Introduce ResilienceStrategyRegistry

src/Polly.Core.Tests/Registry/ResilienceStrategyProviderTests.cs

@@ -0,0 +1,36 @@
+using System.Diagnostics.CodeAnalysis;
+using Polly.Registry;
+
+namespace Polly.Core.Tests.Registry;
+
+public class ResilienceStrategyProviderTests
+{
+    [Fact]
+    public void Get_DoesNotExist_Throws()
+    {
+        new Provider()
+            .Invoking(o => o.Get("not-exists"))
+            .Should()
+            .Throw<KeyNotFoundException>()
+            .WithMessage("Unable to find a resilience strategy associated with the key 'not-exists'. Please ensure that either the resilience strategy or the builder is registered.");
+    }
+
+    [Fact]
+    public void Get_Exist_Ok()
+    {
+        var provider = new Provider { Strategy = new TestResilienceStrategy() };
+
+        provider.Get("exists").Should().Be(provider.Strategy);
+    }
+
+    private class Provider : ResilienceStrategyProvider<string>
+    {
+        public ResilienceStrategy? Strategy { get; set; }
+
+        public override bool TryGet(string key, [NotNullWhen(true)] out ResilienceStrategy? strategy)
+        {
+            strategy = Strategy;
+            return Strategy != null;
+        }
+    }
+}

src/Polly.Core.Tests/Registry/ResilienceStrategyRegistryTests.cs

@@ -0,0 +1,172 @@
+using System.ComponentModel.DataAnnotations;
+using System.Globalization;
+using Polly.Builder;
+using Polly.Registry;
+
+namespace Polly.Core.Tests.Registry;
+
+public class ResilienceStrategyRegistryTests
+{
+    private Action<ResilienceStrategyBuilder> _callback = _ => { };
+
+    [Fact]
+    public void Ctor_Default_Ok()
+    {
+        this.Invoking(_ => new ResilienceStrategyRegistry<string>()).Should().NotThrow();
+    }
+
+    [Fact]
+    public void Ctor_InvalidOptions_Throws()
+    {
+        this.Invoking(_ => new ResilienceStrategyRegistry<string>(new ResilienceStrategyRegistryOptions<string> { BuilderFactory = null! }))
+            .Should()
+            .Throw<ValidationException>().WithMessage("The resilience strategy registry options are invalid.*");
+    }
+
+    [Fact]
+    public void Clear_Ok()
+    {
+        var registry = new ResilienceStrategyRegistry<string>();
+
+        registry.TryAddBuilder("C", (_, b) => b.AddStrategy(new TestResilienceStrategy()));
+
+        registry.TryAdd("A", new TestResilienceStrategy());
+        registry.TryAdd("B", new TestResilienceStrategy());
+        registry.TryAdd("C", new TestResilienceStrategy());
+
+        registry.Clear();
+
+        registry.TryGet("A", out _).Should().BeFalse();
+        registry.TryGet("B", out _).Should().BeFalse();
+        registry.TryGet("C", out _).Should().BeTrue();
+    }
+
+    [Fact]
+    public void Remove_Ok()
+    {
+        var registry = new ResilienceStrategyRegistry<string>();
+
+        registry.TryAdd("A", new TestResilienceStrategy());
+        registry.TryAdd("B", new TestResilienceStrategy());
+
+        registry.Remove("A").Should().BeTrue();
+        registry.Remove("A").Should().BeFalse();
+
+        registry.TryGet("A", out _).Should().BeFalse();
+        registry.TryGet("B", out _).Should().BeTrue();
+    }
+
+    [Fact]
+    public void RemoveBuilder_Ok()
+    {
+        var registry = new ResilienceStrategyRegistry<string>();
+        registry.TryAddBuilder("A", (_, b) => b.AddStrategy(new TestResilienceStrategy()));
+
+        registry.RemoveBuilder("A").Should().BeTrue();
+        registry.RemoveBuilder("A").Should().BeFalse();
+
+        registry.TryGet("A", out _).Should().BeFalse();
+    }
+
+    [Fact]
+    public void GetStrategy_BuilderMultiInstance_EnsureMultipleInstances()
+    {
+        var builderName = "A";
+        var registry = CreateRegistry();
+        var strategies = new HashSet<ResilienceStrategy>();
+        registry.TryAddBuilder(StrategyId.Create(builderName), (_, builder) => builder.AddStrategy(new TestResilienceStrategy()));
+
+        for (int i = 0; i < 100; i++)
+        {
+            var key = StrategyId.Create(builderName, i.ToString(CultureInfo.InvariantCulture));
+
+            strategies.Add(registry.Get(key));
+
+            // call again, the strategy should be already cached
+            strategies.Add(registry.Get(key));
+        }
+
+        strategies.Should().HaveCount(100);
+    }
+
+    [Fact]
+    public void AddBuilder_GetStrategy_EnsureCalled()
+    {
+        var activatorCalls = 0;
+        _callback = _ => activatorCalls++;
+        var registry = CreateRegistry();
+        var called = 0;
+        registry.TryAddBuilder(StrategyId.Create("A"), (key, builder) =>
+        {
+            builder.AddStrategy(new TestResilienceStrategy());
+            builder.Options.Properties.Set(StrategyId.ResilienceKey, key);
+            called++;
+        });
+
+        var key1 = StrategyId.Create("A");
+        var key2 = StrategyId.Create("A", "Instance1");
+        var key3 = StrategyId.Create("A", "Instance2");
+        var keys = new[] { key1, key2, key3 };
+        var strategies = keys.ToDictionary(k => k, registry.Get);
+        foreach (var key in keys)
+        {
+            registry.Get(key);
+        }
+
+        called.Should().Be(3);
+        activatorCalls.Should().Be(3);
+        strategies.Keys.Should().HaveCount(3);
+    }
+
+    [Fact]
+    public void TryGet_NoBuilder_Null()
+    {
+        var registry = CreateRegistry();
+        var key = StrategyId.Create("A");
+
+        registry.TryGet(key, out var strategy).Should().BeFalse();
+        strategy.Should().BeNull();
+    }
+
+    [Fact]
+    public void TryGet_ExplicitStrategyAdded_Ok()
+    {
+        var expectedStrategy = new TestResilienceStrategy();
+        var registry = CreateRegistry();
+        var key = StrategyId.Create("A", "Instance");
+        registry.TryAdd(key, expectedStrategy).Should().BeTrue();
+
+        registry.TryGet(key, out var strategy).Should().BeTrue();
+
+        strategy.Should().BeSameAs(expectedStrategy);
+    }
+
+    [Fact]
+    public void TryAdd_Twice_SecondNotAdded()
+    {
+        var expectedStrategy = new TestResilienceStrategy();
+        var registry = CreateRegistry();
+        var key = StrategyId.Create("A", "Instance");
+        registry.TryAdd(key, expectedStrategy);
+
+        registry.TryAdd(key, new TestResilienceStrategy()).Should().BeFalse();
+
+        registry.TryGet(key, out var strategy).Should().BeTrue();
+        strategy.Should().BeSameAs(expectedStrategy);
+    }
+
+    private ResilienceStrategyRegistry<StrategyId> CreateRegistry()
+    {
+        return new ResilienceStrategyRegistry<StrategyId>(new ResilienceStrategyRegistryOptions<StrategyId>
+        {
+            BuilderFactory = () =>
+            {
+                var builder = new ResilienceStrategyBuilder();
+                _callback(builder);
+                return builder;
+            },
+            StrategyComparer = StrategyId.Comparer,
+            BuilderComparer = StrategyId.BuilderComparer
+        });
+    }
+}

