fix kcp write

transport/internet/kcp/connection.go

@@ -335,7 +335,7 @@ func (v *Connection) Read(b []byte) (int, error) {
 	}
 }
 
-// Write implements the Conn Write method.
+// Write implements io.Writer.
 func (v *Connection) Write(b []byte) (int, error) {
 	totalWritten := 0
 
@@ -352,6 +352,7 @@ func (v *Connection) Write(b []byte) (int, error) {
 			common.Must(rb.Reset(func(bb []byte) (int, error) {
 				return copy(bb[:v.mss], b[totalWritten:]), nil
 			}))
+			v.dataUpdater.WakeUp()
 			totalWritten += rb.Len()
 			if totalWritten == len(b) {
 				return totalWritten, nil
@@ -376,6 +377,7 @@ func (v *Connection) Write(b []byte) (int, error) {
 	}
 }
 
+// WriteMultiBuffer implements buf.Writer.
 func (v *Connection) WriteMultiBuffer(mb buf.MultiBuffer) error {
 	defer mb.Release()
 
@@ -392,6 +394,7 @@ func (v *Connection) WriteMultiBuffer(mb buf.MultiBuffer) error {
 			common.Must(rb.Reset(func(bb []byte) (int, error) {
 				return mb.Read(bb[:v.mss])
 			}))
+			v.dataUpdater.WakeUp()
 			if mb.IsEmpty() {
 				return nil
 			}

transport/internet/kcp/sending.go

@@ -288,15 +288,15 @@ func (v *SendingWorker) Push() *buf.Buffer {
 	v.Lock()
 	defer v.Unlock()
 
-	if !v.window.IsFull() {
+	if v.window.IsFull() {
-		b := v.window.Push(v.nextNumber)
+		return nil
-		v.nextNumber++
-		return b
 	}
-	return nil
+
+	b := v.window.Push(v.nextNumber)
+	v.nextNumber++
+	return b
 }
 
-// Private: Visible for testing.
 func (v *SendingWorker) Write(seg Segment) error {
 	dataSeg := seg.(*DataSegment)