avoid looping forever if there are no more metadata updates

weed/server/filer_grpc_server_sub_meta.go

@@ -49,11 +49,6 @@ func (fs *FilerServer) SubscribeMetadata(req *filer_pb.SubscribeMetadataRequest,
 
 		if processedTsNs != 0 {
 			lastReadTime = time.Unix(0, processedTsNs)
-		} else {
-			if readInMemoryLogErr == log_buffer.ResumeFromDiskError {
-				time.Sleep(1127 * time.Millisecond)
-				continue
-			}
 		}
 
 		glog.V(4).Infof("read in memory %v aggregated subscribe %s from %+v", clientName, req.PathPrefix, lastReadTime)
@@ -66,6 +61,7 @@ func (fs *FilerServer) SubscribeMetadata(req *filer_pb.SubscribeMetadataRequest,
 		}, eachLogEntryFn)
 		if readInMemoryLogErr != nil {
 			if readInMemoryLogErr == log_buffer.ResumeFromDiskError {
+				time.Sleep(1127 * time.Millisecond)
 				continue
 			}
 			glog.Errorf("processed to %v: %v", lastReadTime, readInMemoryLogErr)

weed/util/log_buffer/log_buffer.go

@@ -189,8 +189,12 @@ func (m *LogBuffer) ReadFromBuffer(lastReadTime time.Time) (bufferCopy *bytes.Bu
 	defer m.RUnlock()
 
 	if !m.lastFlushTime.IsZero() && m.lastFlushTime.After(lastReadTime) {
+		if time.Now().Sub(m.lastFlushTime) < m.flushInterval * 2 {
+			diff := m.lastFlushTime.Sub(lastReadTime)
+			glog.V(4).Infof("lastFlush:%v lastRead:%v diff:%v", m.lastFlushTime, lastReadTime, diff)
 			return nil, ResumeFromDiskError
 		}
+	}
 
 	/*
 		fmt.Printf("read buffer %p: %v last stop time: [%v,%v], pos %d, entries:%d, prevBufs:%d\n", m, lastReadTime, m.startTime, m.stopTime, m.pos, len(m.idx), len(m.prevBuffers.buffers))