Throttle message sends

Ooui/Client.js

@@ -114,9 +114,13 @@ socket.addEventListener('open', function (event) {
 });
 
 socket.addEventListener('message', function (event) {
-    const message = JSON.parse (event.data);
+    const messages = JSON.parse (event.data);
-    // console.log('Raw value from server', message.v);
+    console.log("Messages", messages);
-    message.v = fixupValue (message.v);
+    if (Array.isArray (messages)) {
-    // console.log('Message from server', message);
+        messages.forEach (function (m) {
-    processMessage (message);
+            // console.log('Raw value from server', m.v);
+            m.v = fixupValue (m.v);
+            processMessage (m);
+        });
+    }
 });

Ooui/UI.cs

@@ -228,8 +228,8 @@ namespace Ooui
             // Create a new session and let it handle everything from here
             //
             try {
-                var session = new Session (webSocket, element);
+                var session = new Session (webSocket, element, serverToken);
-                await session.RunAsync (serverToken).ConfigureAwait (false);
+                await session.RunAsync ().ConfigureAwait (false);
             }
             catch (WebSocketException ex) when (ex.WebSocketErrorCode == WebSocketError.ConnectionClosedPrematurely) {
                 // The remote party closed the WebSocket connection without completing the close handshake.
@@ -242,50 +242,6 @@ namespace Ooui
             }
         }
 
-        static async Task SendMessageAsync (WebSocket webSocket, Message message, EventTarget target, HashSet<string> createdIds, CancellationToken token)
-        {
-            //
-            // Make sure all the referenced objects have been created
-            //
-            if (message.MessageType == MessageType.Create) {
-                createdIds.Add (message.TargetId);
-            }
-            else {
-                if (!createdIds.Contains (message.TargetId)) {
-                    createdIds.Add (message.TargetId);
-                    await SendStateMessagesAsync (webSocket, target.GetElementById (message.TargetId), createdIds, token).ConfigureAwait (false);
-                }
-                if (message.Value is Array a) {
-                    for (var i = 0; i < a.Length; i++) {
-                        // Console.WriteLine ($"A{i} = {a.GetValue(i)}");
-                        if (a.GetValue (i) is EventTarget e && !createdIds.Contains (e.Id)) {
-                            createdIds.Add (e.Id);
-                            await SendStateMessagesAsync (webSocket, e, createdIds, token).ConfigureAwait (false);
-                        }
-                    }
-                }
-            }
-
-            //
-            // Now actually send this message
-            //
-            if (token.IsCancellationRequested)
-                return;
-            var json = Newtonsoft.Json.JsonConvert.SerializeObject (message);
-            var outputBuffer = new ArraySegment<byte> (Encoding.UTF8.GetBytes (json));
-            await webSocket.SendAsync (outputBuffer, WebSocketMessageType.Text, true, token).ConfigureAwait (false);
-        }
-
-        static async Task SendStateMessagesAsync (WebSocket webSocket, EventTarget target, HashSet<string> createdIds, CancellationToken token)
-        {
-            if (target == null) return;
-
-            foreach (var m in target.StateMessages) {
-                if (token.IsCancellationRequested) return;
-                await SendMessageAsync (webSocket, m, target, createdIds, token).ConfigureAwait (false);
-            }
-        }
-
         static void Error (string message, Exception ex)
         {
             Console.ForegroundColor = ConsoleColor.Red;
@@ -297,27 +253,35 @@ namespace Ooui
         {
             readonly WebSocket webSocket;
             readonly Element element;
+            readonly Action<Message> handleElementMessageSent;
 
-            public Session (WebSocket webSocket, Element element)
+            readonly CancellationTokenSource sessionCts = new CancellationTokenSource ();
+            readonly CancellationTokenSource linkedCts;
+            readonly CancellationToken token;
+
+            readonly HashSet<string> createdIds;
+            readonly List<Message> queuedMessages = new List<Message> ();
+
+            readonly System.Timers.Timer sendThrottle;
+            DateTime lastTransmitTime = DateTime.MinValue;
+            readonly TimeSpan throttleInterval = TimeSpan.FromSeconds (1.0 / 30); // 30 FPS max
+
+            public Session (WebSocket webSocket, Element element, CancellationToken serverToken)
             {
                 this.webSocket = webSocket;
                 this.element = element;
-            }
 
-            public async Task RunAsync (CancellationToken serverToken)
-            {
                 //
                 // Create a new session cancellation token that will trigger
                 // automatically if the server shutsdown or the session shutsdown.
                 //
-                var sessionCts = new CancellationTokenSource ();
+                linkedCts = CancellationTokenSource.CreateLinkedTokenSource (serverToken, sessionCts.Token);
-                var linkedCts = CancellationTokenSource.CreateLinkedTokenSource (serverToken, sessionCts.Token);
+                token = linkedCts.Token;
-                var token = linkedCts.Token;
 
