Implement Ping and PingAsync. Fixes #260

Author: bgrainger

src/MySqlConnector/Core/ServerSession.cs

@@ -507,7 +507,7 @@ private async Task<string> GetRsaPublicKeyAsync(string switchRequestName, Connec
 			throw new MySqlException("Authentication method '{0}' failed. Either use a secure connection, specify the server's RSA public key with ServerRSAPublicKeyFile, or set AllowPublicKeyRetrieval=True.".FormatInvariant(switchRequestName));
 		}
 
-		public async Task<bool> TryPingAsync(IOBehavior ioBehavior, CancellationToken cancellationToken)
+		public async ValueTask<bool> TryPingAsync(IOBehavior ioBehavior, CancellationToken cancellationToken)
 		{
 			VerifyState(State.Connected);
 

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

@@ -135,6 +135,27 @@ private async Task ChangeDatabaseAsync(IOBehavior ioBehavior, string databaseNam
 
 		public new MySqlCommand CreateCommand() => (MySqlCommand) base.CreateCommand();
 
+		public bool Ping() => PingAsync(IOBehavior.Synchronous, CancellationToken.None).GetAwaiter().GetResult();
+		public Task<bool> PingAsync() => PingAsync((m_connectionSettings?.ForceSynchronous ?? false) ? IOBehavior.Synchronous : IOBehavior.Asynchronous, CancellationToken.None).AsTask();
+		public Task<bool> PingAsync(CancellationToken cancellationToken) => PingAsync((m_connectionSettings?.ForceSynchronous ?? false) ? IOBehavior.Synchronous : IOBehavior.Asynchronous, cancellationToken).AsTask();
+
+		private async ValueTask<bool> PingAsync(IOBehavior ioBehavior, CancellationToken cancellationToken)
+		{
+			if (m_session == null)
+				return false;
+			try
+			{
+				if (await m_session.TryPingAsync(ioBehavior, cancellationToken).ConfigureAwait(false))
+					return true;
+			}
+			catch (InvalidOperationException)
+			{
+			}
+
+			SetState(ConnectionState.Closed);
+			return false;
+		}
+
 		public override void Open() => OpenAsync(IOBehavior.Synchronous, CancellationToken.None).GetAwaiter().GetResult();
 
 		public override Task OpenAsync(CancellationToken cancellationToken) =>

tests/MySqlConnector.Tests/ConnectionTests.cs

@@ -152,6 +152,31 @@ public void IncompleteServerHandshake()
 			}
 		}
 
+		[Fact]
+		public void Ping()
+		{
+			using (var connection = new MySqlConnection(m_csb.ConnectionString))
+			{
+				connection.Open();
+				Assert.Equal(ConnectionState.Open, connection.State);
+				Assert.True(connection.Ping());
+				Assert.Equal(ConnectionState.Open, connection.State);
+			}
+		}
+
+		[Fact]
+		public void PingWhenClosed()
+		{
+			using (var connection = new MySqlConnection(m_csb.ConnectionString))
+			{
+				connection.Open();
+				Assert.Equal(ConnectionState.Open, connection.State);
+				m_server.Stop();
+				Assert.False(connection.Ping());
+				Assert.Equal(ConnectionState.Closed, connection.State);
+			}
+		}
+
 		private static async Task WaitForConditionAsync<T>(T expected, Func<T> getValue)
 		{
 			var sw = Stopwatch.StartNew();

tests/MySqlConnector.Tests/FakeMySqlServer.cs

@@ -25,18 +25,21 @@ public void Start()
 
 		public void Stop()
 		{
-			m_cts.Cancel();
-			m_tcpListener.Stop();
-			try
-			{
-				Task.WaitAll(m_tasks.ToArray());
-			}
-			catch (AggregateException)
+			if (m_cts != null)
 			{
+				m_cts.Cancel();
+				m_tcpListener.Stop();
+				try
+				{
+					Task.WaitAll(m_tasks.ToArray());
+				}
+				catch (AggregateException)
+				{
+				}
+				m_tasks.Clear();
+				m_cts.Dispose();
+				m_cts = null;
 			}
-			m_tasks.Clear();
-			m_cts.Dispose();
-			m_cts = null;
 		}
 
 		public int Port => ((IPEndPoint) m_tcpListener.LocalEndpoint).Port;

tests/SideBySide/ConnectAsync.cs

@@ -312,6 +312,32 @@ public async Task CachingSha2WithoutSecureConnection()
 			}
 		}
 
+#if !BASELINE
+		[Fact]
+		public async Task PingNoConnection()
+		{
+			using (var connection = new MySqlConnection())
+				Assert.False(await connection.PingAsync());
+		}
+
+		[Fact]
+		public async Task PingBeforeConnecting()
+		{
+			using (var connection = new MySqlConnection(AppConfig.ConnectionString))
+				Assert.False(await connection.PingAsync());
+		}
+
+		[Fact]
+		public async Task PingConnection()
+		{
+			using (var connection = new MySqlConnection(AppConfig.ConnectionString))
+			{
+				await connection.OpenAsync();
+				Assert.True(await connection.PingAsync());
+			}
+		}
+#endif
+
 		readonly DatabaseFixture m_database;
 	}
 

tests/SideBySide/ConnectSync.cs

@@ -367,6 +367,30 @@ public void Sha256WithoutSecureConnection()
 			}
 		}
 
+		[Fact]
+		public void PingNoConnection()
+		{
+			using (var connection = new MySqlConnection())
+				Assert.False(connection.Ping());
+		}
+
+		[Fact]
+		public void PingBeforeConnecting()
+		{
+			using (var connection = new MySqlConnection(AppConfig.ConnectionString))
+				Assert.False(connection.Ping());
+		}
+
+		[Fact]
+		public void PingConnection()
+		{
+			using (var connection = new MySqlConnection(AppConfig.ConnectionString))
+			{
+				connection.Open();
+				Assert.True(connection.Ping());
+			}
+		}
+
 		readonly DatabaseFixture m_database;
 	}
 }