filer.sync: include last error in stall diagnostics

weed/command/filer_sync.go

@@ -375,8 +375,13 @@ func doSubscribeFilerMetaChanges(clientId int32, clientEpoch int32, sourceGrpcDi
 		lastLogTsNs = now
 		if offsetTsNs == lastProgressedTsNs {
 			for _, t := range filerSink.ActiveTransfers() {
-				glog.V(0).Infof("  %s %s: %d bytes received, %s",
-					t.ChunkFileId, t.Path, t.BytesReceived, t.Status)
+				if t.LastErr != "" {
+					glog.V(0).Infof("  %s %s: %d bytes received, %s, last error: %s",
+						t.ChunkFileId, t.Path, t.BytesReceived, t.Status, t.LastErr)
+				} else {
+					glog.V(0).Infof("  %s %s: %d bytes received, %s",
+						t.ChunkFileId, t.Path, t.BytesReceived, t.Status)
+				}
 			}
 		}
 		lastProgressedTsNs = offsetTsNs

weed/replication/sink/filersink/fetch_write.go

@@ -335,6 +335,7 @@ func (fs *FilerSink) fetchAndWrite(sourceChunk *filer_pb.FileChunk, path string,
 			glog.V(1).Infof("skip retrying stale source %s for %s: %v", sourceChunk.GetFileIdString(), path, retryErr)
 			return false
 		}
+		transferStatus.LastErr = retryErr.Error()
 		if isEofError(retryErr) {
 			eofBackoff = nextEofBackoff(eofBackoff)
 			transferStatus.BytesReceived = int64(len(partialData))

weed/replication/sink/filersink/filer_sink.go

@@ -27,6 +27,7 @@ type ChunkTransferStatus struct {
 	Path          string
 	BytesReceived int64
 	Status        string // "downloading", "uploading", or "waiting 10s" etc.
+	LastErr       string
 }
 
 type FilerSink struct {