/
surveyor.go
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/
surveyor.go
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// Copyright 2018 The Mangos Authors
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use 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 surveyor implements the SURVEYOR protocol. This sends messages
// out to RESPONDENT partners, and receives their responses.
package surveyor
import (
"encoding/binary"
"sync"
"time"
"nanomsg.org/go-mangos"
)
const defaultSurveyTime = time.Second
type surveyor struct {
sock mangos.ProtocolSocket
peers map[uint32]*surveyorP
raw bool
nextID uint32
surveyID uint32
duration time.Duration
timeout time.Time
timer *time.Timer
w mangos.Waiter
init sync.Once
ttl int
sync.Mutex
}
type surveyorP struct {
q chan *mangos.Message
ep mangos.Endpoint
x *surveyor
}
func (x *surveyor) Init(sock mangos.ProtocolSocket) {
x.sock = sock
x.peers = make(map[uint32]*surveyorP)
x.sock.SetRecvError(mangos.ErrProtoState)
x.timer = time.AfterFunc(x.duration,
func() { x.sock.SetRecvError(mangos.ErrProtoState) })
x.timer.Stop()
x.w.Init()
x.w.Add()
go x.sender()
}
func (x *surveyor) Shutdown(expire time.Time) {
x.w.WaitAbsTimeout(expire)
x.Lock()
peers := x.peers
x.peers = make(map[uint32]*surveyorP)
x.Unlock()
for id, peer := range peers {
delete(peers, id)
mangos.DrainChannel(peer.q, expire)
close(peer.q)
}
}
func (x *surveyor) sender() {
defer x.w.Done()
cq := x.sock.CloseChannel()
sq := x.sock.SendChannel()
for {
var m *mangos.Message
select {
case m = <-sq:
if m == nil {
sq = x.sock.SendChannel()
continue
}
case <-cq:
return
}
x.Lock()
for _, pe := range x.peers {
m := m.Dup()
select {
case pe.q <- m:
default:
m.Free()
}
}
x.Unlock()
}
}
// When sending, we should have the survey ID in the header.
func (peer *surveyorP) sender() {
for {
if m := <-peer.q; m == nil {
break
} else {
if peer.ep.SendMsg(m) != nil {
m.Free()
return
}
}
}
}
func (peer *surveyorP) receiver() {
rq := peer.x.sock.RecvChannel()
cq := peer.x.sock.CloseChannel()
for {
m := peer.ep.RecvMsg()
if m == nil {
return
}
if len(m.Body) < 4 {
m.Free()
continue
}
// Get survery ID -- this will be passed in the header up
// to the application. It should include that in the response.
m.Header = append(m.Header, m.Body[:4]...)
m.Body = m.Body[4:]
select {
case rq <- m:
case <-cq:
return
}
}
}
func (x *surveyor) AddEndpoint(ep mangos.Endpoint) {
peer := &surveyorP{ep: ep, x: x, q: make(chan *mangos.Message, 1)}
x.Lock()
x.peers[ep.GetID()] = peer
go peer.receiver()
go peer.sender()
x.Unlock()
}
func (x *surveyor) RemoveEndpoint(ep mangos.Endpoint) {
id := ep.GetID()
x.Lock()
peer := x.peers[id]
delete(x.peers, id)
x.Unlock()
if peer != nil {
close(peer.q)
}
}
func (*surveyor) Number() uint16 {
return mangos.ProtoSurveyor
}
func (*surveyor) PeerNumber() uint16 {
return mangos.ProtoRespondent
}
func (*surveyor) Name() string {
return "surveyor"
}
func (*surveyor) PeerName() string {
return "respondent"
}
func (x *surveyor) SendHook(m *mangos.Message) bool {
if x.raw {
return true
}
x.Lock()
x.surveyID = x.nextID | 0x80000000
x.nextID++
x.sock.SetRecvError(nil)
v := x.surveyID
m.Header = append(m.Header,
byte(v>>24), byte(v>>16), byte(v>>8), byte(v))
if x.duration > 0 {
x.timer.Reset(x.duration)
}
x.Unlock()
return true
}
func (x *surveyor) RecvHook(m *mangos.Message) bool {
if x.raw {
return true
}
x.Lock()
defer x.Unlock()
if len(m.Header) < 4 {
return false
}
if binary.BigEndian.Uint32(m.Header) != x.surveyID {
return false
}
m.Header = m.Header[4:]
return true
}
func (x *surveyor) SetOption(name string, val interface{}) error {
var ok bool
switch name {
case mangos.OptionRaw:
if x.raw, ok = val.(bool); !ok {
return mangos.ErrBadValue
}
if x.raw {
x.timer.Stop()
x.sock.SetRecvError(nil)
} else {
x.sock.SetRecvError(mangos.ErrProtoState)
}
return nil
case mangos.OptionSurveyTime:
x.Lock()
x.duration, ok = val.(time.Duration)
x.Unlock()
if !ok {
return mangos.ErrBadValue
}
return nil
case mangos.OptionTTL:
// We don't do anything with this, but support it for
// symmetry with the respondent socket.
if ttl, ok := val.(int); !ok {
return mangos.ErrBadValue
} else if ttl < 1 || ttl > 255 {
return mangos.ErrBadValue
} else {
x.ttl = ttl
}
return nil
default:
return mangos.ErrBadOption
}
}
func (x *surveyor) GetOption(name string) (interface{}, error) {
switch name {
case mangos.OptionRaw:
return x.raw, nil
case mangos.OptionSurveyTime:
x.Lock()
d := x.duration
x.Unlock()
return d, nil
case mangos.OptionTTL:
return x.ttl, nil
default:
return nil, mangos.ErrBadOption
}
}
// NewSocket allocates a new Socket using the SURVEYOR protocol.
func NewSocket() (mangos.Socket, error) {
return mangos.MakeSocket(&surveyor{duration: defaultSurveyTime}), nil
}