feat: 支持对 server.Conn 写入时调用带有 Callback 的写入函数

新增 server.Conn.WriteWithCallback() 和
server.Conn.WriteStringWithCallback()

server/conn.go

@@ -137,6 +137,12 @@ func (slf *Conn) WriteString(data string, messageType ...int) {
 	slf.Write([]byte(data), messageType...)
 }
 
+// WriteStringWithCallback 与 WriteString 相同，但是会在写入完成后调用 callback
+//   - 当 callback 为 nil 时，与 WriteString 相同
+func (slf *Conn) WriteStringWithCallback(data string, callback func(err error), messageType ...int) {
+	slf.WriteWithCallback([]byte(data), callback, messageType...)
+}
+
 // Write 向连接中写入数据
 //   - messageType: websocket模式中指定消息类型
 func (slf *Conn) Write(data []byte, messageType ...int) {
@@ -153,6 +159,23 @@ func (slf *Conn) Write(data []byte, messageType ...int) {
 	slf.mutex.Unlock()
 }
 
+// WriteWithCallback 与 Write 相同，但是会在写入完成后调用 callback
+//   - 当 callback 为 nil 时，与 Write 相同
+func (slf *Conn) WriteWithCallback(data []byte, callback func(err error), messageType ...int) {
+	if slf.packetPool == nil {
+		return
+	}
+	cp := slf.packetPool.Get()
+	if len(messageType) > 0 {
+		cp.websocketMessageType = messageType[0]
+	}
+	cp.packet = data
+	cp.callback = callback
+	slf.mutex.Lock()
+	slf.packets = append(slf.packets, cp)
+	slf.mutex.Unlock()
+}
+
 // writeLoop 写循环
 func (slf *Conn) writeLoop(wait *sync.WaitGroup) {
 	slf.packetPool = synchronization.NewPool[*connPacket](10*1024,
@@ -161,6 +184,7 @@ func (slf *Conn) writeLoop(wait *sync.WaitGroup) {
 		}, func(data *connPacket) {
 			data.packet = nil
 			data.websocketMessageType = 0
+			data.callback = nil
 		},
 	)
 	defer func() {
@@ -210,9 +234,14 @@ func (slf *Conn) writeLoop(wait *sync.WaitGroup) {
 					_, err = slf.kcp.Write(data.packet)
 				}
 			}
+			callback := data.callback
 			slf.packetPool.Release(data)
 			if err != nil {
-				panic(err)
+				if callback != nil {
+					callback(err)
+				} else {
+					panic(err)
+				}
 			}
 		}
 	}

server/conn_packet.go

@@ -3,4 +3,5 @@ package server
 type connPacket struct {
 	websocketMessageType int
 	packet               []byte
+	callback             func(err error)
 }