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|
package ext
// XXX: There's no logging around heartbeats - how can we do this in a way that is useful
// as a library?
//
// XXX: When we close the session because of a lost heartbeat or because of an error in the
// heartbeating, there is no way to tell that; a Session will just appear to stop working
import (
"encoding/binary"
proto "github.com/inconshreveable/muxado/proto"
"github.com/inconshreveable/muxado/proto/frame"
"io"
"time"
)
const (
defaultHeartbeatInterval = 3 * time.Second
defaultHeartbeatTolerance = 10 * time.Second
)
type Heartbeat struct {
sess proto.ISession
accept proto.ExtAccept
mark chan int
interval time.Duration
tolerance time.Duration
}
func NewDefaultHeartbeat() *Heartbeat {
return NewHeartbeat(defaultHeartbeatInterval, defaultHeartbeatTolerance)
}
func NewHeartbeat(interval, tolerance time.Duration) *Heartbeat {
return &Heartbeat{
mark: make(chan int),
interval: interval,
tolerance: tolerance,
}
}
func (h *Heartbeat) Start(sess proto.ISession, accept proto.ExtAccept) frame.StreamType {
h.sess = sess
h.accept = accept
go h.respond()
go h.request()
go h.check()
return heartbeatExtensionType
}
func (h *Heartbeat) check() {
t := time.NewTimer(h.interval + h.tolerance)
for {
select {
case <-t.C:
// time out waiting for a response!
h.sess.Close()
return
case <-h.mark:
t.Reset(h.interval + h.tolerance)
}
}
}
func (h *Heartbeat) respond() {
// close the session on any errors
defer h.sess.Close()
stream, err := h.accept()
if err != nil {
return
}
// read the next heartbeat id and respond
buf := make([]byte, 4)
for {
_, err := io.ReadFull(stream, buf)
if err != nil {
return
}
_, err = stream.Write(buf)
if err != nil {
return
}
}
}
func (h *Heartbeat) request() {
// close the session on any errors
defer h.sess.Close()
// request highest possible priority for heartbeats
priority := frame.StreamPriority(0x7FFFFFFF)
stream, err := h.sess.OpenStream(priority, heartbeatExtensionType, false)
if err != nil {
return
}
// send heartbeats and then check that we got them back
var id uint32
for {
time.Sleep(h.interval)
if err := binary.Write(stream, binary.BigEndian, id); err != nil {
return
}
var respId uint32
if err := binary.Read(stream, binary.BigEndian, &respId); err != nil {
return
}
if id != respId {
return
}
// record the time
h.mark <- 1
}
}
|
