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session.go
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/
session.go
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package van
import (
"bytes"
"container/list"
"encoding/binary"
"fmt"
"io"
"math/rand"
"net"
"time"
"github.com/reusee/closer"
ic "github.com/reusee/inf-chan"
se "github.com/reusee/selector"
"github.com/reusee/signaler"
)
const (
DATA = byte(1)
ACK = byte(2)
FIN = byte(4)
)
type Session struct {
closer.Closer
*signaler.Signaler
id int64
transports []Transport
conns map[uint32]*Conn
closedConnIds *list.List
newTransport chan Transport
errTransport chan Transport
incomingPackets chan *Packet
incomingPacketsMap map[string]*Packet
incomingAcks chan *Packet
recvIn chan *Packet
Recv chan *Packet
outgoingPackets chan *Packet
outCheckTicker *time.Ticker
sendingPacketsMap map[string]*Packet
outPacketCase *se.Case
// getters
getTransportCount chan int
getStatResend chan int
// statistics and debug
debugEntries []func() []string
resentPackets int
resentBytes int
inBytes int
outBytes int
}
type connIdRange struct {
left uint32
right uint32
}
type Conn struct {
Id uint32
serial uint32
ackSerial uint32
localClosed bool
remoteClosed bool
start time.Time
inBytes int
outBytes int
}
type Packet struct {
Conn *Conn
connId uint32
Type byte
serial uint32
Data []byte
resendAt time.Time
}
func makeSession() *Session {
session := &Session{
Closer: closer.NewCloser(),
Signaler: signaler.NewSignaler(),
conns: make(map[uint32]*Conn),
closedConnIds: list.New(),
newTransport: make(chan Transport, 128),
errTransport: make(chan Transport),
incomingPackets: make(chan *Packet),
incomingPacketsMap: make(map[string]*Packet),
incomingAcks: make(chan *Packet),
recvIn: make(chan *Packet),
Recv: make(chan *Packet),
outgoingPackets: make(chan *Packet),
sendingPacketsMap: make(map[string]*Packet),
outCheckTicker: time.NewTicker(time.Millisecond * 100),
getTransportCount: make(chan int),
getStatResend: make(chan int),
}
recvLink := ic.Link(session.recvIn, session.Recv)
session.OnClose(func() {
close(recvLink)
session.CloseSignaler()
})
session.setDebugEntries()
go session.start()
return session
}
func (s *Session) Log(format string, args ...interface{}) {
s.Signal("Log", fmt.Sprintf(format, args...))
}
func (s *Session) AddDebugEntry(cb func() []string) {
s.debugEntries = append(s.debugEntries, cb)
}
func (s *Session) start() {
var closing bool
selector := se.New()
selector.Add(s.WaitClosing, func() {
closing = true
}, nil)
selector.Add(s.newTransport, func(recv interface{}) {
s.addTransport(recv.(Transport))
}, nil)
selector.Add(s.errTransport, func(recv interface{}) {
s.removeTransport(recv.(Transport))
}, nil)
selector.Add(s.incomingPackets, func(recv interface{}) {
packet := recv.(*Packet)
s.sendAck(packet)
s.handleIncomingPacket(packet)
}, nil)
selector.Add(s.incomingAcks, func(recv interface{}) {
s.handleIncomingAck(recv.(*Packet))
}, nil)
s.outPacketCase = selector.Add(s.outgoingPackets, func(recv interface{}) {
s.handleOutgoingPacket(recv.(*Packet))
}, nil)
selector.Add(s.outCheckTicker.C, func() {
s.checkOutgoingPackets()
}, nil)
// getters
selector.Add(s.getTransportCount, nil, func() interface{} {
return len(s.transports)
})
selector.Add(s.getStatResend, nil, func() interface{} {
return s.resentPackets
})
// main loop
for !closing {
selector.Select()
}
//clear:
for _, c := range s.transports {
c.Close()
}
}
func (s *Session) addTransport(transport Transport) {
transport.(*net.TCPConn).SetWriteBuffer(8 * 1024 * 1024)
