Improve resiliency when invoking DTE

Various minor improvements including:

* Not starting the active document monitoring until initial build completes
* Retrying opening of the startup file if ExecuteCommand fails (IDE might be busy doing something else on the UI thread)
* Not trying to open startup file if we can't determine which one
* Some troubleshooting aids by capturing thrown exceptions for Debug.Fail diagnostics

Fixes #18

Author: kzu

src/Directory.props

@@ -6,6 +6,9 @@
     <PackOnBuild>true</PackOnBuild>
     <PackageProjectUrl>https://clarius.org/SmallSharp</PackageProjectUrl>
     <NoWarn>NU1702;$(NoWarn)</NoWarn>
+
+    <StartAction>Program</StartAction>
+    <StartProgram>$(VsInstallRoot)\Common7\IDE\devenv.exe</StartProgram>
   </PropertyGroup>
 
 </Project>

src/SmallSharp.Build/ActiveDocumentMonitor.cs

@@ -3,6 +3,7 @@
 using System.Diagnostics;
 using System.IO;
 using System.Linq;
+using System.Threading;
 using System.Xml.Linq;
 using Microsoft.VisualStudio.Shell.Interop;
 using Newtonsoft.Json.Linq;
@@ -12,10 +13,12 @@ namespace SmallSharp.Build
     class ActiveDocumentMonitor : MarshalByRefObject, IDisposable, IVsRunningDocTableEvents, IVsSelectionEvents
     {
         FileSystemWatcher watcher;
-        readonly IVsRunningDocumentTable? rdt;
-        readonly IVsMonitorSelection? selection;
-        readonly uint rdtCookie;
-        readonly uint selectionCookie;
+        readonly IServiceProvider services;
+
+        IVsRunningDocumentTable? rdt;
+        IVsMonitorSelection? selection;
+        uint rdtCookie;
+        uint selectionCookie;
 
         string launchProfilesPath;
         string userFile;
@@ -27,6 +30,7 @@ public ActiveDocumentMonitor(string launchProfilesPath, string userFile, string
             this.launchProfilesPath = launchProfilesPath;
             this.userFile = userFile;
             this.flagFile = flagFile;
+            this.services = services;
 
             watcher = new FileSystemWatcher(Path.GetDirectoryName(launchProfilesPath))
             {
@@ -38,7 +42,10 @@ public ActiveDocumentMonitor(string launchProfilesPath, string userFile, string
             watcher.Created += (_, _) => ReloadProfiles();
             watcher.EnableRaisingEvents = true;
             ReloadProfiles();
+        }
 
+        public void Start()
+        {
             rdt = (IVsRunningDocumentTable)services.GetService(typeof(SVsRunningDocumentTable));
             if (rdt != null)
                 rdt.AdviseRunningDocTableEvents(this, out rdtCookie);
@@ -62,20 +69,32 @@ void ReloadProfiles()
             if (!File.Exists(launchProfilesPath))
                 return;
 
-            try
-            {
-                var json = JObject.Parse(File.ReadAllText(launchProfilesPath));
-                if (json.Property("profiles") is not JProperty prop ||
-                    prop.Value is not JObject profiles)
-                    return;
+            var maxAttempts = 5;
+            var exceptions = new List<Exception>();
 
-                startupFiles = profiles.Properties().Select(p => p.Name)
-                    .ToDictionary(x => x, StringComparer.OrdinalIgnoreCase);
-            }
-            catch
+            for (var i = 0; i < maxAttempts; i++)
             {
-                Debug.Fail("Could not read launchSettings.json");
+                try
+                {
+                    var json = JObject.Parse(File.ReadAllText(launchProfilesPath));
+                    if (json.Property("profiles") is not JProperty prop ||
+                        prop.Value is not JObject profiles)
+                        return;
+
+                    startupFiles = profiles.Properties().Select(p => p.Name)
+                        .ToDictionary(x => x, StringComparer.OrdinalIgnoreCase);
+
+                    return;
+                }
+                catch (Exception e)
+                {
+                    exceptions.Add(e);
+                    Thread.Sleep(500);
+                }
             }
+
+            // NOTE: check exceptions list to see why.
+            Debug.Fail("Could not read launchSettings.json");
         }
 
         void UpdateStartupFile(string? path)
@@ -105,24 +124,30 @@ void UpdateStartupFile(string? path)
                         xdoc.Save(userFile);
                     }
                 }
-                catch
+                catch (Exception e)
                 {
-                    Debug.Fail("Failed to load or update .user file.");
+                    Debug.Fail($"Failed to load or update .user file: {e}");
                 }
             }
         }
 
         void IDisposable.Dispose()
         {
             if (rdtCookie != 0 && rdt != null)
-                rdt.UnadviseRunningDocTableEvents(rdtCookie);
+                Try(() => rdt.UnadviseRunningDocTableEvents(rdtCookie));
 
             if (selectionCookie != 0 && selection != null)
-                selection.UnadviseSelectionEvents(selectionCookie);
+                Try(() => selection.UnadviseSelectionEvents(selectionCookie));
 
             watcher.Dispose();
         }
 
+        void Try(Action action)
+        {
+            try { action(); }
+            catch (Exception e) { Debug.WriteLine(e); }
+        }
+
         int IVsRunningDocTableEvents.OnAfterAttributeChange(uint docCookie, uint grfAttribs)
         {
             // The MSBuild targets should have created it in target SelectStartupFile.

