false);
 
 		if (stream_wal)
 		{

src/parsexlog.c

@@ -170,15 +170,16 @@ switchToNextWal(XLogReaderState *xlogreader, xlog_thread_arg *arg)
 	 */
 	if (XLogRecPtrIsInvalid(found))
 	{
-		elog(WARNING, "could not read WAL record at %X/%X",
-			(uint32) (arg->startpoint >> 32), (uint32) (arg->startpoint));
+		elog(WARNING, "Thread [%d]: could not read WAL record at %X/%X",
+			 private_data->thread_num,
+			 (uint32) (arg->startpoint >> 32), (uint32) (arg->startpoint));
 		PrintXLogCorruptionMsg(private_data, ERROR);
 	}
 	arg->startpoint = found;
 
 	elog(VERBOSE, "Thread [%d]: switched to LSN %X/%X",
-			private_data->thread_num,
-			(uint32) (arg->startpoint >> 32), (uint32) (arg->startpoint));
+		 private_data->thread_num,
+		 (uint32) (arg->startpoint >> 32), (uint32) (arg->startpoint));
 
 	return true;
 }
@@ -261,32 +262,6 @@ doExtractPageMap(void *arg)
 					continue;
 				else
 					break;
-
-				/* Adjust next record position */
-				XLogSegNoOffsetToRecPtr(private_data->xlogsegno, 0,
-										extract_arg->startpoint);
-				/* Skip over the page header */
-				found = XLogFindNextRecord(xlogreader, extract_arg->startpoint);
-				/*
-				 * We get invalid WAL record pointer usually when WAL segment is
-				 * absent or is corrupted.
-				 */
-				if (XLogRecPtrIsInvalid(found))
-				{
-					elog(WARNING, "Thread [%d]: could not read WAL record at %X/%X",
-						private_data->thread_num,
-						(uint32) (extract_arg->startpoint >> 32),
-						(uint32) (extract_arg->startpoint));
-					PrintXLogCorruptionMsg(private_data, ERROR);
-				}
-				extract_arg->startpoint = found;
-
-				elog(VERBOSE, "Thread [%d]: switched to LSN %X/%X",
-					 private_data->thread_num,
-					 (uint32) (extract_arg->startpoint >> 32),
-					 (uint32) (extract_arg->startpoint));
-
-				continue;
 			}
 
 			errptr = extract_arg->startpoint ?