https://github.com/kevingosse/silhouette

Implementation of a .NET profiler in C# with NativeAOT
https://github.com/kevingosse/silhouette

Last synced: 5 days ago
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Implementation of a .NET profiler in C# with NativeAOT

• Host: GitHub
• URL: https://github.com/kevingosse/silhouette
• Owner: kevingosse
• Created: 2022-06-11T16:20:42.000Z (over 2 years ago)
• Default Branch: master
• Last Pushed: 2024-12-28T13:04:54.000Z (7 days ago)
• Last Synced: 2024-12-28T13:27:55.805Z (7 days ago)
• Language: C#
• Size: 320 KB
• Stars: 97
• Watchers: 6
• Forks: 13
• Open Issues: 2
• Metadata Files:
  • Readme: README.md

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README

        
Silhouette - A library to build .NET profilers in .NET

=======================

# Quick start

Create a new C# NativeAOT project. Reference the Silhouette nuget package and add a class inheriting from `Silhouette.CorProfilerCallback11Base` (you can use a different version of `CorProfilerCallbackBase` depending on the version of .NET you're targeting). Override the `Initialize` method. It will be called with the highest version number of `ICorProfilerInfo` supported by the target runtime.

```csharp

using Silhouette;

internal partial class CorProfiler : CorProfilerCallback11Base

{

    protected override HResult Initialize(int iCorProfilerInfoVersion)

    {

        if (iCorProfilerInfoVersion < 11)

        {

            return HResult.E_FAIL;

        }

        var result = ICorProfilerInfo11.SetEventMask(COR_PRF_MONITOR.COR_PRF_ENABLE_STACK_SNAPSHOT | COR_PRF_MONITOR.COR_PRF_MONITOR_THREADS);

        return result;

    }

}

```

You also need to expose a `DllGetClassObject` method that will be called by the .NET runtime when initializing the profiler. Use the built-in `ClassFactory` implementation and give it an instance of your `CorProfiler` class.

```csharp

using Silhouette;

using System.Runtime.InteropServices;

internal class DllMain

{

    private static ClassFactory Instance;

    [UnmanagedCallersOnly(EntryPoint = "DllGetClassObject")]

    public static unsafe HResult DllGetClassObject(Guid* rclsid, Guid* riid, nint* ppv)

    {

        // Use your own profiler GUID here

        if (*rclsid != new Guid("0A96F866-D763-4099-8E4E-ED1801BE9FBC"))

        {

            return HResult.E_NOINTERFACE;

        }

        Instance = new ClassFactory(new CorProfiler());

        *ppv = Instance.IClassFactory;

        return 0;

    }

}

```

`CorProfilerXxBase` offers base virtual methods for all `ICorProfilerCallback` methods, so override the ones you're interested in:

```csharp

    protected override HResult ThreadCreated(ThreadId threadId)

    {

        Console.WriteLine($"Thread created: {threadId.Value}");

        return HResult.S_OK;

    }

```

Use the `ICorProfilerInfoXx` fields to access the `ICorProfilerInfo` APIs:

```csharp

    private unsafe string ResolveMethodName(nint ip)

    {

        try

        {

            var functionId = ICorProfilerInfo11.GetFunctionFromIP(ip).ThrowIfFailed();

            var functionInfo = ICorProfilerInfo2.GetFunctionInfo(functionId).ThrowIfFailed();

            using var metaDataImport = ICorProfilerInfo2.GetModuleMetaData(functionInfo.ModuleId, CorOpenFlags.ofRead, KnownGuids.IMetaDataImport).ThrowIfFailed().Wrap();

            var methodProperties = metaDataImport.Value.GetMethodProps(new MdMethodDef(functionInfo.Token)).ThrowIfFailed();

            var typeDefProps = metaDataImport.Value.GetTypeDefProps(methodProperties.Class).ThrowIfFailed();

            return $"{typeDefProps.TypeName}.{methodProperties.Name}";

        }

        catch (Win32Exception)

        {

            return "";

        }

    }

```

Most methods return an instance of `HResult`. You can deconstruct it into a `(HResult error, T result)` and manually check the error code. You can also use the `ThrowIfFailed()` method that will return only the result and throw a `Win32Exception` if the error code is not `S_OK`.