Fix HTTP/2 pings not working with zero connection lifetime

[Copilot]

Issue

When PooledConnectionLifetime is set to TimeSpan.Zero, HTTP/2 keep-alive pings don't work, even if explicitly configured. This is because the connection pool manager optimization that avoids storing connections (when lifetime is zero) skips creating the heartbeat timer needed for ping functionality.

Root Cause

In HttpConnectionPoolManager.cs, there's this optimization condition:

bool avoidStoringConnections =
    settings._maxConnectionsPerServer == int.MaxValue &&
    (settings._pooledConnectionIdleTimeout == TimeSpan.Zero ||
     settings._pooledConnectionLifetime == TimeSpan.Zero);

When this condition is true, the code skips creating the heartbeat timer, regardless of whether the user has configured HTTP/2 keep-alive pings.

Fix

I've modified the condition to also consider whether keep-alive pings are enabled:

bool avoidStoringConnections =
    settings._maxConnectionsPerServer == int.MaxValue &&
    (settings._pooledConnectionIdleTimeout == TimeSpan.Zero ||
     settings._pooledConnectionLifetime == TimeSpan.Zero) &&
    settings._keepAlivePingDelay == Timeout.InfiniteTimeSpan;

This ensures that if pings are configured (keepAlivePingDelay is not InfiniteTimeSpan), connections will be stored and the heartbeat timer will be created, even if the connection lifetime is zero.

I've also added test cases to verify this fix:

1. A test that confirms pings work when PooledConnectionLifetime = TimeSpan.Zero and ping settings are configured
2. A test that confirms the default behavior (no pings) when ping settings aren't configured with zero lifetime

Fixes #113532.

Warning

Firewall rules blocked me from connecting to one or more addresses

I tried to connect to the following addresses, but was blocked by firewall rules:

• dc.services.visualstudio.com
  • Triggering command: /home/REDACTED/work/runtime/runtime/.dotnet/dotnet msbuild /m /nologo /clp:Summary /v:minimal /nr:true /warnaserror /p:TreatWarningsAsErrors=true /p:ContinuousIntegrationBuild=false /home/REDACTED/work/runtime/runtime/artifacts/toolset/restore.proj /t:__WriteToolsetLocation /clp:ErrorsOnly;NoSummary /p:__ToolsetLocationOutputFile=/home/REDACTED/work/runtime/runtime/artifacts/toolset/10.0.0-beta.25260.104.txt (dns block)
• pkgs.dev.azure.com
  • Triggering command: /home/REDACTED/work/runtime/runtime/.dotnet/dotnet msbuild /m /nologo /clp:Summary /v:minimal /nr:true /warnaserror /p:TreatWarningsAsErrors=true /p:ContinuousIntegrationBuild=false /home/REDACTED/work/runtime/runtime/artifacts/toolset/restore.proj /t:__WriteToolsetLocation /clp:ErrorsOnly;NoSummary /p:__ToolsetLocationOutputFile=/home/REDACTED/work/runtime/runtime/artifacts/toolset/10.0.0-beta.25260.104.txt (dns block)

If you need me to access, download, or install something from one of these locations, you can either:

• Configure Actions setup steps to set up my environment, which run before the firewall is enabled
• Add the appropriate URLs or hosts to my firewall allow list

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[stephentoub]

The new test file will need to be added to the .csproj. Otherwise, it won't be included in the built tests.

[Copilot]

The new test file will need to be added to the .csproj. Otherwise, it won't be included in the built tests.

I've added the test file to the System.Net.Http.Functional.Tests.csproj file so it will be included in the built tests (f1088d8).

[stephentoub]

Please write the test(s) in the same style as the rest of the tests and include it or then in an existing test file rather than creating a new one.

[Copilot]

Please write the test(s) in the same style as the rest of the tests and include it or then in an existing test file rather than creating a new one.

I've moved the test methods into the existing SocketsHttpHandlerTest.Http2KeepAlivePing.cs file and removed the separate test file as requested. The tests follow the same style and patterns as the existing tests in that file (2fc0eb7).

Warning

Firewall rules blocked me from connecting to one or more addresses

I tried to connect to the following addresses, but was blocked by firewall rules:

• n3kvsblobprodcus335.vsblob.vsassets.io
  • Triggering command: /home/REDACTED/work/runtime/runtime/.dotnet/dotnet msbuild /m /nologo /clp:Summary /v:minimal /nr:true /warnaserror /p:TreatWarningsAsErrors=true /p:ContinuousIntegrationBuild=false /home/REDACTED/work/runtime/runtime/artifacts/toolset/restore.proj /t:__WriteToolsetLocation /clp:ErrorsOnly;NoSummary /p:__ToolsetLocationOutputFile=/home/REDACTED/work/runtime/runtime/artifacts/toolset/10.0.0-beta.25260.104.txt (dns block)

If you need me to access, download, or install something from one of these locations, you can either:

• Configure Actions setup steps to set up my environment, which run before the firewall is enabled
• Add the appropriate URLs or hosts to my firewall allow list