Reduce IVsFreeThreadedFileChangeEvents2.DirectoryChangedEx2 notifications from VS shell

src/LanguageServer/Microsoft.CodeAnalysis.LanguageServer.UnitTests/LspFileChangeWatcherTests.cs

@@ -3,6 +3,7 @@
 // See the LICENSE file in the project root for more information.
 
 using System.Collections.Concurrent;
+using System.Collections.Immutable;
 using System.Text.Json;
 using Microsoft.CodeAnalysis.LanguageServer.HostWorkspace.FileWatching;
 using Microsoft.CodeAnalysis.Shared.TestHooks;
@@ -61,7 +62,7 @@ public async Task CreatingDirectoryWatchRequestsDirectoryWatch()
         var tempDirectory = tempRoot.CreateDirectory();
 
         // Try creating a context and ensure we created the registration
-        var context = lspFileChangeWatcher.CreateContext([new ProjectSystem.WatchedDirectory(tempDirectory.Path, extensionFilter: null)]);
+        var context = lspFileChangeWatcher.CreateContext([new ProjectSystem.WatchedDirectory(tempDirectory.Path, extensionFilters: ImmutableArray<string>.Empty)]);
         await WaitForFileWatcherAsync(testLspServer);
 
         var watcher = GetSingleFileWatcher(dynamicCapabilitiesRpcTarget);

src/LanguageServer/Microsoft.CodeAnalysis.LanguageServer/HostWorkspace/FileWatching/LspFileChangeWatcher.cs

@@ -75,13 +75,23 @@ public FileChangeContext(ImmutableArray<WatchedDirectory> watchedDirectories, Ls
             // If we have any watched directories, then watch those directories directly
             if (watchedDirectories.Any())
             {
-                var directoryWatches = watchedDirectories.Select(d => new FileSystemWatcher
+                var directoryWatches = watchedDirectories.Select(d =>
                 {
-                    GlobPattern = new RelativePattern
+                    var pattern = "**/*" + d.ExtensionFilters.Length switch
                     {
-                        BaseUri = ProtocolConversions.CreateRelativePatternBaseUri(d.Path),
-                        Pattern = d.ExtensionFilter is not null ? "**/*" + d.ExtensionFilter : "**/*"
-                    }
+                        0 => string.Empty,
+                        1 => d.ExtensionFilters[0],
+                        _ => "{" + string.Join(',', d.ExtensionFilters) + "}"
+                    };
+
+                    return new FileSystemWatcher
+                    {
+                        GlobPattern = new RelativePattern
+                        {
+                            BaseUri = ProtocolConversions.CreateRelativePatternBaseUri(d.Path),
+                            Pattern = pattern
+                        }
+                    };
                 }).ToArray();
 
                 _directoryWatchRegistration = new LspFileWatchRegistration(lspFileChangeWatcher, directoryWatches);

src/LanguageServer/Microsoft.CodeAnalysis.LanguageServer/HostWorkspace/FileWatching/SimpleFileChangeWatcher.cs

@@ -46,8 +46,8 @@ public FileChangeContext(ImmutableArray<WatchedDirectory> watchedDirectories)
                     var watcher = new FileSystemWatcher(watchedDirectory.Path);
                     watcher.IncludeSubdirectories = true;
 
-                    if (watchedDirectory.ExtensionFilter != null)
-                        watcher.Filter = '*' + watchedDirectory.ExtensionFilter;
+                    foreach (var filter in watchedDirectory.ExtensionFilters)
+                        watcher.Filters.Add('*' + filter);
 
                     watcher.Changed += RaiseEvent;
                     watcher.Created += RaiseEvent;

src/LanguageServer/Microsoft.CodeAnalysis.LanguageServer/HostWorkspace/LoadedProject.cs

