added event filter contravariance

#100
JonasSamuelsson · Sep 20, 2020 · 97e06ee · 97e06ee
1 parent 455dc67
commit 97e06ee
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Showing 21 changed files with 121 additions and 78 deletions.
diff --git a/src/Handyman.Mediator/src/IEventFilter.cs b/src/Handyman.Mediator/src/IEventFilter.cs
@@ -1,11 +1,9 @@
 using System.Threading.Tasks;
-using Handyman.Mediator.Pipeline;
 
 namespace Handyman.Mediator
 {
-    public interface IEventFilter<TEvent>
-        where TEvent : IEvent
+    public interface IEventFilter<in TEvent>
     {
-        Task Execute(EventPipelineContext<TEvent> context, EventFilterExecutionDelegate next);
+        Task Execute(TEvent @event, IEventFilterContext context, EventFilterExecutionDelegate next);
     }
 }
diff --git a/src/Handyman.Mediator/src/IEventFilterContext.cs b/src/Handyman.Mediator/src/IEventFilterContext.cs
@@ -0,0 +1,11 @@
+using System;
+using System.Threading;
+
+namespace Handyman.Mediator
+{
+    public interface IEventFilterContext
+    {
+        CancellationToken CancellationToken { get; set; }
+        IServiceProvider ServiceProvider { get; set; }
+    }
+}
diff --git a/src/Handyman.Mediator/src/Pipeline/EventFilterToggle/EventFilterToggleFilterSelector.cs b/src/Handyman.Mediator/src/Pipeline/EventFilterToggle/EventFilterToggleFilterSelector.cs
@@ -13,7 +13,8 @@ public EventFilterToggleFilterSelector(EventFilterToggleMetadata toggleMetadata)
             _toggleMetadata = toggleMetadata;
         }
 
-        public async Task SelectFilters<TEvent>(List<IEventFilter<TEvent>> filters, EventPipelineContext<TEvent> context) where TEvent : IEvent
+        public async Task SelectFilters<TEvent>(List<IEventFilter<TEvent>> filters, EventPipelineContext<TEvent> context)
+            where TEvent : IEvent
         {
             var toggle = context.ServiceProvider.GetRequiredService<IEventFilterToggle>();
             var enabled = await toggle.IsEnabled(_toggleMetadata, context).ConfigureAwait();

diff --git a/src/Handyman.Mediator/src/Pipeline/EventFilterToggle/IEventFilterToggle.cs b/src/Handyman.Mediator/src/Pipeline/EventFilterToggle/IEventFilterToggle.cs
@@ -4,8 +4,7 @@ namespace Handyman.Mediator.Pipeline.EventFilterToggle
 {
     public interface IEventFilterToggle
     {
-        Task<bool> IsEnabled<TEvent>(EventFilterToggleMetadata toggleMetadata,
-            EventPipelineContext<TEvent> pipelineContext)
+        Task<bool> IsEnabled<TEvent>(EventFilterToggleMetadata toggleMetadata, EventPipelineContext<TEvent> pipelineContext)
             where TEvent : IEvent;
     }
 }
diff --git a/src/Handyman.Mediator/src/Pipeline/EventHandlerToggle/EventHandlerToggleHandlerSelector.cs b/src/Handyman.Mediator/src/Pipeline/EventHandlerToggle/EventHandlerToggleHandlerSelector.cs
@@ -13,7 +13,8 @@ public EventHandlerToggleHandlerSelector(EventHandlerToggleMetadata toggleMetada
             _toggleMetadata = toggleMetadata;
         }
 
