From 140fd6d6c4dd931b864d38b104b262bfdaf3f7b5 Mon Sep 17 00:00:00 2001
From: Yicheng Qin <qycqycqycqycqyc@gmail.com>
Date: Sun, 14 Sep 2014 16:45:45 -0700
Subject: [PATCH] raft: restart using last written entry also

---
 main.go           | 2 +-
 raft/log.go       | 5 +++++
 raft/node_test.go | 3 ++-
 raft/raft.go      | 3 +--
 wal/wal.go        | 1 -
 5 files changed, 9 insertions(+), 5 deletions(-)

diff --git a/main.go b/main.go
index 368251353..15cbee4ce 100644
--- a/main.go
+++ b/main.go
@@ -107,7 +107,7 @@ func startRaft(id int64, peerIDs []int64, waldir string) (raft.Node, *wal.WAL) {
 
 	// restart a node from previous wal
 	// TODO(xiangli): check snapshot; not open from one
-	w, err := wal.OpenAtIndex(waldir, 1)
+	w, err := wal.OpenAtIndex(waldir, 0)
 	if err != nil {
 		log.Fatal(err)
 	}
diff --git a/raft/log.go b/raft/log.go
index 9165d8c0b..cbfa90ee4 100644
--- a/raft/log.go
+++ b/raft/log.go
@@ -38,6 +38,11 @@ func (l *raftLog) isEmpty() bool {
 	return l.offset == 0 && len(l.ents) == 1
 }
 
+func (l *raftLog) load(ents []pb.Entry) {
+	l.ents = ents
+	l.unstable = l.offset + int64(len(ents))
+}
+
 func (l *raftLog) String() string {
 	return fmt.Sprintf("offset=%d committed=%d applied=%d len(ents)=%d", l.offset, l.committed, l.applied, len(l.ents))
 }
diff --git a/raft/node_test.go b/raft/node_test.go
index dbbb92cfd..eb461611a 100644
--- a/raft/node_test.go
+++ b/raft/node_test.go
@@ -171,6 +171,7 @@ func TestNode(t *testing.T) {
 
 func TestNodeRestart(t *testing.T) {
 	entries := []raftpb.Entry{
+		{},
 		{Term: 1, Index: 1},
 		{Term: 1, Index: 2, Data: []byte("foo")},
 	}
@@ -179,7 +180,7 @@ func TestNodeRestart(t *testing.T) {
 	want := Ready{
 		State: emptyState,
 		// commit upto index commit index in st
-		CommittedEntries: entries[:st.Commit],
+		CommittedEntries: entries[1 : st.Commit+1],
 	}
 
 	n := Restart(1, []int64{1}, 0, 0, st, entries)
diff --git a/raft/raft.go b/raft/raft.go
index e8aa88cfe..4ddaf95bc 100644
--- a/raft/raft.go
+++ b/raft/raft.go
@@ -503,8 +503,7 @@ func (r *raft) loadEnts(ents []pb.Entry) {
 	if !r.raftLog.isEmpty() {
 		panic("cannot load entries when log is not empty")
 	}
-	r.raftLog.append(0, ents...)
-	r.raftLog.unstable = r.raftLog.lastIndex() + 1
+	r.raftLog.load(ents)
 }
 
 func (r *raft) loadState(state pb.State) {
diff --git a/wal/wal.go b/wal/wal.go
index 5d431b35e..57c994103 100644
--- a/wal/wal.go
+++ b/wal/wal.go
@@ -65,7 +65,6 @@ type WAL struct {
 }
 
 // Create creates a WAL ready for appending records.
-// The index of first record saved MUST be 0.
 func Create(dirpath string) (*WAL, error) {
 	log.Printf("path=%s wal.create", dirpath)
 	if Exist(dirpath) {