raft: Address comment

raft/raft.go

@@ -1211,16 +1211,6 @@ func (r *raft) handleSnapshot(m pb.Message) {
 // restore recovers the state machine from a snapshot. It restores the log and the
 // configuration of state machine.
 func (r *raft) restore(s pb.Snapshot) bool {
-	// The normal peer can't become learner.
-	if !r.isLearner {
-		for _, id := range s.Metadata.ConfState.Learners {
-			if id == r.id {
-				r.logger.Errorf("%x can't become learner when restores snapshot [index: %d, term: %d]", r.id, s.Metadata.Index, s.Metadata.Term)
-				return false
-			}
-		}
-	}
-
 	if s.Metadata.Index <= r.raftLog.committed {
 		return false
 	}
@@ -1231,6 +1221,16 @@ func (r *raft) restore(s pb.Snapshot) bool {
 		return false
 	}
 
+	// The normal peer can't become learner.
+	if !r.isLearner {
+		for _, id := range s.Metadata.ConfState.Learners {
+			if id == r.id {
+				r.logger.Errorf("%x can't become learner when restores snapshot [index: %d, term: %d]", r.id, s.Metadata.Index, s.Metadata.Term)
+				return false
+			}
+		}
+	}
+
 	r.logger.Infof("%x [commit: %d, lastindex: %d, lastterm: %d] starts to restore snapshot [index: %d, term: %d]",
 		r.id, r.raftLog.committed, r.raftLog.lastIndex(), r.raftLog.lastTerm(), s.Metadata.Index, s.Metadata.Term)
 

raft/raft_test.go

@@ -429,7 +429,7 @@ func TestLearnerCannotVote(t *testing.T) {
 	n2.Step(pb.Message{From: 1, To: 2, Term: 2, Type: pb.MsgVote, LogTerm: 11, Index: 11})
 
 	if len(n2.msgs) != 0 {
-		t.Error("n2 is learner, can't vote")
+		t.Errorf("expect learner not to vote, but received %v messages", n2.msgs)
 	}
 }
 
@@ -706,9 +706,8 @@ func TestLearnerLogReplication(t *testing.T) {
 	if n1.state != StateLeader {
 		t.Errorf("peer 1 state: %s, want %s", n1.state, StateLeader)
 	}
-
 	if !n2.isLearner {
-		t.Error("peer 2 is not learner, want yes")
+		t.Error("peer 2 state: not learner, want yes")
 	}
 
 	nextCommitted := n1.raftLog.committed + 1
@@ -718,7 +717,7 @@ func TestLearnerLogReplication(t *testing.T) {
 	}
 
 	if n1.raftLog.committed != n2.raftLog.committed {
-		t.Error("peer 2 must receive the entry from leader, but not")
+		t.Errorf("peer 2 wants committed to %d, but still %d", n1.raftLog.committed, n2.raftLog.committed)
 	}
 
 	match := n1.getProgress(2).Match