main: add a helper function for starting raft

main.go

@@ -49,29 +49,7 @@ func main() {
 		log.Fatalf("main: cannot create data directory: %v", err)
 	}
 
-	waldir := path.Join(*dir, "wal")
-
-	var w *wal.WAL
-	var n raft.Node
-	if wal.Exist(waldir) {
-		// TODO(xiangli): check snapshot; not open from zero
-		w, err = wal.OpenFromIndex(waldir, 0)
-		if err != nil {
-			log.Fatal(err)
-		}
-		// TODO(xiangli): save/recovery nodeID?
-		_, st, ents, err := w.ReadAll()
-		if err != nil {
-			log.Fatal(err)
-		}
-		n = raft.Restart(id, peers.Ids(), 10, 1, st, ents)
-	} else {
-		w, err = wal.Create(waldir)
-		if err != nil {
-			log.Fatal(err)
-		}
-		n = raft.Start(id, peers.Ids(), 10, 1)
-	}
+	n, w := startRaft(id, peers.Ids(), path.Join(*dir, "wal"))
 
 	tk := time.NewTicker(100 * time.Millisecond)
 	s := &etcdserver.Server{
@@ -89,3 +67,32 @@ func main() {
 	http.Handle("/", h)
 	log.Fatal(http.ListenAndServe(*laddr, nil))
 }
+
+// startRaft starts a raft node from the given wal dir.
+// If the wal dir does not exist, startRaft will start a new raft node.
+// If the wal dir exists, startRaft will restart the previous raft node.
+// startRaft returns the started raft node and the opened wal.
+func startRaft(id int64, peerIds []int64, waldir string) (raft.Node, *wal.WAL) {
+	if !wal.Exist(waldir) {
+		w, err := wal.Create(waldir)
+		if err != nil {
+			log.Fatal(err)
+		}
+		n := raft.Start(id, peerIds, 10, 1)
+		return n, w
+	}
+
+	// restart a node from previous wal
+	// TODO(xiangli): check snapshot; not open from zero
+	w, err := wal.OpenFromIndex(waldir, 0)
+	if err != nil {
+		log.Fatal(err)
+	}
+	// TODO(xiangli): save/recovery nodeID?
+	_, st, ents, err := w.ReadAll()
+	if err != nil {
+		log.Fatal(err)
+	}
+	n := raft.Restart(id, peerIds, 10, 1, st, ents)
+	return n, w
+}