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udp_transporter.go
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/
udp_transporter.go
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package transporter
import (
"bytes"
"encoding/gob"
"math/rand"
"net"
"github.com/go-distributed/epaxos/message"
"github.com/golang/glog"
)
const defaultUDPSize = 8192
type UDPTransporter struct {
Addrs []*net.UDPAddr
Self uint8
FastQuorum uint8
All uint8
Conns []*net.UDPConn
ch chan message.Message
stop chan struct{}
encBuffer *bytes.Buffer //TODO: race condition
decBuffer *bytes.Buffer
enc *gob.Encoder
dec *gob.Decoder
}
func NewUDPTransporter(addrStrs []string,
self uint8, size int) (*UDPTransporter, error) {
var err error
addrs := make([]*net.UDPAddr, size)
conns := make([]*net.UDPConn, size)
gob.Register(&message.Propose{})
gob.Register(&message.PreAccept{})
gob.Register(&message.PreAcceptOk{})
gob.Register(&message.PreAcceptReply{})
gob.Register(&message.Accept{})
gob.Register(&message.AcceptReply{})
gob.Register(&message.Commit{})
gob.Register(&message.Prepare{})
gob.Register(&message.PrepareReply{})
for i := range addrs {
addrs[i], err = net.ResolveUDPAddr("udp", addrStrs[i])
if err != nil {
return nil, err
}
// get incoming connection
if uint8(i) == self {
conns[i], err = net.ListenUDP("udp", addrs[i])
if err != nil {
return nil, err
}
}
}
nt := &UDPTransporter{
Addrs: addrs,
Self: self,
FastQuorum: uint8(size) - 2,
All: uint8(size),
Conns: conns,
stop: make(chan struct{}),
encBuffer: new(bytes.Buffer),
decBuffer: new(bytes.Buffer),
}
nt.enc = gob.NewEncoder(nt.encBuffer)
nt.dec = gob.NewDecoder(nt.decBuffer)
return nt, nil
}
func (nt *UDPTransporter) Send(to uint8, msg message.Message) {
go func() {
buf := new(bytes.Buffer)
enc := gob.NewEncoder(buf)
if err := enc.Encode(&msg); err != nil {
glog.Warning("Encoding error ", err)
}
_, err := nt.Conns[to].Write(buf.Bytes())
if err != nil {
glog.Warning("UDP write error ", err)
}
}()
}
func (nt *UDPTransporter) MulticastFastquorum(msg message.Message) {
skip := uint8(rand.Intn(int(nt.All)))
if skip == nt.Self {
skip = (skip + 1) % nt.All
}
for i := uint8(0); i < nt.All; i++ {
if i == nt.Self || i == skip {
continue
}
nt.Send(i, msg)
}
}
func (nt *UDPTransporter) Broadcast(msg message.Message) {
for i := uint8(0); i < nt.All; i++ {
if i == nt.Self {
continue
}
nt.Send(i, msg)
}
}
func (nt *UDPTransporter) RegisterChannel(ch chan message.Message) {
nt.ch = ch
}
func (nt *UDPTransporter) Start() error {
// get outgoint connection
var err error
for i := range nt.Conns {
if i == int(nt.Self) {
continue
}
nt.Conns[i], err = net.DialUDP("udp", nil, nt.Addrs[i])
if err != nil {
return err
}
}
// start receive loop
var msg message.Message
b := make([]byte, defaultUDPSize)
buf := new(bytes.Buffer)
go func() {
for {
select {
case <-nt.stop:
return
default:
}
// receive message
n, _, err := nt.Conns[nt.Self].ReadFrom(b)
if err != nil {
glog.Warning("UDP read error ", err)
continue
}
buf.Reset()
buf.Write(b[:n])
dec := gob.NewDecoder(buf)
err = dec.Decode(&msg)
if err != nil {
glog.Warning("Decoding error ", err)
}
nt.ch <- msg
}
}()
return nil
}
func (nt *UDPTransporter) Stop() {
close(nt.stop)
// stop network
for _, conn := range nt.Conns {
conn.Close()
}
}