rafthttp: add stream

rafthttp/http.go

@@ -159,14 +159,14 @@ func (h *streamHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 	w.WriteHeader(http.StatusOK)
 	w.(http.Flusher).Flush()
 
-	done, err := p.StartStreaming(w.(WriteFlusher), from, term)
+	stream := newStreamServer(w.(WriteFlusher), from, term)
+	err = p.attachStream(stream)
 	if err != nil {
-		log.Printf("rafthttp: streaming request ignored due to start streaming error: %v", err)
-		// TODO: consider http status and info here
-		http.Error(w, "error enable streaming", http.StatusInternalServerError)
+		log.Printf("rafthttp: %v", err)
+		http.Error(w, err.Error(), http.StatusBadRequest)
 		return
 	}
-	<-done
+	<-stream.stopNotify()
 }
 
 type writerToResponse interface {

rafthttp/peer.go

@@ -45,27 +45,6 @@ const (
 	ConnWriteTimeout = 5 * time.Second
 )
 
-func NewPeer(tr http.RoundTripper, u string, id types.ID, cid types.ID, r Raft, fs *stats.FollowerStats, shouldstop chan struct{}) *peer {
-	p := &peer{
-		id:          id,
-		active:      true,
-		tr:          tr,
-		u:           u,
-		cid:         cid,
-		r:           r,
-		fs:          fs,
-		shouldstop:  shouldstop,
-		batcher:     NewBatcher(100, appRespBatchMs*time.Millisecond),
-		propBatcher: NewProposalBatcher(100, propBatchMs*time.Millisecond),
-		q:           make(chan *raftpb.Message, senderBufSize),
-	}
-	p.wg.Add(connPerSender)
-	for i := 0; i < connPerSender; i++ {
-		go p.handle()
-	}
-	return p
-}
-
 type peer struct {
 	id  types.ID
 	cid types.ID
@@ -75,13 +54,11 @@ type peer struct {
 	fs         *stats.FollowerStats
 	shouldstop chan struct{}
 
-	strmCln     *streamClient
 	batcher     *Batcher
 	propBatcher *ProposalBatcher
 	q           chan *raftpb.Message
 
-	strmSrvMu sync.Mutex
-	strmSrv   *streamServer
+	stream *stream
 
 	// wait for the handling routines
 	wg sync.WaitGroup
@@ -95,22 +72,26 @@ type peer struct {
 	paused  bool
 }
 
-// StartStreaming enables streaming in the peer using the given writer,
-// which provides a fast and efficient way to send appendEntry messages.
-func (p *peer) StartStreaming(w WriteFlusher, to types.ID, term uint64) (<-chan struct{}, error) {
-	p.strmSrvMu.Lock()
-	defer p.strmSrvMu.Unlock()
-	if p.strmSrv != nil {
-		// ignore lower-term streaming request
-		if term < p.strmSrv.term {
-			return nil, fmt.Errorf("out of data streaming request: term %d, request term %d", term, p.strmSrv.term)
-		}
-		// stop the existing one
-		p.strmSrv.stop()
-		p.strmSrv = nil
+func NewPeer(tr http.RoundTripper, u string, id types.ID, cid types.ID, r Raft, fs *stats.FollowerStats, shouldstop chan struct{}) *peer {
+	p := &peer{
+		id:          id,
+		active:      true,
+		tr:          tr,
+		u:           u,
+		cid:         cid,
+		r:           r,
+		fs:          fs,
+		stream:      &stream{},
+		shouldstop:  shouldstop,
+		batcher:     NewBatcher(100, appRespBatchMs*time.Millisecond),
+		propBatcher: NewProposalBatcher(100, propBatchMs*time.Millisecond),
+		q:           make(chan *raftpb.Message, senderBufSize),
+	}
+	p.wg.Add(connPerSender)
+	for i := 0; i < connPerSender; i++ {
+		go p.handle()
 	}
-	p.strmSrv = startStreamServer(w, to, term, p.fs)
-	return p.strmSrv.stopNotify(), nil
+	return p
 }
 
 func (p *peer) Update(u string) {
@@ -130,9 +111,13 @@ func (p *peer) Send(m raftpb.Message) error {
 		return nil
 	}
 