@@ -53,11 +53,7 @@ public LoadedProject(ProjectSystemProject projectSystemProject, SolutionServices
         // TODO: we only should listen for add/removals here, but we can't specify such a filter now
         _projectDirectory = Path.GetDirectoryName(_projectFilePath)!;
 
-        _fileChangeContext = fileWatcher.CreateContext([
-            new(_projectDirectory, ".cs"),
-            new(_projectDirectory, ".cshtml"),
-            new(_projectDirectory, ".razor")
-        ]);
+        _fileChangeContext = fileWatcher.CreateContext([new(_projectDirectory, [".cs", ".cshtml", ".razor"])]);
         _fileChangeContext.FileChanged += FileChangedContext_FileChanged;
 
         // Start watching for file changes for the project file as well

src/VisualStudio/Core/Def/ProjectSystem/FileChangeWatcher.cs

@@ -44,10 +44,10 @@ public FileChangeWatcher(
     {
         _fileChangeService = fileChangeService;
 
-        // 📝 Empirical testing during high activity (e.g. solution close) showed strong batching performance even
-        // though the batching delay is 0.
+        // 📝 Empirical testing during high activity (e.g. solution open/close) showed strong batching performance
+        // with batching delay of 500 ms.
         _taskQueue = new AsyncBatchingWorkQueue<WatcherOperation>(
-            TimeSpan.Zero,
+            TimeSpan.FromMilliseconds(500),
             ProcessBatchAsync,
             listenerProvider.GetListener(FeatureAttribute.Workspace),
             CancellationToken.None);
@@ -98,10 +98,10 @@ private readonly struct WatcherOperation
         private readonly Kind _kind;
 
         /// <summary>
-        /// The extension filter to apply for <see cref="Kind.WatchDirectory"/>. This value may be
-        /// <see langword="null"/> to disable the extension filter.
+        /// The extension filters to apply for <see cref="Kind.WatchDirectory"/>. This value may be
+        /// empty to disable the extension filter.
         /// </summary>
-        private readonly string? _filter;
+        private readonly ImmutableArray<string> _filters;
 
         /// <summary>
         /// The file change flags to apply for <see cref="Kind.WatchFiles"/>.
@@ -139,13 +139,13 @@ private readonly struct WatcherOperation
         /// </summary>
         private readonly OneOrMany<string> _paths;
 
-        private WatcherOperation(Kind kind, string directory, string? filter, IVsFreeThreadedFileChangeEvents2 sink, List<uint> cookies)
+        private WatcherOperation(Kind kind, string directory, ImmutableArray<string> filters, IVsFreeThreadedFileChangeEvents2 sink, List<uint> cookies)
         {
             Contract.ThrowIfFalse(kind is Kind.WatchDirectory);
             _kind = kind;
 
             _paths = new OneOrMany<string>(directory);
-            _filter = filter;
+            _filters = filters;
             _sink = sink;
             _cookies = cookies;
 
@@ -165,7 +165,7 @@ private WatcherOperation(Kind kind, OneOrMany<string> files, _VSFILECHANGEFLAGS
             _tokens = tokens;
 
             // Other watching fields are not used for this kind
-            _filter = null;
+            _filters = ImmutableArray<string>.Empty;
             _cookies = null!;
         }
 
@@ -177,7 +177,7 @@ private WatcherOperation(Kind kind, List<uint> cookies)
             _cookies = cookies;
 
             // Other watching fields are not used for this kind
-            _filter = null;
+            _filters = ImmutableArray<string>.Empty;
             _fileChangeFlags = 0;
             _sink = null!;
             _tokens = OneOrMany<Context.RegularWatchedFile>.Empty;
@@ -192,7 +192,7 @@ private WatcherOperation(Kind kind, OneOrMany<Context.RegularWatchedFile> tokens
             _tokens = tokens;
 
             // Other watching fields are not used for this kind
-            _filter = null;
+            _filters = ImmutableArray<string>.Empty;
             _fileChangeFlags = 0;
             _sink = null!;
             _cookies = null!;
@@ -207,8 +207,8 @@ private enum Kind
             UnwatchFiles,
         }
 