s.transports = append(s.transports, transport)
s.Signal("NewTransport", len(s.transports))
// start reader
var err error
go func() {
var serial uint32
var length uint16
var packetType byte
var connId uint32
for {
// read conn id
err = binary.Read(transport, binary.LittleEndian, &connId)
if err != nil {
goto error_occur
}
// read packet type
err = binary.Read(transport, binary.LittleEndian, &packetType)
if err != nil {
goto error_occur
}
// data or ack
switch packetType {
case DATA: // data
err = binary.Read(transport, binary.LittleEndian, &serial)
if err != nil {
goto error_occur
}
err = binary.Read(transport, binary.LittleEndian, &length)
if err != nil {
goto error_occur
}
data := make([]byte, length)
n, err := io.ReadFull(transport, data)
if err != nil || n != int(length) {
goto error_occur
}
s.incomingPackets <- &Packet{
Type: DATA,
connId: connId, // check conn in main thread, ensuring thread safety
serial: serial,
Data: data,
}
case FIN: // finish
err = binary.Read(transport, binary.LittleEndian, &serial)
if err != nil {
goto error_occur
}
s.incomingPackets <- &Packet{
Type: FIN,
connId: connId,
serial: serial,
}
case ACK:
err := binary.Read(transport, binary.LittleEndian, &serial)
if err != nil {
goto error_occur
}
s.incomingAcks <- &Packet{
Type: ACK,
connId: connId,
serial: serial,
}
}
}
return
error_occur:
if !s.IsClosing { // transport error
s.errTransport <- transport
}
return
}()
}
func (s *Session) removeTransport(transport Transport) {
s.Log("transport error")
index := -1
for i, c := range s.transports {
if c == transport {
index = i
break
}
}
if index > 0 { // delete
s.Log("remove transport")
s.transports[index].Close()
s.Signal("RemoveTransport", len(s.transports))
s.transports = append(s.transports[:index], s.transports[index+1:]...)
}
if len(s.transports) == 0 {
panic("No transport. fixme") //TODO
}
}
func (s *Session) makeConn() *Conn {
conn := &Conn{
start: time.Now(),
}
return conn
}
func (s *Session) closeConn(conn *Conn) {
delete(s.conns, conn.Id)
// insert id
merged := false
for e := s.closedConnIds.Front(); e != nil; e = e.Next() {
r := e.Value.(*connIdRange)
if conn.Id == r.left-1 {
r.left = conn.Id
merged = true
break
} else if conn.Id == r.right+1 {
r.right = conn.Id
merged = true
// try merge next range
if next := e.Next(); next != nil {
nr := next.Value.(*connIdRange)
if nr.left == r.right+1 {
r.right = nr.right
s.closedConnIds.Remove(next)
}
}
break
} else if conn.Id < r.left-1 {
r := &connIdRange{
left: conn.Id,
right: conn.Id,
}
s.closedConnIds.InsertBefore(r, e)
merged = true
break
}
}
if !merged {
r := &connIdRange{
left: conn.Id,
right: conn.Id,
}
s.closedConnIds.PushBack(r)
}
}
func (s *Session) handleOutgoingPacket(packet *Packet) {
s.sendingPacketsMap[fmt.Sprintf("%d:%d", packet.Conn.Id, packet.serial)] = packet
s.sendPacket(packet)
}
func (s *Session) checkOutgoingPackets() {
now := time.Now()
for _, packet := range s.sendingPacketsMap {
if now.After(packet.resendAt) {
s.Log("resend %d", packet.serial)
s.sendPacket(packet)
}
}
}
func (s *Session) Send(conn *Conn, data []byte) uint32 {
packet := &Packet{
Type: DATA,
Conn: conn,
serial: conn.serial,
Data: data,
}
conn.serial++
conn.outBytes += len(packet.Data)
s.outBytes += len(packet.Data)
s.outgoingPackets <- packet
return packet.serial
}
func (s *Session) Finish(conn *Conn) {
packet := &Packet{
Type: FIN,
Conn: conn,
serial: conn.serial,
}
conn.serial++
s.outgoingPackets <- packet
conn.localClosed = true
if conn.remoteClosed {
