Try a different fix

Synchronously run the OnInitialize of the service to load the addin assemblies on the UI thread, then dispatch the actual composing to a background task.
This should prevent deadlock issues, and ensure that the first init is called on the UI thread

1 files changed, 33 insertions, 40 deletions

diff --git a/main/src/core/MonoDevelop.Ide/MonoDevelop.Ide.Composition/CompositionManager.cs b/main/src/core/MonoDevelop.Ide/MonoDevelop.Ide.Composition/CompositionManager.cs
index 838daf1378..2cc3ca4b88 100644
--- a/main/src/core/MonoDevelop.Ide/MonoDevelop.Ide.Composition/CompositionManager.cs
+++ b/main/src/core/MonoDevelop.Ide/MonoDevelop.Ide.Composition/CompositionManager.cs
@@ -56,23 +56,12 @@ namespace MonoDevelop.Ide.Composition
 			new AttributedPartDiscoveryV1 (StandardResolver),
 			new AttributedPartDiscovery (StandardResolver, true));
 
-		static Action HandleMefQueriedBeforeCompletion = UninitializedThrowException;
-
-		static void UninitializedLogWarning ()
-			=> LoggingService.LogWarning ("UI thread queried MEF while it was still being built:{0}{1}", Environment.NewLine, Environment.StackTrace);
-
-		static void UninitializedThrowException ()
-			=> throw new InvalidOperationException ("MEF queried while it was still being built");
-
-		static void ConfigureUninitializedMefHandling (bool throwException)
-			=> HandleMefQueriedBeforeCompletion = throwException ? new Action (UninitializedThrowException) : new Action (UninitializedLogWarning);
-
 		public static CompositionManager Instance {

 			get {

 				if (instance == null) {

 					var task = Runtime.GetService<CompositionManager> ();

-					if (!task.IsCompleted && Runtime.IsMainThread) {

-						HandleMefQueriedBeforeCompletion ();

+					if (!task.IsCompleted) {
+						LoggingService.LogWarning ("UI thread queried MEF while it was still being built:{0}{1}", Environment.NewLine, Environment.StackTrace);
 					}

 					instance = task.WaitAndGetResult ();

 				}

@@ -83,7 +72,19 @@ namespace MonoDevelop.Ide.Composition
 

 		protected override Task OnInitialize (ServiceProvider serviceProvider)
 		{
-			return Task.Run (async () => await InitializeInstanceAsync ());

+			Runtime.AssertMainThread ();
+
+			var timings = new Dictionary<string, long> ();
+			var metadata = new CompositionLoadMetadata (timings);
+
+			var timer = Counters.CompositionLoad.BeginTiming (metadata);
+			var stepTimer = System.Diagnostics.Stopwatch.StartNew ();
+
+			var mefAssemblies = ReadAssembliesFromAddins (timer);
+
+			timings ["ReadFromAddins"] = stepTimer.ElapsedMilliseconds;
+
+			return Task.Run (() => InitializeInstanceAsync (timer, mefAssemblies));
 		}
 
 		/// <summary>
@@ -115,50 +116,42 @@ namespace MonoDevelop.Ide.Composition
 		{
 		}
 
-		async Task InitializeInstanceAsync ()
+		async Task InitializeInstanceAsync (ITimeTracker<CompositionLoadMetadata> timer, HashSet<Assembly> mefAssemblies)
 		{

-			var timings = new Dictionary<string, long> ();

-			var metadata = new CompositionLoadMetadata (timings);

-

-			using (var timer = Counters.CompositionLoad.BeginTiming (metadata)) {
-				var fullTimer = System.Diagnostics.Stopwatch.StartNew ();

-				var stepTimer = System.Diagnostics.Stopwatch.StartNew ();

-

-				var mefAssemblies = await Runtime.RunInMainThread (() => ReadAssembliesFromAddins (timer));
-				ConfigureUninitializedMefHandling (throwException: false);
-				timings ["ReadFromAddins"] = stepTimer.ElapsedMilliseconds;

-				stepTimer.Restart ();

-
-				var caching = new Caching (mefAssemblies, new IdeRuntimeCompositionExceptionHandler ());
+			var metadata = timer.Metadata;
+			var fullTimer = System.Diagnostics.Stopwatch.StartNew ();
+			var stepTimer = System.Diagnostics.Stopwatch.StartNew ();
 
-				// Try to use cached MEF data
+			var caching = new Caching (mefAssemblies, new IdeRuntimeCompositionExceptionHandler ());
 
+			// Try to use cached MEF data
+			using (timer) {
 				var canUse = metadata.ValidCache = caching.CanUse ();
-				if (canUse) {

+				if (canUse) {
 					LoggingService.LogInfo ("Creating MEF composition from cache");
 					RuntimeComposition = await TryCreateRuntimeCompositionFromCache (caching);
-				}

-				timings ["LoadFromCache"] = stepTimer.ElapsedMilliseconds;

+				}
+				metadata.Timings ["LoadFromCache"] = stepTimer.ElapsedMilliseconds;
 				stepTimer.Restart ();
 
 				// Otherwise fallback to runtime discovery.
-				if (RuntimeComposition == null) {

+				if (RuntimeComposition == null) {
 					LoggingService.LogInfo ("Creating MEF composition from runtime");
-					var (runtimeComposition, catalog) = await CreateRuntimeCompositionFromDiscovery (caching, timer);

+					var (runtimeComposition, catalog) = await CreateRuntimeCompositionFromDiscovery (caching, timer);
 					RuntimeComposition = runtimeComposition;
 
 					CachedComposition cacheManager = new CachedComposition ();
 					caching.Write (RuntimeComposition, catalog, cacheManager).Ignore ();
-				}

-				timings ["LoadRuntimeComposition"] = stepTimer.ElapsedMilliseconds;

-				stepTimer.Restart ();

+				}
+				metadata.Timings ["LoadRuntimeComposition"] = stepTimer.ElapsedMilliseconds;
+				stepTimer.Restart ();
 
 				ExportProviderFactory = RuntimeComposition.CreateExportProviderFactory ();
 				ExportProvider = ExportProviderFactory.CreateExportProvider ();
 				HostServices = Microsoft.VisualStudio.LanguageServices.VisualStudioMefHostServices.Create (ExportProvider);
-

-				timings ["CreateServices"] = stepTimer.ElapsedMilliseconds;

-				metadata.Duration = fullTimer.ElapsedMilliseconds;

+
+				metadata.Timings ["CreateServices"] = stepTimer.ElapsedMilliseconds;
+				metadata.Duration = fullTimer.ElapsedMilliseconds;
 			}

 		}