sending window

transport/internet/kcp/sending.go

@@ -1,5 +1,146 @@
 package kcp
 
+type SendingWindow struct {
+	start uint32
+	cap   uint32
+	len   uint32
+	last  uint32
+
+	data []*DataSegment
+	prev []uint32
+	next []uint32
+
+	kcp *KCP
+}
+
+func NewSendingWindow(kcp *KCP, size uint32) *SendingWindow {
+	window := &SendingWindow{
+		start: 0,
+		cap:   size,
+		len:   0,
+		last:  0,
+		data:  make([]*DataSegment, size),
+		prev:  make([]uint32, size),
+		next:  make([]uint32, size),
+	}
+	return window
+}
+
+func (this *SendingWindow) Len() int {
+	return int(this.len)
+}
+
+func (this *SendingWindow) Push(seg *DataSegment) {
+	pos := (this.start + this.len) % this.cap
+	this.data[pos] = seg
+	if this.len > 0 {
+		this.next[this.last] = pos
+		this.prev[pos] = this.last
+	}
+	this.last = pos
+	this.len++
+}
+
+func (this *SendingWindow) First() *DataSegment {
+	return this.data[this.start]
+}
+
+func (this *SendingWindow) Clear(una uint32) {
+	for this.Len() > 0 {
+		if this.data[this.start].Number < una {
+			this.Remove(0)
+		}
+	}
+}
+
+func (this *SendingWindow) Remove(idx uint32) {
+	pos := (this.start + idx) % this.cap
+	seg := this.data[pos]
+	seg.Release()
+	this.data[pos] = nil
+	if pos == this.start {
+		if this.len == 1 {
+			this.len = 0
+			this.start = 0
+			this.last = 0
+		} else {
+			delta := this.next[pos] - this.start
+			this.start = this.next[pos]
+			this.len -= delta
+		}
+	} else if pos == this.last {
+		this.last = this.prev[pos]
+	} else {
+		this.next[this.prev[pos]] = this.next[pos]
+		this.prev[this.next[pos]] = this.prev[pos]
+	}
+}
+
+func (this *SendingWindow) HandleFastAck(number uint32) {
+	for i := this.start; ; i = this.next[i] {
+		seg := this.data[i]
+		if _itimediff(number, seg.Number) < 0 {
+			break
+		}
+		if number != seg.Number {
+			seg.ackSkipped++
+		}
+		if i == this.last {
+			break
+		}
+	}
+}
+
+func (this *SendingWindow) Flush() bool {
+	current := this.kcp.current
+	resent := uint32(this.kcp.fastresend)
+	if this.kcp.fastresend <= 0 {
+		resent = 0xffffffff
+	}
+	lost := false
+	segSent := false
+
+	for i := this.start; ; i = this.next[i] {
+		segment := this.data[i]
+		needsend := false
+		if segment.transmit == 0 {
+			needsend = true
+			segment.transmit++
+			segment.timeout = current + this.kcp.rx_rto
+		} else if _itimediff(current, segment.timeout) >= 0 {
+			needsend = true
+			segment.transmit++
+			segment.timeout = current + this.kcp.rx_rto
+			lost = true
+		} else if segment.ackSkipped >= resent {
+			needsend = true
+			segment.transmit++
+			segment.ackSkipped = 0
+			segment.timeout = current + this.kcp.rx_rto
+			lost = true
+		}
+
+		if needsend {
+			segment.Timestamp = current
+			segment.SendingNext = this.kcp.snd_una
+			segment.Opt = 0
+			if this.kcp.state == StateReadyToClose {
+				segment.Opt = SegmentOptionClose
+			}
+
+			this.kcp.output.Write(segment)
+			segSent = true
+		}
+		if i == this.last {
+			break
+		}
+	}
+
+	this.kcp.HandleLost(lost)
+
+	return segSent
+}
+
 type SendingQueue struct {
 	start uint32
 	cap   uint32