Merge pull request #228 from caleblloyd/f_connection_lifetime

Implement Connection Lifetime.

Author: bgrainger

docs/content/connection-options.md

@@ -103,6 +103,11 @@ Connection pooling is enabled by default.  These options are used to configure i
     <td>true</td>
     <td>When true, the MySqlConnection object is drawn from the appropriate pool, or if necessary, is created and added to the appropriate pool. Recognized values are true, false, yes, and no.</td>
   </tr>
+  <tr>
+    <td>Connection Lifetime, ConnectionLifeTime</td>
+    <td>0</td>
+    <td>When a connection is returned to the pool, its creation time is compared with the current time, and the connection is destroyed if that time span (in seconds) exceeds the value specified by Connection Lifetime. This is useful in clustered configurations to force load balancing between a running server and a server just brought online. A value of zero (0) causes pooled connections to have the maximum connection timeout.</td>
+  </tr>
   <tr>
     <td>Connection Reset, ConnectionReset	</td>
     <td>false</td>

src/MySqlConnector/MySqlClient/ConnectionPool.cs

@@ -53,11 +53,26 @@ public async Task<MySqlSession> GetSessionAsync(IOBehavior ioBehavior, Cancellat
 			}
 		}
 
+		private bool SessionIsHealthy(MySqlSession session)
+		{
+			if (!session.IsConnected)
+				return false;
+			if (session.PoolGeneration != m_generation)
+				return false;
+			if (session.DatabaseOverride != null)
+				return false;
+			if (m_connectionSettings.ConnectionLifeTime > 0
+			    && (DateTime.UtcNow - session.CreatedUtc).TotalSeconds >= m_connectionSettings.ConnectionLifeTime)
+				return false;
+
+			return true;
+		}
+
 		public void Return(MySqlSession session)
 		{
 			try
 			{
-				if (session.IsConnected && session.PoolGeneration == m_generation && session.DatabaseOverride == null)
+				if (SessionIsHealthy(session))
 					m_sessions.Enqueue(session);
 				else
 					session.DisposeAsync(IOBehavior.Synchronous, CancellationToken.None).ConfigureAwait(false);

src/MySqlConnector/MySqlClient/MySqlConnectionStringBuilder.cs

@@ -73,6 +73,12 @@ public bool Pooling
 			set => MySqlConnectionStringOption.Pooling.SetValue(this, value);
 		}
 
+		public uint ConnectionLifeTime
+		{
+			get => MySqlConnectionStringOption.ConnectionLifeTime.GetValue(this);
+			set => MySqlConnectionStringOption.ConnectionLifeTime.SetValue(this, value);
+		}
+
 		public bool ConnectionReset
 		{
 			get => MySqlConnectionStringOption.ConnectionReset.GetValue(this);
@@ -223,6 +229,7 @@ internal abstract class MySqlConnectionStringOption
 
 		// Connection Pooling Options
 		public static readonly MySqlConnectionStringOption<bool> Pooling;
+		public static readonly MySqlConnectionStringOption<uint> ConnectionLifeTime;
 		public static readonly MySqlConnectionStringOption<bool> ConnectionReset;
 		public static readonly MySqlConnectionStringOption<uint> MinimumPoolSize;
 		public static readonly MySqlConnectionStringOption<uint> MaximumPoolSize;
@@ -306,6 +313,10 @@ static MySqlConnectionStringOption()
 				keys: new[] { "Pooling" },
 				defaultValue: true));
 
+			AddOption(ConnectionLifeTime = new MySqlConnectionStringOption<uint>(
+				keys: new[] { "Connection Lifetime", "ConnectionLifeTime" },
+				defaultValue: 0));
+
 			AddOption(ConnectionReset = new MySqlConnectionStringOption<bool>(
 				keys: new[] { "Connection Reset", "ConnectionReset" },
 				defaultValue: true));

src/MySqlConnector/Serialization/ConnectionSettings.cs

@@ -36,6 +36,7 @@ public ConnectionSettings(MySqlConnectionStringBuilder csb)
 
 			// Connection Pooling Options
 			Pooling = csb.Pooling;
+			ConnectionLifeTime = (int)csb.ConnectionLifeTime;
 			ConnectionReset = csb.ConnectionReset;
 			if (csb.MinimumPoolSize > csb.MaximumPoolSize)
 				throw new MySqlException("MaximumPoolSize must be greater than or equal to MinimumPoolSize");
@@ -77,6 +78,7 @@ private ConnectionSettings(ConnectionSettings other, bool? useCompression)
 
