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receiving.go
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receiving.go
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package kcp
import (
"sync"
"v2ray.com/core/common/alloc"
)
type ReceivingWindow struct {
start uint32
size uint32
list []*DataSegment
}
func NewReceivingWindow(size uint32) *ReceivingWindow {
return &ReceivingWindow{
start: 0,
size: size,
list: make([]*DataSegment, size),
}
}
func (this *ReceivingWindow) Size() uint32 {
return this.size
}
func (this *ReceivingWindow) Position(idx uint32) uint32 {
return (idx + this.start) % this.size
}
func (this *ReceivingWindow) Set(idx uint32, value *DataSegment) bool {
pos := this.Position(idx)
if this.list[pos] != nil {
return false
}
this.list[pos] = value
return true
}
func (this *ReceivingWindow) Remove(idx uint32) *DataSegment {
pos := this.Position(idx)
e := this.list[pos]
this.list[pos] = nil
return e
}
func (this *ReceivingWindow) RemoveFirst() *DataSegment {
return this.Remove(0)
}
func (this *ReceivingWindow) Advance() {
this.start++
if this.start == this.size {
this.start = 0
}
}
type AckList struct {
writer SegmentWriter
timestamps []uint32
numbers []uint32
nextFlush []uint32
}
func NewAckList(writer SegmentWriter) *AckList {
return &AckList{
writer: writer,
timestamps: make([]uint32, 0, 32),
numbers: make([]uint32, 0, 32),
nextFlush: make([]uint32, 0, 32),
}
}
func (this *AckList) Add(number uint32, timestamp uint32) {
this.timestamps = append(this.timestamps, timestamp)
this.numbers = append(this.numbers, number)
this.nextFlush = append(this.nextFlush, 0)
}
func (this *AckList) Clear(una uint32) {
count := 0
for i := 0; i < len(this.numbers); i++ {
if this.numbers[i] >= una {
if i != count {
this.numbers[count] = this.numbers[i]
this.timestamps[count] = this.timestamps[i]
this.nextFlush[count] = this.nextFlush[i]
}
count++
}
}
if count < len(this.numbers) {
this.numbers = this.numbers[:count]
this.timestamps = this.timestamps[:count]
this.nextFlush = this.nextFlush[:count]
}
}
func (this *AckList) Flush(current uint32, rto uint32) {
seg := NewAckSegment()
for i := 0; i < len(this.numbers) && !seg.IsFull(); i++ {
if this.nextFlush[i] <= current {
seg.PutNumber(this.numbers[i])
seg.PutTimestamp(this.timestamps[i])
this.nextFlush[i] = current + rto/2
}
}
if seg.Count > 0 {
this.writer.Write(seg)
seg.Release()
}
}
type ReceivingWorker struct {
sync.RWMutex
conn *Connection
leftOver *alloc.Buffer
window *ReceivingWindow
acklist *AckList
nextNumber uint32
windowSize uint32
}
func NewReceivingWorker(kcp *Connection) *ReceivingWorker {
worker := &ReceivingWorker{
conn: kcp,
window: NewReceivingWindow(kcp.Config.GetReceivingBufferSize()),
windowSize: kcp.Config.GetReceivingInFlightSize(),
}
worker.acklist = NewAckList(worker)
return worker
}
func (this *ReceivingWorker) ProcessSendingNext(number uint32) {
this.Lock()
defer this.Unlock()
this.acklist.Clear(number)
}
func (this *ReceivingWorker) ProcessSegment(seg *DataSegment) {
this.Lock()
defer this.Unlock()
number := seg.Number
idx := number - this.nextNumber
if idx >= this.windowSize {
return
}
this.acklist.Clear(seg.SendingNext)
this.acklist.Add(number, seg.Timestamp)
if !this.window.Set(idx, seg) {
seg.Release()
}
}
func (this *ReceivingWorker) Read(b []byte) int {
this.Lock()
defer this.Unlock()
total := 0
if this.leftOver != nil {
nBytes := copy(b, this.leftOver.Value)
if nBytes < this.leftOver.Len() {
this.leftOver.SliceFrom(nBytes)
return nBytes
}
this.leftOver.Release()
this.leftOver = nil
total += nBytes
}
for total < len(b) {
seg := this.window.RemoveFirst()
if seg == nil {
break
}
this.window.Advance()
this.nextNumber++
nBytes := copy(b[total:], seg.Data.Value)
total += nBytes
if nBytes < seg.Data.Len() {
seg.Data.SliceFrom(nBytes)
this.leftOver = seg.Data
seg.Data = nil
seg.Release()
break
}
seg.Release()
}
return total
}
func (this *ReceivingWorker) Flush(current uint32) {
this.Lock()
defer this.Unlock()
this.acklist.Flush(current, this.conn.roundTrip.Timeout())
}
func (this *ReceivingWorker) Write(seg Segment) {
ackSeg := seg.(*AckSegment)
ackSeg.Conv = this.conn.conv
ackSeg.ReceivingNext = this.nextNumber
ackSeg.ReceivingWindow = this.nextNumber + this.windowSize
if this.conn.state == StateReadyToClose {
ackSeg.Option = SegmentOptionClose
}
this.conn.output.Write(ackSeg)
}
func (this *ReceivingWorker) CloseRead() {
}
func (this *ReceivingWorker) UpdateNecessary() bool {
return len(this.acklist.numbers) > 0
}