Fix HTTP/2 pings not working with zero connection lifetime (#115735)

* Fix HTTP/2 pings with zero connection lifetime

Co-authored-by: stephentoub <[email protected]>

* Extend existing test instead of adding new ones

---------

Co-authored-by: copilot-swe-agent[bot] <[email protected]>
Co-authored-by: stephentoub <[email protected]>
Co-authored-by: Stephen Toub <[email protected]>

Author: Copilot

src/libraries/System.Net.Http/src/System/Net/Http/SocketsHttpHandler/HttpConnectionPoolManager.cs

@@ -69,10 +69,13 @@ public HttpConnectionPoolManager(HttpConnectionSettings settings)
             // However, we can only do such optimizations if we're not also tracking
             // connections per server, as we use data in the associated data structures
             // to do that tracking.
+            // Additionally, we should not avoid storing connections if keep-alive ping is configured,
+            // as the heartbeat timer is needed for ping functionality.
             bool avoidStoringConnections =
                 settings._maxConnectionsPerServer == int.MaxValue &&
                 (settings._pooledConnectionIdleTimeout == TimeSpan.Zero ||
-                 settings._pooledConnectionLifetime == TimeSpan.Zero);
+                 settings._pooledConnectionLifetime == TimeSpan.Zero) &&
+                settings._keepAlivePingDelay == Timeout.InfiniteTimeSpan;
 
             // Start out with the timer not running, since we have no pools.
             // When it does run, run it with a frequency based on the idle timeout.

src/libraries/System.Net.Http/tests/FunctionalTests/SocketsHttpHandlerTest.Http2KeepAlivePing.cs

@@ -95,16 +95,18 @@ await Http2LoopbackServer.CreateClientAndServerAsync(async uri =>
 
         [OuterLoop("Runs long")]
         [Theory]
-        [InlineData(HttpKeepAlivePingPolicy.Always)]
-        [InlineData(HttpKeepAlivePingPolicy.WithActiveRequests)]
-        public async Task KeepAliveConfigured_KeepAlivePingsAreSentAccordingToPolicy(HttpKeepAlivePingPolicy policy)
+        [InlineData(HttpKeepAlivePingPolicy.Always, -1)]
+        [InlineData(HttpKeepAlivePingPolicy.WithActiveRequests, -1)]
+        [InlineData(HttpKeepAlivePingPolicy.WithActiveRequests, 0)]
+        public async Task KeepAliveConfigured_KeepAlivePingsAreSentAccordingToPolicy(HttpKeepAlivePingPolicy policy, int connectionLifetimeMilliseconds)
         {
             await Http2LoopbackServer.CreateClientAndServerAsync(async uri =>
             {
                 SocketsHttpHandler handler = CreateSocketsHttpHandler(allowAllCertificates: true);
                 handler.KeepAlivePingTimeout = TimeSpan.FromSeconds(10);
                 handler.KeepAlivePingPolicy = policy;
                 handler.KeepAlivePingDelay = TimeSpan.FromSeconds(1);
+                handler.PooledConnectionLifetime = TimeSpan.FromMilliseconds(connectionLifetimeMilliseconds);
 
                 using HttpClient client = new HttpClient(handler);
                 client.DefaultRequestVersion = HttpVersion.Version20;