Use pre-boxed values in diagnostics (#50013)

Author: sebastienros

src/Http/Routing/src/RoutingMetrics.cs

@@ -9,6 +9,10 @@ internal sealed class RoutingMetrics
 {
     public const string MeterName = "Microsoft.AspNetCore.Routing";
 
+     // Reuse boxed object for common values
+    private static readonly object BoxedTrue = true;
+    private static readonly object BoxedFalse = false;
+
     private readonly Meter _meter;
     private readonly Counter<long> _matchAttemptsCounter;
 
@@ -29,7 +33,7 @@ public void MatchSuccess(string route, bool isFallback)
         _matchAttemptsCounter.Add(1,
             new KeyValuePair<string, object?>("http.route", route),
             new KeyValuePair<string, object?>("aspnetcore.routing.match_status", "success"),
-            new KeyValuePair<string, object?>("aspnetcore.routing.is_fallback", isFallback));
+            new KeyValuePair<string, object?>("aspnetcore.routing.is_fallback", isFallback ? BoxedTrue : BoxedFalse));
     }
 
     public void MatchFailure()

src/Mvc/Mvc.ViewFeatures/src/Diagnostics/MvcDiagnostics.cs

@@ -310,6 +310,10 @@ public AfterViewEventData(IView view, ViewContext viewContext)
 /// </summary>
 public sealed class ViewFoundEventData : EventData
 {
+    // Reuse boxed object for common values
+    private static readonly object BoxedTrue = true;
+    private static readonly object BoxedFalse = false;
+
     /// <summary>
     /// The name of the event.
     /// </summary>
@@ -364,7 +368,7 @@ public ViewFoundEventData(ActionContext actionContext, bool isMainPage, ActionRe
     protected override KeyValuePair<string, object> this[int index] => index switch
     {
         0 => new KeyValuePair<string, object>(nameof(ActionContext), ActionContext),
-        1 => new KeyValuePair<string, object>(nameof(IsMainPage), IsMainPage),
+        1 => new KeyValuePair<string, object>(nameof(IsMainPage), IsMainPage ? BoxedTrue : BoxedFalse),
         2 => new KeyValuePair<string, object>(nameof(Result), Result),
         3 => new KeyValuePair<string, object>(nameof(ViewName), ViewName),
         4 => new KeyValuePair<string, object>(nameof(View), View),
@@ -377,6 +381,10 @@ public ViewFoundEventData(ActionContext actionContext, bool isMainPage, ActionRe
 /// </summary>
 public sealed class ViewNotFoundEventData : EventData
 {
+    // Reuse boxed object for common values
+    private static readonly object BoxedTrue = true;
+    private static readonly object BoxedFalse = false;
+
     /// <summary>
     /// The name of the event.
     /// </summary>
@@ -431,7 +439,7 @@ public ViewNotFoundEventData(ActionContext actionContext, bool isMainPage, Actio
     protected override KeyValuePair<string, object> this[int index] => index switch
     {
         0 => new KeyValuePair<string, object>(nameof(ActionContext), ActionContext),
-        1 => new KeyValuePair<string, object>(nameof(IsMainPage), IsMainPage),
+        1 => new KeyValuePair<string, object>(nameof(IsMainPage), IsMainPage ? BoxedTrue : BoxedFalse),
         2 => new KeyValuePair<string, object>(nameof(Result), Result),
         3 => new KeyValuePair<string, object>(nameof(ViewName), ViewName),
         4 => new KeyValuePair<string, object>(nameof(SearchedLocations), SearchedLocations),