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peer.go
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peer.go
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// Copyright 2015 CoreOS, Inc.
//
// 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 (
"bytes"
"errors"
"fmt"
"log"
"net/http"
"sync"
"time"
"github.com/coreos/etcd/etcdserver/stats"
"github.com/coreos/etcd/pkg/pbutil"
"github.com/coreos/etcd/pkg/types"
"github.com/coreos/etcd/raft/raftpb"
)
const (
connPerSender = 4
// senderBufSize is the size of sender buffer, which helps hold the
// temporary network latency.
// The size ensures that sender does not drop messages when the network
// is out of work for less than 1 second in good path.
senderBufSize = 64
appRespBatchMs = 50
propBatchMs = 10
ConnReadTimeout = 5 * time.Second
ConnWriteTimeout = 5 * time.Second
)
type peer struct {
sync.Mutex
id types.ID
cid types.ID
tr http.RoundTripper
r Raft
fs *stats.FollowerStats
errorc chan error
batcher *Batcher
propBatcher *ProposalBatcher
q chan *raftpb.Message
stream *stream
// wait for the handling routines
wg sync.WaitGroup
// the url this sender post to
u string
// if the last send was successful, the sender is active.
// Or it is inactive
active bool
errored error
paused bool
stopped bool
}
func NewPeer(tr http.RoundTripper, u string, id types.ID, cid types.ID, r Raft, fs *stats.FollowerStats, errorc chan error) *peer {
p := &peer{
id: id,
active: true,
tr: tr,
u: u,
cid: cid,
r: r,
fs: fs,
stream: &stream{},
errorc: errorc,
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
}
func (p *peer) Update(u string) {
p.Lock()
defer p.Unlock()
if p.stopped {
// TODO: not panic here?
panic("peer: update a stopped peer")
}
p.u = u
}
// Send sends the data to the remote node. It is always non-blocking.
// It may be fail to send data if it returns nil error.
// TODO (xiangli): reasonable retry logic
func (p *peer) Send(m raftpb.Message) error {
p.Lock()
defer p.Unlock()
if p.stopped {
return errors.New("peer: stopped")
}
if p.paused {
return nil
}
// move all the stream related stuff into stream
p.stream.invalidate(m.Term)
if shouldInitStream(m) && !p.stream.isOpen() {
u := p.u
// todo: steam open should not block.
p.stream.open(types.ID(m.From), p.id, p.cid, m.Term, p.tr, u, p.r)
p.batcher.Reset(time.Now())
}
var err error
switch {
case isProposal(m):
p.propBatcher.Batch(m)
case canBatch(m) && p.stream.isOpen():
if !p.batcher.ShouldBatch(time.Now()) {
err = p.send(m)
}
case canUseStream(m):
if ok := p.stream.write(m); !ok {
err = p.send(m)
}
default:
err = p.send(m)
}
// send out batched MsgProp if needed
// TODO: it is triggered by all outcoming send now, and it needs
// more clear solution. Either use separate goroutine to trigger it
// or use streaming.
if !p.propBatcher.IsEmpty() {
t := time.Now()
if !p.propBatcher.ShouldBatch(t) {
p.send(p.propBatcher.Message)
p.propBatcher.Reset(t)
}
}
return err
}
func (p *peer) send(m raftpb.Message) error {
// TODO: don't block. we should be able to have 1000s
// of messages out at a time.
select {
case p.q <- &m:
return nil
default:
log.Printf("sender: dropping %s because maximal number %d of sender buffer entries to %s has been reached",
m.Type, senderBufSize, p.u)
return fmt.Errorf("reach maximal serving")
}
}
// Stop performs any necessary finalization and terminates the peer
// elegantly.
func (p *peer) Stop() {
close(p.q)
p.wg.Wait()
p.Lock()
defer p.Unlock()
p.stream.stop()
p.stopped = true
}
func (p *peer) handle() {
defer p.wg.Done()
for m := range p.q {
start := time.Now()
err := p.post(pbutil.MustMarshal(m))
end := time.Now()
p.Lock()
if err != nil {
if p.errored == nil || p.errored.Error() != err.Error() {
log.Printf("sender: error posting to %s: %v", p.id, err)
p.errored = err
}
if p.active {
log.Printf("sender: the connection with %s became inactive", p.id)
p.active = false
}
if m.Type == raftpb.MsgApp && p.fs != nil {
p.fs.Fail()
}
} else {
if !p.active {
log.Printf("sender: the connection with %s became active", p.id)
p.active = true
p.errored = nil
}
if m.Type == raftpb.MsgApp && p.fs != nil {
p.fs.Succ(end.Sub(start))
}
}
p.Unlock()
}
}
// post POSTs a data payload to a url. Returns nil if the POST succeeds,
// error on any failure.
func (p *peer) post(data []byte) error {
p.Lock()
req, err := http.NewRequest("POST", p.u, bytes.NewBuffer(data))
p.Unlock()
if err != nil {
return err
}
req.Header.Set("Content-Type", "application/protobuf")
req.Header.Set("X-Etcd-Cluster-ID", p.cid.String())
resp, err := p.tr.RoundTrip(req)
if err != nil {
return err
}
resp.Body.Close()
switch resp.StatusCode {
case http.StatusPreconditionFailed:
err := fmt.Errorf("conflicting cluster ID with the target cluster (%s != %s)", resp.Header.Get("X-Etcd-Cluster-ID"), p.cid)
select {
case p.errorc <- err:
default:
}
return nil
case http.StatusForbidden:
err := fmt.Errorf("the member has been permanently removed from the cluster")
select {
case p.errorc <- err:
default:
}
return nil
case http.StatusNoContent:
return nil
default:
return fmt.Errorf("unexpected http status %s while posting to %q", http.StatusText(resp.StatusCode), req.URL.String())
}
}
// attachStream attaches a streamSever to the peer.
func (p *peer) attachStream(sw *streamWriter) error {
p.Lock()
defer p.Unlock()
if p.stopped {
return errors.New("peer: stopped")
}
sw.fs = p.fs
return p.stream.attach(sw)
}
// Pause pauses the peer. The peer will simply drops all incoming
// messages without retruning an error.
func (p *peer) Pause() {
p.Lock()
defer p.Unlock()
p.paused = true
}
// Resume resumes a paused peer.
func (p *peer) Resume() {
p.Lock()
defer p.Unlock()
p.paused = false
}
func isProposal(m raftpb.Message) bool { return m.Type == raftpb.MsgProp }