-        public static WatcherOperation WatchDirectory(string directory, string? filter, IVsFreeThreadedFileChangeEvents2 sink, List<uint> cookies)
-            => new(Kind.WatchDirectory, directory, filter, sink, cookies);
+        public static WatcherOperation WatchDirectory(string directory, ImmutableArray<string> filters, IVsFreeThreadedFileChangeEvents2 sink, List<uint> cookies)
+            => new(Kind.WatchDirectory, directory, filters, sink, cookies);
 
         public static WatcherOperation WatchFile(string path, _VSFILECHANGEFLAGS fileChangeFlags, IVsFreeThreadedFileChangeEvents2 sink, Context.RegularWatchedFile token)
             => new(Kind.WatchFiles, OneOrMany.Create(path), fileChangeFlags, sink, OneOrMany.Create(token));
@@ -252,21 +252,15 @@ public static WatcherOperation CombineRange(ImmutableSegmentedList<WatcherOperat
                 {
                     case Kind.WatchFiles:
                         for (var i = 0; i < op._paths.Count; i++)
-                        {
                             fileNamesBuilder.Add(op._paths[i]);
-                        }
 
                         for (var i = 0; i < op._tokens.Count; i++)
-                        {
                             tokensBuilder.Add(op._tokens[i]);
-                        }
                         break;
 
                     case Kind.UnwatchFiles:
                         for (var i = 0; i < op._tokens.Count; i++)
-                        {
                             tokensBuilder.Add(op._tokens[i]);
-                        }
                         break;
 
                     case Kind.UnwatchDirectories:
@@ -297,7 +291,7 @@ public bool CanCombineWith(in WatcherOperation other)
             if (_kind == Kind.WatchDirectory)
                 return false;
 
-            return (_kind == other._kind);
+            return _kind == other._kind && _sink == other._sink;
         }
 
         public async ValueTask ApplyAsync(IVsAsyncFileChangeEx2 service, CancellationToken cancellationToken)
@@ -310,8 +304,8 @@ public async ValueTask ApplyAsync(IVsAsyncFileChangeEx2 service, CancellationTok
                     var cookie = await service.AdviseDirChangeAsync(_paths[0], watchSubdirectories: true, _sink, cancellationToken).ConfigureAwait(false);
                     _cookies.Add(cookie);
 
-                    if (_filter != null)
-                        await service.FilterDirectoryChangesAsync(cookie, [_filter], cancellationToken).ConfigureAwait(false);
+                    if (_filters != null)
+                        await service.FilterDirectoryChangesAsync(cookie, _filters.ToArray(), cancellationToken).ConfigureAwait(false);
 
                     return;
 
@@ -367,8 +361,13 @@ public Context(FileChangeWatcher fileChangeWatcher, ImmutableArray<WatchedDirect
 
             foreach (var watchedDirectory in watchedDirectories)
             {
-                _fileChangeWatcher._taskQueue.AddWork(watchedDirectories.Select(
-                    watchedDirectory => WatcherOperation.WatchDirectory(watchedDirectory.Path, watchedDirectory.ExtensionFilter, this, _directoryWatchCookies)));
+                var item = WatcherOperation.WatchDirectory(
+                    watchedDirectory.Path,
+                    watchedDirectory.ExtensionFilters,
+                    this,
+                    _directoryWatchCookies);
+
+                _fileChangeWatcher._taskQueue.AddWork(item);
             }
         }
 

src/Workspaces/Core/Portable/Workspace/ProjectSystem/FileWatchedPortableExecutableReferenceFactory.cs

@@ -109,7 +109,7 @@ static ImmutableArray<WatchedDirectory> GetAdditionalWatchedDirectories()
                 referenceDirectories.Add(Path.Combine(Environment.GetFolderPath(Environment.SpecialFolder.UserProfile), ".nuget", "packages"));
             }
 