-	p.maybeStopStream(m.Term)
-	if shouldInitStream(m) && !p.hasStreamClient() {
-		p.initStream(types.ID(m.From), types.ID(m.To), m.Term)
+	// move all the stream related stuff into stream
+	p.stream.invalidate(m.Term)
+	if shouldInitStream(m) && !p.stream.isOpen() {
+		p.mu.Lock()
+		u := p.u
+		p.mu.Unlock()
+		p.stream.open(p.id, types.ID(m.To), p.cid, m.Term, p.tr, u, p.r)
 		p.batcher.Reset(time.Now())
 	}
 
@@ -140,12 +125,12 @@ func (p *peer) Send(m raftpb.Message) error {
 	switch {
 	case isProposal(m):
 		p.propBatcher.Batch(m)
-	case canBatch(m) && p.hasStreamClient():
+	case canBatch(m) && p.stream.isOpen():
 		if !p.batcher.ShouldBatch(time.Now()) {
 			err = p.send(m)
 		}
 	case canUseStream(m):
-		if ok := p.tryStream(m); !ok {
+		if ok := p.stream.write(m); !ok {
 			err = p.send(m)
 		}
 	default:
@@ -183,74 +168,7 @@ func (p *peer) send(m raftpb.Message) error {
 func (p *peer) Stop() {
 	close(p.q)
 	p.wg.Wait()
-	p.strmSrvMu.Lock()
-	if p.strmSrv != nil {
-		p.strmSrv.stop()
-		p.strmSrv = nil
-	}
-	p.strmSrvMu.Unlock()
-	if p.strmCln != nil {
-		p.strmCln.stop()
-	}
-}
-
-// Pause pauses the peer. The peer will simply drops all incoming
-// messages without retruning an error.
-func (p *peer) Pause() {
-	p.mu.Lock()
-	defer p.mu.Unlock()
-	p.paused = true
-}
-
-// Resume resumes a paused peer.
-func (p *peer) Resume() {
-	p.mu.Lock()
-	defer p.mu.Unlock()
-	p.paused = false
-}
-
-func (p *peer) maybeStopStream(term uint64) {
-	if p.strmCln != nil && term > p.strmCln.term {
-		p.strmCln.stop()
-		p.strmCln = nil
-	}
-	p.strmSrvMu.Lock()
-	defer p.strmSrvMu.Unlock()
-	if p.strmSrv != nil && term > p.strmSrv.term {
-		p.strmSrv.stop()
-		p.strmSrv = nil
-	}
-}
-
-func (p *peer) hasStreamClient() bool {
-	return p.strmCln != nil && !p.strmCln.isStopped()
-}
-
-func (p *peer) initStream(from, to types.ID, term uint64) {
-	strmCln := newStreamClient(from, to, term, p.r)
-	p.mu.Lock()
-	u := p.u
-	p.mu.Unlock()
-	if err := strmCln.start(p.tr, u, p.cid); err != nil {
-		log.Printf("rafthttp: start stream client error: %v", err)
-		return
-	}
-	p.strmCln = strmCln
-}
-
-func (p *peer) tryStream(m raftpb.Message) bool {
-	p.strmSrvMu.Lock()
-	defer p.strmSrvMu.Unlock()
-	if p.strmSrv == nil || m.Term != p.strmSrv.term {
-		return false
-	}
-	if err := p.strmSrv.send(m.Entries); err != nil {
-		log.Printf("rafthttp: send stream message error: %v", err)
-		p.strmSrv.stop()
-		p.strmSrv = nil
-		return false
-	}
-	return true
+	p.stream.stop()
 }
 
 func (p *peer) handle() {
@@ -327,4 +245,25 @@ func (p *peer) post(data []byte) error {
 	}
 }
 
