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http_transporter.go
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http_transporter.go
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/**
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you 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 messenger
import (
"bytes"
"encoding/hex"
"errors"
"fmt"
"io"
"io/ioutil"
"net"
"net/http"
"net/url"
"os"
"strings"
"sync"
"syscall"
"time"
log "github.com/golang/glog"
"github.com/mesos/mesos-go/upid"
"golang.org/x/net/context"
)
var (
discardOnStopError = fmt.Errorf("discarding message because transport is shutting down")
errNotStarted = errors.New("HTTP transport has not been started")
errTerminal = errors.New("HTTP transport is terminated")
errAlreadyRunning = errors.New("HTTP transport is already running")
)
// httpTransporter is a subset of the Transporter interface
type httpTransporter interface {
Send(ctx context.Context, msg *Message) error
Recv() (*Message, error)
Inject(ctx context.Context, msg *Message) error
Install(messageName string)
Start() (upid.UPID, <-chan error)
Stop(graceful bool) error
}
type notStartedState struct {
h *HTTPTransporter
}
type stoppedState struct{}
type runningState struct {
*notStartedState
}
/* -- not-started state */
func (s *notStartedState) Send(ctx context.Context, msg *Message) error { return errNotStarted }
func (s *notStartedState) Recv() (*Message, error) { return nil, errNotStarted }
func (s *notStartedState) Inject(ctx context.Context, msg *Message) error { return errNotStarted }
func (s *notStartedState) Stop(graceful bool) error { return errNotStarted }
func (s *notStartedState) Install(messageName string) { s.h.install(messageName) }
func (s *notStartedState) Start() (upid.UPID, <-chan error) {
s.h.state = &runningState{s}
return s.h.start()
}
/* -- stopped state */
func (s *stoppedState) Send(ctx context.Context, msg *Message) error { return errTerminal }
func (s *stoppedState) Recv() (*Message, error) { return nil, errTerminal }
func (s *stoppedState) Inject(ctx context.Context, msg *Message) error { return errTerminal }
func (s *stoppedState) Stop(graceful bool) error { return errTerminal }
func (s *stoppedState) Install(messageName string) {}
func (s *stoppedState) Start() (upid.UPID, <-chan error) {
ch := make(chan error, 1)
ch <- errTerminal
return upid.UPID{}, ch
}
/* -- running state */
func (s *runningState) Send(ctx context.Context, msg *Message) error { return s.h.send(ctx, msg) }
func (s *runningState) Recv() (*Message, error) { return s.h.recv() }
func (s *runningState) Inject(ctx context.Context, msg *Message) error { return s.h.inject(ctx, msg) }
func (s *runningState) Stop(graceful bool) error {
s.h.state = &stoppedState{}
return s.h.stop(graceful)
}
func (s *runningState) Start() (upid.UPID, <-chan error) {
ch := make(chan error, 1)
ch <- errAlreadyRunning
return upid.UPID{}, ch
}
// HTTPTransporter implements the interfaces of the Transporter.
type HTTPTransporter struct {
// If the host is empty("") then it will listen on localhost.
// If the port is empty("") then it will listen on random port.
upid upid.UPID
listener net.Listener // TODO(yifan): Change to TCPListener.
mux *http.ServeMux
tr *http.Transport
client *http.Client // TODO(yifan): Set read/write deadline.
messageQueue chan *Message
address net.IP // optional binding address
shouldQuit chan struct{}
stateLock sync.RWMutex // protect lifecycle (start/stop) funcs
state httpTransporter
}
// NewHTTPTransporter creates a new http transporter with an optional binding address.
func NewHTTPTransporter(upid upid.UPID, address net.IP) *HTTPTransporter {
tr := &http.Transport{}
result := &HTTPTransporter{
upid: upid,
messageQueue: make(chan *Message, defaultQueueSize),
mux: http.NewServeMux(),
client: &http.Client{Transport: tr},
tr: tr,
address: address,
shouldQuit: make(chan struct{}),
}
result.state = ¬StartedState{result}
return result
}
func (t *HTTPTransporter) getState() httpTransporter {
t.stateLock.RLock()
defer t.stateLock.RUnlock()
return t.state
}
// some network errors are probably recoverable, attempt to determine that here.