s.closeConn(conn)
}
}
func (s *Session) sendPacket(packet *Packet) {
// check transport
if len(s.transports) == 0 {
return
}
// pack packet
buf := new(bytes.Buffer)
binary.Write(buf, binary.LittleEndian, packet.Conn.Id)
buf.WriteByte(packet.Type)
binary.Write(buf, binary.LittleEndian, packet.serial)
if packet.Type == DATA {
binary.Write(buf, binary.LittleEndian, uint16(len(packet.Data)))
buf.Write(packet.Data)
}
// select transport
transport := s.transports[0]
if len(s.transports) > 0 {
transport = s.transports[rand.Intn(len(s.transports))]
}
// write to transport
s.Log("Start send through %v", transport)
t0 := time.Now()
transport.SetWriteDeadline(time.Now().Add(time.Second * 5))
n, err := transport.Write(buf.Bytes())
s.Log("Sent in %v", time.Now().Sub(t0))
if err != nil || n != len(buf.Bytes()) {
if !s.IsClosing {
s.removeTransport(transport)
return
}
}
// stat
if packet.resendAt.Year() > 1970 { // is resend
s.resentPackets++
s.resentBytes += len(packet.Data)
}
// set packet
packet.resendAt = time.Now().Add(time.Second * 5)
}
func (s *Session) sendAck(packet *Packet) {
// check transport
if len(s.transports) == 0 {
return
}
// pack
buf := new(bytes.Buffer)
binary.Write(buf, binary.LittleEndian, packet.connId)
buf.WriteByte(ACK)
binary.Write(buf, binary.LittleEndian, packet.serial)
// select transport
transport := s.transports[0]
if len(s.transports) > 0 {
transport = s.transports[rand.Intn(len(s.transports))]
}
// write to transport
transport.SetWriteDeadline(time.Now().Add(time.Second * 5))
n, err := transport.Write(buf.Bytes())
if err != nil || n != len(buf.Bytes()) {
if !s.IsClosing {
s.removeTransport(transport)
}
}
}
func (s *Session) handleIncomingPacket(packet *Packet) {
conn, ok := s.conns[packet.connId]
if !ok {
// check whether closed
isClosed := false
for e := s.closedConnIds.Back(); e != nil; e = e.Prev() {
r := e.Value.(*connIdRange)
if packet.connId > r.right {
break
}
if packet.connId >= r.left && packet.connId <= r.right {
isClosed = true
break
}
}
if isClosed {
return
}
// create new incoming conn
conn = s.makeConn()
conn.Id = packet.connId
s.conns[conn.Id] = conn
s.Signal("NewConn", conn)
s.Log("NewConn from remote %d", conn.Id)
}
packet.Conn = conn
s.Log("incoming data %d", packet.serial)
if packet.serial == conn.ackSerial { // in order
s.Log("in order %d", packet.serial)
s.recvIn <- packet
conn.ackSerial++
conn.inBytes += len(packet.Data)
s.inBytes += len(packet.Data)
if packet.Type == FIN {
conn.remoteClosed = true
if conn.localClosed { // close conn
s.closeConn(conn)
}
}
} else if packet.serial > conn.ackSerial { // out of order
s.Log("out of order %d", packet.serial)
s.incomingPacketsMap[fmt.Sprintf("%d:%d", conn.Id, packet.serial)] = packet
} else if packet.serial < conn.ackSerial { // duplicated
s.Log("dup %d", packet.serial)
}
// try pop
nextKey := fmt.Sprintf("%d:%d", conn.Id, conn.ackSerial)
packet, ok = s.incomingPacketsMap[nextKey]
for ok {
s.Log("provide %d", packet.serial)
s.recvIn <- packet
conn.ackSerial++
conn.inBytes += len(packet.Data)
s.inBytes += len(packet.Data)
if packet.Type == FIN {
conn.remoteClosed = true
if conn.localClosed { // close conn
s.closeConn(conn)
}
}
delete(s.incomingPacketsMap, nextKey)
nextKey = fmt.Sprintf("%d:%d", conn.Id, conn.ackSerial)
packet, ok = s.incomingPacketsMap[nextKey]
}
}
func (s *Session) handleIncomingAck(packet *Packet) {
key := fmt.Sprintf("%d:%d", packet.connId, packet.serial)
if _, ok := s.sendingPacketsMap[key]; ok {
delete(s.sendingPacketsMap, key)
}
}