Update readme + small fixes

README.md

@@ -1,2 +1,88 @@
 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 "<unknown>";
+        }
+    }
+```
+
+Most methods return an instance of `HResult<T>`. 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`.
+

src/ManagedDotnetProfiler/CorProfiler.cs

@@ -677,7 +677,13 @@ private string GetTypeNameFromClassId(ClassId classId)
 
     private string GetFunctionFullName(FunctionId functionId)
     {
-        var functionInfo = ICorProfilerInfo2.GetFunctionInfo(functionId).ThrowIfFailed();
+        var (result, functionInfo) = ICorProfilerInfo2.GetFunctionInfo(functionId);
+
+        if (!result)
+        {
+            return $"Failed ({result})";
+        }
+
         var metaDataImport = ICorProfilerInfo2.GetModuleMetaData(functionInfo.ModuleId, CorOpenFlags.ofRead, KnownGuids.IMetaDataImport).ThrowIfFailed();
         var methodProperties = metaDataImport.GetMethodProps(new MdMethodDef(functionInfo.Token)).ThrowIfFailed();
         var typeDefProps = metaDataImport.GetTypeDefProps(methodProperties.Class).ThrowIfFailed();

src/ManagedDotnetProfiler/DllMain.cs

@@ -1,4 +1,5 @@
-using System.Runtime.InteropServices;
+using System;
+using System.Runtime.InteropServices;
 using Silhouette;
 
 namespace ManagedDotnetProfiler;
@@ -8,8 +9,13 @@ public class DllMain
     private static ClassFactory Instance;
 
     [UnmanagedCallersOnly(EntryPoint = "DllGetClassObject")]
-    public static unsafe int DllGetClassObject(void* rclsid, void* riid, nint* ppv)
+    public static unsafe HResult DllGetClassObject(Guid* rclsid, Guid* riid, nint* ppv)
     {
+        if (*rclsid != new Guid("0A96F866-D763-4099-8E4E-ED1801BE9FBC"))
+        {
+            return HResult.E_NOINTERFACE;
+        }
+
         Instance = new ClassFactory(new CorProfiler());
         *ppv = Instance.IClassFactory;
 

src/TestApp/launch.cmd

@@ -1,4 +1,4 @@
 @set CORECLR_ENABLE_PROFILING=1
-@set CORECLR_PROFILER={846F5F1C-F9AE-4B07-969E-05C26BC060D8}
-@set CORECLR_PROFILER_PATH=E:\git\ManagedDotnetProfiler\ManagedDotnetProfiler\bin\Release\net9.0\win-x64\publish\ManagedDotnetProfiler.dll
+@set CORECLR_PROFILER={0A96F866-D763-4099-8E4E-ED1801BE9FBC}
+@set CORECLR_PROFILER_PATH=..\..\..\..\ManagedDotnetProfiler\bin\Release\net9.0\win-x64\publish\ManagedDotnetProfiler.dll
 @TestApp.exe