websocket: Use io.Writer interface

The SendData function type and the Endpoint.Write methods are very close
to what the io.Writer interface provides. Let's use it instead.

pkg/crc/api/websocket/endpoint.go

@@ -1,14 +1,15 @@
 package websocket
 
 import (
+	"io"
 	"sync"
 )
 
 type Endpoint interface {
 	addClient(client *wsClient)
 	deleteClient(client *wsClient)
 	setHandler(handler *EndpointHandler)
-	Write([]byte)
+	io.Writer
 }
 
 type endpoint struct {
@@ -46,7 +47,7 @@ func (e *endpoint) deleteClient(client *wsClient) {
 }
 
 // send data bytes to clients
-func (e *endpoint) Write(data []byte) {
+func (e *endpoint) Write(data []byte) (int, error) {
 	e.clientsMutex.Lock()
 	defer e.clientsMutex.Unlock()
 
@@ -58,6 +59,8 @@ func (e *endpoint) Write(data []byte) {
 			go client.closeSlow()
 		}
 	}
+
+	return len(data), nil
 }
 
 func (e *endpoint) setHandler(handler *EndpointHandler) {

pkg/crc/api/websocket/handler.go

@@ -1,31 +1,33 @@
 package websocket
 
+import (
+	"io"
+)
+
 type EndpointHandler struct {
-	listeners []ConnectionListener
-	sendData  SendData
+	listeners  []ConnectionListener
+	dataSender io.Writer
 }
 
-type SendData func([]byte)
-
 type ConnectionListener interface {
 	// called when first client connected
-	start(sendData SendData)
+	start(dataSender io.Writer)
 	// called when all clients close connections
 	stop()
 }
 
-func NewEndpointHandler(data SendData) *EndpointHandler {
+func NewEndpointHandler(dataSender io.Writer) *EndpointHandler {
 	handler := &EndpointHandler{
-		listeners: make([]ConnectionListener, 0),
-		sendData:  data,
+		listeners:  make([]ConnectionListener, 0),
+		dataSender: dataSender,
 	}
 
 	return handler
 }
 
 func (h *EndpointHandler) hasClient() {
 	for _, l := range h.listeners {
-		l.start(h.sendData)
+		l.start(h.dataSender)
 	}
 }
 

pkg/crc/api/websocket/server.go

@@ -121,7 +121,7 @@ func writeTimeout(ctx goContext.Context, timeout time.Duration, c *websocket.Con
 
 func createStatusEndpoint(machine machine.Client) Endpoint {
 	statusEndpoint := NewEndpoint()
-	statusEndpointHandler := NewEndpointHandler(statusEndpoint.Write)
+	statusEndpointHandler := NewEndpointHandler(statusEndpoint)
 	statusEndpoint.setHandler(statusEndpointHandler)
 	statusEndpointHandler.addListener(NewStatusListener(machine))
 	return statusEndpoint

pkg/crc/api/websocket/status.go

@@ -2,6 +2,7 @@ package websocket
 
 import (
 	"encoding/json"
+	"io"
 	"time"
 
 	"github.com/crc-org/crc/pkg/crc/logging"
@@ -20,7 +21,7 @@ func NewStatusListener(machine machine.Client) ConnectionListener {
 	}
 }
 
-func (s StatusConnectionListener) start(sendData SendData) {
+func (s StatusConnectionListener) start(dataSender io.Writer) {
 
 	ticker := time.NewTicker(2000 * time.Millisecond)
 	go func() {
@@ -41,7 +42,10 @@ func (s StatusConnectionListener) start(sendData SendData) {
 					logging.Errorf("unexpected error during status object to JSON conversion: %v", err)
 					continue
 				}
-				sendData(bytes)
+				_, err = dataSender.Write(bytes)
+				if err != nil {
+					logging.Errorf("unexpected error during writing data to WebSocket: %v", err)
+				}
 			}
 		}
 	}()