-            return referenceDirectories.SelectAsArray(static d => new WatchedDirectory(d, ".dll"));
+            return referenceDirectories.SelectAsArray(static d => new WatchedDirectory(d, [".dll"]));
         }
     }
 

src/Workspaces/Core/Portable/Workspace/ProjectSystem/IFileChangeWatcher.cs

@@ -4,6 +4,7 @@
 
 using System;
 using System.Collections.Immutable;
+using System.Linq;
 
 namespace Microsoft.CodeAnalysis.ProjectSystem;
 
@@ -26,7 +27,7 @@ internal interface IFileChangeWatcher
 /// </remarks>
 internal sealed class WatchedDirectory
 {
-    public WatchedDirectory(string path, string? extensionFilter)
+    public WatchedDirectory(string path, ImmutableArray<string> extensionFilters)
     {
         // We are doing string comparisons with this path, so ensure it has a trailing directory separator so we don't get confused with sibling
         // paths that won't actually be covered. For example, if we're watching C:\Directory we wouldn't see changes to C:\DirectorySibling\Foo.txt.
@@ -35,32 +36,32 @@ public WatchedDirectory(string path, string? extensionFilter)
             path += System.IO.Path.DirectorySeparatorChar;
         }
 
-        if (extensionFilter != null && !extensionFilter.StartsWith("."))
+        if (extensionFilters.Any(static filter => !filter.StartsWith(".")))
         {
-            throw new ArgumentException($"{nameof(extensionFilter)} should start with a period.", nameof(extensionFilter));
+            throw new ArgumentException($"{nameof(extensionFilters)} should only contain entries starting with a period.", nameof(extensionFilters));
         }
 
         Path = path;
-        ExtensionFilter = extensionFilter;
+        ExtensionFilters = extensionFilters;
     }
 
     public string Path { get; }
 
     /// <summary>
     /// If non-null, only watch the directory for changes to a specific extension. String always starts with a period.
     /// </summary>
-    public string? ExtensionFilter { get; }
+    public ImmutableArray<string> ExtensionFilters { get; }
 
     public static bool FilePathCoveredByWatchedDirectories(ImmutableArray<WatchedDirectory> watchedDirectories, string filePath, StringComparison stringComparison)
     {
         foreach (var watchedDirectory in watchedDirectories)
         {
             if (filePath.StartsWith(watchedDirectory.Path, stringComparison))
             {
-                // If ExtensionFilter is null, then we're watching for all files in the directory so the prior check
-                // of the directory containment was sufficient. If it isn't null, then we have to check the extension
+                // If ExtensionFilters is empty, then we're watching for all files in the directory so the prior check
+                // of the directory containment was sufficient. If it isn't empty, then we have to check the extension
                 // matches.
-                if (watchedDirectory.ExtensionFilter == null || filePath.EndsWith(watchedDirectory.ExtensionFilter, stringComparison))
+                if (watchedDirectory.ExtensionFilters.Length == 0 || watchedDirectory.ExtensionFilters.Any(filter => filePath.EndsWith(filter, stringComparison)))
                 {
                     return true;
                 }

src/Workspaces/Core/Portable/Workspace/ProjectSystem/ProjectSystemProject.cs

@@ -222,8 +222,8 @@ static ImmutableArray<WatchedDirectory> GetWatchedDirectories(string? language,
 
             return language switch
             {
-                LanguageNames.VisualBasic => [new(rootPath, ".vb")],
-                LanguageNames.CSharp => [new(rootPath, ".cs"), new(rootPath, ".razor"), new(rootPath, ".cshtml")],
+                LanguageNames.VisualBasic => [new(rootPath, [".vb"])],
+                LanguageNames.CSharp => [new(rootPath, [".cs", ".razor", ".cshtml"])],
                 _ => []
             };
         }