-        public async Task SelectHandlers<TEvent>(List<IEventHandler<TEvent>> handlers, EventPipelineContext<TEvent> context) where TEvent : IEvent
+        public async Task SelectHandlers<TEvent>(List<IEventHandler<TEvent>> handlers, EventPipelineContext<TEvent> context)
+            where TEvent : IEvent
         {
             var toggle = context.ServiceProvider.GetRequiredService<IEventHandlerToggle>();
             var enabled = await toggle.IsEnabled(_toggleMetadata, context).ConfigureAwait();

diff --git a/src/Handyman.Mediator/src/Pipeline/EventHandlerToggle/IEventHandlerToggle.cs b/src/Handyman.Mediator/src/Pipeline/EventHandlerToggle/IEventHandlerToggle.cs
@@ -4,8 +4,7 @@ namespace Handyman.Mediator.Pipeline.EventHandlerToggle
 {
     public interface IEventHandlerToggle
     {
-        Task<bool> IsEnabled<TEvent>(EventHandlerToggleMetadata toggleMetadata,
-            EventPipelineContext<TEvent> pipelineContext)
+        Task<bool> IsEnabled<TEvent>(EventHandlerToggleMetadata toggleMetadata, EventPipelineContext<TEvent> pipelineContext)
             where TEvent : IEvent;
     }
 }
diff --git a/src/Handyman.Mediator/src/Pipeline/EventPipeline.cs b/src/Handyman.Mediator/src/Pipeline/EventPipeline.cs
@@ -8,20 +8,6 @@ namespace Handyman.Mediator.Pipeline
     internal abstract class EventPipeline
     {
         internal abstract Task Execute(IEvent @event, IServiceProvider serviceProvider, CancellationToken cancellationToken);
-
-        private static Task Execute<TEvent>(List<IEventHandler<TEvent>> handlers, TEvent @event, CancellationToken cancellationToken) where TEvent : IEvent
-        {
-            cancellationToken.ThrowIfCancellationRequested();
-
-            var tasks = new List<Task>(handlers.Count);
-
-            foreach (var handler in handlers)
-            {
-                tasks.Add(handler.Handle(@event, cancellationToken));
-            }
-
-            return Task.WhenAll(tasks);
-        }
     }
 
     internal abstract class EventPipeline<TEvent> : EventPipeline
@@ -65,7 +51,7 @@ Task Execute()
                 if (index < filterCount)
                 {
                     context.CancellationToken.ThrowIfCancellationRequested();
-                    return filters[index++].Execute(context, Execute);
+                    return filters[index++].Execute(context.Event, context, Execute);
                 }
 
                 context.CancellationToken.ThrowIfCancellationRequested();

diff --git a/src/Handyman.Mediator/src/Pipeline/EventPipelineContext.cs b/src/Handyman.Mediator/src/Pipeline/EventPipelineContext.cs
@@ -3,7 +3,8 @@
 
 namespace Handyman.Mediator.Pipeline
 {
-    public class EventPipelineContext<TEvent> : IPipelineContext
+    public class EventPipelineContext<TEvent> : IEventFilterContext, IPipelineContext
+        where TEvent : IEvent
     {
         public CancellationToken CancellationToken { get; set; }
         public TEvent Event { get; set; }

