syncthing/lib/beacon/beacon.go
2019-08-22 12:30:57 +02:00

116 lines
2.5 KiB
Go

// Copyright (C) 2014 The Syncthing Authors.
//
// This Source Code Form is subject to the terms of the Mozilla Public
// License, v. 2.0. If a copy of the MPL was not distributed with this file,
// You can obtain one at https://mozilla.org/MPL/2.0/.
package beacon
import (
"fmt"
"net"
"time"
"github.com/thejerf/suture"
"github.com/syncthing/syncthing/lib/util"
)
type recv struct {
data []byte
src net.Addr
}
type Interface interface {
suture.Service
fmt.Stringer
Send(data []byte)
Recv() ([]byte, net.Addr)
Error() error
}
type cast struct {
*suture.Supervisor
name string
reader util.ServiceWithError
writer util.ServiceWithError
outbox chan recv
inbox chan []byte
stopped chan struct{}
}
// newCast creates a base object for multi- or broadcasting. Afterwards the
// caller needs to set reader and writer with the addReader and addWriter
// methods to get a functional implementation of Interface.
func newCast(name string) *cast {
return &cast{
Supervisor: suture.New(name, suture.Spec{
// Don't retry too frenetically: an error to open a socket or
// whatever is usually something that is either permanent or takes
// a while to get solved...
FailureThreshold: 2,
FailureBackoff: 60 * time.Second,
// Only log restarts in debug mode.
Log: func(line string) {
l.Debugln(line)
},
PassThroughPanics: true,
}),
name: name,
inbox: make(chan []byte),
outbox: make(chan recv, 16),
stopped: make(chan struct{}),
}
}
func (c *cast) addReader(svc func(chan struct{}) error) {
c.reader = c.createService(svc, "reader")
c.Add(c.reader)
}
func (c *cast) addWriter(svc func(stop chan struct{}) error) {
c.writer = c.createService(svc, "writer")
c.Add(c.writer)
}
func (c *cast) createService(svc func(chan struct{}) error, suffix string) util.ServiceWithError {
return util.AsServiceWithError(func(stop chan struct{}) error {
l.Debugln("Starting", c.name, suffix)
err := svc(stop)
l.Debugf("Stopped %v %v: %v", c.name, suffix, err)
return err
})
}
func (c *cast) Stop() {
c.Supervisor.Stop()
close(c.stopped)
}
func (c *cast) String() string {
return fmt.Sprintf("%s@%p", c.name, c)
}
func (c *cast) Send(data []byte) {
select {
case c.inbox <- data:
case <-c.stopped:
}
}
func (c *cast) Recv() ([]byte, net.Addr) {
select {
case recv := <-c.outbox:
return recv.data, recv.src
case <-c.stopped:
}
return nil, nil
}
func (c *cast) Error() error {
if err := c.reader.Error(); err != nil {
return err
}
return c.writer.Error()
}