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stream.go
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stream.go
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// Copyright 2015 The etcd Authors
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package rafthttp
import (
"fmt"
"io"
"io/ioutil"
"net"
"net/http"
"path"
"strings"
"sync"
"time"
"github.com/coreos/etcd/etcdserver/stats"
"github.com/coreos/etcd/pkg/httputil"
"github.com/coreos/etcd/pkg/types"
"github.com/coreos/etcd/raft/raftpb"
"github.com/coreos/etcd/version"
"github.com/coreos/go-semver/semver"
)
const (
streamTypeMessage streamType = "message"
streamTypeMsgAppV2 streamType = "msgappv2"
streamBufSize = 4096
)
var (
errUnsupportedStreamType = fmt.Errorf("unsupported stream type")
// the key is in string format "major.minor.patch"
supportedStream = map[string][]streamType{
"2.0.0": {},
"2.1.0": {streamTypeMsgAppV2, streamTypeMessage},
"2.2.0": {streamTypeMsgAppV2, streamTypeMessage},
"2.3.0": {streamTypeMsgAppV2, streamTypeMessage},
}
)
type streamType string
func (t streamType) endpoint() string {
switch t {
case streamTypeMsgAppV2:
return path.Join(RaftStreamPrefix, "msgapp")
case streamTypeMessage:
return path.Join(RaftStreamPrefix, "message")
default:
plog.Panicf("unhandled stream type %v", t)
return ""
}
}
func (t streamType) String() string {
switch t {
case streamTypeMsgAppV2:
return "stream MsgApp v2"
case streamTypeMessage:
return "stream Message"
default:
return "unknown stream"
}
}
var (
// linkHeartbeatMessage is a special message used as heartbeat message in
// link layer. It never conflicts with messages from raft because raft
// doesn't send out messages without From and To fields.
linkHeartbeatMessage = raftpb.Message{Type: raftpb.MsgHeartbeat}
)
func isLinkHeartbeatMessage(m raftpb.Message) bool {
return m.Type == raftpb.MsgHeartbeat && m.From == 0 && m.To == 0
}
type outgoingConn struct {
t streamType
io.Writer
http.Flusher
io.Closer
}
// streamWriter writes messages to the attached outgoingConn.
type streamWriter struct {
peerID types.ID
status *peerStatus
fs *stats.FollowerStats
r Raft
mu sync.Mutex // guard field working and closer
closer io.Closer
working bool
msgc chan raftpb.Message
connc chan *outgoingConn
stopc chan struct{}
done chan struct{}
}
// startStreamWriter creates a streamWrite and starts a long running go-routine that accepts
// messages and writes to the attached outgoing connection.
func startStreamWriter(id types.ID, status *peerStatus, fs *stats.FollowerStats, r Raft) *streamWriter {
w := &streamWriter{
peerID: id,
status: status,
fs: fs,
r: r,
msgc: make(chan raftpb.Message, streamBufSize),
connc: make(chan *outgoingConn),
stopc: make(chan struct{}),
done: make(chan struct{}),
}
go w.run()
return w
}
func (cw *streamWriter) run() {
var (
msgc chan raftpb.Message
heartbeatc <-chan time.Time
t streamType
enc encoder
flusher http.Flusher
batched int
)
tickc := time.Tick(ConnReadTimeout / 3)
unflushed := 0
plog.Infof("started streaming with peer %s (writer)", cw.peerID)
for {
select {
case <-heartbeatc:
err := enc.encode(linkHeartbeatMessage)
unflushed += linkHeartbeatMessage.Size()
if err == nil {
flusher.Flush()
batched = 0
sentBytes.WithLabelValues(cw.peerID.String()).Add(float64(unflushed))
unflushed = 0
continue
}
cw.status.deactivate(failureType{source: t.String(), action: "heartbeat"}, err.Error())
cw.close()
plog.Warningf("lost the TCP streaming connection with peer %s (%s writer)", cw.peerID, t)
heartbeatc, msgc = nil, nil
case m := <-msgc:
err := enc.encode(m)
if err == nil {
unflushed += m.Size()
if len(msgc) == 0 || batched > streamBufSize/2 {
flusher.Flush()
sentBytes.WithLabelValues(cw.peerID.String()).Add(float64(unflushed))
unflushed = 0
batched = 0
} else {
batched++
}
continue
}
cw.status.deactivate(failureType{source: t.String(), action: "write"}, err.Error())
