Introduce ObjectPool and use it for ResilienceContext pooling

src/Polly.Core.Tests/ExecutionRejectedExceptionTests.cs

@@ -1,11 +1,11 @@
-namespace Polly.Core.Tests.Timeout;
+namespace Polly.Core.Tests;
 
 public class ExecutionRejectedExceptionTests
 {
     [Fact]
     public void Ctor_Ok()
     {
-        new CustomException().Message.Should().Be("Exception of type 'Polly.Core.Tests.Timeout.ExecutionRejectedExceptionTests+CustomException' was thrown.");
+        new CustomException().Message.Should().Be("Exception of type 'Polly.Core.Tests.ExecutionRejectedExceptionTests+CustomException' was thrown.");
         new CustomException("Dummy").Message.Should().Be("Dummy");
     }
 

src/Polly.Core.Tests/Utils/BinarySerializationUtil.cs → src/Polly.Core.Tests/Helpers/BinarySerializationUtil.cs

@@ -2,7 +2,7 @@
 
 using System;
 
-namespace Polly.Core.Tests.Utils;
+namespace Polly.Core.Tests.Helpers;
 
 /// <summary>
 /// Utility that serializes and deserializes the exceptions using the binary formatter.

src/Polly.Core.Tests/Utils/FakeTimeProvider.cs → src/Polly.Core.Tests/Helpers/FakeTimeProvider.cs

@@ -1,7 +1,7 @@
 using Moq;
 using Polly.Utils;
 
-namespace Polly.Core.Tests.Utils;
+namespace Polly.Core.Tests.Helpers;
 
 internal class FakeTimeProvider : Mock<TimeProvider>
 {

src/Polly.Core.Tests/Utils/TestArguments.cs → src/Polly.Core.Tests/Helpers/TestArguments.cs

@@ -1,6 +1,6 @@
 using Polly.Strategy;
 
-namespace Polly.Core.Tests.Utils;
+namespace Polly.Core.Tests.Helpers;
 
 public class TestArguments : IResilienceArguments
 {

src/Polly.Core.Tests/Utils/TestResilienceStrategy.cs → src/Polly.Core.Tests/Helpers/TestResilienceStrategy.cs

@@ -1,4 +1,4 @@
-namespace Polly.Core.Tests.Utils;
+namespace Polly.Core.Tests.Helpers;
 
 public class TestResilienceStrategy : ResilienceStrategy
 {

src/Polly.Core.Tests/Utils/TestUtils.cs → src/Polly.Core.Tests/Helpers/TestUtils.cs

@@ -1,4 +1,4 @@
-namespace Polly.Core.Tests.Utils;
+namespace Polly.Core.Tests.Helpers;
 
 #pragma warning disable CA1031 // Do not catch general exception types
 

src/Polly.Core.Tests/Polly.Core.Tests.csproj

@@ -16,6 +16,6 @@
   </ItemGroup>
 
   <ItemGroup>
-    <Using Include="Polly.Core.Tests.Utils" />
+    <Using Include="Polly.Core.Tests.Helpers" />
   </ItemGroup>
 </Project>

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

@@ -1,6 +1,3 @@
-using System;
-using System.Collections.Generic;
-
 namespace Polly.Core.Tests.Registry;
 
 public record StrategyId(Type Type, string BuilderName, string InstanceName = "")

src/Polly.Core.Tests/ResilienceContextTests.cs

@@ -16,6 +16,16 @@ public void Get_EnsureDefaults()
         AssertDefaults(context);
     }
 
+    [Fact]
+    public void Get_EnsurePooled()
+    {
+        var context = ResilienceContext.Get();
+
+        ResilienceContext.Return(context);
+
+        ResilienceContext.Get().Should().BeSameAs(context);
+    }
+
     [Fact]
     public void Return_Null_Throws()
     {

src/Polly.Core.Tests/Retry/RetryDelayGeneratorTests.cs

@@ -1,8 +1,5 @@
-using System;
-using System.Threading.Tasks;
 using Polly.Retry;
 using Polly.Strategy;
-using Xunit;
 
 namespace Polly.Core.Tests.Retry;
 

src/Polly.Core.Tests/Retry/RetryHelperTests.cs

@@ -1,4 +1,3 @@
-using System;
 using Polly.Retry;
 
