Avoid loading the Elfie dll until the user actualy enables the search feature.

src/VisualStudio/Core/Def/SymbolSearch/SymbolSearchService.Update.cs

@@ -44,8 +44,6 @@ internal partial class SymbolSearchService
         private const string MicrosoftAssemblyReferencesName = "MicrosoftAssemblyReferences";
         private static readonly LinkedList<string> s_log = new LinkedList<string>();
 
-        private readonly int _dataFormatVersion = AddReferenceDatabase.TextFileFormatVersion;
-
         /// <summary>
         /// Cancellation support for the task we use to keep the local database up to date.
         /// When VS shuts down it will dispose us.  We'll cancel the task at that point.
@@ -58,9 +56,6 @@ internal partial class SymbolSearchService
         private readonly ConcurrentDictionary<string, object> _sourceToUpdateSentinel =
             new ConcurrentDictionary<string, object>();
 
-        private readonly DirectoryInfo _cacheDirectoryInfo;
-        //private readonly FileInfo _databaseFileInfo;
-
         // Interfaces that abstract out the external functionality we need.  Used so we can easily
         // mock behavior during tests.
         private readonly IPackageInstallerService _installerService;
@@ -70,6 +65,7 @@ internal partial class SymbolSearchService
         private readonly IRemoteControlService _remoteControlService;
         private readonly IPatchService _patchService;
         private readonly IDatabaseFactoryService _databaseFactoryService;
+        private readonly string _localSettingsDirectory;
         private readonly Func<Exception, bool> _reportAndSwallowException;
 
         public void Dispose()
@@ -125,23 +121,26 @@ internal Task UpdateSourceInBackgroundAsync(string source)
 
             // We were the first ones to try to update this source.  Spawn off a task to do
             // the updating.
-            return new Updater(this, source).UpdateInBackgroundAsync();
+            return new Updater(this, source, _localSettingsDirectory).UpdateInBackgroundAsync();
         }
 
         private class Updater
         {
             private readonly SymbolSearchService _service;
             private readonly string _source;
+            private readonly DirectoryInfo _cacheDirectoryInfo;
             private readonly FileInfo _databaseFileInfo;
 
-            public Updater(SymbolSearchService service, string source)
+            public Updater(SymbolSearchService service, string source, string localSettingsDirectory)
             {
                 _service = service;
                 _source = source;
 
-                var fileName = ConvertToFileName(source);
+                _cacheDirectoryInfo = new DirectoryInfo(Path.Combine(
+                    localSettingsDirectory, "PackageCache", string.Format(Invariant($"Format{AddReferenceDatabase.TextFileFormatVersion}"))));
+
                 _databaseFileInfo = new FileInfo(
-                    Path.Combine(_service._cacheDirectoryInfo.FullName, fileName + ".txt"));
+                    Path.Combine(_cacheDirectoryInfo.FullName, ConvertToFileName(source) + ".txt"));
             }
 
             /// <summary>
@@ -254,12 +253,12 @@ private void CleanCacheDirectory()
                 _service.LogInfo("Cleaning cache directory");
 
                 // (intentionally not wrapped in IOUtilities.  If this throws we want to restart).
-                if (!_service._ioService.Exists(_service._cacheDirectoryInfo))
+                if (!_service._ioService.Exists(_cacheDirectoryInfo))
                 {
                     _service.LogInfo("Creating cache directory");
 
                     // (intentionally not wrapped in IOUtilities.  If this throws we want to restart).
-                    _service._ioService.Create(_service._cacheDirectoryInfo);
+                    _service._ioService.Create(_cacheDirectoryInfo);
                     _service.LogInfo("Cache directory created");
                 }
 
@@ -268,7 +267,7 @@ private void CleanCacheDirectory()
 
             private async Task<TimeSpan> DownloadFullDatabaseAsync()
             {
-                var serverPath = Invariant($"Elfie_V{_service._dataFormatVersion}/Latest.xml");
+                var serverPath = Invariant($"Elfie_V{AddReferenceDatabase.TextFileFormatVersion}/Latest.xml");
 
