From 072644969e276d6071bed13cbf95320d25b8d468 Mon Sep 17 00:00:00 2001
From: Chris Lu <chris.lu@gmail.com>
Date: Thu, 18 Apr 2019 20:04:44 -0700
Subject: [PATCH] refactoring

---
 unmaintained/volume_tailer/volume_tailer.go | 75 ++++++++++++---------
 1 file changed, 44 insertions(+), 31 deletions(-)

diff --git a/unmaintained/volume_tailer/volume_tailer.go b/unmaintained/volume_tailer/volume_tailer.go
index 8a662ef5e..b90517009 100644
--- a/unmaintained/volume_tailer/volume_tailer.go
+++ b/unmaintained/volume_tailer/volume_tailer.go
@@ -3,6 +3,7 @@ package main
 import (
 	"context"
 	"flag"
+	"fmt"
 
 	"github.com/chrislusf/seaweedfs/weed/operation"
 	"github.com/chrislusf/seaweedfs/weed/pb/volume_server_pb"
@@ -11,6 +12,7 @@ import (
 	"github.com/chrislusf/seaweedfs/weed/storage"
 	"github.com/spf13/viper"
 	"golang.org/x/tools/godoc/util"
+	"google.golang.org/grpc"
 
 	"io"
 	"log"
@@ -31,16 +33,50 @@ func main() {
 
 	vid := storage.VolumeId(*volumeId)
 
+	err := TailVolume(*master, grpcDialOption, vid, func(n *storage.Needle) (err error) {
+		if n.Size == 0 {
+			println("-", n.String())
+			return nil
+		} else {
+			println("+", n.String())
+		}
+
+		if *showTextFile {
+
+			data := n.Data
+			if n.IsGzipped() {
+				if data, err = operation.UnGzipData(data); err != nil {
+					return err
+				}
+			}
+			if util.IsText(data) {
+				println(string(data))
+			}
+
+			println("-", n.String(), "compressed", n.IsGzipped(), "original size", len(data))
+		}
+		return nil
+	})
+
+	if err != nil {
+		log.Printf("Error VolumeTail volume %d: %v", vid, err)
+	}
+
+}
+
+func TailVolume(master string, grpcDialOption grpc.DialOption, vid storage.VolumeId, fn func(n *storage.Needle) error) error {
 	// find volume location, replication, ttl info
-	lookup, err := operation.Lookup(*master, vid.String())
+	lookup, err := operation.Lookup(master, vid.String())
 	if err != nil {
-		log.Printf("Error looking up volume %d: %v", vid, err)
-		return
+		return fmt.Errorf("Error looking up volume %d: %v", vid, err)
 	}
+	if len(lookup.Locations) == 0 {
+		return fmt.Errorf("unable to locate volume %d", vid)
+	}
+
 	volumeServer := lookup.Locations[0].Url
-	log.Printf("volume %d is on volume server %s", vid, volumeServer)
 
-	err = operation.WithVolumeServerClient(volumeServer, grpcDialOption, func(client volume_server_pb.VolumeServerClient) error {
+	return operation.WithVolumeServerClient(volumeServer, grpcDialOption, func(client volume_server_pb.VolumeServerClient) error {
 
 		stream, err := client.VolumeTail(context.Background(), &volume_server_pb.VolumeTailRequest{
 			VolumeId:        uint32(vid),
@@ -84,36 +120,13 @@ func main() {
 			n.ParseNeedleHeader(needleHeader)
 			n.ReadNeedleBodyBytes(needleBody, storage.CurrentVersion)
 
-			if n.Size == 0 {
-				println("-", n.String())
-				continue
-			} else {
-				println("+", n.String())
-			}
-
-			if *showTextFile {
-
-				data := n.Data
-				if n.IsGzipped() {
-					if data, err = operation.UnGzipData(data); err != nil {
-						continue
-					}
-				}
-				if util.IsText(data) {
-					println(string(data))
-				}
+			err = fn(n)
 
-				println("-", n.String(), "compressed", n.IsGzipped(), "original size", len(data))
+			if err != nil {
+				return err
 			}
 
 		}
-
 		return nil
-
 	})
-
-	if err != nil {
-		log.Printf("Error VolumeTail volume %d: %v", vid, err)
-	}
-
 }