From 165e323fab58eba59dd45e9eb4d53aa74a937460 Mon Sep 17 00:00:00 2001
From: v2ray <admin@v2ray.com>
Date: Mon, 4 Jul 2016 13:37:42 +0200
Subject: [PATCH] refine sending window size

---
 transport/internet/kcp/config.go       |  6 +++++-
 transport/internet/kcp/sending.go      | 11 +++++++++--
 transport/internet/kcp/sending_test.go |  2 +-
 3 files changed, 15 insertions(+), 4 deletions(-)

diff --git a/transport/internet/kcp/config.go b/transport/internet/kcp/config.go
index 5e8345dd..e64674c3 100644
--- a/transport/internet/kcp/config.go
+++ b/transport/internet/kcp/config.go
@@ -14,7 +14,7 @@ func (this *Config) Apply() {
 	effectiveConfig = *this
 }
 
-func (this *Config) GetSendingWindowSize() uint32 {
+func (this *Config) GetSendingInFlightSize() uint32 {
 	size := this.UplinkCapacity * 1024 * 1024 / this.Mtu / (1000 / this.Tti) / 2
 	if size == 0 {
 		size = 8
@@ -22,6 +22,10 @@ func (this *Config) GetSendingWindowSize() uint32 {
 	return size
 }
 
+func (this *Config) GetSendingWindowSize() uint32 {
+	return this.GetSendingInFlightSize() * 4
+}
+
 func (this *Config) GetSendingQueueSize() uint32 {
 	return this.WriteBuffer / this.Mtu
 }
diff --git a/transport/internet/kcp/sending.go b/transport/internet/kcp/sending.go
index e1c6fcb7..97cb3fbe 100644
--- a/transport/internet/kcp/sending.go
+++ b/transport/internet/kcp/sending.go
@@ -16,11 +16,12 @@ type SendingWindow struct {
 	prev []uint32
 	next []uint32
 
+	inFlightSize uint32
 	writer       SegmentWriter
 	onPacketLoss func(bool)
 }
 
-func NewSendingWindow(size uint32, writer SegmentWriter, onPacketLoss func(bool)) *SendingWindow {
+func NewSendingWindow(size uint32, inFlightSize uint32, writer SegmentWriter, onPacketLoss func(bool)) *SendingWindow {
 	window := &SendingWindow{
 		start:        0,
 		cap:          size,
@@ -31,6 +32,7 @@ func NewSendingWindow(size uint32, writer SegmentWriter, onPacketLoss func(bool)
 		next:         make([]uint32, size),
 		writer:       writer,
 		onPacketLoss: onPacketLoss,
+		inFlightSize: inFlightSize,
 	}
 	return window
 }
@@ -116,6 +118,7 @@ func (this *SendingWindow) Flush(current uint32, resend uint32, rto uint32) {
 	}
 
 	lost := false
+	var inFlightSize uint32
 
 	for i := this.start; ; i = this.next[i] {
 		segment := this.data[i]
@@ -139,6 +142,10 @@ func (this *SendingWindow) Flush(current uint32, resend uint32, rto uint32) {
 
 		if needsend {
 			this.writer.Write(segment)
+			inFlightSize++
+			if inFlightSize >= this.inFlightSize {
+				break
+			}
 		}
 		if i == this.last {
 			break
@@ -230,7 +237,7 @@ func NewSendingWorker(kcp *KCP) *SendingWorker {
 		windowSize:       effectiveConfig.GetSendingWindowSize(),
 		controlWindow:    effectiveConfig.GetSendingWindowSize(),
 	}
-	worker.window = NewSendingWindow(effectiveConfig.GetSendingWindowSize(), worker, worker.OnPacketLoss)
+	worker.window = NewSendingWindow(effectiveConfig.GetSendingWindowSize(), effectiveConfig.GetSendingInFlightSize(), worker, worker.OnPacketLoss)
 	return worker
 }
 
diff --git a/transport/internet/kcp/sending_test.go b/transport/internet/kcp/sending_test.go
index 6e8709ad..39e9ea10 100644
--- a/transport/internet/kcp/sending_test.go
+++ b/transport/internet/kcp/sending_test.go
@@ -66,7 +66,7 @@ func TestSendingQueueClear(t *testing.T) {
 func TestSendingWindow(t *testing.T) {
 	assert := assert.On(t)
 
-	window := NewSendingWindow(5, nil, nil)
+	window := NewSendingWindow(5, 5, nil, nil)
 	window.Push(&DataSegment{
 		Number: 0,
 	})