Create System.Diagnostics.Metrics-based runtime metrics listener

tracer/src/Datadog.Trace.Trimming/build/Datadog.Trace.Trimming.xml

@@ -614,6 +614,7 @@
       <type fullname="System.Func`5" />
       <type fullname="System.Func`6" />
       <type fullname="System.GC" />
+      <type fullname="System.GCGenerationInfo" />
       <type fullname="System.GCMemoryInfo" />
       <type fullname="System.Globalization.CultureInfo" />
       <type fullname="System.Globalization.DateTimeStyles" />

tracer/src/Datadog.Trace/Configuration/TracerSettings.cs

@@ -179,6 +179,16 @@ not null when string.Equals(value, "otlp", StringComparison.OrdinalIgnoreCase) =
 
             RuntimeMetricsEnabled = runtimeMetricsEnabledResult.WithDefault(false);
 
+            RuntimeMetricsDiagnosticsMetricsApiEnabled = config.WithKeys(ConfigurationKeys.RuntimeMetricsDiagnosticsMetricsApiEnabled).AsBool(false);
+
+#if !NET6_0_OR_GREATER
+            if (RuntimeMetricsEnabled && RuntimeMetricsDiagnosticsMetricsApiEnabled)
+            {
+                Log.Warning(
+                    $"{ConfigurationKeys.RuntimeMetricsDiagnosticsMetricsApiEnabled} was enabled, but System.Diagnostics.Metrics is only available on .NET 6+. Using standard runtime metrics collector.");
+                telemetry.Record(ConfigurationKeys.RuntimeMetricsDiagnosticsMetricsApiEnabled, false, ConfigurationOrigins.Calculated);
+            }
+#endif
             OtelMetricExportIntervalMs = config
                             .WithKeys(ConfigurationKeys.OpenTelemetry.MetricExportIntervalMs)
                             .AsInt32(defaultValue: 10_000);
@@ -1053,6 +1063,15 @@ not null when string.Equals(value, "otlp", StringComparison.OrdinalIgnoreCase) =
         /// </summary>
         internal bool RuntimeMetricsEnabled { get; }
 
+        /// <summary>
+        /// Gets a value indicating whether the experimental runtime metrics collector which uses the
+        /// <a href="https://learn.microsoft.com/en-us/dotnet/core/diagnostics/metrics">System.Diagnostics.Metrics</a> API.
+        /// This collector can only be enabled when using .NET 6+, and will only include ASP.NET Core metrics
+        /// when using .NET 8+.
+        /// </summary>
+        /// <seealso cref="ConfigurationKeys.RuntimeMetricsDiagnosticsMetricsApiEnabled"/>
+        internal bool RuntimeMetricsDiagnosticsMetricsApiEnabled { get; }
+
         /// <summary>
         /// Gets a value indicating whether libdatadog data pipeline
         /// is enabled.

tracer/src/Datadog.Trace/Configuration/supported-configurations-docs.yaml

@@ -555,6 +555,13 @@ DD_RUNTIME_METRICS_ENABLED: |
   Configuration key for enabling or disabling runtime metrics sent to DogStatsD.
   Default value is <c>false</c> (disabled).
 
+DD_RUNTIME_METRICS_DIAGNOSTICS_METRICS_API_ENABLED: |
+  Enables an experimental runtime metrics collector which uses the 
+  <a href="https://learn.microsoft.com/en-us/dotnet/core/diagnostics/metrics">System.Diagnostics.Metrics</a> API.
+  This collector can only be enabled when using .NET 6+, and will only include ASP.NET Core metrics
+  when using .NET 8+.
+  Default value is <c>false</c> (disabled).
+
 DD_SERVICE: |
   Configuration key for the application's default service name.
   Used as the service name for top-level spans,

tracer/src/Datadog.Trace/Configuration/supported-configurations.json

@@ -868,6 +868,11 @@
         "A"
       ]
     },
+    "DD_RUNTIME_METRICS_DIAGNOSTICS_METRICS_API_ENABLED": {
+      "version": [
+        "A"
+      ]
+    },
     "DD_SERVICE": {
       "version": [
         "A"

tracer/src/Datadog.Trace/Generated/net461/Datadog.Trace.SourceGenerators/ConfigurationKeysGenerator/ConfigurationKeys.g.cs

@@ -215,6 +215,15 @@ internal static partial class ConfigurationKeys
     [System.Obsolete("This parameter is obsolete and should be replaced by `DD_TRACE_RATE_LIMIT`")]
     public const string MaxTracesSubmittedPerSecond = "DD_MAX_TRACES_PER_SECOND";
 