+// attachStream attaches a streamSever to the peer.
+func (p *peer) attachStream(server *streamServer) error {
+	server.fs = p.fs
+	return p.stream.attach(server)
+}
+
+// Pause pauses the peer. The peer will simply drops all incoming
+// messages without retruning an error.
+func (p *peer) Pause() {
+	p.mu.Lock()
+	defer p.mu.Unlock()
+	p.paused = true
+}
+
+// Resume resumes a paused peer.
+func (p *peer) Resume() {
+	p.mu.Lock()
+	defer p.mu.Unlock()
+	p.paused = false
+}
+
 func isProposal(m raftpb.Message) bool { return m.Type == raftpb.MsgProp }

rafthttp/streamer.go

@@ -20,10 +20,12 @@ import (
 	"fmt"
 	"io"
 	"log"
+	"math"
 	"net/http"
 	"net/url"
 	"path"
 	"strconv"
+	"sync"
 	"time"
 
 	"github.com/coreos/etcd/etcdserver/stats"
@@ -37,11 +39,105 @@ const (
 	streamBufSize = 4096
 )
 
+// TODO: a stream might hava one stream server or one stream client, but not both.
+type stream struct {
+	// the server might be attached asynchronously with the owner of the stream
+	// use a mutex to protect it
+	sync.Mutex
+	server *streamServer
+
+	client *streamClient
+}
+
+func (s *stream) open(id, to, cid types.ID, term uint64, tr http.RoundTripper, u string, r Raft) error {
+	if s.client != nil {
+		panic("open: stream is open")
+	}
+
+	c, err := newStreamClient(id, to, cid, term, tr, u, r)
+	if err != nil {
+		log.Printf("stream: error opening stream: %v", err)
+		return err
+	}
+	s.client = c
+	return nil
+}
+
+func (s *stream) attach(server *streamServer) error {
+	s.Lock()
+	defer s.Unlock()
+	if s.server != nil {
+		// ignore lower-term streaming request
+		if server.term < s.server.term {
+			return fmt.Errorf("cannot attach out of data stream server [%d / %d]", server.term, s.server.term)
+		}
+		s.server.stop()
+	}
+	s.server = server
+	return nil
+}
+
+func (s *stream) write(m raftpb.Message) bool {
+	s.Lock()
+	defer s.Unlock()
+	if s.server == nil {
+		return false
+	}
+	if m.Term != s.server.term {
+		if m.Term > s.server.term {
+			panic("expected server to be invalidated when there is a higher term message")
+		}
+		return false
+	}
+	// todo: early unlock?
+	if err := s.server.send(m.Entries); err != nil {
+		log.Printf("stream: error sending message: %v", err)
+		log.Printf("stream: stopping the stream server...")
+		s.server.stop()
+		s.server = nil
+		return false
+	}
+	return true
+}
+
+// invalidate stops the sever/client that is running at
+// a term lower than the given term.
+func (s *stream) invalidate(term uint64) {
+	s.Lock()
+	defer s.Unlock()
+
+	if s.server != nil {
+		if s.server.term < term {
+			s.server.stop()
+			s.server = nil
+		}
+	}
+	if s.client != nil {
+		if s.client.term < term {
+			s.client.stop()
+			s.client = nil
+		}
+	}
+}
+
+func (s *stream) stop() {
+	s.invalidate(math.MaxUint64)
+}
+
+func (s *stream) isOpen() bool {
+	if s.client != nil && s.client.isStopped() {
+		s.client = nil
+	}
+	return s.client != nil
+}
+
 type WriteFlusher interface {
 	io.Writer
 	http.Flusher
 }
 
+// TODO: rename it to streamWriter.
+// TODO: replace fs with stream stats
 type streamServer struct {
 	to   types.ID
 	term uint64
@@ -50,16 +146,16 @@ type streamServer struct {
 	done chan struct{}
 }
 