diff --git a/src/Handyman.Mediator/src/Pipeline/IEventFilterSelector.cs b/src/Handyman.Mediator/src/Pipeline/IEventFilterSelector.cs
@@ -5,6 +5,7 @@ namespace Handyman.Mediator.Pipeline
 {
     public interface IEventFilterSelector
     {
-        Task SelectFilters<TEvent>(List<IEventFilter<TEvent>> filters, EventPipelineContext<TEvent> context) where TEvent : IEvent;
+        Task SelectFilters<TEvent>(List<IEventFilter<TEvent>> filters, EventPipelineContext<TEvent> context)
+            where TEvent : IEvent;
     }
 }
diff --git a/src/Handyman.Mediator/src/Pipeline/IEventHandlerExecutionStrategy.cs b/src/Handyman.Mediator/src/Pipeline/IEventHandlerExecutionStrategy.cs
@@ -5,6 +5,7 @@ namespace Handyman.Mediator.Pipeline
 {
     public interface IEventHandlerExecutionStrategy
     {
-        Task Execute<TEvent>(List<IEventHandler<TEvent>> handlers, EventPipelineContext<TEvent> context) where TEvent : IEvent;
+        Task Execute<TEvent>(List<IEventHandler<TEvent>> handlers, EventPipelineContext<TEvent> context)
+            where TEvent : IEvent;
     }
 }
diff --git a/src/Handyman.Mediator/src/Pipeline/IEventHandlerSelector.cs b/src/Handyman.Mediator/src/Pipeline/IEventHandlerSelector.cs
@@ -5,6 +5,7 @@ namespace Handyman.Mediator.Pipeline
 {
     public interface IEventHandlerSelector
     {
-        Task SelectHandlers<TEvent>(List<IEventHandler<TEvent>> handlers, EventPipelineContext<TEvent> context) where TEvent : IEvent;
+        Task SelectHandlers<TEvent>(List<IEventHandler<TEvent>> handlers, EventPipelineContext<TEvent> context)
+            where TEvent : IEvent;
     }
 }
diff --git a/src/Handyman.Mediator/src/Pipeline/ToggleBase.cs b/src/Handyman.Mediator/src/Pipeline/ToggleBase.cs
@@ -9,32 +9,32 @@ namespace Handyman.Mediator.Pipeline
 {
     public abstract class ToggleBase : IEventFilterToggle, IEventHandlerToggle, IRequestFilterToggle, IRequestHandlerToggle, IRequestHandlerExperimentToggle
     {
-        public virtual Task<bool> IsEnabled<TEvent>(EventFilterToggleMetadata toggleMetadata,
-            EventPipelineContext<TEvent> pipelineContext) where TEvent : IEvent
+        public virtual Task<bool> IsEnabled<TEvent>(EventFilterToggleMetadata toggleMetadata, EventPipelineContext<TEvent> pipelineContext)
+            where TEvent : IEvent
         {
             return IsEnabled((IToggleMetadata)toggleMetadata, pipelineContext);
         }
 
-        public virtual Task<bool> IsEnabled<TEvent>(EventHandlerToggleMetadata toggleMetadata,
-            EventPipelineContext<TEvent> pipelineContext) where TEvent : IEvent
+        public virtual Task<bool> IsEnabled<TEvent>(EventHandlerToggleMetadata toggleMetadata, EventPipelineContext<TEvent> pipelineContext)
+            where TEvent : IEvent
         {
             return IsEnabled((IToggleMetadata)toggleMetadata, pipelineContext);
         }
 
-        public virtual Task<bool> IsEnabled<TRequest, TResponse>(RequestFilterToggleMetadata toggleMetadata,
-            RequestPipelineContext<TRequest> pipelineContext) where TRequest : IRequest<TResponse>
+        public virtual Task<bool> IsEnabled<TRequest, TResponse>(RequestFilterToggleMetadata toggleMetadata, RequestPipelineContext<TRequest> pipelineContext)
+            where TRequest : IRequest<TResponse>
         {
             return IsEnabled(toggleMetadata, pipelineContext);
         }
 
-        public virtual Task<bool> IsEnabled<TRequest, TResponse>(RequestHandlerToggleMetadata toggleMetadata,
-            RequestPipelineContext<TRequest> pipelineContext) where TRequest : IRequest<TResponse>
+        public virtual Task<bool> IsEnabled<TRequest, TResponse>(RequestHandlerToggleMetadata toggleMetadata, RequestPipelineContext<TRequest> pipelineContext)
+            where TRequest : IRequest<TResponse>
         {
             return IsEnabled(toggleMetadata, pipelineContext);
         }
 
