disable/trim MetricsHandler when System.Diagnostics.Metrics.Meter.IsSupported is false (#114326)

Co-authored-by: Anton Firszov <[email protected]>

Author: pavelsavara

eng/testing/linker/project.csproj.template

@@ -53,7 +53,7 @@
     <MicrosoftNetCoreAppRuntimePackDir>{MicrosoftNetCoreAppRuntimePackDir}</MicrosoftNetCoreAppRuntimePackDir>
 
     <RepositoryEngineeringDir>{RepositoryEngineeringDir}</RepositoryEngineeringDir>
-    <_ExtraTrimmerArgs>{ExtraTrimmerArgs} $(_ExtraTrimmerArgs)</_ExtraTrimmerArgs>
+    <_ExtraTrimmerArgs>{ExtraTrimmerArgs} $(_ExtraTrimmerArgs) --dump-dependencies</_ExtraTrimmerArgs>
     {AdditionalProperties}
 
     <!-- Needed for PublishAot -->

src/libraries/System.Net.Http/src/ILLink/ILLink.Substitutions.xml

@@ -24,10 +24,6 @@
     <EmitCompilerGeneratedFiles Condition="'$(Configuration)' == 'Debug' and '$(TargetPlatformIdentifier)' == 'browser'">true</EmitCompilerGeneratedFiles>
   </PropertyGroup>
 
-  <ItemGroup>
-    <ILLinkSubstitutionsXmls Include="$(ILLinkDirectory)ILLink.Substitutions.xml" />
-  </ItemGroup>
-
   <ItemGroup Condition="'$(TargetPlatformIdentifier)' != ''">
     <Compile Include="System\Net\Http\ByteArrayContent.cs" />
     <Compile Include="System\Net\Http\CancellationHelper.cs" />

src/libraries/System.Net.Http/src/System.Net.Http.csproj

@@ -24,7 +24,7 @@ internal sealed class DiagnosticsHandler : HttpMessageHandlerStage
 
         public DiagnosticsHandler(HttpMessageHandler innerHandler, DistributedContextPropagator propagator, bool autoRedirect = false)
         {
-            Debug.Assert(IsGloballyEnabled());
+            Debug.Assert(GlobalHttpSettings.DiagnosticsHandler.EnableActivityPropagation);
             Debug.Assert(innerHandler is not null && propagator is not null);
 
             _innerHandler = innerHandler;
@@ -71,8 +71,6 @@ private static bool IsEnabled()
             return activity;
         }
 
-        internal static bool IsGloballyEnabled() => GlobalHttpSettings.DiagnosticsHandler.EnableActivityPropagation;
-
         internal override ValueTask<HttpResponseMessage> SendAsync(HttpRequestMessage request, bool async, CancellationToken cancellationToken)
         {
             if (IsEnabled())
@@ -89,7 +87,7 @@ internal override ValueTask<HttpResponseMessage> SendAsync(HttpRequestMessage re
 
         private async ValueTask<HttpResponseMessage> SendAsyncCore(HttpRequestMessage request, bool async, CancellationToken cancellationToken)
         {
-            // HttpClientHandler is responsible to call static DiagnosticsHandler.IsEnabled() before forwarding request here.
+            // HttpClientHandler is responsible to call static GlobalHttpSettings.DiagnosticsHandler.IsEnabled before forwarding request here.
             // It will check if propagation is on (because parent Activity exists or there is a listener) or off (forcibly disabled)
             // This code won't be called unless consumer unsubscribes from DiagnosticListener right after the check.
             // So some requests happening right after subscription starts might not be instrumented. Similarly,

src/libraries/System.Net.Http/src/System/Net/Http/DiagnosticsHandler.cs

@@ -1,6 +1,9 @@
 // Licensed to the .NET Foundation under one or more agreements.
 // The .NET Foundation licenses this file to you under the MIT license.
 
+using System;
+using System.Diagnostics.CodeAnalysis;
+
 namespace System.Net.Http
 {
     /// <summary>
@@ -10,12 +13,21 @@ internal static class GlobalHttpSettings
     {
         internal static class DiagnosticsHandler
         {
+            [FeatureSwitchDefinition("System.Net.Http.EnableActivityPropagation")]
             public static bool EnableActivityPropagation { get; } = RuntimeSettingParser.QueryRuntimeSettingSwitch(
                 "System.Net.Http.EnableActivityPropagation",
                 "DOTNET_SYSTEM_NET_HTTP_ENABLEACTIVITYPROPAGATION",
                 true);
         }
 