                 _service.LogInfo($"Downloading and processing full database: {serverPath}");
 
@@ -332,7 +331,7 @@ private async Task WriteDatabaseFile(byte[] bytes)
                     () =>
                     {
                         var guidString = Guid.NewGuid().ToString();
-                        var tempFilePath = Path.Combine(_service._cacheDirectoryInfo.FullName, guidString + ".tmp");
+                        var tempFilePath = Path.Combine(_cacheDirectoryInfo.FullName, guidString + ".tmp");
 
                         _service.LogInfo($"Temp file path: {tempFilePath}");
 
@@ -402,7 +401,7 @@ private async Task<TimeSpan> PatchLocalDatabaseAsync()
                 var databaseVersion = database.DatabaseVersion;
 
                 // Now attempt to download and apply patch file.
-                var serverPath = Invariant($"Elfie_V{_service._dataFormatVersion}/{database.DatabaseVersion}_Patch.xml");
+                var serverPath = Invariant($"Elfie_V{AddReferenceDatabase.TextFileFormatVersion}/{database.DatabaseVersion}_Patch.xml");
 
                 _service.LogInfo("Downloading and processing patch file: " + serverPath);
 

src/VisualStudio/Core/Def/SymbolSearch/SymbolSearchService.cs

@@ -36,7 +36,8 @@ internal partial class SymbolSearchService :
         ISymbolSearchService,
         IDisposable
     {
-        private ConcurrentDictionary<string, AddReferenceDatabase> _sourceToDatabase = new ConcurrentDictionary<string, AddReferenceDatabase>();
+        // Value is typed as 'object' so we don't load the elfie dll until actually necessary.
+        private ConcurrentDictionary<string, object> _sourceToDatabase = new ConcurrentDictionary<string, object>();
 
         public SymbolSearchService(
             VSShell.SVsServiceProvider serviceProvider,
@@ -104,12 +105,9 @@ private static IRemoteControlService CreateRemoteControlService(VSShell.SVsServi
             _remoteControlService = remoteControlService;
             _patchService = patchService;
             _databaseFactoryService = databaseFactoryService;
+            _localSettingsDirectory = localSettingsDirectory;
             _reportAndSwallowException = reportAndSwallowException;
 
-            _cacheDirectoryInfo = new DirectoryInfo(Path.Combine(
-                localSettingsDirectory, "PackageCache", string.Format(Invariant($"Format{_dataFormatVersion}"))));
-            // _databaseFileInfo = new FileInfo(Path.Combine(_cacheDirectoryInfo.FullName, "NuGetCache.txt"));
-
             _cancellationTokenSource = cancellationTokenSource;
             _cancellationToken = _cancellationTokenSource.Token;
         }
@@ -117,13 +115,14 @@ private static IRemoteControlService CreateRemoteControlService(VSShell.SVsServi
         public IEnumerable<PackageWithTypeResult> FindPackagesWithType(
             string source, string name, int arity, CancellationToken cancellationToken)
         {
-            AddReferenceDatabase database;
-            if (!_sourceToDatabase.TryGetValue(source, out database))
+            object databaseObj;
+            if (!_sourceToDatabase.TryGetValue(source, out databaseObj))
             {
                 // Don't have a database to search.  
                 yield break;
             }
 
+            var database = databaseObj as AddReferenceDatabase;
             if (name == "var")
             {
                 // never find anything named 'var'.
@@ -190,13 +189,14 @@ private static IRemoteControlService CreateRemoteControlService(VSShell.SVsServi
             string name, int arity, CancellationToken cancellationToken)
         {
             // Our reference assembly data is stored in the nuget.org DB.
-            AddReferenceDatabase database;
-            if (!_sourceToDatabase.TryGetValue(NugetOrgSource, out database))
+            object databaseObj;
+            if (!_sourceToDatabase.TryGetValue(NugetOrgSource, out databaseObj))
             {
                 // Don't have a database to search.  
                 yield break;
             }
 
+            var database = (AddReferenceDatabase)databaseObj;
             if (name == "var")
             {
                 // never find anything named 'var'.