-        public virtual Task<bool> IsEnabled<TRequest, TResponse>(RequestHandlerExperimentMetadata experimentMetadata,
-            RequestPipelineContext<TRequest> pipelineContext) where TRequest : IRequest<TResponse>
+        public virtual Task<bool> IsEnabled<TRequest, TResponse>(RequestHandlerExperimentMetadata experimentMetadata, RequestPipelineContext<TRequest> pipelineContext)
+            where TRequest : IRequest<TResponse>
         {
             return IsEnabled(experimentMetadata, pipelineContext);
         }

diff --git a/src/Handyman.Mediator/src/Pipeline/WhenAllEventHandlerExecutionStrategy.cs b/src/Handyman.Mediator/src/Pipeline/WhenAllEventHandlerExecutionStrategy.cs
@@ -8,7 +8,8 @@ public sealed class WhenAllEventHandlerExecutionStrategy : IEventHandlerExecutio
     {
         public static readonly IEventHandlerExecutionStrategy Instance = new WhenAllEventHandlerExecutionStrategy();
 
-        public Task Execute<TEvent>(List<IEventHandler<TEvent>> handlers, EventPipelineContext<TEvent> context) where TEvent : IEvent
+        public Task Execute<TEvent>(List<IEventHandler<TEvent>> handlers, EventPipelineContext<TEvent> context)
+            where TEvent : IEvent
         {
             return Task.WhenAll(handlers.Select(x => x.Handle(context.Event, context.CancellationToken)));
         }

diff --git a/src/Handyman.Mediator/tests/EventFilterOrderingTests.cs b/src/Handyman.Mediator/tests/EventFilterOrderingTests.cs
@@ -1,8 +1,7 @@
-using System.Threading;
-using System.Threading.Tasks;
-using Handyman.Mediator.Pipeline;
-using Microsoft.Extensions.DependencyInjection;
+using Microsoft.Extensions.DependencyInjection;
 using Shouldly;
+using System.Threading;
+using System.Threading.Tasks;
 using Xunit;
 
 namespace Handyman.Mediator.Tests
@@ -37,9 +36,9 @@ private class Filter : IOrderedFilter, IEventFilter<Event>
             public int Order { get; set; }
             public string Text { get; set; }
 
-            public Task Execute(EventPipelineContext<Event> context, EventFilterExecutionDelegate next)
+            public Task Execute(Event @event, IEventFilterContext context, EventFilterExecutionDelegate next)
             {
-                context.Event.Text += Text;
+                @event.Text += Text;
                 return next();
             }
         }

diff --git a/src/Handyman.Mediator/tests/EventFilterTests.cs b/src/Handyman.Mediator/tests/EventFilterTests.cs
@@ -0,0 +1,38 @@
+using Lamar;
+using Microsoft.Extensions.DependencyInjection;
+using Shouldly;
+using System.Threading.Tasks;
+using Xunit;
+
+namespace Handyman.Mediator.Tests
+{
+    public class EventFilterTests
+    {
+        [Fact]
+        public async Task ShouldExecuteFilters()
+        {
+            // using Lamar for dependency injection as it has support for constrained open generics
+
+            var container = new Container(services => services.AddTransient<IEventFilter<IMarker>, Filter>());
+
+            await new Mediator(container).Publish(new Event());
+
+            Filter.Executed.ShouldBeTrue();
+        }
+
+        private class Event : IEvent, IMarker { }
+
+        private interface IMarker { }
+
+        private class Filter : IEventFilter<IMarker>
+        {
+            public static bool Executed;
+
+            public Task Execute(IMarker @event, IEventFilterContext context, EventFilterExecutionDelegate next)
+            {
+                Executed = true;
+                return Task.CompletedTask;
+            }
+        }
+    }
+}
diff --git a/src/Handyman.Mediator/tests/EventPipelineTests.cs b/src/Handyman.Mediator/tests/EventPipelineTests.cs
@@ -1,8 +1,7 @@
-using System.Threading;
-using System.Threading.Tasks;
-using Handyman.Mediator.Pipeline;
-using Microsoft.Extensions.DependencyInjection;
+using Microsoft.Extensions.DependencyInjection;
 using Shouldly;
+using System.Threading;
+using System.Threading.Tasks;
 using Xunit;
 
 namespace Handyman.Mediator.Tests
@@ -34,8 +33,7 @@ private class EventFilter : IEventFilter<Event>
         {
             public bool Executed { get; set; }
 
