Fix connection timeout when server doesn't respond. Fixes #739

Author: bgrainger

src/MySqlConnector/Core/ConnectionPool.cs

@@ -20,7 +20,7 @@ internal sealed class ConnectionPool
 
 		public SslProtocols SslProtocols { get; set; }
 
-		public async ValueTask<ServerSession> GetSessionAsync(MySqlConnection connection, IOBehavior ioBehavior, CancellationToken cancellationToken)
+		public async ValueTask<ServerSession> GetSessionAsync(MySqlConnection connection, int startTickCount, IOBehavior ioBehavior, CancellationToken cancellationToken)
 		{
 			cancellationToken.ThrowIfCancellationRequested();
 
@@ -108,7 +108,7 @@ public async ValueTask<ServerSession> GetSessionAsync(MySqlConnection connection
 				session = new ServerSession(this, m_generation, Interlocked.Increment(ref m_lastSessionId));
 				if (Log.IsInfoEnabled())
 					Log.Info("Pool{0} no pooled session available; created new Session{1}", m_logArguments[0], session.Id);
-				await session.ConnectAsync(ConnectionSettings, m_loadBalancer, ioBehavior, cancellationToken).ConfigureAwait(false);
+				await session.ConnectAsync(ConnectionSettings, startTickCount, m_loadBalancer, ioBehavior, cancellationToken).ConfigureAwait(false);
 				AdjustHostConnectionCount(session, 1);
 				session.OwningConnection = new WeakReference<MySqlConnection>(connection);
 				int leasedSessionsCountNew;
@@ -353,7 +353,7 @@ private async Task CreateMinimumPooledSessions(IOBehavior ioBehavior, Cancellati
 				{
 					var session = new ServerSession(this, m_generation, Interlocked.Increment(ref m_lastSessionId));
 					Log.Info("Pool{0} created Session{1} to reach minimum pool size", m_logArguments[0], session.Id);
-					await session.ConnectAsync(ConnectionSettings, m_loadBalancer, ioBehavior, cancellationToken).ConfigureAwait(false);
+					await session.ConnectAsync(ConnectionSettings, Environment.TickCount, m_loadBalancer, ioBehavior, cancellationToken).ConfigureAwait(false);
 					AdjustHostConnectionCount(session, 1);
 					lock (m_sessions)
 						m_sessions.AddFirst(session);

src/MySqlConnector/Core/ServerSession.cs

@@ -309,7 +309,7 @@ public async Task DisposeAsync(IOBehavior ioBehavior, CancellationToken cancella
 				m_state = State.Closed;
 		}
 
-		public async Task ConnectAsync(ConnectionSettings cs, ILoadBalancer? loadBalancer, IOBehavior ioBehavior, CancellationToken cancellationToken)
+		public async Task ConnectAsync(ConnectionSettings cs, int startTickCount, ILoadBalancer? loadBalancer, IOBehavior ioBehavior, CancellationToken cancellationToken)
 		{
 			try
 			{
@@ -349,6 +349,8 @@ public async Task ConnectAsync(ConnectionSettings cs, ILoadBalancer? loadBalance
 					}
 
 					var byteHandler = m_socket is null ? new StreamByteHandler(m_stream!) : (IByteHandler) new SocketByteHandler(m_socket);
+					if (cs.ConnectionTimeout != 0)
+						byteHandler.RemainingTimeout = Math.Max(1, cs.ConnectionTimeoutMilliseconds - unchecked(Environment.TickCount - startTickCount));
 					m_payloadHandler = new StandardPayloadHandler(byteHandler);
 
 					payload = await ReceiveAsync(ioBehavior, cancellationToken).ConfigureAwait(false);

src/MySqlConnector/MySql.Data.MySqlClient/MySqlConnection.cs

@@ -287,6 +287,8 @@ private async Task OpenAsync(IOBehavior? ioBehavior, CancellationToken cancellat
 			if (State != ConnectionState.Closed)
 				throw new InvalidOperationException("Cannot Open when State is {0}.".FormatInvariant(State));
 
+			var openStartTickCount = Environment.TickCount;
+
 			SetState(ConnectionState.Connecting);
 
 			var pool = ConnectionPool.GetPool(m_connectionString);
@@ -309,7 +311,7 @@ private async Task OpenAsync(IOBehavior? ioBehavior, CancellationToken cancellat
 
 			try
 			{
-				m_session = await CreateSessionAsync(pool, ioBehavior, cancellationToken).ConfigureAwait(false);
+				m_session = await CreateSessionAsync(pool, openStartTickCount, ioBehavior, cancellationToken).ConfigureAwait(false);
 
 				m_hasBeenOpened = true;
 				SetState(ConnectionState.Open);
@@ -621,7 +623,7 @@ internal void FinishQuerying(bool hasWarnings)
 			}
 		}
 
