vendor: Update github.com/xtaci/kcp

vendor/github.com/xtaci/kcp-go/emitter.go

@@ -0,0 +1,50 @@
+package kcp
+
+import (
+	"net"
+	"sync/atomic"
+)
+
+var defaultEmitter Emitter
+
+const emitQueue = 8192
+
+func init() {
+	defaultEmitter.init()
+}
+
+type (
+	emitPacket struct {
+		conn    net.PacketConn
+		to      net.Addr
+		data    []byte
+		recycle bool
+	}
+
+	// Emitter is the global packet sender
+	Emitter struct {
+		ch chan emitPacket
+	}
+)
+
+func (e *Emitter) init() {
+	e.ch = make(chan emitPacket, emitQueue)
+	go e.emitTask()
+}
+
+// keepon writing packets to kernel
+func (e *Emitter) emitTask() {
+	for p := range e.ch {
+		if n, err := p.conn.WriteTo(p.data, p.to); err == nil {
+			atomic.AddUint64(&DefaultSnmp.OutSegs, 1)
+			atomic.AddUint64(&DefaultSnmp.OutBytes, uint64(n))
+		}
+		if p.recycle {
+			xmitBuf.Put(p.data)
+		}
+	}
+}
+
+func (e *Emitter) emit(p emitPacket) {
+	e.ch <- p
+}