+        internal static class MetricsHandler
+        {
+            [FeatureSwitchDefinition("System.Diagnostics.Metrics.Meter.IsSupported")]
+            public static bool IsGloballyEnabled { get; } = RuntimeSettingParser.QueryRuntimeSettingSwitch(
+                "System.Diagnostics.Metrics.Meter.IsSupported",
+                true);
+        }
+
         internal static class SocketsHttpHandler
         {
 #if !TARGET_BROWSER && !TARGET_WASI

src/libraries/System.Net.Http/src/System/Net/Http/GlobalHttpSettings.cs

@@ -45,8 +45,11 @@ private HttpMessageHandler Handler
 
                         // MetricsHandler should be descendant of DiagnosticsHandler in the handler chain to make sure the 'http.request.duration'
                         // metric is recorded before stopping the request Activity. This is needed to make sure that our telemetry supports Exemplars.
-                        handler = new MetricsHandler(handler, _nativeMeterFactory, out _);
-                        if (DiagnosticsHandler.IsGloballyEnabled())
+                        if (GlobalHttpSettings.MetricsHandler.IsGloballyEnabled)
+                        {
+                            handler = new MetricsHandler(handler, _nativeMeterFactory, out _);
+                        }
+                        if (GlobalHttpSettings.DiagnosticsHandler.EnableActivityPropagation)
                         {
                             handler = new DiagnosticsHandler(handler, DistributedContextPropagator.Current);
                         }

src/libraries/System.Net.Http/src/System/Net/Http/HttpClientHandler.AnyMobile.cs

@@ -45,8 +45,11 @@ private HttpMessageHandler Handler
 
                 // MetricsHandler should be descendant of DiagnosticsHandler in the handler chain to make sure the 'http.request.duration'
                 // metric is recorded before stopping the request Activity. This is needed to make sure that our telemetry supports Exemplars.
-                handler = new MetricsHandler(handler, _meterFactory, out _);
-                if (DiagnosticsHandler.IsGloballyEnabled())
+                if (GlobalHttpSettings.MetricsHandler.IsGloballyEnabled)
+                {
+                    handler = new MetricsHandler(handler, _meterFactory, out _);
+                }
+                if (GlobalHttpSettings.DiagnosticsHandler.EnableActivityPropagation)
                 {
                     handler = new DiagnosticsHandler(handler, DistributedContextPropagator.Current);
                 }

src/libraries/System.Net.Http/src/System/Net/Http/HttpClientHandler.cs

@@ -3,6 +3,7 @@
 
 using System.Collections.Generic;
 using System.Diagnostics;
+using System.Diagnostics.CodeAnalysis;
 using System.Diagnostics.Metrics;
 using System.Threading;
 using System.Threading.Tasks;
@@ -17,6 +18,8 @@ internal sealed class MetricsHandler : HttpMessageHandlerStage
 
         public MetricsHandler(HttpMessageHandler innerHandler, IMeterFactory? meterFactory, out Meter meter)
         {
+            Debug.Assert(GlobalHttpSettings.MetricsHandler.IsGloballyEnabled);
+
             _innerHandler = innerHandler;
 
             meter = meterFactory?.Create("System.Net.Http") ?? SharedMeter.Instance;
@@ -49,6 +52,8 @@ internal override ValueTask<HttpResponseMessage> SendAsync(HttpRequestMessage re
 
         private async ValueTask<HttpResponseMessage> SendAsyncWithMetrics(HttpRequestMessage request, bool async, CancellationToken cancellationToken)
         {
+            Debug.Assert(GlobalHttpSettings.MetricsHandler.IsGloballyEnabled);
+
             (long startTimestamp, bool recordCurrentRequests) = RequestStart(request);
             HttpResponseMessage? response = null;
             Exception? exception = null;

src/libraries/System.Net.Http/src/System/Net/Http/Metrics/MetricsHandler.cs

@@ -85,7 +85,7 @@ public static void AddConnectionLinkToRequestActivity(Activity connectionSetupAc
             Debug.Assert(connectionSetupActivity is not null);
 
             // We only support links for request activities created by the "System.Net.Http" ActivitySource.
-            if (DiagnosticsHandler.s_activitySource.HasListeners())
+            if (GlobalHttpSettings.DiagnosticsHandler.EnableActivityPropagation && DiagnosticsHandler.s_activitySource.HasListeners())
             {
                 Activity? requestActivity = Activity.Current;
                 if (requestActivity?.Source == DiagnosticsHandler.s_activitySource)

src/libraries/System.Net.Http/src/System/Net/Http/SocketsHttpHandler/ConnectionPool/ConnectionSetupDistributedTracing.cs

@@ -87,7 +87,9 @@ internal sealed partial class HttpConnectionPool
                         ThrowGetVersionException(request, 3, reasonException);
                     }
 
-                    long queueStartingTimestamp = HttpTelemetry.Log.IsEnabled() || Settings._metrics!.RequestsQueueDuration.Enabled ? Stopwatch.GetTimestamp() : 0;
+                    long queueStartingTimestamp = HttpTelemetry.Log.IsEnabled() || (GlobalHttpSettings.MetricsHandler.IsGloballyEnabled && Settings._metrics!.RequestsQueueDuration.Enabled)
+                        ? Stopwatch.GetTimestamp()
+                        : 0;
                     Activity? waitForConnectionActivity = ConnectionSetupDistributedTracing.StartWaitForConnectionActivity(authority);
 
                     if (!TryGetPooledHttp3Connection(request, out Http3Connection? connection, out http3ConnectionWaiter))