 namespace Polly.Core.Tests.Retry;

src/Polly.Core.Tests/Retry/RetryResilienceStrategyBuilderExtensionsTests.cs

@@ -1,7 +1,6 @@
 using System.ComponentModel.DataAnnotations;
 using Polly.Builder;
 using Polly.Retry;
-using Xunit;
 
 namespace Polly.Core.Tests.Retry;
 

src/Polly.Core.Tests/Strategy/OutcomeEventTests.cs

@@ -1,5 +1,3 @@
-using System;
-using System.Threading.Tasks;
 using Polly.Strategy;
 
 namespace Polly.Core.Tests.Strategy;

src/Polly.Core.Tests/Strategy/OutcomeGeneratorTests.cs

@@ -1,5 +1,3 @@
-using System;
-using System.Threading.Tasks;
 using Polly.Strategy;
 
 namespace Polly.Core.Tests.Strategy;

src/Polly.Core.Tests/Strategy/OutcomePredicateTests.cs

@@ -1,5 +1,3 @@
-using System;
-using System.Threading.Tasks;
 using Polly.Strategy;
 
 namespace Polly.Core.Tests.Strategy;

src/Polly.Core.Tests/Strategy/OutcomeTests.cs

@@ -1,4 +1,3 @@
-using System;
 using Polly.Strategy;
 
 namespace Polly.Core.Tests.Strategy;

src/Polly.Core.Tests/Strategy/SimpleEventTests.cs

@@ -1,14 +1,14 @@
 using Polly.Strategy;
 
-namespace Polly.Core.Tests.Timeout;
+namespace Polly.Core.Tests.Strategy;
 
 public class SimpleEventTests
 {
     [Fact]
     public async Task Add_EnsureOrdering()
     {
         var ev = new DummyEvent();
-        List<int> raisedEvents = new List<int>();
+        var raisedEvents = new List<int>();
 
         ev.Add(() => raisedEvents.Add(1));
         ev.Add(args => raisedEvents.Add(2));
@@ -41,7 +41,7 @@ public async Task CreateHandler_Ok(int count)
         var ev = new DummyEvent();
         var events = new List<int>();
 
-        for (int i = 0; i < count; i++)
+        for (var i = 0; i < count; i++)
         {
             ev.Add(() => events.Add(i));
         }

src/Polly.Core.Tests/Timeout/TimeoutAttributeTests.cs

@@ -1,4 +1,3 @@
-using System.ComponentModel.DataAnnotations;
 using Polly.Timeout;
 
 namespace Polly.Core.Tests.Timeout;

src/Polly.Core.Tests/Timeout/TimeoutStrategyOptionsTests.cs

@@ -1,7 +1,6 @@
 using System.ComponentModel.DataAnnotations;
 using Polly.Timeout;
 using Polly.Utils;
-using Xunit;
 
 namespace Polly.Core.Tests.Timeout;
 

src/Polly.Core.Tests/Timeout/TimeoutUtilTests.cs

@@ -1,6 +1,4 @@
-using System;
 using Polly.Timeout;
-using Xunit;
 