                 //
                 // Keep a list of all the elements for which we've transmitted the initial state
                 //
-                var createdIds = new HashSet<string> {
+                createdIds = new HashSet<string> {
                     "window",
                     "document",
                     "document.body",
@@ -326,38 +290,38 @@ namespace Ooui
                 //
                 // Preparse handlers for the element
                 //
-                Action<Message> onElementMessage = null;
+                handleElementMessageSent = QueueMessage;
-                onElementMessage = async m => {
+
-                    if (webSocket == null) return;
+                //
-                    try {
+                // Create a timer to use as a throttle when sending messages
-                        await SendMessageAsync (webSocket, m, element, createdIds, token).ConfigureAwait (false);
+                //
-                    }
+                sendThrottle = new System.Timers.Timer (throttleInterval.TotalMilliseconds);
-                    catch (Exception ex) {                        
+                sendThrottle.Elapsed += (s, e) => {
-                        if (webSocket.State == WebSocketState.Aborted) {
+                    // e.SignalTime
-                            Error ("WebSocket is aborted, cancelling session", ex);
+                    System.Console.WriteLine ("TICK SEND THROTTLE FOR {0}", element);
-                            element.MessageSent -= onElementMessage;
+                    if ((e.SignalTime - lastTransmitTime) >= throttleInterval) {
-                            sessionCts.Cancel ();
+                        sendThrottle.Enabled = false;
-                        }
+                        lastTransmitTime = e.SignalTime;
-                        else {
+                        TransmitQueuedMessages ();
-                            Error ("Failed to handle element message", ex);
-                        }
                     }
                 };
+            }
 
+            public async Task RunAsync ()
+            {
                 //
                 // Start watching for changes in the element
                 //
-                element.MessageSent += onElementMessage;
+                element.MessageSent += handleElementMessageSent;
 
                 try {
                     //
                     // Add it to the document body
                     //
-                    await SendMessageAsync (webSocket, Message.Call ("document.body", "appendChild", element),
+                    QueueMessage (Message.Call ("document.body", "appendChild", element));
-                        element, createdIds, token).ConfigureAwait (false);
 
                     //
-                    // Listen for events
+                    // Start the Read Loop
                     //
                     var receiveBuffer = new byte[1024];
 
@@ -396,7 +360,74 @@ namespace Ooui
                     }
                 }
                 finally {
-                    element.MessageSent -= onElementMessage;
+                    element.MessageSent -= handleElementMessageSent;
+                }
+            }
+
+            void QueueStateMessages (EventTarget target)
+            {
+                if (target == null) return;
+                foreach (var m in target.StateMessages) {
+                    QueueMessage (m);
+                }
+            }
+
+            void QueueMessage (Message message)
+            {
+                //
+                // Make sure all the referenced objects have been created
+                //
+                if (message.MessageType == MessageType.Create) {
+                    createdIds.Add (message.TargetId);
+                }
+                else {
+                    if (!createdIds.Contains (message.TargetId)) {
+                        createdIds.Add (message.TargetId);
+                        QueueStateMessages (element.GetElementById (message.TargetId));
+                    }
+                    if (message.Value is Array a) {
+                        for (var i = 0; i < a.Length; i++) {
+                            // Console.WriteLine ($"A{i} = {a.GetValue(i)}");
+                            if (a.GetValue (i) is EventTarget e && !createdIds.Contains (e.Id)) {
+                                createdIds.Add (e.Id);
+                                QueueStateMessages (e);
+                            }
+                        }
+                    }
+                }
+
+                //
+                // Add it to the queue
+                //
+                lock (queuedMessages) queuedMessages.Add (message);
+                sendThrottle.Enabled = true;
+            }
+
+            async void TransmitQueuedMessages ()
+            {
+                try {
+                    //
+                    // Dequeue as many messages as we can
+                    //
+                    var messagesToSend = new List<Message> ();
+                    lock (queuedMessages) {
+                        messagesToSend.AddRange (queuedMessages);
+                        queuedMessages.Clear ();
+                    }
+                    if (messagesToSend.Count == 0)
+                        return;
+
+                    //
+                    // Now actually send this message
+                    //
+                    var json = Newtonsoft.Json.JsonConvert.SerializeObject (messagesToSend);
+                    var outputBuffer = new ArraySegment<byte> (Encoding.UTF8.GetBytes (json));
+                    await webSocket.SendAsync (outputBuffer, WebSocketMessageType.Text, true, token).ConfigureAwait (false);
+                }
+                catch (Exception ex) {                        
+                    Error ("Failed to send queued messages, aborting session", ex);
+                    element.MessageSent -= handleElementMessageSent;
+                    sessionCts.Cancel ();
                 }
             }
         }