rafthttp: {from, to} -> {local, remote} in stream

{from, to} nameings are confused when it both dials and receives
messages from the remote. Change it to {local, remote} for better
clarity.

rafthttp/stream.go

@@ -248,15 +248,15 @@ func (cw *streamWriter) stop() {
 // streamReader is a long-running go-routine that dials to the remote stream
 // endponit and reads messages from the response body returned.
 type streamReader struct {
-	tr       http.RoundTripper
-	picker   *urlPicker
-	t        streamType
-	from, to types.ID
-	cid      types.ID
-	status   *peerStatus
-	recvc    chan<- raftpb.Message
-	propc    chan<- raftpb.Message
-	errorc   chan<- error
+	tr            http.RoundTripper
+	picker        *urlPicker
+	t             streamType
+	local, remote types.ID
+	cid           types.ID
+	status        *peerStatus
+	recvc         chan<- raftpb.Message
+	propc         chan<- raftpb.Message
+	errorc        chan<- error
 
 	mu         sync.Mutex
 	msgAppTerm uint64
@@ -266,13 +266,13 @@ type streamReader struct {
 	done       chan struct{}
 }
 
-func startStreamReader(tr http.RoundTripper, picker *urlPicker, t streamType, from, to, cid types.ID, status *peerStatus, recvc chan<- raftpb.Message, propc chan<- raftpb.Message, errorc chan<- error) *streamReader {
+func startStreamReader(tr http.RoundTripper, picker *urlPicker, t streamType, local, remote, cid types.ID, status *peerStatus, recvc chan<- raftpb.Message, propc chan<- raftpb.Message, errorc chan<- error) *streamReader {
 	r := &streamReader{
 		tr:     tr,
 		picker: picker,
 		t:      t,
-		from:   from,
-		to:     to,
+		local:  local,
+		remote: remote,
 		cid:    cid,
 		status: status,
 		recvc:  recvc,
@@ -330,9 +330,9 @@ func (cr *streamReader) decodeLoop(rc io.ReadCloser, t streamType) error {
 	cr.mu.Lock()
 	switch t {
 	case streamTypeMsgApp:
-		dec = &msgAppDecoder{r: rc, local: cr.from, remote: cr.to, term: cr.msgAppTerm}
+		dec = &msgAppDecoder{r: rc, local: cr.local, remote: cr.remote, term: cr.msgAppTerm}
 	case streamTypeMsgAppV2:
-		dec = newMsgAppV2Decoder(rc, cr.from, cr.to)
+		dec = newMsgAppV2Decoder(rc, cr.local, cr.remote)
 	case streamTypeMessage:
 		dec = &messageDecoder{r: rc}
 	default:
@@ -406,18 +406,18 @@ func (cr *streamReader) dial(t streamType) (io.ReadCloser, error) {
 	cr.mu.Unlock()
 
 	uu := u
-	uu.Path = path.Join(t.endpoint(), cr.from.String())
+	uu.Path = path.Join(t.endpoint(), cr.local.String())
 
 	req, err := http.NewRequest("GET", uu.String(), nil)
 	if err != nil {
 		cr.picker.unreachable(u)
 		return nil, fmt.Errorf("failed to make http request to %s (%v)", u, err)
 	}
-	req.Header.Set("X-Server-From", cr.from.String())
+	req.Header.Set("X-Server-From", cr.local.String())
 	req.Header.Set("X-Server-Version", version.Version)
 	req.Header.Set("X-Min-Cluster-Version", version.MinClusterVersion)
 	req.Header.Set("X-Etcd-Cluster-ID", cr.cid.String())
-	req.Header.Set("X-Raft-To", cr.to.String())
+	req.Header.Set("X-Raft-To", cr.remote.String())
 	if t == streamTypeMsgApp {
 		req.Header.Set("X-Raft-Term", strconv.FormatUint(term, 10))
 	}
@@ -452,7 +452,7 @@ func (cr *streamReader) dial(t streamType) (io.ReadCloser, error) {
 		return resp.Body, nil
 	case http.StatusNotFound:
 		resp.Body.Close()
-		return nil, fmt.Errorf("remote member %s could not recognize local member", cr.to)
+		return nil, fmt.Errorf("remote member %s could not recognize local member", cr.remote)
 	case http.StatusPreconditionFailed:
 		b, err := ioutil.ReadAll(resp.Body)
 		if err != nil {
@@ -463,11 +463,11 @@ func (cr *streamReader) dial(t streamType) (io.ReadCloser, error) {
 
 		switch strings.TrimSuffix(string(b), "\n") {
 		case errIncompatibleVersion.Error():
-			plog.Errorf("request sent was ignored by peer %s (server version incompatible)", cr.to)
+			plog.Errorf("request sent was ignored by peer %s (server version incompatible)", cr.remote)
 			return nil, errIncompatibleVersion
 		case errClusterIDMismatch.Error():
 			plog.Errorf("request sent was ignored (cluster ID mismatch: remote[%s]=%s, local=%s)",
-				cr.to, resp.Header.Get("X-Etcd-Cluster-ID"), cr.cid)
+				cr.remote, resp.Header.Get("X-Etcd-Cluster-ID"), cr.cid)
 			return nil, errClusterIDMismatch
 		default:
 			return nil, fmt.Errorf("unhandled error %q when precondition failed", string(b))

rafthttp/stream_test.go

@@ -89,8 +89,8 @@ func TestStreamReaderDialRequest(t *testing.T) {
 		sr := &streamReader{
 			tr:         tr,
 			picker:     mustNewURLPicker(t, []string{"http://localhost:2380"}),
-			from:       types.ID(1),
-			to:         types.ID(2),
+			local:      types.ID(1),
+			remote:     types.ID(2),
 			cid:        types.ID(1),
 			msgAppTerm: 1,
 		}
@@ -143,8 +143,8 @@ func TestStreamReaderDialResult(t *testing.T) {
 		sr := &streamReader{
 			tr:     tr,
 			picker: mustNewURLPicker(t, []string{"http://localhost:2380"}),
-			from:   types.ID(1),
-			to:     types.ID(2),
+			local:  types.ID(1),
+			remote: types.ID(2),
 			cid:    types.ID(1),
 			errorc: make(chan error, 1),
 		}
@@ -206,8 +206,8 @@ func TestStreamReaderDialDetectUnsupport(t *testing.T) {
 		sr := &streamReader{
 			tr:     tr,
 			picker: mustNewURLPicker(t, []string{"http://localhost:2380"}),
-			from:   types.ID(1),
-			to:     types.ID(2),
+			local:  types.ID(1),
+			remote: types.ID(2),
 			cid:    types.ID(1),
 		}