-		private async ValueTask<ServerSession> CreateSessionAsync(ConnectionPool? pool, IOBehavior? ioBehavior, CancellationToken cancellationToken)
+		private async ValueTask<ServerSession> CreateSessionAsync(ConnectionPool? pool, int startTickCount, IOBehavior? ioBehavior, CancellationToken cancellationToken)
 		{
 			var connectionSettings = GetInitializedConnectionSettings();
 			var actualIOBehavior = ioBehavior ?? (connectionSettings.ForceSynchronous ? IOBehavior.Synchronous : IOBehavior.Asynchronous);
@@ -633,7 +635,7 @@ private async ValueTask<ServerSession> CreateSessionAsync(ConnectionPool? pool,
 				// the cancellation token for connection is controlled by 'cancellationToken' (if it can be cancelled), ConnectionTimeout
 				// (from the connection string, if non-zero), or a combination of both
 				if (connectionSettings.ConnectionTimeout != 0)
-					timeoutSource = new CancellationTokenSource(TimeSpan.FromMilliseconds(connectionSettings.ConnectionTimeoutMilliseconds));
+					timeoutSource = new CancellationTokenSource(TimeSpan.FromMilliseconds(Math.Max(1, connectionSettings.ConnectionTimeoutMilliseconds - unchecked(Environment.TickCount - startTickCount))));
 				if (cancellationToken.CanBeCanceled && timeoutSource is object)
 					linkedSource = CancellationTokenSource.CreateLinkedTokenSource(cancellationToken, timeoutSource.Token);
 				var connectToken = linkedSource?.Token ?? timeoutSource?.Token ?? cancellationToken;
@@ -642,7 +644,7 @@ private async ValueTask<ServerSession> CreateSessionAsync(ConnectionPool? pool,
 				if (pool is object)
 				{
 					// this returns an open session
-					return await pool.GetSessionAsync(this, actualIOBehavior, connectToken).ConfigureAwait(false);
+					return await pool.GetSessionAsync(this, startTickCount, actualIOBehavior, connectToken).ConfigureAwait(false);
 				}
 				else
 				{
@@ -653,7 +655,7 @@ private async ValueTask<ServerSession> CreateSessionAsync(ConnectionPool? pool,
 					var session = new ServerSession();
 					session.OwningConnection = new WeakReference<MySqlConnection>(this);
 					Log.Info("Created new non-pooled Session{0}", session.Id);
-					await session.ConnectAsync(connectionSettings, loadBalancer, actualIOBehavior, connectToken).ConfigureAwait(false);
+					await session.ConnectAsync(connectionSettings, startTickCount, loadBalancer, actualIOBehavior, connectToken).ConfigureAwait(false);
 					return session;
 				}
 			}
@@ -662,6 +664,10 @@ private async ValueTask<ServerSession> CreateSessionAsync(ConnectionPool? pool,
 				var messageSuffix = (pool?.IsEmpty ?? false) ? " All pooled connections are in use." : "";
 				throw new MySqlException(MySqlErrorCode.UnableToConnectToHost, "Connect Timeout expired." + messageSuffix, ex);
 			}
+			catch (MySqlException ex) when (timeoutSource?.IsCancellationRequested ?? false)
+			{
+				throw new MySqlException(MySqlErrorCode.UnableToConnectToHost, "Connect Timeout expired.", ex);
+			}
 			finally
 			{
 				linkedSource?.Dispose();

tests/MySqlConnector.Tests/ConnectionTests.cs

@@ -184,6 +184,26 @@ public void PingWhenClosed()
 			Assert.Equal(ConnectionState.Closed, connection.State);
 		}
 
+		[Fact]
+		public void ConnectionTimeout()
+		{
+			m_server.BlockOnConnect = true;
+			var csb = new MySqlConnectionStringBuilder(m_csb.ConnectionString);
+			csb.ConnectionTimeout = 4;
+			using var connection = new MySqlConnection(csb.ConnectionString);
+			var stopwatch = Stopwatch.StartNew();
+			try
+			{
+				connection.Open();
+				Assert.False(true);
+			}
+			catch (MySqlException ex)
+			{
+				Assert.InRange(stopwatch.ElapsedMilliseconds, 3900, 4100);
+				Assert.Equal(MySqlErrorCode.UnableToConnectToHost, (MySqlErrorCode) ex.Number);
+			}
+		}
+
 		private static async Task WaitForConditionAsync<T>(T expected, Func<T> getValue)
 		{
 			var sw = Stopwatch.StartNew();

tests/MySqlConnector.Tests/FakeMySqlServer.cs

@@ -50,6 +50,7 @@ public void Stop()
 
 		public bool SuppressAuthPluginNameTerminatingNull { get; set; }
 		public bool SendIncompletePostHandshakeResponse { get; set; }
+		public bool BlockOnConnect { get; set; }
 
 		internal void ClientDisconnected() => Interlocked.Decrement(ref m_activeConnections);
 

tests/MySqlConnector.Tests/FakeMySqlServerConnection.cs

@@ -26,6 +26,9 @@ public async Task RunAsync(TcpClient client, CancellationToken token)
 				using (client)
 				using (var stream = client.GetStream())
 				{
+					if (m_server.BlockOnConnect)
+						Thread.Sleep(TimeSpan.FromSeconds(10));
+
 					await SendAsync(stream, 0, WriteInitialHandshake);
 					await ReadPayloadAsync(stream, token); // handshake response