Adding Abort to C# Websocket (#3352)

# Description of Changes

The implementation of a solution to #3044 , this adds an `Abort`
function to the `WebSocket`, which runs if `Disconnect` is called when
the `WebSocket` is not connected.

# API and ABI breaking changes

Not API breaking.

# Expected complexity level and risk

1

# Testing

- [X] Test locally with a C# CLI test client. 
**Note**: Before change (either on Rust of C# server), server would see
4 `Debug` log entries about connecting, but not see the `Info` log about
the client connection ending like would normally be seen in a
disconnect. After change, server shows no log entries at all, because
connection is properly aborted.
- [x] Test locally with a C# WebGL test client.

---------

Signed-off-by: rekhoff <r.ekhoff@clockworklabs.io>
Co-authored-by: John Detter <4099508+jdetter@users.noreply.github.com>

Author: rekhoff

sdks/csharp/src/SpacetimeDBClient.cs

@@ -508,6 +508,14 @@ public void Disconnect()
             {
                 webSocket.Close();
             }
+#if UNITY_WEBGL && !UNITY_EDITOR
+            else if (webSocket.IsConnecting)
+#else
+            else if (webSocket.IsConnecting || webSocket.IsNoneState)
+#endif
+            {
+                webSocket.Abort(); // forceful during connecting
+            }
 
             _parseCancellationTokenSource.Cancel();
         }

sdks/csharp/src/WebSocket.cs

@@ -38,6 +38,7 @@ public struct ConnectOptions
         private readonly ConcurrentQueue<Action> dispatchQueue = new();
 
         protected ClientWebSocket Ws = new();
+        private CancellationTokenSource? _connectCts;
 
         public WebSocket(ConnectOptions options)
         {
@@ -60,9 +61,13 @@ public WebSocket(ConnectOptions options)
 #if UNITY_WEBGL && !UNITY_EDITOR
         private bool _isConnected = false;
         private bool _isConnecting = false;
+        private bool _cancelConnectRequested = false;
         public bool IsConnected => _isConnected;
-#else
+        public bool IsConnecting => _isConnecting;
+#else 
         public bool IsConnected { get { return Ws != null && Ws.State == WebSocketState.Open; } }
+        public bool IsConnecting { get { return Ws != null && Ws.State == WebSocketState.Connecting; } }
+        public bool IsNoneState { get { return Ws != null && Ws.State == WebSocketState.None; } }
 #endif
 
 #if UNITY_WEBGL && !UNITY_EDITOR
@@ -147,6 +152,7 @@ public async Task Connect(string? auth, string host, string nameOrAddress, Conne
             if (_isConnecting || _isConnected) return;
 
             _isConnecting = true;
+            _cancelConnectRequested = false;
             try
             {
                 var uri = $"{host}/v1/database/{nameOrAddress}/subscribe?connection_id={connectionId}&compression={compression}";
@@ -167,6 +173,11 @@ public async Task Connect(string? auth, string host, string nameOrAddress, Conne
                     dispatchQueue.Enqueue(() => OnConnectError?.Invoke(
                         new Exception("Failed to connect WebSocket")));
                 }
+                else if (_cancelConnectRequested)
+                {
+                    // If cancel was requested before open, proactively close now.
+                    WebSocket_Close(_webglSocketId, (int)WebSocketCloseStatus.NormalClosure, "Canceled during connect.");
+                }
             }
             catch (Exception e)
             {
@@ -192,7 +203,7 @@ public async Task Connect(string? auth, string host, string nameOrAddress, Conne
             var url = new Uri(uri);
             Ws.Options.AddSubProtocol(_options.Protocol);
 
-            var source = new CancellationTokenSource(10000);
+            _connectCts = new CancellationTokenSource(10000);
             if (!string.IsNullOrEmpty(auth))
             {
                 Ws.Options.SetRequestHeader("Authorization", $"Bearer {auth}");
@@ -204,7 +215,7 @@ public async Task Connect(string? auth, string host, string nameOrAddress, Conne
 
             try
             {
-                await Ws.ConnectAsync(url, source.Token);
+                await Ws.ConnectAsync(url, _connectCts.Token);
                 if (Ws.State == WebSocketState.Open)
                 {
                     if (OnConnect != null)
@@ -376,14 +387,35 @@ await Ws.CloseAsync(WebSocketCloseStatus.MessageTooBig, closeMessage,
 #endif
         }
 