func isRecoverableError(err error) bool {
if urlErr, ok := err.(*url.Error); ok {
log.V(2).Infof("checking url.Error for recoverability")
return urlErr.Op == "Post" && isRecoverableError(urlErr.Err)
} else if netErr, ok := err.(*net.OpError); ok && netErr.Err != nil {
log.V(2).Infof("checking net.OpError for recoverability: %#v", err)
if netErr.Temporary() {
return true
}
//TODO(jdef) this is pretty hackish, there's probably a better way
//TODO(jdef) should also check for EHOSTDOWN and EHOSTUNREACH
return (netErr.Op == "dial" && netErr.Net == "tcp" && netErr.Err == syscall.ECONNREFUSED)
}
log.V(2).Infof("unrecoverable error: %#v", err)
return false
}
type recoverableError struct {
Err error
}
func (e *recoverableError) Error() string {
if e == nil {
return ""
}
return e.Err.Error()
}
// Send sends the message to its specified upid.
func (t *HTTPTransporter) Send(ctx context.Context, msg *Message) (sendError error) {
return t.getState().Send(ctx, msg)
}
func (t *HTTPTransporter) send(ctx context.Context, msg *Message) (sendError error) {
log.V(2).Infof("Sending message to %v via http\n", msg.UPID)
req, err := t.makeLibprocessRequest(msg)
if err != nil {
log.Errorf("Failed to make libprocess request: %v\n", err)
return err
}
duration := 1 * time.Second
for attempt := 0; attempt < 5; attempt++ { //TODO(jdef) extract/parameterize constant
if sendError != nil {
duration *= 2
log.Warningf("attempting to recover from error '%v', waiting before retry: %v", sendError, duration)
select {
case <-ctx.Done():
return ctx.Err()
case <-time.After(duration):
// ..retry request, continue
case <-t.shouldQuit:
return discardOnStopError
}
}
sendError = t.httpDo(ctx, req, func(resp *http.Response, err error) error {
if err != nil {
if isRecoverableError(err) {
return &recoverableError{Err: err}
}
log.Infof("Failed to POST: %v\n", err)
return err
}
defer resp.Body.Close()
// ensure master acknowledgement.
if (resp.StatusCode != http.StatusOK) &&
(resp.StatusCode != http.StatusAccepted) {
msg := fmt.Sprintf("Master %s rejected %s. Returned status %s.",
msg.UPID, msg.RequestURI(), resp.Status)
log.Warning(msg)
return fmt.Errorf(msg)
}
return nil
})
if sendError == nil {
// success
return
} else if _, ok := sendError.(*recoverableError); ok {
// recoverable, attempt backoff?
continue
}
// unrecoverable
break
}
if recoverable, ok := sendError.(*recoverableError); ok {
sendError = recoverable.Err
}
return
}
func (t *HTTPTransporter) httpDo(ctx context.Context, req *http.Request, f func(*http.Response, error) error) error {
select {
case <-ctx.Done():
return ctx.Err()
case <-t.shouldQuit:
return discardOnStopError
default: // continue
}
c := make(chan error, 1)
go func() { c <- f(t.client.Do(req)) }()
select {
case <-ctx.Done():
t.tr.CancelRequest(req)
<-c // Wait for f to return.
return ctx.Err()
case err := <-c:
return err
case <-t.shouldQuit:
t.tr.CancelRequest(req)
<-c // Wait for f to return.
return discardOnStopError
}
}
// Recv returns the message, one at a time.
func (t *HTTPTransporter) Recv() (*Message, error) {
return t.getState().Recv()
}
func (t *HTTPTransporter) recv() (*Message, error) {
select {
default:
select {
case msg := <-t.messageQueue:
return msg, nil
case <-t.shouldQuit:
}
case <-t.shouldQuit:
}
return nil, discardOnStopError
}
//Inject places a message into the incoming message queue.
func (t *HTTPTransporter) Inject(ctx context.Context, msg *Message) error {
return t.getState().Inject(ctx, msg)
}
func (t *HTTPTransporter) inject(ctx context.Context, msg *Message) error {
select {
case <-ctx.Done():
return ctx.Err()
case <-t.shouldQuit:
return discardOnStopError
default: // continue
}
select {
case t.messageQueue <- msg:
return nil
case <-ctx.Done():
return ctx.Err()
case <-t.shouldQuit:
return discardOnStopError
}
}
// Install the request URI according to the message's name.