cw.close()
plog.Warningf("lost the TCP streaming connection with peer %s (%s writer)", cw.peerID, t)
heartbeatc, msgc = nil, nil
cw.r.ReportUnreachable(m.To)
case conn := <-cw.connc:
if cw.close() {
plog.Warningf("closed an existing TCP streaming connection with peer %s (%s writer)", cw.peerID, t)
}
t = conn.t
switch conn.t {
case streamTypeMsgAppV2:
enc = newMsgAppV2Encoder(conn.Writer, cw.fs)
case streamTypeMessage:
enc = &messageEncoder{w: conn.Writer}
default:
plog.Panicf("unhandled stream type %s", conn.t)
}
flusher = conn.Flusher
unflushed = 0
cw.mu.Lock()
cw.status.activate()
cw.closer = conn.Closer
cw.working = true
cw.mu.Unlock()
plog.Infof("established a TCP streaming connection with peer %s (%s writer)", cw.peerID, t)
heartbeatc, msgc = tickc, cw.msgc
case <-cw.stopc:
if cw.close() {
plog.Infof("closed the TCP streaming connection with peer %s (%s writer)", cw.peerID, t)
}
close(cw.done)
plog.Infof("stopped streaming with peer %s (writer)", cw.peerID)
return
}
}
}
func (cw *streamWriter) writec() (chan<- raftpb.Message, bool) {
cw.mu.Lock()
defer cw.mu.Unlock()
return cw.msgc, cw.working
}
func (cw *streamWriter) close() bool {
cw.mu.Lock()
defer cw.mu.Unlock()
if !cw.working {
return false
}
cw.closer.Close()
if len(cw.msgc) > 0 {
cw.r.ReportUnreachable(uint64(cw.peerID))
}
cw.msgc = make(chan raftpb.Message, streamBufSize)
cw.working = false
return true
}
func (cw *streamWriter) attach(conn *outgoingConn) bool {
select {
case cw.connc <- conn:
return true
case <-cw.done:
return false
}
}
func (cw *streamWriter) stop() {
close(cw.stopc)
<-cw.done
}
// streamReader is a long-running go-routine that dials to the remote stream
// endpoint and reads messages from the response body returned.
type streamReader struct {
peerID types.ID
typ streamType
tr *Transport
picker *urlPicker
status *peerStatus
recvc chan<- raftpb.Message
propc chan<- raftpb.Message
errorc chan<- error
mu sync.Mutex
paused bool
cancel func()
closer io.Closer
stopc chan struct{}
done chan struct{}
}
func (r *streamReader) start() {
r.stopc = make(chan struct{})
r.done = make(chan struct{})
if r.errorc == nil {
r.errorc = r.tr.ErrorC
}
go r.run()
}
func (cr *streamReader) run() {
t := cr.typ
plog.Infof("started streaming with peer %s (%s reader)", cr.peerID, t)
for {
rc, err := cr.dial(t)
if err != nil {
if err != errUnsupportedStreamType {
cr.status.deactivate(failureType{source: t.String(), action: "dial"}, err.Error())
}
} else {
cr.status.activate()
plog.Infof("established a TCP streaming connection with peer %s (%s reader)", cr.peerID, cr.typ)
err := cr.decodeLoop(rc, t)
plog.Warningf("lost the TCP streaming connection with peer %s (%s reader)", cr.peerID, cr.typ)
switch {
// all data is read out
case err == io.EOF:
// connection is closed by the remote
case isClosedConnectionError(err):
default:
cr.status.deactivate(failureType{source: t.String(), action: "read"}, err.Error())
}
}
select {
// Wait 100ms to create a new stream, so it doesn't bring too much
// overhead when retry.
case <-time.After(100 * time.Millisecond):
case <-cr.stopc:
close(cr.done)
plog.Infof("stopped streaming with peer %s (%s reader)", cr.peerID, t)
return
}
}
}
func (cr *streamReader) decodeLoop(rc io.ReadCloser, t streamType) error {
var dec decoder
cr.mu.Lock()
switch t {
case streamTypeMsgAppV2:
dec = newMsgAppV2Decoder(rc, cr.tr.ID, cr.peerID)
case streamTypeMessage:
dec = &messageDecoder{r: rc}
default:
plog.Panicf("unhandled stream type %s", t)
}
cr.closer = rc
cr.mu.Unlock()
for {
m, err := dec.decode()
if err != nil {
cr.mu.Lock()
cr.close()
cr.mu.Unlock()
return err
}
receivedBytes.WithLabelValues(types.ID(m.From).String()).Add(float64(m.Size()))
cr.mu.Lock()
paused := cr.paused
cr.mu.Unlock()
if paused {
continue
}
if isLinkHeartbeatMessage(m) {
// raft is not interested in link layer
// heartbeat message, so we should ignore
// it.
