Async Refactor

.editorconfig

@@ -0,0 +1,6 @@
+[*.cs]
+
+# CS1998: Async method lacks 'await' operators and will run synchronously
+dotnet_diagnostic.CS1998.severity = suggestion
+# CA2007: Consider calling ConfigureAwait on the awaited task
+dotnet_diagnostic.CA2007.severity = warning

BenchmarkDotNet.slnx

@@ -8,9 +8,13 @@
     <Project Path="samples/BenchmarkDotNet.Samples.FSharp/BenchmarkDotNet.Samples.FSharp.fsproj" />
     <Project Path="samples/BenchmarkDotNet.Samples/BenchmarkDotNet.Samples.csproj" DefaultStartup="true" />
   </Folder>
+  <Folder Name="/Solution Items/">
+    <File Path=".editorconfig" />
+  </Folder>
   <Folder Name="/src/">
     <Project Path="src/BenchmarkDotNet.Analyzers/BenchmarkDotNet.Analyzers.csproj" />
     <Project Path="src/BenchmarkDotNet.Annotations/BenchmarkDotNet.Annotations.csproj" />
+    <Project Path="src/BenchmarkDotNet.CodeFixers/BenchmarkDotNet.CodeFixers.csproj" />
     <Project Path="src/BenchmarkDotNet.Diagnostics.dotMemory/BenchmarkDotNet.Diagnostics.dotMemory.csproj" />
     <Project Path="src/BenchmarkDotNet.Diagnostics.dotTrace/BenchmarkDotNet.Diagnostics.dotTrace.csproj" />
     <Project Path="src/BenchmarkDotNet.Diagnostics.Windows/BenchmarkDotNet.Diagnostics.Windows.csproj" />

build/BenchmarkDotNet.Build/BuildContext.cs

@@ -31,6 +31,7 @@ public class BuildContext : FrostingContext
 
     public FilePath SolutionFile { get; }
     public FilePath AnalyzersProjectFile { get; }
+    public FilePath CodeFixersProjectFile { get; }
     public FilePath TemplatesTestsProjectFile { get; }
     public FilePathCollection AllPackableSrcProjects { get; }
     public FilePath VersionsFile { get; }
@@ -66,6 +67,7 @@ public BuildContext(ICakeContext context)
 
         SolutionFile = RootDirectory.CombineWithFilePath("BenchmarkDotNet.slnx");
         AnalyzersProjectFile = RootDirectory.Combine("src").Combine("BenchmarkDotNet.Analyzers").CombineWithFilePath("BenchmarkDotNet.Analyzers.csproj");
+        CodeFixersProjectFile = RootDirectory.Combine("src").Combine("BenchmarkDotNet.CodeFixers").CombineWithFilePath("BenchmarkDotNet.CodeFixers.csproj");
 
         TemplatesTestsProjectFile = RootDirectory.Combine("templates")
             .CombineWithFilePath("BenchmarkDotNet.Templates.csproj");

build/BenchmarkDotNet.Build/Runners/BuildRunner.cs

@@ -8,7 +8,6 @@
 using Cake.Common.Tools.DotNet.Workload.Install;
 using Cake.Core;
 using Cake.Core.IO;
-using System;
 using System.IO;
 using System.Linq;
 
@@ -51,7 +50,6 @@ public void PackWeaver()
         {
             MSBuildSettings = context.MsBuildSettingsRestore,
         };
-        MaybeAppendArgument(restoreSettings);
         context.DotNetRestore(weaverPath.GetDirectory().FullPath, restoreSettings);
 
         context.Information("BuildSystemProvider: " + context.BuildSystem().Provider);
@@ -63,7 +61,6 @@ public void PackWeaver()
             Configuration = context.BuildConfiguration,
             Verbosity = context.BuildVerbosity
         };
-        MaybeAppendArgument(buildSettings);
         context.DotNetBuild(weaverPath.FullPath, buildSettings);
 
         var packSettings = new DotNetPackSettings
@@ -72,7 +69,6 @@ public void PackWeaver()
             MSBuildSettings = context.MsBuildSettingsPack,
             Configuration = context.BuildConfiguration
         };
-        MaybeAppendArgument(packSettings);
         context.DotNetPack(weaverPath.FullPath, packSettings);
     }
 
@@ -140,6 +136,16 @@ public void BuildAnalyzers()
                 Verbosity = context.BuildVerbosity,
                 ArgumentCustomization = args => args.Append($"-p:MccVersion={version}")
             });
+
+            context.DotNetBuild(context.CodeFixersProjectFile.FullPath, new DotNetBuildSettings
+            {
+                NoRestore = true,
+                DiagnosticOutput = true,
+                MSBuildSettings = context.MsBuildSettingsBuild,
+                Configuration = context.BuildConfiguration,
+                Verbosity = context.BuildVerbosity,
+                ArgumentCustomization = args => args.Append($"-p:MccVersion={version}")
+            });
         }
     }
 

build/common.props

@@ -60,7 +60,7 @@
 
   <PropertyGroup>
     <!-- Increment this when the BenchmarkDotNet.Weaver package needs to be re-packed. -->
-    <WeaverVersionSuffix>-3</WeaverVersionSuffix>
+    <WeaverVersionSuffix>-4</WeaverVersionSuffix>
   </PropertyGroup>
 
