Merge pull request hashicorp#97 from abligh/dont-close-transport-twice

Ensure we don't call the shutdown future more than once

future.go

@@ -97,6 +97,9 @@ type shutdownFuture struct {
 }
 
 func (s *shutdownFuture) Error() error {
+	if s.raft == nil {
+		return nil
+	}
 	for s.raft.getRoutines() > 0 {
 		time.Sleep(5 * time.Millisecond)
 	}

raft.go

@@ -412,9 +412,11 @@ func (r *Raft) Shutdown() Future {
 		close(r.shutdownCh)
 		r.shutdown = true
 		r.setState(Shutdown)
+		return &shutdownFuture{r}
 	}
 
-	return &shutdownFuture{r}
+	// avoid closing transport twice
+	return &shutdownFuture{nil}
 }
 
 // Snapshot is used to manually force Raft to take a snapshot.

raft_test.go

@@ -451,7 +451,10 @@ func TestRaft_AfterShutdown(t *testing.T) {
 	}
 
 	// Should be idempotent
-	raft.Shutdown()
+	if f := raft.Shutdown(); f.Error() != nil {
+		t.Fatalf("shutdown should be idempotent")
+	}
+
 }
 
 func TestRaft_SingleNode(t *testing.T) {