-            public Task Execute(EventPipelineContext<Event> context,
-                EventFilterExecutionDelegate next)
+            public Task Execute(Event @event, IEventFilterContext context, EventFilterExecutionDelegate next)
             {
                 Executed = true;
                 return next();

diff --git a/src/Handyman.Mediator/tests/EventProcessingCancellationTests.cs b/src/Handyman.Mediator/tests/EventProcessingCancellationTests.cs
@@ -123,7 +123,7 @@ public EventFilter(CancellationTokenSource cancellationTokenSource)
 
             public bool Executed { get; set; }
 
-            public Task Execute(EventPipelineContext<Event> context, EventFilterExecutionDelegate next)
+            public Task Execute(Event @event, IEventFilterContext context, EventFilterExecutionDelegate next)
             {
                 _cancellationTokenSource.Cancel();
                 Executed = true;

diff --git a/src/Handyman.Mediator/tests/Handyman.Mediator.Tests.csproj b/src/Handyman.Mediator/tests/Handyman.Mediator.Tests.csproj
@@ -1,22 +1,30 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
-	<PropertyGroup>
-		<TargetFrameworks>net472;netcoreapp2.1;netcoreapp3.0;netcoreapp3.1</TargetFrameworks>
-	</PropertyGroup>
+   <PropertyGroup>
+      <TargetFrameworks>net472;netcoreapp2.1;netcoreapp3.0;netcoreapp3.1</TargetFrameworks>
+   </PropertyGroup>
 
-	<ItemGroup>
-		<PackageReference Include="Microsoft.Extensions.DependencyInjection" Version="3.0.0" />
-		<PackageReference Include="Microsoft.NET.Test.Sdk" Version="16.3.0" />
-		<PackageReference Include="Shouldly" Version="3.0.2" />
-		<PackageReference Include="xunit" Version="2.4.1" />
-		<PackageReference Include="xunit.runner.visualstudio" Version="2.4.1">
-			<PrivateAssets>all</PrivateAssets>
-			<IncludeAssets>runtime; build; native; contentfiles; analyzers</IncludeAssets>
-		</PackageReference>
-	</ItemGroup>
+   <ItemGroup>
+      <PackageReference Include="Lamar" Version="4.3.1" />
+      <PackageReference Include="Microsoft.NET.Test.Sdk" Version="16.3.0" />
+      <PackageReference Include="Shouldly" Version="3.0.2" />
+      <PackageReference Include="xunit" Version="2.4.1" />
+      <PackageReference Include="xunit.runner.visualstudio" Version="2.4.1">
+         <PrivateAssets>all</PrivateAssets>
+         <IncludeAssets>runtime; build; native; contentfiles; analyzers</IncludeAssets>
+      </PackageReference>
+   </ItemGroup>
 
-	<ItemGroup>
-		<ProjectReference Include="..\src\Handyman.Mediator.csproj" />
-	</ItemGroup>
+   <ItemGroup Condition=" '$(TargetFramework)' == 'net472' ">
+      <PackageReference Include="Microsoft.Extensions.DependencyInjection" Version="2.2.0" />
+   </ItemGroup>
+
+   <ItemGroup Condition=" '$(TargetFramework)' != 'net472' ">
+      <PackageReference Include="Microsoft.Extensions.DependencyInjection" Version="3.1.7" />
+   </ItemGroup>
+
+   <ItemGroup>
+      <ProjectReference Include="..\src\Handyman.Mediator.csproj" />
+   </ItemGroup>
 
 </Project>
diff --git a/src/Handyman.Mediator/tests/Pipeline/EventFilterToggle/EventFilterToggleTests.cs b/src/Handyman.Mediator/tests/Pipeline/EventFilterToggle/EventFilterToggleTests.cs
@@ -43,7 +43,7 @@ private class ToggleEnabledEventFilter : IEventFilter<Event>
         {
             public bool Executed { get; set; }
 
