filer: able to tail meta data changes

weed/filer2/filer_notify.go

@@ -77,3 +77,40 @@ func (f *Filer) logFlushFunc(startTime, stopTime time.Time, buf []byte) {
 	}
 }
 
+func (f *Filer) ReadLogBuffer(lastReadTime time.Time, eachEventFn func(fullpath string, eventNotification *filer_pb.EventNotification) error) (newLastReadTime time.Time, err error) {
+
+	var buf []byte
+	newLastReadTime, buf = f.metaLogBuffer.ReadFromBuffer(lastReadTime)
+
+	for pos := 0; pos+4 < len(buf); {
+
+		size := util.BytesToUint32(buf[pos : pos+4])
+		entryData := buf[pos+4 : pos+4+int(size)]
+
+		logEntry := &filer_pb.LogEntry{}
+		err = proto.Unmarshal(entryData, logEntry)
+		if err != nil {
+			glog.Errorf("unexpected unmarshal filer_pb.LogEntry: %v", err)
+			return lastReadTime, fmt.Errorf("unexpected unmarshal filer_pb.LogEntry: %v", err)
+		}
+
+		event := &filer_pb.FullEventNotification{}
+		err = proto.Unmarshal(logEntry.Data, event)
+		if err != nil {
+			glog.Errorf("unexpected unmarshal filer_pb.FullEventNotification: %v", err)
+			return lastReadTime, fmt.Errorf("unexpected unmarshal filer_pb.FullEventNotification: %v", err)
+		}
+
+		err = eachEventFn(event.Directory, event.EventNotification)
+
+		if err != nil {
+			return
+		}
+
+		pos += 4 + int(size)
+
+	}
+
+	return
+
+}