src/SmallSharp.Build/MonitorActiveDocument.cs

@@ -27,9 +27,19 @@ public override bool Execute()
                 {
                     if (WindowsInterop.GetServiceProvider() is IServiceProvider services)
                     {
-                        BuildEngine4.RegisterTaskObject(nameof(ActiveDocumentMonitor),
-                            new ActiveDocumentMonitor(LaunchProfiles, UserFile, FlagFile, services),
+                        var documentMonitor = new ActiveDocumentMonitor(LaunchProfiles, UserFile, FlagFile, services);
+
+                        BuildEngine4.RegisterTaskObject(nameof(ActiveDocumentMonitor), documentMonitor,
                             RegisteredTaskObjectLifetime.AppDomain, false);
+
+                        // Start monitoring at the end of the build, to avoid slowing down the DTB
+                        BuildEngine4.RegisterTaskObject("StartMonitor",
+                            new DisposableAction(() => documentMonitor.Start()),
+                            RegisteredTaskObjectLifetime.Build, false);
+                    }
+                    else
+                    {
+                        Debug.Fail("Failed to get IServiceProvider to monitor for active document.");
                     }
                 }
                 else

src/SmallSharp.Build/OpenStartupFile.cs

@@ -1,6 +1,4 @@
-using System;
-using System.IO;
-using EnvDTE;
+using System.IO;
 using Microsoft.Build.Framework;
 using Microsoft.Build.Utilities;
 
@@ -15,7 +13,7 @@ public class OpenStartupFile : Task
 
         public override bool Execute()
         {
-            if (FlagFile == null || StartupFile == null)
+            if (string.IsNullOrEmpty(FlagFile) || string.IsNullOrEmpty(StartupFile))
                 return true;
 
             if (!File.Exists(FlagFile) ||
@@ -24,7 +22,7 @@ public override bool Execute()
                 // This defers the opening until the build completes.
                 BuildEngine4.RegisterTaskObject(
                     StartupFile,
-                    new DisposableAction(() => WindowsInterop.EnsureOpened(StartupFile)),
+                    new DisposableAction(() => WindowsInterop.EnsureOpened(StartupFile!)),
                     RegisteredTaskObjectLifetime.Build, false);
 
                 File.WriteAllText(FlagFile, StartupFile);

src/SmallSharp.Build/SmallSharp.Build.csproj

@@ -3,6 +3,7 @@
   <PropertyGroup>
     <TargetFramework>net472</TargetFramework>
     <PackFolder>build\netstandard2.0</PackFolder>
+    <PackNone>true</PackNone>
   </PropertyGroup>
 
   <ItemGroup>
@@ -17,4 +18,8 @@
     <PackageReference Include="Newtonsoft.Json" Version="12.0.3" PrivateAssets="all" />
   </ItemGroup>
 
+  <ItemGroup>
+    <None Update="SmallSharp.targets" CopyToOutputDirectory="PreserveNewest" />
+  </ItemGroup>
+
 </Project>

src/SmallSharp/SmallSharp.targets renamed to src/SmallSharp.Build/SmallSharp.targets

@@ -4,19 +4,13 @@
   <UsingTask AssemblyFile="SmallSharp.Build.dll" TaskName="OpenStartupFile" Condition="'$(BuildingInsideVisualStudio)' == 'true'" />
 
   <PropertyGroup>
-    <DefaultItemExcludesInProjectFolder>*$(DefaultLanguageSourceExtension)</DefaultItemExcludesInProjectFolder>
     <MSBuildShortVersion>$(MSBuildVersion.TrimEnd('0123456789').TrimEnd('.'))</MSBuildShortVersion>
     <UserProjectNamespace>
       <Namespace Prefix="msb" Uri="http://schemas.microsoft.com/developer/msbuild/2003" />
     </UserProjectNamespace>
     <StartupFile>$(ActiveDebugProfile)</StartupFile>
   </PropertyGroup>
 
-  <ItemGroup>
-    <None Include="*$(DefaultLanguageSourceExtension)" Exclude="$(ActiveDebugProfile)" />
-    <Compile Include="$(ActiveDebugProfile)" Condition="Exists('$(ActiveDebugProfile)')" />
-  </ItemGroup>
-
   <ItemGroup>
     <CompilerVisibleProperty Include="MSBuildProjectDirectory" />
     <CompilerVisibleProperty Include="ActiveDebugProfile" />
@@ -27,12 +21,20 @@
   </ItemGroup>
 