-            public Task Execute(EventPipelineContext<Event> context, EventFilterExecutionDelegate next)
+            public Task Execute(Event @event, IEventFilterContext context, EventFilterExecutionDelegate next)
             {
                 Executed = true;
                 return next();
@@ -54,7 +54,7 @@ private class ToggleDisabledEventFilter : IEventFilter<Event>
         {
             public bool Executed { get; set; }
 
-            public Task Execute(EventPipelineContext<Event> context, EventFilterExecutionDelegate next)
+            public Task Execute(Event @event, IEventFilterContext context, EventFilterExecutionDelegate next)
             {
                 Executed = true;
                 return next();
@@ -66,8 +66,8 @@ private class EventFilterToggle : IEventFilterToggle
             public bool Enabled { get; set; }
             public EventFilterToggleMetadata ToggleMetadata { get; set; }
 
-            public Task<bool> IsEnabled<TEvent>(EventFilterToggleMetadata toggleMetadata,
-                EventPipelineContext<TEvent> pipelineContext) where TEvent : IEvent
+            public Task<bool> IsEnabled<TEvent>(EventFilterToggleMetadata toggleMetadata, EventPipelineContext<TEvent> pipelineContext)
+                where TEvent : IEvent
             {
                 ToggleMetadata = toggleMetadata;
                 return Task.FromResult(Enabled);

diff --git a/src/Handyman.Mediator/tests/Pipeline/EventHandlerToggle/EventHandlerToggleTests.cs b/src/Handyman.Mediator/tests/Pipeline/EventHandlerToggle/EventHandlerToggleTests.cs
@@ -64,8 +64,8 @@ private class EventHandlerToggle : IEventHandlerToggle
             public bool Enabled { get; set; }
             public EventHandlerToggleMetadata ToggleMetadata { get; set; }
 
-            public Task<bool> IsEnabled<TEvent>(EventHandlerToggleMetadata toggleMetadata,
-                EventPipelineContext<TEvent> pipelineContext) where TEvent : IEvent
+            public Task<bool> IsEnabled<TEvent>(EventHandlerToggleMetadata toggleMetadata, EventPipelineContext<TEvent> pipelineContext)
+                where TEvent : IEvent
             {
                 ToggleMetadata = toggleMetadata;
                 return Task.FromResult(Enabled);

diff --git a/src/Handyman.Mediator/tests/Pipeline/EventPipelineCustomizationTests.cs b/src/Handyman.Mediator/tests/Pipeline/EventPipelineCustomizationTests.cs
@@ -42,7 +42,8 @@ public override void Configure(IEventPipelineBuilder builder, IServiceProvider s
 
         private class EventFilterSelector : IEventFilterSelector
         {
-            public Task SelectFilters<TEvent>(List<IEventFilter<TEvent>> filters, EventPipelineContext<TEvent> context) where TEvent : IEvent
+            public Task SelectFilters<TEvent>(List<IEventFilter<TEvent>> filters, EventPipelineContext<TEvent> context)
+                where TEvent : IEvent
             {
                 filters.Add(new EventFilter<TEvent> { Action = context.ServiceProvider.GetRequiredService<Action<string>>() });
                 return Task.CompletedTask;
@@ -59,11 +60,10 @@ private class EventHandlerSelector : IEventHandlerSelector
         }
 
         private class EventFilter<TEvent> : IEventFilter<TEvent>
-            where TEvent : IEvent
         {
             public Action<string> Action { get; set; }
 
-            public Task Execute(EventPipelineContext<TEvent> context, EventFilterExecutionDelegate next)
+            public Task Execute(TEvent @event, IEventFilterContext context, EventFilterExecutionDelegate next)
             {
                 Action("filter");
                 return next();