raft: error on ignored proposal and wait for EntryConfChange results

fixes: #43
Signed-off-by: Bogdan Kanivets <[email protected]>

node.go

@@ -466,7 +466,7 @@ func (n *node) ProposeConfChange(ctx context.Context, cc pb.ConfChangeI) error {
 	if err != nil {
 		return err
 	}
-	return n.Step(ctx, msg)
+	return n.stepWait(ctx, msg)
 }
 
 func (n *node) step(ctx context.Context, m pb.Message) error {

raft.go

@@ -1229,7 +1229,7 @@ func stepLeader(r *raft, m pb.Message) error {
 
 				if refused != "" {
 					r.logger.Infof("%x ignoring conf change %v at config %s: %s", r.id, cc, r.prs.Config, refused)
-					m.Entries[i] = pb.Entry{Type: pb.EntryNormal}
+					return ErrProposalDropped
 				} else {
 					r.pendingConfIndex = r.raftLog.lastIndex() + uint64(i) + 1
 				}

raft_test.go

@@ -3283,24 +3283,17 @@ func TestStepConfig(t *testing.T) {
 }
 
 // TestStepIgnoreConfig tests that if raft step the second msgProp in
-// EntryConfChange type when the first one is uncommitted, the node will set
-// the proposal to noop and keep its original state.
+// EntryConfChange type when the first one is uncommitted, the node will drop second msgProp and return ErrProposalDropped.
 func TestStepIgnoreConfig(t *testing.T) {
 	// a raft that cannot make progress
 	r := newTestRaft(1, 10, 1, newTestMemoryStorage(withPeers(1, 2)))
 	r.becomeCandidate()
 	r.becomeLeader()
 	r.Step(pb.Message{From: 1, To: 1, Type: pb.MsgProp, Entries: []pb.Entry{{Type: pb.EntryConfChange}}})
-	index := r.raftLog.lastIndex()
 	pendingConfIndex := r.pendingConfIndex
-	r.Step(pb.Message{From: 1, To: 1, Type: pb.MsgProp, Entries: []pb.Entry{{Type: pb.EntryConfChange}}})
-	wents := []pb.Entry{{Type: pb.EntryNormal, Term: 1, Index: 3, Data: nil}}
-	ents, err := r.raftLog.entries(index+1, noLimit)
-	if err != nil {
-		t.Fatalf("unexpected error %v", err)
-	}
-	if !reflect.DeepEqual(ents, wents) {
-		t.Errorf("ents = %+v, want %+v", ents, wents)
+	err := r.Step(pb.Message{From: 1, To: 1, Type: pb.MsgProp, Entries: []pb.Entry{{Type: pb.EntryConfChange}}})
+	if err != ErrProposalDropped {
+		t.Fatalf("Expected %v, got %v", ErrProposalDropped, err)
 	}
 	if r.pendingConfIndex != pendingConfIndex {
 		t.Errorf("pendingConfIndex = %d, want %d", r.pendingConfIndex, pendingConfIndex)