Updates to implementation

src/OpenTelemetry.Instrumentation.AspNet/AspNetMetricsInstrumentationOptions.cs

@@ -1,9 +1,5 @@
 using System;
-using System.Collections.Generic;
 using System.Diagnostics;
-using System.Linq;
-using System.Text;
-using System.Threading.Tasks;
 using System.Web;
 
 namespace OpenTelemetry.Instrumentation.AspNet;
@@ -12,17 +8,30 @@ public class AspNetMetricsInstrumentationOptions
     /// <summary>
     /// Delegate for enrichment of recorded metric with additional tags.
     /// </summary>
+    /// <param name="metricName">The name of the metric being enriched.</param>
     /// <param name="context"><see cref="HttpContext"/>: the HttpContext object. Both Request and Response are available.</param>
     /// <param name="tags"><see cref="TagList"/>: List of current tags. You can add additional tags to this list. </param>
-    public delegate void AspNetMetricEnrichmentFunc(string name, HttpContext context, ref TagList tags);
+    public delegate void AspNetMetricEnrichmentFunc(string metricName, HttpContext context, ref TagList tags);
 
     /// <summary>
-    /// Gets or sets a Filter function that determines whether or not to collect telemetry about requests on a per request basis.
-    /// The Filter gets the HttpContext, and should return a boolean.
-    /// If Filter returns true, the request is collected.
-    /// If Filter returns false or throw exception, the request is filtered out.
+    /// Gets or sets a filter function that determines whether or not to
+    /// collect telemetry on a per request basis.
     /// </summary>
-    public Func<HttpContext, bool> Filter { get; set; }
+    /// <remarks>
+    /// Notes:
+    /// <list type="bullet">
+    /// <item>The first parameter is the name of the metric being
+    /// filtered.</item>
+    /// <item>The return value for the filter function is interpreted as:
+    /// <list type="bullet">
+    /// <item>If filter returns <see langword="true" />, the request is
+    /// collected.</item>
+    /// <item>If filter returns <see langword="false" /> or throws an
+    /// exception the request is NOT collected.</item>
+    /// </list></item>
+    /// </list>
+    /// </remarks>
+    public Func<string, HttpContext, bool> Filter { get; set; }
 
     /// <summary>
     /// Gets or sets an function to enrich a recorded metric with additional custom tags.

src/OpenTelemetry.Instrumentation.AspNet/Implementation/HttpInMetricsListener.cs

@@ -25,13 +25,14 @@ namespace OpenTelemetry.Instrumentation.AspNet.Implementation;
 internal sealed class HttpInMetricsListener : IDisposable
 {
     private readonly Histogram<double> httpServerDuration;
-    private readonly AspNetMetricsInstrumentationOptions options;
+    private readonly AspNetMetricsInstrumentationOptions options;
+    private readonly string httpServerDurationMetricName = "http.server.duration";
     private readonly string onStopActivityEventName = "OnStopActivity";
 
     public HttpInMetricsListener(Meter meter, AspNetMetricsInstrumentationOptions options)
     {
         this.options = options;
-        this.httpServerDuration = meter.CreateHistogram<double>("http.server.duration", "ms", "Measures the duration of inbound HTTP requests.");
+        this.httpServerDuration = meter.CreateHistogram<double>(this.httpServerDurationMetricName, "ms", "Measures the duration of inbound HTTP requests.");
         TelemetryHttpModule.Options.OnRequestStoppedCallback += this.OnStopActivity;
     }
 
@@ -44,7 +45,7 @@ private void OnStopActivity(Activity activity, HttpContext context)
     {
         try
         {
-            if (this.options.Filter?.Invoke(context) == false && Activity.Current != null)
+            if (this.options.Filter?.Invoke(this.httpServerDurationMetricName, context) == false && Activity.Current != null)
             {
                 AspNetInstrumentationEventSource.Log.RequestIsFilteredOut(Activity.Current.OperationName);
                 return;
@@ -69,7 +70,7 @@ private void OnStopActivity(Activity activity, HttpContext context)
         {
             try
             {
-                this.options.Enrich(this.onStopActivityEventName, context, ref tags);
+                this.options.Enrich(this.httpServerDurationMetricName, context, ref tags);
             }
             catch (Exception ex)
             {