feat: 新增ReadMessageAsync接口,进行不阻塞读取消息

conn.go

@@ -967,28 +967,12 @@ func (c *Conn) handleProtocolError(message string) error {
 // permanent. Once this method returns a non-nil error, all subsequent calls to
 // this method return the same error.
 func (c *Conn) NextReader() (messageType int, r io.Reader, err error) {
-	// Close previous reader, only relevant for decompression.
-	if c.reader != nil {
-		c.reader.Close()
-		c.reader = nil
-	}
-
-	c.messageReader = nil
-	c.readLength = 0
-
 	for c.readErr == nil {
-		frameType, err := c.advanceFrame()
+		frameType, _, err := c.nextReader()
 		if err != nil {
-			c.readErr = hideTempErr(err)
 			break
 		}
-
 		if frameType == TextMessage || frameType == BinaryMessage {
-			c.messageReader = &messageReader{c}
-			c.reader = c.messageReader
-			if c.readDecompress {
-				c.reader = c.newDecompressionReader(c.reader)
-			}
 			return frameType, c.reader, nil
 		}
 	}
@@ -1004,6 +988,29 @@ func (c *Conn) NextReader() (messageType int, r io.Reader, err error) {
 	return noFrame, nil, c.readErr
 }
 
+func (c *Conn) nextReader() (messageType int, r io.Reader, err error) {
+	if c.reader != nil {
+		c.reader.Close()
+		c.reader = nil
+	}
+
+	c.messageReader = nil
+	c.readLength = 0
+
+	frameType, err := c.advanceFrame()
+	if err != nil {
+		c.readErr = hideTempErr(err)
+	} else if frameType == TextMessage || frameType == BinaryMessage {
+		c.messageReader = &messageReader{c}
+		c.reader = c.messageReader
+		if c.readDecompress {
+			c.reader = c.newDecompressionReader(c.reader)
+		}
+		return frameType, c.reader, nil
+	}
+	return noFrame, nil, c.readErr
+}
+
 type messageReader struct{ c *Conn }
 
 func (r *messageReader) Read(b []byte) (int, error) {
@@ -1069,6 +1076,18 @@ func (c *Conn) ReadMessage() (messageType int, p []byte, err error) {
 	return messageType, p, err
 }
 
+// ReadMessage is a helper method for getting a reader using NextReader and
+// reading from that reader to a buffer.
+func (c *Conn) ReadMessageAsync() (messageType int, p []byte, err error) {
+	var r io.Reader
+	messageType, r, err = c.nextReader()
+	if err != nil {
+		return messageType, nil, err
+	}
+	p, err = ioutil.ReadAll(r)
+	return messageType, p, err
+}
+
 // SetReadDeadline sets the read deadline on the underlying network connection.
 // After a read has timed out, the websocket connection state is corrupt and
 // all future reads will return an error. A zero value for t means reads will