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xsub.go
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xsub.go
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// Copyright 2019 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 xsub implements the raw SUB protocol. This protocol simply
// passes through all messages received, and does not filter them.
package xsub
import (
"sync"
"time"
"nanomsg.org/go/mangos/v2/protocol"
)
// Protocol identity information.
const (
Self = protocol.ProtoSub
Peer = protocol.ProtoPub
SelfName = "sub"
PeerName = "pub"
)
type pipe struct {
p protocol.Pipe
s *socket
}
type socket struct {
closed bool
closeQ chan struct{}
recvQLen int
recvExpire time.Duration
recvQ chan *protocol.Message
sizeQ chan struct{}
sync.Mutex
}
var (
nilQ <-chan time.Time
)
const defaultQLen = 128
func (s *socket) SendMsg(*protocol.Message) error {
return protocol.ErrProtoOp
}
func (s *socket) RecvMsg() (*protocol.Message, error) {
// For now this uses a simple unified queue for the entire
// socket. Later we can look at moving this to priority queues
// based on socket pipes.
timeQ := nilQ
for {
s.Lock()
if s.recvExpire > 0 {
timeQ = time.After(s.recvExpire)
}
closeQ := s.closeQ
sizeQ := s.sizeQ
recvQ := s.recvQ
s.Unlock()
select {
case <-closeQ:
return nil, protocol.ErrClosed
case <-timeQ:
return nil, protocol.ErrRecvTimeout
case <-sizeQ:
continue
case m := <-recvQ:
return m, nil
}
}
}
func (s *socket) SetOption(name string, value interface{}) error {
switch name {
case protocol.OptionRecvDeadline:
if v, ok := value.(time.Duration); ok {
s.Lock()
s.recvExpire = v
s.Unlock()
return nil
}
return protocol.ErrBadValue
case protocol.OptionReadQLen:
if v, ok := value.(int); ok && v >= 0 {
recvQ := make(chan *protocol.Message, v)
sizeQ := make(chan struct{})
s.Lock()
s.recvQ = recvQ
sizeQ, s.sizeQ = s.sizeQ, sizeQ
s.recvQLen = v
s.Unlock()
close(sizeQ)
// This leaks a few messages. But it doesn't really
// matter. Resizing the queue tosses the messages.
return nil
}
return protocol.ErrBadValue
}
return protocol.ErrBadOption
}
func (s *socket) GetOption(option string) (interface{}, error) {
switch option {
case protocol.OptionRaw:
return true, nil
case protocol.OptionRecvDeadline:
s.Lock()
v := s.recvExpire
s.Unlock()
return v, nil
case protocol.OptionReadQLen:
s.Lock()
v := s.recvQLen
s.Unlock()
return v, nil
}
return nil, protocol.ErrBadOption
}
func (s *socket) AddPipe(pp protocol.Pipe) error {
p := &pipe{
p: pp,
s: s,
}
s.Lock()
defer s.Unlock()
if s.closed {
return protocol.ErrClosed
}
go p.receiver()
return nil
}
func (s *socket) RemovePipe(protocol.Pipe) {
}
func (s *socket) OpenContext() (protocol.Context, error) {
return nil, protocol.ErrProtoOp
}
func (*socket) Info() protocol.Info {
return protocol.Info{
Self: Self,
Peer: Peer,
SelfName: SelfName,
PeerName: PeerName,
}
}
func (s *socket) Close() error {
s.Lock()
if s.closed {
s.Unlock()
return protocol.ErrClosed
}
s.closed = true
s.Unlock()
close(s.closeQ)
return nil
}
func (p *pipe) receiver() {
s := p.s
for {
m := p.p.RecvMsg()
if m == nil {
break
}
s.Lock()
recvQ := s.recvQ
s.Unlock()
// No need to test for resizing or close here, because we
// never block anyway.
select {
case recvQ <- m:
default:
m.Free()
}
}
p.close()
}
func (p *pipe) close() {
_ = p.p.Close()
}
// NewProtocol returns a new protocol implementation.
func NewProtocol() protocol.Protocol {
s := &socket{
closeQ: make(chan struct{}),
sizeQ: make(chan struct{}),
recvQ: make(chan *protocol.Message, defaultQLen),
recvQLen: defaultQLen,
}
return s
}
// NewSocket allocates a raw Socket using the PULL protocol.
func NewSocket() (protocol.Socket, error) {
return protocol.MakeSocket(NewProtocol()), nil
}