Fixed the cancellation

The client was still trying to send event to a full channel even tho no one was listening on it. So we added a `done` channel to tell the goroutine to stop when the client it stoped.

client.go

@@ -80,6 +80,7 @@ type Client struct {
 	password string
 	uuid     string
 	conn     net.Conn
+	done     chan struct{}
 	wg       sync.WaitGroup
 	clientOptions
 }
@@ -167,11 +168,15 @@ func (c *Client) Stop() error {
 		return ErrNotConnected
 	}
 
+	// Close the connection to stop the blocking read call.
 	err := c.conn.Close()
 
+	// In case the goroutine handling the events was trying to send an event
+	// on the channel, we tell it to stop so we can close the event channel safely.
+	close(c.done)
+
 	c.wg.Wait()
 
-	c.conn = nil
 	return err
 }
 
@@ -213,6 +218,7 @@ func (c *Client) register() error {
 // See https://mariadb.com/kb/en/mariadb-maxscale-6-change-data-capture-cdc-protocol/#request-data
 func (c *Client) requestData(database, table, version, gtid string) (<-chan Event, error) {
 	events := make(chan Event, 1)
+	c.done = make(chan struct{}, 1)
 
 	cmd, err := c.formatRequestDataCommand(database, table, version, gtid)
 	if err != nil {
@@ -268,7 +274,14 @@ func (c *Client) handleEvents(data chan<- Event) error {
 		if err != nil {
 			return err
 		}
-		data <- event
+
+		// If the client is stopped, we stop sending events on the channel.
+		// Otherwise it would block forever if no one is receiving from it.
+		select {
+		case data <- event:
+		case <-c.done:
+			return nil
+		}
 	}
 	return scanner.Err()
 }