 			// Connection Pooling Options
 			Pooling = other.Pooling;
+			ConnectionLifeTime = other.ConnectionLifeTime;
 			ConnectionReset = other.ConnectionReset;
 			MinimumPoolSize = other.MinimumPoolSize;
 			MaximumPoolSize = other.MaximumPoolSize;
@@ -112,6 +114,7 @@ private ConnectionSettings(ConnectionSettings other, bool? useCompression)
 
 		// Connection Pooling Options
 		internal readonly bool Pooling;
+		internal readonly int ConnectionLifeTime;
 		internal readonly bool ConnectionReset;
 		internal readonly int MinimumPoolSize;
 		internal readonly int MaximumPoolSize;

src/MySqlConnector/Serialization/MySqlSession.cs

@@ -23,13 +23,15 @@ public MySqlSession()
 
 		public MySqlSession(ConnectionPool pool, int poolGeneration)
 		{
+			CreatedUtc = DateTime.UtcNow;
 			Pool = pool;
 			PoolGeneration = poolGeneration;
 		}
 
 		public ServerVersion ServerVersion { get; set; }
 		public int ConnectionId { get; set; }
 		public byte[] AuthPluginData { get; set; }
+		public DateTime CreatedUtc { get; }
 		public ConnectionPool Pool { get; }
 		public int PoolGeneration { get; }
 		public string DatabaseOverride { get; set; }

tests/MySqlConnector.Tests/MySqlConnectionStringBuilderTests.cs

@@ -17,6 +17,7 @@ public void Defaults()
 #if BASELINE
 			Assert.Equal(false, csb.ConnectionReset);
 #else
+			Assert.Equal(0u, csb.ConnectionLifeTime);
 			Assert.Equal(true, csb.ConnectionReset);
 #endif
 			Assert.Equal(15u, csb.ConnectionTimeout);
@@ -59,6 +60,7 @@ public void ParseConnectionString()
 				                   "Character Set=latin1;" +
 				                   "Compress=true;" +
 				                   "connect timeout=30;" +
+				                   "connection lifetime=15;" +
 				                   "ConnectionReset=false;" +
 				                   "Convert Zero Datetime=true;" +
 #if !BASELINE
@@ -82,6 +84,7 @@ public void ParseConnectionString()
 			Assert.Equal("file.pfx", csb.CertificateFile);
 			Assert.Equal("Pass1234", csb.CertificatePassword);
 			Assert.Equal("latin1", csb.CharacterSet);
+			Assert.Equal(15u, csb.ConnectionLifeTime);
 			Assert.Equal(false, csb.ConnectionReset);
 			Assert.Equal(30u, csb.ConnectionTimeout);
 			Assert.Equal(true, csb.ConvertZeroDateTime);

tests/SideBySide/ConnectionPool.cs

@@ -159,6 +159,35 @@ public async Task WaitTimeout()
 			}
 		}
 
+		[Theory]
+		[InlineData(2u, 3u, true)]
+		[InlineData(180u, 3u, false)]
+		public async Task ConnectionLifeTime(uint lifeTime, uint delaySeconds, bool shouldTimeout)
+		{
+			var csb = AppConfig.CreateConnectionStringBuilder();
+			csb.Pooling = true;
+			csb.MinimumPoolSize = 0;
+			csb.MaximumPoolSize = 1;
+			csb.ConnectionLifeTime = lifeTime;
+			int serverThread;
+
+			using (var connection = new MySqlConnection(csb.ConnectionString))
+			{
+				await connection.OpenAsync();
+				serverThread = connection.ServerThread;
+				await Task.Delay(TimeSpan.FromSeconds(delaySeconds));
+			}
+
+			using (var connection = new MySqlConnection(csb.ConnectionString))
+			{
+				await connection.OpenAsync();
+				if (shouldTimeout)
+					Assert.NotEqual(serverThread, connection.ServerThread);
+				else
+					Assert.Equal(serverThread, connection.ServerThread);
+			}
+		}
+
 		[Fact]
 		public async Task CharacterSet()
 		{

tests/SideBySide/SideBySide.csproj

@@ -15,8 +15,9 @@
     <PreserveCompilationContext>true</PreserveCompilationContext>
     <AssemblyName>SideBySide</AssemblyName>
     <PackageId>SideBySide</PackageId>
-    <GenerateRuntimeConfigurationFiles>true</GenerateRuntimeConfigurationFiles>
     <ServerGarbageCollection>true</ServerGarbageCollection>
+    <ConcurrentGarbageCollection>true</ConcurrentGarbageCollection>
+    <ThreadPoolMinThreads>64</ThreadPoolMinThreads>
   </PropertyGroup>
 
  <ItemGroup>