Merge pull request #103 from github/limited-streamer-retries

capped streamer retries

Author: Shlomi Noach

go/binlog/gomysql_reader.go

@@ -63,15 +63,6 @@ func (this *GoMySQLReader) ConnectBinlogStreamer(coordinates mysql.BinlogCoordin
 	return err
 }
 
-func (this *GoMySQLReader) Reconnect() error {
-	this.binlogSyncer.Close()
-	connectCoordinates := &mysql.BinlogCoordinates{LogFile: this.currentCoordinates.LogFile, LogPos: 4}
-	if err := this.ConnectBinlogStreamer(*connectCoordinates); err != nil {
-		return err
-	}
-	return nil
-}
-
 func (this *GoMySQLReader) GetCurrentBinlogCoordinates() *mysql.BinlogCoordinates {
 	this.currentCoordinatesMutex.Lock()
 	defer this.currentCoordinatesMutex.Unlock()

go/logic/streamer.go

@@ -189,18 +189,27 @@ func (this *EventsStreamer) StreamEvents(canStopStreaming func() bool) error {
 		}
 	}()
 	// The next should block and execute forever, unless there's a serious error
+	var successiveFailures int64
+	var lastAppliedRowsEventHint mysql.BinlogCoordinates
 	for {
 		if err := this.binlogReader.StreamEvents(canStopStreaming, this.eventsChannel); err != nil {
 			log.Infof("StreamEvents encountered unexpected error: %+v", err)
 			this.migrationContext.MarkPointOfInterest()
 			time.Sleep(ReconnectStreamerSleepSeconds * time.Second)
 
-			// Reposition at same binlog file. Single attempt (TODO: make multiple attempts?)
-			lastAppliedRowsEventHint := this.binlogReader.LastAppliedRowsEventHint
+			// See if there's retry overflow
+			if this.binlogReader.LastAppliedRowsEventHint.Equals(&lastAppliedRowsEventHint) {
+				successiveFailures += 1
+			} else {
+				successiveFailures = 0
+			}
+			if successiveFailures > this.migrationContext.MaxRetries() {
+				return fmt.Errorf("%d successive failures in streamer reconnect at coordinates %+v", lastAppliedRowsEventHint)
+			}
+
+			// Reposition at same binlog file.
+			lastAppliedRowsEventHint = this.binlogReader.LastAppliedRowsEventHint
 			log.Infof("Reconnecting... Will resume at %+v", lastAppliedRowsEventHint)
-			// if err := this.binlogReader.Reconnect(); err != nil {
-			// 	return err
-			// }
 			if err := this.initBinlogReader(this.GetReconnectBinlogCoordinates()); err != nil {
 				return err
 			}