func (t *HTTPTransporter) Install(msgName string) {
t.getState().Install(msgName)
}
func (t *HTTPTransporter) install(msgName string) {
requestURI := fmt.Sprintf("/%s/%s", t.upid.ID, msgName)
t.mux.HandleFunc(requestURI, t.messageDecoder)
}
type loggedListener struct {
delegate net.Listener
done <-chan struct{}
}
func (l *loggedListener) Accept() (c net.Conn, err error) {
c, err = l.delegate.Accept()
if c != nil {
log.Infoln("accepted connection from", c.RemoteAddr())
c = logConnection(c)
} else if err != nil {
select {
case <-l.done:
default:
log.Errorln("failed to accept connection:", err.Error())
}
}
return
}
func (l *loggedListener) Close() (err error) {
err = l.delegate.Close()
if err != nil {
select {
case <-l.done:
default:
log.Errorln("error closing listener:", err.Error())
}
} else {
log.Infoln("closed listener")
}
return
}
func (l *loggedListener) Addr() net.Addr { return l.delegate.Addr() }
func logConnection(c net.Conn) net.Conn {
w := hex.Dumper(os.Stdout)
r := io.TeeReader(c, w)
return &loggedConnection{
Conn: c,
reader: r,
}
}
type loggedConnection struct {
net.Conn
reader io.Reader
}
func (c *loggedConnection) Read(b []byte) (int, error) {
return c.reader.Read(b)
}
// Listen starts listen on UPID. If UPID is empty, the transporter
// will listen on a random port, and then fill the UPID with the
// host:port it is listening.
func (t *HTTPTransporter) listen() error {
var host string
if t.address != nil {
host = t.address.String()
} else {
host = t.upid.Host
}
var port string
if t.upid.Port != "" {
port = t.upid.Port
} else {
port = "0"
}
// NOTE: Explicitly specifies IPv4 because Libprocess
// only supports IPv4 for now.
ln, err := net.Listen("tcp4", net.JoinHostPort(host, port))
if err != nil {
log.Errorf("HTTPTransporter failed to listen: %v\n", err)
return err
}
// Save the host:port in case they are not specified in upid.
host, port, _ = net.SplitHostPort(ln.Addr().String())
log.Infoln("listening on", host, "port", port)
if len(t.upid.Host) == 0 {
t.upid.Host = host
}
if len(t.upid.Port) == 0 || t.upid.Port == "0" {
t.upid.Port = port
}
if log.V(3) {
t.listener = &loggedListener{delegate: ln, done: t.shouldQuit}
} else {
t.listener = ln
}
return nil
}
// Start starts the http transporter
func (t *HTTPTransporter) Start() (upid.UPID, <-chan error) {
t.stateLock.Lock()
defer t.stateLock.Unlock()
return t.state.Start()
}
// start expects to be guarded by stateLock
func (t *HTTPTransporter) start() (upid.UPID, <-chan error) {
ch := make(chan error, 1)
if err := t.listen(); err != nil {
ch <- err
return upid.UPID{}, ch
}
// TODO(yifan): Set read/write deadline.
go func() {
s := &http.Server{
ReadTimeout: DefaultReadTimeout,
WriteTimeout: DefaultWriteTimeout,
Handler: t.mux,
}
err := s.Serve(t.listener)
select {
case <-t.shouldQuit:
log.V(1).Infof("HTTP server stopped because of shutdown")
ch <- nil
default:
if err != nil && log.V(1) {
log.Errorln("HTTP server stopped with error", err.Error())
} else {
log.V(1).Infof("HTTP server stopped")
}
ch <- err
t.Stop(false)
}
}()
return t.upid, ch
}
// Stop stops the http transporter by closing the listener.
func (t *HTTPTransporter) Stop(graceful bool) error {
t.stateLock.Lock()
defer t.stateLock.Unlock()
return t.state.Stop(graceful)
}
// stop expects to be guarded by stateLock
func (t *HTTPTransporter) stop(graceful bool) error {
close(t.shouldQuit)
log.Info("stopping HTTP transport")
//TODO(jdef) if graceful, wait for pending requests to terminate
err := t.listener.Close()
return err
}
// UPID returns the upid of the transporter.