+    /// <summary>
+    /// Enables an experimental runtime metrics collector which uses the 
+    /// <a href="https://learn.microsoft.com/en-us/dotnet/core/diagnostics/metrics">System.Diagnostics.Metrics</a> API.
+    /// This collector can only be enabled when using .NET 6+, and will only include ASP.NET Core metrics
+    /// when using .NET 8+.
+    /// Default value is <c>false</c> (disabled).
+    /// </summary>
+    public const string RuntimeMetricsDiagnosticsMetricsApiEnabled = "DD_RUNTIME_METRICS_DIAGNOSTICS_METRICS_API_ENABLED";
+
     /// <summary>
     /// Configuration key for enabling or disabling runtime metrics sent to DogStatsD.
     /// Default value is <c>false</c> (disabled).

tracer/src/Datadog.Trace/Generated/net6.0/Datadog.Trace.SourceGenerators/ConfigurationKeysGenerator/ConfigurationKeys.g.cs

@@ -215,6 +215,15 @@ internal static partial class ConfigurationKeys
     [System.Obsolete("This parameter is obsolete and should be replaced by `DD_TRACE_RATE_LIMIT`")]
     public const string MaxTracesSubmittedPerSecond = "DD_MAX_TRACES_PER_SECOND";
 
+    /// <summary>
+    /// Enables an experimental runtime metrics collector which uses the 
+    /// <a href="https://learn.microsoft.com/en-us/dotnet/core/diagnostics/metrics">System.Diagnostics.Metrics</a> API.
+    /// This collector can only be enabled when using .NET 6+, and will only include ASP.NET Core metrics
+    /// when using .NET 8+.
+    /// Default value is <c>false</c> (disabled).
+    /// </summary>
+    public const string RuntimeMetricsDiagnosticsMetricsApiEnabled = "DD_RUNTIME_METRICS_DIAGNOSTICS_METRICS_API_ENABLED";
+
     /// <summary>
     /// Configuration key for enabling or disabling runtime metrics sent to DogStatsD.
     /// Default value is <c>false</c> (disabled).

tracer/src/Datadog.Trace/Generated/netcoreapp3.1/Datadog.Trace.SourceGenerators/ConfigurationKeysGenerator/ConfigurationKeys.g.cs

@@ -215,6 +215,15 @@ internal static partial class ConfigurationKeys
     [System.Obsolete("This parameter is obsolete and should be replaced by `DD_TRACE_RATE_LIMIT`")]
     public const string MaxTracesSubmittedPerSecond = "DD_MAX_TRACES_PER_SECOND";
 
+    /// <summary>
+    /// Enables an experimental runtime metrics collector which uses the 
+    /// <a href="https://learn.microsoft.com/en-us/dotnet/core/diagnostics/metrics">System.Diagnostics.Metrics</a> API.
+    /// This collector can only be enabled when using .NET 6+, and will only include ASP.NET Core metrics
+    /// when using .NET 8+.
+    /// Default value is <c>false</c> (disabled).
+    /// </summary>
+    public const string RuntimeMetricsDiagnosticsMetricsApiEnabled = "DD_RUNTIME_METRICS_DIAGNOSTICS_METRICS_API_ENABLED";
+
     /// <summary>
     /// Configuration key for enabling or disabling runtime metrics sent to DogStatsD.
     /// Default value is <c>false</c> (disabled).

tracer/src/Datadog.Trace/Generated/netstandard2.0/Datadog.Trace.SourceGenerators/ConfigurationKeysGenerator/ConfigurationKeys.g.cs

@@ -215,6 +215,15 @@ internal static partial class ConfigurationKeys
     [System.Obsolete("This parameter is obsolete and should be replaced by `DD_TRACE_RATE_LIMIT`")]
     public const string MaxTracesSubmittedPerSecond = "DD_MAX_TRACES_PER_SECOND";
 
+    /// <summary>
+    /// Enables an experimental runtime metrics collector which uses the 
+    /// <a href="https://learn.microsoft.com/en-us/dotnet/core/diagnostics/metrics">System.Diagnostics.Metrics</a> API.
+    /// This collector can only be enabled when using .NET 6+, and will only include ASP.NET Core metrics
+    /// when using .NET 8+.
+    /// Default value is <c>false</c> (disabled).
+    /// </summary>
+    public const string RuntimeMetricsDiagnosticsMetricsApiEnabled = "DD_RUNTIME_METRICS_DIAGNOSTICS_METRICS_API_ENABLED";
+
     /// <summary>
     /// Configuration key for enabling or disabling runtime metrics sent to DogStatsD.
     /// Default value is <c>false</c> (disabled).