-func startStreamServer(w WriteFlusher, to types.ID, term uint64, fs *stats.FollowerStats) *streamServer {
+// newStreamServer starts and returns a new started stream server.
+// The caller should call stop when finished, to shut it down.
+func newStreamServer(w WriteFlusher, to types.ID, term uint64) *streamServer {
 	s := &streamServer{
 		to:   to,
 		term: term,
-		fs:   fs,
 		q:    make(chan []raftpb.Entry, streamBufSize),
 		done: make(chan struct{}),
 	}
 	go s.handle(w)
-	log.Printf("rafthttp: starting server stream to %s at term %d", to, term)
 	return s
 }
 
@@ -78,13 +174,6 @@ func (s *streamServer) send(ents []raftpb.Entry) error {
 	}
 }
 
-func (s *streamServer) stop() {
-	close(s.q)
-	<-s.done
-}
-
-func (s *streamServer) stopNotify() <-chan struct{} { return s.done }
-
 func (s *streamServer) handle(w WriteFlusher) {
 	defer func() {
 		close(s.done)
@@ -103,6 +192,15 @@ func (s *streamServer) handle(w WriteFlusher) {
 	}
 }
 
+func (s *streamServer) stop() {
+	close(s.q)
+	<-s.done
+}
+
+func (s *streamServer) stopNotify() <-chan struct{} { return s.done }
+
+// TODO: rename it to streamReader.
+// TODO: move the raft interface out of the reader.
 type streamClient struct {
 	id   types.ID
 	to   types.ID
@@ -113,44 +211,41 @@ type streamClient struct {
 	done   chan struct{}
 }
 
-func newStreamClient(id, to types.ID, term uint64, r Raft) *streamClient {
-	return &streamClient{
+// newStreamClient starts and returns a new started stream client.
+// The caller should call stop when finished, to shut it down.
+func newStreamClient(id, to, cid types.ID, term uint64, tr http.RoundTripper, u string, r Raft) (*streamClient, error) {
+	s := &streamClient{
 		id:   id,
 		to:   to,
 		term: term,
 		r:    r,
 		done: make(chan struct{}),
 	}
-}
 
-// Dial dials to the remote url, and sends streaming request. If it succeeds,
-// it returns nil error, and the caller should call Handle function to keep
-// receiving appendEntry messages.
-func (s *streamClient) start(tr http.RoundTripper, u string, cid types.ID) error {
 	uu, err := url.Parse(u)
 	if err != nil {
-		return fmt.Errorf("parse url %s error: %v", u, err)
+		return nil, fmt.Errorf("parse url %s error: %v", u, err)
 	}
 	uu.Path = path.Join(RaftStreamPrefix, s.id.String())
 	req, err := http.NewRequest("GET", uu.String(), nil)
 	if err != nil {
-		return fmt.Errorf("new request to %s error: %v", u, err)
+		return nil, fmt.Errorf("new request to %s error: %v", u, err)
 	}
 	req.Header.Set("X-Etcd-Cluster-ID", cid.String())
 	req.Header.Set("X-Raft-To", s.to.String())
 	req.Header.Set("X-Raft-Term", strconv.FormatUint(s.term, 10))
 	resp, err := tr.RoundTrip(req)
 	if err != nil {
-		return fmt.Errorf("error posting to %q: %v", u, err)
+		return nil, fmt.Errorf("error posting to %q: %v", u, err)
 	}
 	if resp.StatusCode != http.StatusOK {
 		resp.Body.Close()
-		return fmt.Errorf("unhandled http status %d", resp.StatusCode)
+		return nil, fmt.Errorf("unhandled http status %d", resp.StatusCode)
 	}
 	s.closer = resp.Body
 	go s.handle(resp.Body)
 	log.Printf("rafthttp: starting client stream to %s at term %d", s.to, s.term)
-	return nil
+	return s, nil
 }
 
 func (s *streamClient) stop() {