Cleanup ResiliencePipelineRegistry internals (#1510)

Author: martintmk

src/Polly.Core/Registry/RegistryPipelineComponentBuilder.cs

@@ -0,0 +1,72 @@
+using Polly.Telemetry;
+using Polly.Utils.Pipeline;
+
+namespace Polly.Registry;
+
+/// <summary>
+/// Builds a <see cref="PipelineComponent"/> used by the registry.
+/// </summary>
+internal class RegistryPipelineComponentBuilder<TBuilder, TKey>
+    where TBuilder : ResiliencePipelineBuilderBase
+    where TKey : notnull
+{
+    private readonly Func<TBuilder> _activator;
+    private readonly TKey _key;
+    private readonly string _builderName;
+    private readonly string? _instanceName;
+    private readonly Action<TBuilder, ConfigureBuilderContext<TKey>> _configure;
+
+    public RegistryPipelineComponentBuilder(
+        Func<TBuilder> activator,
+        TKey key,
+        string builderName,
+        string? instanceName,
+        Action<TBuilder, ConfigureBuilderContext<TKey>> configure)
+    {
+        _activator = activator;
+        _key = key;
+        _builderName = builderName;
+        _instanceName = instanceName;
+        _configure = configure;
+    }
+
+    internal PipelineComponent CreateComponent()
+    {
+        var builder = CreateBuilder();
+        var telemetry = new ResilienceStrategyTelemetry(
+            new ResilienceTelemetrySource(_builderName, _instanceName, null),
+            builder.Listener);
+
+        var initialPipeline = builder.ComponentFactory();
+
+        if (builder.ReloadTokenProducer is null)
+        {
+            return initialPipeline;
+        }
+
+        return PipelineComponentFactory.CreateReloadable(
+            initialPipeline,
+            builder.ReloadTokenProducer(),
+            () => CreateBuilder().ComponentFactory(),
+            telemetry);
+    }
+
+    private Builder CreateBuilder()
+    {
+        var context = new ConfigureBuilderContext<TKey>(_key, _builderName, _instanceName);
+        var builder = _activator();
+        builder.Name = _builderName;
+        builder.InstanceName = _instanceName;
+        _configure(builder, context);
+
+        return new(
+            builder.BuildPipelineComponent,
+            context.ReloadTokenProducer,
+            builder.TelemetryListener);
+    }
+
+    private record Builder(
+        Func<PipelineComponent> ComponentFactory,
+        Func<Func<CancellationToken>>? ReloadTokenProducer,
+        TelemetryListener? Listener);
+}

src/Polly.Core/Registry/ResiliencePipelineRegistry.TResult.cs

@@ -49,13 +49,17 @@ public ResiliencePipeline<TResult> GetOrAdd(TKey key, Action<ResiliencePipelineB
         {
             var context = new ConfigureBuilderContext<TKey>(key, _builderNameFormatter(key), _instanceNameFormatter?.Invoke(key));
 
-            return _pipelines.GetOrAdd(key, static (_, factory) =>
+            return _pipelines.GetOrAdd(key, k =>
             {
-                var component = CreatePipelineComponent(factory.instance._activator, factory.context, factory.configure);
+                var component = new RegistryPipelineComponentBuilder<ResiliencePipelineBuilder<TResult>, TKey>(
+                    _activator,
+                    k,
+                    _builderNameFormatter(k),
+                    _instanceNameFormatter?.Invoke(k),
+                    configure).CreateComponent();
 
                 return new ResiliencePipeline<TResult>(component, DisposeBehavior.Reject);
-            },
-            (instance: this, context, configure));
+            });
         }
 
         public bool TryAddBuilder(TKey key, Action<ResiliencePipelineBuilder<TResult>, ConfigureBuilderContext<TKey>> configure) => _builders.TryAdd(key, configure);

src/Polly.Core/Registry/ResiliencePipelineRegistry.cs

@@ -1,6 +1,5 @@
 using System.ComponentModel.DataAnnotations;
 using System.Diagnostics.CodeAnalysis;
-using Polly.Telemetry;
 using Polly.Utils.Pipeline;
 
 namespace Polly.Registry;
@@ -124,15 +123,17 @@ public ResiliencePipeline GetOrAddPipeline(TKey key, Action<ResiliencePipelineBu
             return pipeline;
         }
 
-        var context = new ConfigureBuilderContext<TKey>(key, _builderNameFormatter(key), _instanceNameFormatter?.Invoke(key));
-
-        return _pipelines.GetOrAdd(key, static (_, factory) =>
+        return _pipelines.GetOrAdd(key, k =>
         {
-            var component = CreatePipelineComponent(factory.instance._activator, factory.context, factory.configure);
+            var component = new RegistryPipelineComponentBuilder<ResiliencePipelineBuilder, TKey>(
+                _activator,
+                k,
+                _builderNameFormatter(k),
+                _instanceNameFormatter?.Invoke(k),
+                configure).CreateComponent();
 
             return new ResiliencePipeline(component, DisposeBehavior.Reject);
-        },
-        (instance: this, context, configure));
+        });
     }
 
     /// <summary>
@@ -260,36 +261,6 @@ public async ValueTask DisposeAsync()
         }
     }
 
-    private static PipelineComponent CreatePipelineComponent<TBuilder>(
-        Func<TBuilder> activator,
-        ConfigureBuilderContext<TKey> context,
-        Action<TBuilder, ConfigureBuilderContext<TKey>> configure)
-        where TBuilder : ResiliencePipelineBuilderBase
-    {
-        Func<TBuilder> factory = () =>
-        {
-            var builder = activator();
-            builder.Name = context.BuilderName;
-            builder.InstanceName = context.BuilderInstanceName;
-            configure(builder, context);
-
-            return builder;
-        };
-
-        var builder = factory();
-        var pipeline = builder.BuildPipelineComponent();
-        var telemetry = new ResilienceStrategyTelemetry(
-            new ResilienceTelemetrySource(context.BuilderName, context.BuilderInstanceName, null),
-            builder.TelemetryListener);
-
-        if (context.ReloadTokenProducer is null)
-        {
-            return pipeline;
-        }
-
-        return PipelineComponentFactory.CreateReloadable(pipeline, context.ReloadTokenProducer(), () => factory().BuildPipelineComponent(), telemetry);
-    }
-
     private GenericRegistry<TResult> GetGenericRegistry<TResult>()
     {
         if (_genericRegistry.TryGetValue(typeof(TResult), out var genericRegistry))