[http] Avoid boxing of status code tags

src/OpenTelemetry.Instrumentation.Http/CHANGELOG.md

@@ -3,8 +3,11 @@
 ## Unreleased
 
 * Fixed an issue of missing `http.client.duration` metric data in case of
-network failures (when response is not available).
-([#4098](https://github.com/open-telemetry/opentelemetry-dotnet/pull/4098))
+  network failures (when response is not available).
+  ([#4098](https://github.com/open-telemetry/opentelemetry-dotnet/pull/4098))
+
+* Improve perf by avoiding boxing of common status codes values.
+  ([#4361](https://github.com/open-telemetry/opentelemetry-dotnet/pull/4361))
 
 ## 1.0.0-rc9.14
 

src/OpenTelemetry.Instrumentation.Http/Implementation/HttpHandlerDiagnosticListener.cs

@@ -209,7 +209,7 @@ public void OnStopActivity(Activity activity, object payload)
 
                 if (this.stopResponseFetcher.TryFetch(payload, out HttpResponseMessage response) && response != null)
                 {
-                    activity.SetTag(SemanticConventions.AttributeHttpStatusCode, (int)response.StatusCode);
+                    activity.SetTag(SemanticConventions.AttributeHttpStatusCode, TelemetryHelper.GetBoxedStatusCode(response.StatusCode));
 
                     if (currentStatusCode == ActivityStatusCode.Unset)
                     {

src/OpenTelemetry.Instrumentation.Http/Implementation/HttpHandlerMetricsDiagnosticListener.cs

@@ -62,7 +62,7 @@ public override void OnEventWritten(string name, object payload)
 
                     if (this.stopResponseFetcher.TryFetch(payload, out HttpResponseMessage response) && response != null)
                     {
-                        tags.Add(new KeyValuePair<string, object>(SemanticConventions.AttributeHttpStatusCode, (int)response.StatusCode));
+                        tags.Add(new KeyValuePair<string, object>(SemanticConventions.AttributeHttpStatusCode, TelemetryHelper.GetBoxedStatusCode(response.StatusCode)));
                     }
 
                     // We are relying here on HttpClient library to set duration before writing the stop event.

src/OpenTelemetry.Instrumentation.Http/Implementation/HttpWebRequestActivitySource.netfx.cs

@@ -123,7 +123,7 @@ private static void AddResponseTags(HttpWebResponse response, Activity activity)
         {
             if (activity.IsAllDataRequested)
             {
-                activity.SetTag(SemanticConventions.AttributeHttpStatusCode, (int)response.StatusCode);
+                activity.SetTag(SemanticConventions.AttributeHttpStatusCode, TelemetryHelper.GetBoxedStatusCode(response.StatusCode));
 
                 activity.SetStatus(SpanHelper.ResolveSpanStatusForHttpStatusCode(activity.Kind, (int)response.StatusCode));
 

src/OpenTelemetry.Instrumentation.Http/Implementation/TelemetryHelper.cs

@@ -0,0 +1,111 @@
+// <copyright file="TelemetryHelper.cs" company="OpenTelemetry Authors">
+// Copyright The OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+// </copyright>
+
+using System.Net;
+
+namespace OpenTelemetry.Instrumentation.Http.Implementation;
+
+internal static class TelemetryHelper
+{
+#pragma warning disable SA1509 // Opening braces should not be preceded by blank line
+    // Status Codes listed at http://www.iana.org/assignments/http-status-codes/http-status-codes.xhtml
+    private static readonly Dictionary<HttpStatusCode, object> BoxedStatusCodes = new()
+    {
+        { HttpStatusCode.Continue, 100 },
+        { HttpStatusCode.SwitchingProtocols, 101 },
+        /*{ 102, 102 },*/
+
+        { HttpStatusCode.OK, 200 },
+        { HttpStatusCode.Created, 201 },
+        { HttpStatusCode.Accepted, 202 },
+        { HttpStatusCode.NonAuthoritativeInformation, 203 },
+        { HttpStatusCode.NoContent, 204 },
+        { HttpStatusCode.ResetContent, 205 },
+        { HttpStatusCode.PartialContent, 206 },
+        /*{ 207, 207 },
+        { 208, 208 },
+        { 226, 226 },*/
+
+        { HttpStatusCode.MultipleChoices, 300 },
+        { HttpStatusCode.Ambiguous, 300 },
+        { HttpStatusCode.MovedPermanently, 301 },
+        { HttpStatusCode.Moved, 301 },
+        { HttpStatusCode.Found, 302 },
+        { HttpStatusCode.Redirect, 302 },
+        { HttpStatusCode.SeeOther, 303 },
+        { HttpStatusCode.RedirectMethod, 303 },
+        { HttpStatusCode.NotModified, 304 },
+        { HttpStatusCode.UseProxy, 305 },
+        { HttpStatusCode.Unused, 306 },
+        { HttpStatusCode.TemporaryRedirect, 307 },
+        { HttpStatusCode.RedirectKeepVerb, 307 },
+        /*{ 308, 308 },*/
+
+        { HttpStatusCode.BadRequest, 400 },
+        { HttpStatusCode.Unauthorized, 401 },
+        { HttpStatusCode.PaymentRequired, 402 },
+        { HttpStatusCode.Forbidden, 403 },
+        { HttpStatusCode.NotFound, 404 },
+        { HttpStatusCode.MethodNotAllowed, 405 },
+        { HttpStatusCode.NotAcceptable, 406 },
+        { HttpStatusCode.ProxyAuthenticationRequired, 407 },
+        { HttpStatusCode.RequestTimeout, 408 },
+        { HttpStatusCode.Conflict, 409 },
+        { HttpStatusCode.Gone, 410 },
+        { HttpStatusCode.LengthRequired, 411 },
+        { HttpStatusCode.PreconditionFailed, 412 },
+        { HttpStatusCode.RequestEntityTooLarge, 413 },
+        { HttpStatusCode.RequestUriTooLong, 414 },
+        { HttpStatusCode.UnsupportedMediaType, 415 },
+        { HttpStatusCode.RequestedRangeNotSatisfiable, 416 },
+        { HttpStatusCode.ExpectationFailed, 417 },
+        /*{ 418, 418 },
+        { 419, 419 },
+        { 421, 421 },
+        { 422, 422 },
+        { 423, 423 },
+        { 424, 424 },*/
+        { HttpStatusCode.UpgradeRequired, 426 },
+        /*{ 428, 428 },
+        { 429, 429 },
+        { 431, 431 },
+        { 451, 451 },
+        { 499, 499 },*/
+
+        { HttpStatusCode.InternalServerError, 500 },
+        { HttpStatusCode.NotImplemented, 501 },
+        { HttpStatusCode.BadGateway, 502 },
+        { HttpStatusCode.ServiceUnavailable, 503 },
+        { HttpStatusCode.GatewayTimeout, 504 },
+        { HttpStatusCode.HttpVersionNotSupported, 505 },
+        /*{ 506, 506 },
+        { 507, 507 },
+        { 508, 508 },
+        { 510, 510 },
+        { 511, 511 },*/
+    };
+#pragma warning restore SA1509 // Opening braces should not be preceded by blank line
+
+    public static object GetBoxedStatusCode(HttpStatusCode statusCode)
+    {
+        if (BoxedStatusCodes.TryGetValue(statusCode, out var result))
+        {
+            return result;
+        }
+
+        return (int)statusCode;
+    }
+}