   <!-- NOTE: we only require VS16.8+ when running in the IDE, since for CLI builds we just do targets stuff -->
-  <Target Name="EnsureVisualStudio" BeforeTargets="BeforeCompile;CoreCompile" 
+  <Target Name="EnsureVisualStudio" BeforeTargets="BeforeCompile;CoreCompile"
           Condition="$(MSBuildShortVersion) &lt; '16.8' and '$(BuildingInsideVisualStudio)' == 'true'">
     <!-- Top-level programs require this, so does our source generator. -->
     <Error Text="SmallSharp requires Visual Studio 16.8 or greater." />
   </Target>
 
+  <Target Name="SelectTopLevelCompile" BeforeTargets="BeforeCompile;CoreCompile;CompileDesignTime" DependsOnTargets="SelectStartupFile">
+    <ItemGroup>
+      <None Include="*$(DefaultLanguageSourceExtension)" />
+      <Compile Remove="*$(DefaultLanguageSourceExtension)" />
+      <Compile Include="$(StartupFile)" Condition="Exists('$(StartupFile)')" />
+    </ItemGroup>
+  </Target>
+
   <Target Name="SelectStartupFile" BeforeTargets="BeforeCompile;CoreCompile"
           Condition="'$(StartupFile)' == '' or !Exists('$(StartupFile)')">
 
@@ -122,12 +124,9 @@
     <Warning Text="Could not set ActiveDebugProfile=$(StartupFile). Run the project once to fix it."
              Condition="'$(StartupFile)' != '' and '$(StartupDebugProfile)' != '$(StartupFile)'"/>
 
-    <ItemGroup>
-      <Compile Include="$(StartupFile)" Condition="'$(StartupFile)' != ''" />
-    </ItemGroup>
   </Target>
 
-  <Target Name="OpenStartupFile" 
+  <Target Name="OpenStartupFile"
           BeforeTargets="CompileDesignTime"
           DependsOnTargets="SelectStartupFile"
           Condition="'$(OpenStartupFile)' != 'false' and 
@@ -144,7 +143,7 @@
   <Target Name="MonitorActiveDocument" AfterTargets="CompileDesignTime">
     <MonitorActiveDocument FlagFile="$([System.IO.Path]::Combine('$(MSBuildProjectDirectory)', '$(BaseIntermediateOutputPath)', 'OpenedStartupFile.txt'))"
                            LaunchProfiles="$([System.IO.Path]::Combine('$(MSBuildProjectDirectory)', 'Properties', 'launchSettings.json'))"
-                           UserFile="$([System.IO.Path]::Combine('$(MSBuildProjectDirectory)', '$(MSBuildProjectFile).user'))" />  
+                           UserFile="$([System.IO.Path]::Combine('$(MSBuildProjectDirectory)', '$(MSBuildProjectFile).user'))" />
   </Target>
 
   <!-- Adds the additional files that the source generator uses to emit the launch profiles. -->

src/SmallSharp.Build/WindowsInterop.cs

@@ -1,4 +1,5 @@
 using System;
+using System.Collections.Generic;
 using System.Diagnostics;
 using System.IO;
 using System.Linq;
@@ -21,18 +22,29 @@ public static void EnsureOpened(string filePath, TimeSpan delay = default)
             if (delay != default)
                 Thread.Sleep(delay);
 
-            try
-            {
-                var dte = GetDTE();
-                if (dte == null)
-                    return;
+            var dte = GetDTE();
+            if (dte == null)
+                return;
 
-                dte.ExecuteCommand("File.OpenFile", filePath);
-            }
-            catch
+            var maxAttempts = 5;
+            var exceptions = new List<Exception>();
+
+            for (var i = 0; i < maxAttempts; i++)
             {
-                Debug.Fail($"Failed to open {filePath}.");
+                try
+                {
+                    dte.ExecuteCommand("File.OpenFile", filePath);
+                    return;
+                }
+                catch (Exception e)
+                {
+                    exceptions.Add(e);
+                    Thread.Sleep(500);
+                }
             }
+
+            // NOTE: inspect exceptions variable
+            Debug.Fail($"Failed to open {filePath} after 5 attempts.");
         }
 
         public static IServiceProvider? GetServiceProvider(TimeSpan delay = default)
@@ -52,9 +64,9 @@ public static void EnsureOpened(string filePath, TimeSpan delay = default)
 
                 return new OleServiceProvider(dte);
             }
-            catch
+            catch (Exception e)
             {
-                Debug.Fail("Failed to get IDE service provider.");
+                Debug.Fail($"Failed to get IDE service provider: {e}");
                 return null;
             }
         }