From c39103c365ee57dbc14624b1092c6c0946d53242 Mon Sep 17 00:00:00 2001
From: Martin Taillefer <mataille@microsoft.com>
Date: Sat, 6 Jan 2024 06:52:41 -0800
Subject: [PATCH] Expose the ResilienceHandler type.

Fixes #4759
---
 ...icrosoft.Extensions.Http.Resilience.csproj |  1 +
 .../{Internal => }/ResilienceHandler.cs       | 39 ++++++++++++++++---
 .../Resilience/ResilienceHandlerTest.cs       |  2 +-
 3 files changed, 36 insertions(+), 6 deletions(-)
 rename src/Libraries/Microsoft.Extensions.Http.Resilience/Resilience/{Internal => }/ResilienceHandler.cs (64%)

diff --git a/src/Libraries/Microsoft.Extensions.Http.Resilience/Microsoft.Extensions.Http.Resilience.csproj b/src/Libraries/Microsoft.Extensions.Http.Resilience/Microsoft.Extensions.Http.Resilience.csproj
index 26ad109d592..ac92ad2d833 100644
--- a/src/Libraries/Microsoft.Extensions.Http.Resilience/Microsoft.Extensions.Http.Resilience.csproj
+++ b/src/Libraries/Microsoft.Extensions.Http.Resilience/Microsoft.Extensions.Http.Resilience.csproj
@@ -15,6 +15,7 @@
     <InjectSharedDataValidation>true</InjectSharedDataValidation>
     <InjectSharedPools>true</InjectSharedPools>
     <InjectSharedDiagnosticIds>true</InjectSharedDiagnosticIds>
+    <InjectExperimentalAttributeOnLegacy>true</InjectExperimentalAttributeOnLegacy>
   </PropertyGroup>
 
   <PropertyGroup>
diff --git a/src/Libraries/Microsoft.Extensions.Http.Resilience/Resilience/Internal/ResilienceHandler.cs b/src/Libraries/Microsoft.Extensions.Http.Resilience/Resilience/ResilienceHandler.cs
similarity index 64%
rename from src/Libraries/Microsoft.Extensions.Http.Resilience/Resilience/Internal/ResilienceHandler.cs
rename to src/Libraries/Microsoft.Extensions.Http.Resilience/Resilience/ResilienceHandler.cs
index 5e979cf835c..a79d62e0975 100644
--- a/src/Libraries/Microsoft.Extensions.Http.Resilience/Resilience/Internal/ResilienceHandler.cs
+++ b/src/Libraries/Microsoft.Extensions.Http.Resilience/Resilience/ResilienceHandler.cs
@@ -2,29 +2,58 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 
 using System;
+using System.Diagnostics.CodeAnalysis;
 using System.Net.Http;
 using System.Threading;
 using System.Threading.Tasks;
 using Microsoft.Extensions.Http.Diagnostics;
+using Microsoft.Extensions.Http.Resilience.Internal;
+using Microsoft.Shared.DiagnosticIds;
+using Microsoft.Shared.Diagnostics;
 using Polly;
 
-namespace Microsoft.Extensions.Http.Resilience.Internal;
+namespace Microsoft.Extensions.Http.Resilience;
 
 /// <summary>
-/// Base class for resilience handler, i.e. handlers that use resilience strategies  to send the requests.
+/// Base class for resilience handler, i.e. handlers that use resilience strategies to send the requests.
 /// </summary>
-internal sealed class ResilienceHandler : DelegatingHandler
+[Experimental(diagnosticId: DiagnosticIds.Experiments.Resilience, UrlFormat = DiagnosticIds.UrlFormat)]
+public class ResilienceHandler : DelegatingHandler
 {
     private readonly Func<HttpRequestMessage, ResiliencePipeline<HttpResponseMessage>> _pipelineProvider;
 
+    /// <summary>
+    /// Initializes a new instance of the <see cref="ResilienceHandler"/> class.
+    /// </summary>
+    /// <param name="pipelineProvider">The pipeline provider that supplies pipelines in response to an http message.</param>
+    /// <exception cref="ArgumentNullException">If <paramref name="pipelineProvider"/> is <see langword="null"/>.</exception>
     public ResilienceHandler(Func<HttpRequestMessage, ResiliencePipeline<HttpResponseMessage>> pipelineProvider)
     {
-        _pipelineProvider = pipelineProvider;
+        _pipelineProvider = Throw.IfNull(pipelineProvider);
     }
 
-    /// <inheritdoc/>
+    /// <summary>
+    /// Initializes a new instance of the <see cref="ResilienceHandler"/> class.
+    /// </summary>
+    /// <param name="pipeline">The pipeline to use for the message.</param>
+    /// <exception cref="ArgumentNullException">If <paramref name="pipeline"/> is <see langword="null"/>.</exception>
+    public ResilienceHandler(ResiliencePipeline<HttpResponseMessage> pipeline)
+    {
+        _ = Throw.IfNull(pipeline);
+        _pipelineProvider = _ => pipeline;
+    }
+
+    /// <summary>
+    /// Sends an HTTP request to the inner handler to send to the server as an asynchronous operation.
+    /// </summary>
+    /// <param name="request">The HTTP request message to send to the server.</param>
+    /// <param name="cancellationToken">A cancellation token to cancel operation.</param>
+    /// <returns>The task object representing the asynchronous operation.</returns>
+    /// <exception cref="ArgumentNullException">If <paramref name="request"/> is <see langword="null"/>.</exception>
     protected override async Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, CancellationToken cancellationToken)
     {
+        _ = Throw.IfNull(request);
+
         var pipeline = _pipelineProvider(request);
         var created = false;
         if (request.GetResilienceContext() is not ResilienceContext context)
diff --git a/test/Libraries/Microsoft.Extensions.Http.Resilience.Tests/Resilience/ResilienceHandlerTest.cs b/test/Libraries/Microsoft.Extensions.Http.Resilience.Tests/Resilience/ResilienceHandlerTest.cs
index 19413422148..45840010e87 100644
--- a/test/Libraries/Microsoft.Extensions.Http.Resilience.Tests/Resilience/ResilienceHandlerTest.cs
+++ b/test/Libraries/Microsoft.Extensions.Http.Resilience.Tests/Resilience/ResilienceHandlerTest.cs
@@ -22,7 +22,7 @@ public class ResilienceHandlerTest
     [Theory]
     public async Task SendAsync_EnsureRequestMetadataFlows(bool resilienceContextSet)
     {
-        using var handler = new ResilienceHandler(_ => ResiliencePipeline<HttpResponseMessage>.Empty);
+        using var handler = new ResilienceHandler(ResiliencePipeline<HttpResponseMessage>.Empty);
         using var invoker = new HttpMessageInvoker(handler);
         using var request = new HttpRequestMessage();