raft: fix heartbeat

raft/raft.go

@@ -189,7 +189,7 @@ func (r *raft) sendAppend(to int64) {
 // sendHeartbeat sends RRPC, without entries to the given peer.
 func (r *raft) sendHeartbeat(to int64) {
 	pr := r.prs[to]
-	index := max(pr.next-1, r.raftLog.lastIndex())
+	index := max(pr.next-1, r.raftLog.offset)
 	m := pb.Message{
 		To:      to,
 		Type:    msgApp,

raft/raft_test.go

@@ -731,6 +731,68 @@ func TestLeaderAppResp(t *testing.T) {
 	}
 }
 
+// When the leader receives a heartbeat tick, it should
+// send a msgApp with m.Index = max(progress.next-1,log.offset) and empty
+// entries.
+func TestBcastBeat(t *testing.T) {
+	offset := int64(1000)
+	// make a state machine with log.offset = 1000
+	s := pb.Snapshot{
+		Index: offset,
+		Term:  1,
+		Nodes: []int64{1, 2},
+	}
+	sm := newRaft(1, []int64{1, 2}, 0, 0)
+	sm.Term = 1
+	sm.restore(s)
+
+	sm.becomeCandidate()
+	sm.becomeLeader()
+	for i := 0; i < 10; i++ {
+		sm.appendEntry(pb.Entry{})
+	}
+
+	tests := []struct {
+		pnext  int64
+		windex int64
+		wterm  int64
+		wto    int64
+	}{
+		{offset + 1, offset, 1, 2},
+		{offset + 2, offset + 1, 2, 2},
+		// pr.next -1 < offset
+		{offset, offset, 1, 2},
+		{offset - 1, offset, 1, 2},
+	}
+
+	for i, tt := range tests {
+		sm.prs[2].match = 0
+		sm.prs[2].next = tt.pnext
+
+		sm.Step(pb.Message{Type: msgBeat})
+		msgs := sm.ReadMessages()
+		if len(msgs) != 1 {
+			t.Fatalf("#%d: len(msgs) = %v, want 1", i, len(msgs))
+		}
+		m := msgs[0]
+		if m.Type != msgApp {
+			t.Fatalf("#%d: type = %v, want = %v", i, m.Type, msgApp)
+		}
+		if m.Index != tt.windex {
+			t.Fatalf("#%d: prevIndex = %d, want %d", i, m.Index, tt.windex)
+		}
+		if m.LogTerm != tt.wterm {
+			t.Fatalf("#%d: prevTerm = %d, want %d", i, m.LogTerm, tt.wterm)
+		}
+		if m.To != tt.wto {
+			t.Fatalf("#%d: to = %d, want %d", i, m.To, tt.wto)
+		}
+		if len(m.Entries) != 0 {
+			t.Fatalf("#%d: len(entries) = %d, want 0", i, len(m.Entries))
+		}
+	}
+}
+
 // tests the output of the statemachine when receiving msgBeat
 func TestRecvMsgBeat(t *testing.T) {
 	tests := []struct {