continue
}
recvc := cr.recvc
if m.Type == raftpb.MsgProp {
recvc = cr.propc
}
select {
case recvc <- m:
default:
if cr.status.isActive() {
plog.MergeWarningf("dropped internal raft message from %s since receiving buffer is full (overloaded network)", types.ID(m.From))
}
plog.Debugf("dropped %s from %s since receiving buffer is full", m.Type, types.ID(m.From))
}
}
}
func (cr *streamReader) stop() {
close(cr.stopc)
cr.mu.Lock()
if cr.cancel != nil {
cr.cancel()
}
cr.close()
cr.mu.Unlock()
<-cr.done
}
func (cr *streamReader) dial(t streamType) (io.ReadCloser, error) {
u := cr.picker.pick()
uu := u
uu.Path = path.Join(t.endpoint(), cr.tr.ID.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 %v (%v)", u, err)
}
req.Header.Set("X-Server-From", cr.tr.ID.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.tr.ClusterID.String())
req.Header.Set("X-Raft-To", cr.peerID.String())
setPeerURLsHeader(req, cr.tr.URLs)
cr.mu.Lock()
select {
case <-cr.stopc:
cr.mu.Unlock()
return nil, fmt.Errorf("stream reader is stopped")
default:
}
cr.cancel = httputil.RequestCanceler(cr.tr.streamRt, req)
cr.mu.Unlock()
resp, err := cr.tr.streamRt.RoundTrip(req)
if err != nil {
cr.picker.unreachable(u)
return nil, err
}
rv := serverVersion(resp.Header)
lv := semver.Must(semver.NewVersion(version.Version))
if compareMajorMinorVersion(rv, lv) == -1 && !checkStreamSupport(rv, t) {
httputil.GracefulClose(resp)
cr.picker.unreachable(u)
return nil, errUnsupportedStreamType
}
switch resp.StatusCode {
case http.StatusGone:
httputil.GracefulClose(resp)
cr.picker.unreachable(u)
err := fmt.Errorf("the member has been permanently removed from the cluster")
select {
case cr.errorc <- err:
default:
}
return nil, err
case http.StatusOK:
return resp.Body, nil
case http.StatusNotFound:
httputil.GracefulClose(resp)
cr.picker.unreachable(u)
return nil, fmt.Errorf("peer %s faild to fine local node %s", cr.peerID, cr.tr.ID)
case http.StatusPreconditionFailed:
b, err := ioutil.ReadAll(resp.Body)
if err != nil {
cr.picker.unreachable(u)
return nil, err
}
httputil.GracefulClose(resp)
cr.picker.unreachable(u)
switch strings.TrimSuffix(string(b), "\n") {
case errIncompatibleVersion.Error():
plog.Errorf("request sent was ignored by peer %s (server version incompatible)", cr.peerID)
return nil, errIncompatibleVersion
case errClusterIDMismatch.Error():
plog.Errorf("request sent was ignored (cluster ID mismatch: peer[%s]=%s, local=%s)",
cr.peerID, resp.Header.Get("X-Etcd-Cluster-ID"), cr.tr.ClusterID)
return nil, errClusterIDMismatch
default:
return nil, fmt.Errorf("unhandled error %q when precondition failed", string(b))
}
default:
httputil.GracefulClose(resp)
cr.picker.unreachable(u)
return nil, fmt.Errorf("unhandled http status %d", resp.StatusCode)
}
}
func (cr *streamReader) close() {
if cr.closer != nil {
cr.closer.Close()
}
cr.closer = nil
}
func (cr *streamReader) pause() {
cr.mu.Lock()
defer cr.mu.Unlock()
cr.paused = true
}
func (cr *streamReader) resume() {
cr.mu.Lock()
defer cr.mu.Unlock()
cr.paused = false
}
func isClosedConnectionError(err error) bool {
operr, ok := err.(*net.OpError)
return ok && operr.Err.Error() == "use of closed network connection"
}
// checkStreamSupport checks whether the stream type is supported in the
// given version.
func checkStreamSupport(v *semver.Version, t streamType) bool {
nv := &semver.Version{Major: v.Major, Minor: v.Minor}
for _, s := range supportedStream[nv.String()] {
if s == t {
return true
}
}
return false
}