Another attempt at avoiding BuildXL assembly load

Author: dfederm

src/Build/BackEnd/BuildManager/BuildManager.cs

@@ -562,7 +562,13 @@ public void BeginBuild(BuildParameters parameters)
 #if FEATURE_REPORTFILEACCESSES
                 if (_buildParameters.ReportFileAccesses)
                 {
-                    EnableDetouredNodeLauncher();
+                    // To properly report file access, we need to disable the in-proc node which won't be detoured.
+                    _buildParameters.DisableInProcNode = true;
+
+                    // Node reuse must be disabled as future builds will not be able to listen to events raised by detours.
+                    _buildParameters.EnableNodeReuse = false;
+
+                    _componentFactories.ReplaceFactory(BuildComponentType.NodeLauncher, DetouredNodeLauncherFactory.CreateComponent);
                 }
 #endif
 
@@ -717,25 +723,6 @@ void InitializeCaches()
             }
         }
 
-#if FEATURE_REPORTFILEACCESSES
-        /// <summary>
-        /// Configure the build to use I/O tracking for nodes.
-        /// </summary>
-        /// <remarks>
-        /// Must be a separate method to avoid loading the BuildXL assembly when not opted in.
-        /// </remarks>
-        private void EnableDetouredNodeLauncher()
-        {
-            // To properly report file access, we need to disable the in-proc node which won't be detoured.
-            _buildParameters.DisableInProcNode = true;
-
-            // Node reuse must be disabled as future builds will not be able to listen to events raised by detours.
-            _buildParameters.EnableNodeReuse = false;
-
-            _componentFactories.ReplaceFactory(BuildComponentType.NodeLauncher, DetouredNodeLauncher.CreateComponent);
-        }
-#endif
-
         private static void AttachDebugger()
         {
             if (Debugger.IsAttached)

src/Build/BackEnd/Components/Communications/DetouredNodeLauncher.cs

@@ -25,12 +25,6 @@ internal sealed class DetouredNodeLauncher : INodeLauncher, IBuildComponent
 
         private IFileAccessManager _fileAccessManager;
 
-        public static IBuildComponent CreateComponent(BuildComponentType type)
-        {
-            ErrorUtilities.VerifyThrowArgumentOutOfRange(type == BuildComponentType.NodeLauncher, nameof(type));
-            return new DetouredNodeLauncher();
-        }
-
         public void InitializeComponent(IBuildComponentHost host)
         {
             _fileAccessManager = (IFileAccessManager)host.GetComponent(BuildComponentType.FileAccessManager);

src/Build/BackEnd/Components/Communications/DetouredNodeLauncherFactory.cs

@@ -0,0 +1,29 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+#if FEATURE_REPORTFILEACCESSES
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+using Microsoft.Build.Shared;
+
+namespace Microsoft.Build.BackEnd
+{
+    /// <summary>
+    /// Factory for creating the DetouredNodeLauncher
+    /// </summary>
+    /// <remarks>
+    /// Must be a separate class to avoid loading the BuildXL assemblies when not opted in.
+    /// </remarks>
+    internal static class DetouredNodeLauncherFactory
+    {
+        public static IBuildComponent CreateComponent(BuildComponentType type)
+        {
+            ErrorUtilities.VerifyThrowArgumentOutOfRange(type == BuildComponentType.NodeLauncher, nameof(type));
+            return new DetouredNodeLauncher();
+        }
+    }
+}
+#endif

src/Build/Microsoft.Build.csproj

@@ -155,6 +155,7 @@
     <Compile Include="BackEnd\Components\ProjectCache\*.cs" />
     <Compile Include="BackEnd\Components\Communications\CurrentHost.cs" />
     <Compile Include="BackEnd\Components\Communications\DetouredNodeLauncher.cs" />
+    <Compile Include="BackEnd\Components\Communications\DetouredNodeLauncherFactory.cs" />
     <Compile Include="BackEnd\Components\Communications\SerializationContractInitializer.cs" />
     <Compile Include="BackEnd\Components\Communications\ServerNodeEndpointOutOfProc.cs" />
     <Compile Include="BackEnd\Components\FileAccesses\IFileAccessManager.cs" />