 namespace Polly.Core.Tests.Timeout;
 public class TimeoutUtilTests

src/Polly.Core.Tests/Utils/ObjectPoolTests.cs

@@ -0,0 +1,111 @@
+using Polly.Utils;
+
+namespace Polly.Core.Tests.Utils;
+
+public class ObjectPoolTests
+{
+    [Fact]
+    public void GetAnd_ReturnObject_SameInstance()
+    {
+        // Arrange
+        var pool = new ObjectPool<object>(() => new object(), _ => true);
+
+        var obj1 = pool.Get();
+        pool.Return(obj1);
+
+        // Act
+        var obj2 = pool.Get();
+
+        // Assert
+        Assert.Same(obj1, obj2);
+    }
+
+    [Fact]
+    public void MaxCapacity_Ok()
+    {
+        ObjectPool<object>.MaxCapacity.Should().Be((Environment.ProcessorCount * 2) - 1);
+    }
+
+    [Fact]
+    public void MaxCapacity_Respected()
+    {
+        // Arrange
+        var pool = new ObjectPool<object>(() => new object(), _ => true);
+        var items1 = GetStoreReturn(pool);
+
+        // Act
+        var items2 = GetStoreReturn(pool);
+
+        // Assert
+        items1.Should().BeEquivalentTo(items2);
+    }
+
+    [Fact]
+    public void MaxCapacityOverflow_Respected()
+    {
+        // Arrange
+        var count = ObjectPool<object>.MaxCapacity + 10;
+        var pool = new ObjectPool<object>(() => new object(), _ => true);
+        var items1 = GetStoreReturn(pool, count);
+
+        // Act
+        var items2 = GetStoreReturn(pool, count);
+
+        // Assert
+        items1.Last().Should().NotBeSameAs(items2.Last());
+    }
+
+    [Fact]
+    public void CreatedByPolicy()
+    {
+        // Arrange
+        var policy = new ListPolicy();
+        var pool = new ObjectPool<List<int>>(ListPolicy.Create, ListPolicy.Return);
+
+        // Act
+        var list = pool.Get();
+
+        // Assert
+        Assert.Equal(17, list.Capacity);
+    }
+
+    [Fact]
+    public void Return_RejectedByPolicy()
+    {
+        // Arrange
+        var policy = new ListPolicy();
+        var pool = new ObjectPool<List<int>>(ListPolicy.Create, ListPolicy.Return);
+        var list1 = pool.Get();
+        list1.Capacity = 20;
+
+        // Act
+        pool.Return(list1);
+        var list2 = pool.Get();
+
+        // Assert
+        Assert.NotSame(list1, list2);
+    }
+
+    private static List<object> GetStoreReturn(ObjectPool<object> pool, int? count = null)
+    {
+        var items = new List<object>();
+        for (int i = 0; i < (count ?? ObjectPool<object>.MaxCapacity); i++)
+        {
+            items.Add(pool.Get());
+        }
+
+        foreach (var item in items)
+        {
+            pool.Return(item);
+        }
+
+        return items;
+    }
+
+    private class ListPolicy
+    {
+        public static List<int> Create() => new(17);
+
+        public static bool Return(List<int> obj) => obj.Capacity == 17;
+    }
+}

src/Polly.Core.Tests/Utils/TimeSpanAttributeTests.cs

@@ -1,4 +1,3 @@
-using System;
 using System.ComponentModel.DataAnnotations;
 
 namespace Polly.Core.Tests.Utils;

src/Polly.Core.Tests/Utils/ValidationContextExtensions.cs → src/Polly.Core.Tests/Utils/ValidationContextExtensionsTests.cs

@@ -2,7 +2,7 @@
 
 namespace Polly.Core.Tests.Utils;
 
-public class ValidationContextExtensions
+public class ValidationContextExtensionsTests
 {
     [Fact]
     public void GetMemberName_Ok()

src/Polly.Core/ResilienceContext.cs

@@ -12,7 +12,9 @@ namespace Polly;
 /// </remarks>
 public sealed class ResilienceContext
 {
-    internal const bool ContinueOnCapturedContextDefault = false;
+    private const bool ContinueOnCapturedContextDefault = false;
+
+    private static readonly ObjectPool<ResilienceContext> Pool = new(static () => new ResilienceContext(), static c => c.Reset());
 
     private ResilienceContext()
     {
@@ -61,7 +63,7 @@ private ResilienceContext()
     /// After the execution is finished you should return the <see cref="ResilienceContext"/> back to the pool
     /// by calling <see cref="Return(ResilienceContext)"/> method.
     /// </remarks>
-    public static ResilienceContext Get() => new();
+    public static ResilienceContext Get() => Pool.Get();
 
     /// <summary>
     /// Returns a <paramref name="context"/> back to the pool.
@@ -71,7 +73,7 @@ public static void Return(ResilienceContext context)
     {
         Guard.NotNull(context);
 
-        context.Reset();
+        Pool.Return(context);
     }
 
     [ExcludeFromCodeCoverage]
@@ -90,13 +92,15 @@ internal ResilienceContext Initialize<TResult>(bool isSynchronous)
         return this;
     }
 
-    private void Reset()
+    private bool Reset()
     {
         IsSynchronous = false;
         ResultType = typeof(UnknownResult);
         ContinueOnCapturedContext = false;
         CancellationToken = default;
         ((IDictionary<string, object?>)Properties).Clear();
+
+        return true;
     }
 
     /// <summary>