Merge pull request #1908 from bdarnell/error-fixes

raft: remove panic when we see a proposal with no leader.

raft/raft.go

@@ -482,7 +482,8 @@ func stepLeader(r *raft, m pb.Message) {
 func stepCandidate(r *raft, m pb.Message) {
 	switch m.Type {
 	case pb.MsgProp:
-		panic("no leader")
+		log.Printf("raft: %x no leader at term %d; dropping proposal", r.id, r.Term)
+		return
 	case pb.MsgApp:
 		r.becomeFollower(r.Term, m.From)
 		r.handleAppendEntries(m)
@@ -513,7 +514,8 @@ func stepFollower(r *raft, m pb.Message) {
 	switch m.Type {
 	case pb.MsgProp:
 		if r.lead == None {
-			panic("no leader")
+			log.Printf("raft: %x no leader at term %d; dropping proposal", r.id, r.Term)
+			return
 		}
 		m.To = r.lead
 		r.send(m)

raft/storage.go

@@ -180,18 +180,18 @@ func (ms *MemoryStorage) Compact(i uint64, cs *pb.ConfState, data []byte) error
 }
 
 // Append the new entries to storage.
-func (ms *MemoryStorage) Append(entries []pb.Entry) {
+func (ms *MemoryStorage) Append(entries []pb.Entry) error {
 	ms.Lock()
 	defer ms.Unlock()
 	if len(entries) == 0 {
-		return
+		return nil
 	}
 	first := ms.snapshot.Metadata.Index + 1
 	last := entries[0].Index + uint64(len(entries)) - 1
 
 	// shortcut if there is no new entry.
 	if last < first {
-		return
+		return nil
 	}
 	// truncate old entries
 	if first > entries[0].Index {
@@ -209,4 +209,5 @@ func (ms *MemoryStorage) Append(entries []pb.Entry) {
 		log.Panicf("missing log entry [last: %d, append at: %d]",
 			ms.snapshot.Metadata.Index+uint64(len(ms.ents)), entries[0].Index)
 	}
+	return nil
 }