src/Polly.Core.Tests/Registry/StrategyId.cs

@@ -0,0 +1,25 @@
+using System;
+using System.Collections.Generic;
+
+namespace Polly.Core.Tests.Registry;
+
+public record StrategyId(Type Type, string BuilderName, string InstanceName = "")
+{
+    public static readonly ResiliencePropertyKey<StrategyId> ResilienceKey = new("Polly.StrategyId");
+
+    public static StrategyId Create<T>(string builderName, string instanceName = "")
+        => new(typeof(T), builderName, instanceName);
+    public static StrategyId Create(string builderName, string instanceName = "")
+        => new(typeof(StrategyId), builderName, instanceName);
+
+    public static readonly IEqualityComparer<StrategyId> Comparer = EqualityComparer<StrategyId>.Default;
+
+    public static readonly IEqualityComparer<StrategyId> BuilderComparer = new BuilderResilienceKeyComparer();
+
+    private sealed class BuilderResilienceKeyComparer : IEqualityComparer<StrategyId>
+    {
+        public bool Equals(StrategyId? x, StrategyId? y) => x?.Type == y?.Type && x?.BuilderName == y?.BuilderName;
+
+        public int GetHashCode(StrategyId obj) => (obj.Type, obj.BuilderName).GetHashCode();
+    }
+}

src/Polly.Core/Registry/ResilienceStrategyProvider.cs

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+using System.Diagnostics.CodeAnalysis;
+
+namespace Polly.Registry;
+
+#pragma warning disable CA1716 // Identifiers should not match keywords
+
+/// <summary>
+/// Represents a provider for resilience strategies that are accessible by <typeparamref name="TKey"/>.
+/// </summary>
+/// <typeparam name="TKey">The type of the key.</typeparam>
+public abstract class ResilienceStrategyProvider<TKey>
+    where TKey : notnull
+{
+    /// <summary>
+    /// Retrieves a resilience strategy from the provider using the specified key.
+    /// </summary>
+    /// <param name="key">The key used to identify the resilience strategy.</param>
+    /// <returns>The resilience strategy associated with the specified key.</returns>
+    /// <exception cref="KeyNotFoundException">Thrown when no resilience strategy is found for the specified key.</exception>
+    public virtual ResilienceStrategy Get(TKey key)
+    {
+        if (TryGet(key, out var strategy))
+        {
+            return strategy;
+        }
+
+        throw new KeyNotFoundException($"Unable to find a resilience strategy associated with the key '{key}'. " +
+            $"Please ensure that either the resilience strategy or the builder is registered.");
+    }
+
+    /// <summary>
+    /// Tries to get a resilience strategy from the provider using the specified key.
+    /// </summary>
+    /// <param name="key">The key used to identify the resilience strategy.</param>
+    /// <param name="strategy">The output resilience strategy if found, null otherwise.</param>
+    /// <returns>true if the strategy was found, false otherwise.</returns>
+    public abstract bool TryGet(TKey key, [NotNullWhen(true)] out ResilienceStrategy? strategy);
+}