+        /// <summary>
+        /// Cancel an in-flight ConnectAsync. Safe to call if no connect is pending.
+        /// </summary>
+        public void CancelConnect()
+        {
+#if UNITY_WEBGL && !UNITY_EDITOR
+            // No CTS on WebGL. Mark cancel intent so that when socket id arrives or open fires,
+            // we immediately close and avoid reporting a connected state.
+            _cancelConnectRequested = true;
+#else
+            try { _connectCts?.Cancel(); } catch { /* ignore */ }
+#endif
+        }
+
         public Task Close(WebSocketCloseStatus code = WebSocketCloseStatus.NormalClosure)
         {
 #if UNITY_WEBGL && !UNITY_EDITOR
-            if (_isConnected && _webglSocketId >= 0)
+            if (_webglSocketId >= 0)
             {
+                // If connected or connecting with a valid socket id, request a close.
                 WebSocket_Close(_webglSocketId, (int)code, "Disconnecting normally.");
+                _cancelConnectRequested = false; // graceful close intent
                 _isConnected = false;
             }
+            else if (_isConnecting)
+            {
+                // We don't yet have a socket id; remember to cancel once it arrives/opens.
+                _cancelConnectRequested = true;
+            }
 #else
             if (Ws?.State == WebSocketState.Open)
             {
@@ -393,6 +425,35 @@ public Task Close(WebSocketCloseStatus code = WebSocketCloseStatus.NormalClosure
             return Task.CompletedTask;
         }
 
+        /// <summary>
+        /// Forcefully abort the WebSocket connection. This terminates any in-flight connect/receive/send
+        /// and ensures the server-side socket is torn down promptly. Prefer Close() for graceful shutdowns.
+        /// </summary>
+        public void Abort()
+        {
+#if UNITY_WEBGL && !UNITY_EDITOR
+            if (_webglSocketId >= 0)
+            {
+                WebSocket_Close(_webglSocketId, (int)WebSocketCloseStatus.NormalClosure, "Aborting connection.");
+                _isConnected = false;
+            }
+            else if (_isConnecting)
+            {
+                // No socket yet; ensure we close immediately once it opens.
+                _cancelConnectRequested = true;
+            }
+#else
+            try
+            {
+                Ws?.Abort();
+            }
+            catch
+            {
+                // Intentionally swallow; Abort is best-effort.
+            }
+#endif
+        }
+
         private Task? senderTask;
         private readonly ConcurrentQueue<ClientMessage> messageSendQueue = new();
 
@@ -459,11 +520,21 @@ public WebSocketState GetState()
         {
             return Ws!.State;
         }
+
 #if UNITY_WEBGL && !UNITY_EDITOR
         public void HandleWebGLOpen(int socketId)
         {
             if (socketId == _webglSocketId)
             {
+                if (_cancelConnectRequested)
+                {
+                    // Immediately close instead of reporting connected.
+                    WebSocket_Close(_webglSocketId, (int)WebSocketCloseStatus.NormalClosure, "Canceled during connect.");
+                    _isConnecting = false;
+                    _isConnected = false;
+                    _cancelConnectRequested = false;
+                    return;
+                }
                 _isConnected = true;
                 if (OnConnect != null)
                     dispatchQueue.Enqueue(() => OnConnect());
@@ -484,6 +555,9 @@ public void HandleWebGLClose(int socketId, int code, string reason)
             if (socketId == _webglSocketId && OnClose != null)
             {
                 _isConnected = false;
+                _isConnecting = false;
+                _webglSocketId = -1;
+                _cancelConnectRequested = false;
                 var ex = code != (int)WebSocketCloseStatus.NormalClosure ? new Exception($"WebSocket closed with code {code}: {reason}") : null;
                 dispatchQueue.Enqueue(() => OnClose?.Invoke(ex));
             }
@@ -494,6 +568,8 @@ public void HandleWebGLError(int socketId)
             UnityEngine.Debug.Log($"HandleWebGLError: {socketId}");
             if (socketId == _webglSocketId && OnConnectError != null)
             {
+                _isConnecting = false;
+                _webglSocketId = -1;
                 dispatchQueue.Enqueue(() => OnConnectError(new Exception($"Socket {socketId} error.")));
             }
         }