func (t *HTTPTransporter) UPID() upid.UPID {
t.stateLock.Lock()
defer t.stateLock.Unlock()
return t.upid
}
func (t *HTTPTransporter) messageDecoder(w http.ResponseWriter, r *http.Request) {
// Verify it's a libprocess request.
from, err := getLibprocessFrom(r)
if err != nil {
log.Errorf("Ignoring the request, because it's not a libprocess request: %v\n", err)
w.WriteHeader(http.StatusBadRequest)
return
}
decoder := DecodeHTTP(w, r)
defer decoder.Cancel(true)
t.processRequests(from, decoder.Requests())
// log an error if there's one waiting, otherwise move on
select {
case err, ok := <-decoder.Err():
if ok {
log.Errorf("failed to decode HTTP message: %v", err)
}
default:
}
}
func (t *HTTPTransporter) processRequests(from *upid.UPID, incoming <-chan *Request) {
for {
select {
case r, ok := <-incoming:
if !ok || !t.processOneRequest(from, r) {
return
}
case <-t.shouldQuit:
return
}
}
}
func (t *HTTPTransporter) processOneRequest(from *upid.UPID, request *Request) (keepGoing bool) {
// regardless of whether we write a Response we must close this chan
defer close(request.response)
keepGoing = true
//TODO(jdef) this is probably inefficient given the current implementation of the
// decoder: no need to make another copy of data that's already competely buffered
data, err := ioutil.ReadAll(request.Body)
if err != nil {
// this is unlikely given the current implementation of the decoder:
// the body has been completely buffered in memory already
log.Errorf("failed to read HTTP body: %v", err)
return
}
log.V(2).Infof("Receiving %q %v from %v, length %v", request.Method, request.URL, from, len(data))
m := &Message{
UPID: from,
Name: extractNameFromRequestURI(request.RequestURI),
Bytes: data,
}
// deterministic behavior and output..
select {
case <-t.shouldQuit:
keepGoing = false
select {
case t.messageQueue <- m:
default:
}
case t.messageQueue <- m:
select {
case <-t.shouldQuit:
keepGoing = false
default:
}
}
// Only send back an HTTP response if this isn't from libprocess
// (which we determine by looking at the User-Agent). This is
// necessary because older versions of libprocess would try and
// recv the data and parse it as an HTTP request which would
// fail thus causing the socket to get closed (but now
// libprocess will ignore responses, see ignore_data).
// see https://github.com/apache/mesos/blob/adecbfa6a216815bd7dc7d26e721c4c87e465c30/3rdparty/libprocess/src/process.cpp#L2192
if _, ok := parseLibprocessAgent(request.Header); !ok {
log.V(2).Infof("not libprocess agent, sending a 202")
request.response <- Response{
code: 202,
reason: "Accepted",
} // should never block
}
return
}
func (t *HTTPTransporter) makeLibprocessRequest(msg *Message) (*http.Request, error) {
if msg.UPID == nil {
panic(fmt.Sprintf("message is missing UPID: %+v", msg))
}
hostport := net.JoinHostPort(msg.UPID.Host, msg.UPID.Port)
targetURL := fmt.Sprintf("http://%s%s", hostport, msg.RequestURI())
log.V(2).Infof("libproc target URL %s", targetURL)
req, err := http.NewRequest("POST", targetURL, bytes.NewReader(msg.Bytes))
if err != nil {
log.Errorf("Failed to create request: %v\n", err)
return nil, err
}
req.Header.Add("Libprocess-From", t.upid.String())
req.Header.Add("Content-Type", "application/x-protobuf")
req.Header.Add("Connection", "Keep-Alive")
return req, nil
}
func getLibprocessFrom(r *http.Request) (*upid.UPID, error) {
if r.Method != "POST" {
return nil, fmt.Errorf("Not a POST request")
}
if agent, ok := parseLibprocessAgent(r.Header); ok {
return upid.Parse(agent)
}
lf, ok := r.Header["Libprocess-From"]
if ok {
// TODO(yifan): Just take the first field for now.
return upid.Parse(lf[0])
}
return nil, fmt.Errorf("Cannot find 'User-Agent' or 'Libprocess-From'")
}
func parseLibprocessAgent(h http.Header) (string, bool) {
const prefix = "libprocess/"
if ua, ok := h["User-Agent"]; ok {
for _, agent := range ua {
if strings.HasPrefix(agent, prefix) {
return agent[len(prefix):], true
}
}
}
return "", false
}