Configure pooled connection lifetime in client factory (#1862)

Author: JamesNK

src/Grpc.Net.ClientFactory/GrpcClientServiceExtensions.cs

@@ -334,13 +334,23 @@ private static IHttpClientBuilder AddGrpcHttpClient<
 
             services.PostConfigure<HttpClientFactoryOptions>(name, options =>
             {
-                options.HttpMessageHandlerBuilderActions.Add(static builder =>
+                options.HttpMessageHandlerBuilderActions.Add(builder =>
                 {
                     if (builder.PrimaryHandler == null)
                     {
                         // This will throw in .NET Standard 2.0 with a prompt that a user must set a handler.
                         // Because it throws it should only be called in PostConfigure if no handler has been set.
                         var handler = HttpHandlerFactory.CreatePrimaryHandler();
+#if NET5_0_OR_GREATER
+                        if (handler is SocketsHttpHandler socketsHttpHandler)
+                        {
+                            // A channel is created once per client, lives forever, and the primary handler never changes.
+                            // It's possible that long lived connections cause the client to miss out on DNS changes.
+                            // Replicate the core benefit of a handler lifetime (periodic connection recreation)
+                            // by setting PooledConnectionLifetime to handler lifetime.
+                            socketsHttpHandler.PooledConnectionLifetime = options.HandlerLifetime;
+                        }
+#endif
 #if NET5_0
                         handler = HttpHandlerFactory.EnsureTelemetryHandler(handler);
 #endif

test/Grpc.Net.ClientFactory.Tests/DefaultGrpcClientFactoryTests.cs

@@ -195,7 +195,8 @@ public void CreateClient_NoPrimaryHandlerNet5OrLater_SocketsHttpHandlerConfigure
             // Arrange
             var services = new ServiceCollection();
             services
-                .AddGrpcClient<TestGreeterClient>(o => o.Address = new Uri("https://localhost"));
+                .AddGrpcClient<TestGreeterClient>(o => o.Address = new Uri("https://localhost"))
+                .SetHandlerLifetime(TimeSpan.FromSeconds(10));
 
             var serviceProvider = services.BuildServiceProvider(validateScopes: true);
 
@@ -206,20 +207,22 @@ public void CreateClient_NoPrimaryHandlerNet5OrLater_SocketsHttpHandlerConfigure
             var handler = handlerFactory.CreateHandler(nameof(TestGreeterClient));
 
             // Assert
-            var hasSocketsHttpHandler = false;
+            SocketsHttpHandler? socketsHttpHandler = null;
             HttpMessageHandler? currentHandler = handler;
             while (currentHandler is DelegatingHandler delegatingHandler)
             {
                 currentHandler = delegatingHandler.InnerHandler;
 
-                if (currentHandler?.GetType() == typeof(SocketsHttpHandler))
+                if (currentHandler is SocketsHttpHandler s)
                 {
-                    hasSocketsHttpHandler = true;
+                    socketsHttpHandler = s;
                     break;
                 }
             }
 
-            Assert.IsTrue(hasSocketsHttpHandler);
+            Assert.IsNotNull(socketsHttpHandler);
+            Assert.AreEqual(true, socketsHttpHandler!.EnableMultipleHttp2Connections);
+            Assert.AreEqual(TimeSpan.FromSeconds(10), socketsHttpHandler!.PooledConnectionLifetime);
         }
 #endif