   <ItemGroup>

docs/articles/features/cancellation.md

@@ -0,0 +1,46 @@
+# Cooperative Cancellation in Benchmarks
+
+BenchmarkDotNet supports cooperative cancellation, allowing benchmarks to gracefully respond to cancellation requests such as Ctrl+C.
+
+## CancellationToken Injection
+
+For long-running individual benchmark iterations, you can make your benchmarks cooperatively cancellable by marking a property or field with the `[BenchmarkCancellation]` attribute:
+
+[!code-csharp[IntroCancellationToken.cs](../../../samples/BenchmarkDotNet.Samples/IntroCancellationToken.cs)]
+
+You can also use a field instead of a property:
+
+```csharp
+public class MyBenchmarks
+{
+    [BenchmarkCancellation]
+    public CancellationToken CancellationToken;
+
+    [Benchmark]
+    public async Task MyBenchmark()
+    {
+        await Task.Delay(100, CancellationToken);
+    }
+}
+```
+
+## How It Works
+
+1. **Attribute Detection**: BenchmarkDotNet automatically detects properties or fields marked with `[BenchmarkCancellation]`
+2. **Automatic Injection**: Before running benchmarks, the framework injects the current cancellation token
+3. **Cooperative Checking**: Your benchmark code passes the token to async methods or calls `ThrowIfCancellationRequested()`
+
+## Best Practices
+
+1. **Pass to async methods**: Pass the token to async framework methods that already support cancellation
+2. **Don't swallow cancellation**: Let `OperationCanceledException` propagate
+3. **Check periodically in tight loops**: For CPU-bound loops, check every N iterations to balance responsiveness and overhead
+
+## Requirements
+
+Properties and fields marked with `[BenchmarkCancellation]` must be:
+- Of type `System.Threading.CancellationToken`
+- Public
+- For properties: must have a public setter (init-only setters are supported)
+
+Both static and instance members are supported.

samples/BenchmarkDotNet.Samples/BenchmarkDotNet.Samples.csproj

@@ -26,6 +26,7 @@
     <PackageReference Include="System.IO.Hashing" Version="[$(SihVersion)]" />
   </ItemGroup>
   <ItemGroup>
+    <PackageReference Include="Microsoft.Bcl.AsyncInterfaces" Version="10.0.5" />
     <PackageReference Include="System.Drawing.Common" Version="10.0.3" />
     <!-- The Test SDK is required only for the VSTest Adapter to work -->
     <PackageReference Include="Microsoft.NET.Test.Sdk" Version="18.0.1" />

samples/BenchmarkDotNet.Samples/IntroCancellationToken.cs

@@ -0,0 +1,32 @@
+using System.Threading;
+using System.Threading.Tasks;
+using BenchmarkDotNet.Attributes;
+
+namespace BenchmarkDotNet.Samples;
+
+/// <summary>
+/// Demonstrates cooperative cancellation using [BenchmarkCancellation] attribute.
+/// When a benchmark class has a property or field marked with [BenchmarkCancellation], BenchmarkDotNet automatically
+/// injects the cancellation token, allowing benchmarks to check for cancellation during execution.
+/// This is useful for long-running async benchmarks that should respond to Ctrl+C or other cancellation signals.
+/// </summary>
+public class IntroCancellationToken
+{
+    [BenchmarkCancellation]
+    public CancellationToken CancellationToken { get; set; }
+
+    [Benchmark]
+    public async Task AsyncBenchmark()
+    {
+        for (int i = 0; i < 100; i++)
+        {
+            await DoWorkAsync(CancellationToken);
+        }
+    }
+
+    private async Task DoWorkAsync(CancellationToken cancellationToken)
+    {
+        // Simulate some async work
+        await Task.Delay(100, cancellationToken);
+    }
+}

samples/Directory.Build.props

@@ -2,5 +2,6 @@
   <PropertyGroup>
     <GenerateDocumentationFile>false</GenerateDocumentationFile>
     <IsPackable>false</IsPackable>
+    <NoWarn>$(NoWarn);CA2007</NoWarn>
   </PropertyGroup>
 </Project>

src/BenchmarkDotNet.Analyzers/AnalyzerReleases.Unshipped.md

@@ -3,6 +3,12 @@
 Rule ID  | Category | Severity | Notes
 ---------|----------|----------|--------------------
 BDN1305  |  Usage   | Error	   | [ParamsSource] cannot reference write-only property
+BDN1600  |  Usage   | Error    | Fields or properties annotated with [BenchmarkCancellation] must be of type CancellationToken
+BDN1601  |  Usage   | Error    | Fields annotated with [BenchmarkCancellation] must be public
+BDN1602  |  Usage   | Error    | Properties annotated with [BenchmarkCancellation] must be public
+BDN1603  |  Usage   | Error    | [BenchmarkCancellation] attribute is not valid on readonly fields
+BDN1604  |  Usage   | Error    | Properties annotated with [BenchmarkCancellation] must have a public setter
+BDN1605  |  Usage   | Info     | Async benchmarks should have a [BenchmarkCancellation] property for cancellation support
 
 
 ### Removed Rules