Avoid delays be initializing UI using UIThreadNormalPriority

This stops UI initialization happening on background priority when there is no other activity.

Author: jcansdale

src/GitHub.Exports/Helpers/ThreadingHelper.cs

@@ -59,17 +59,6 @@ public static IAwaitable SwitchToPoolThreadAsync(TaskScheduler scheduler = null)
                 new AwaitableWrapper(scheduler ?? TaskScheduler.Default);
         }
 
-        // HACK: This is a workaround because the following doesn't seem to work.
-        //await JoinableTaskFactory
-        //   .WithPriority(VsTaskRunContext.UIThreadNormalPriority)
-        //   .SwitchToMainThreadAsync();
-        public static Task RunOnMainThreadNormalPriority(Action action)
-        {
-            var service = (IVsTaskSchedulerService2)VsTaskLibraryHelper.ServiceInstance;
-            var scheduler = service.GetTaskScheduler((uint)VsTaskRunContext.UIThreadNormalPriority);
-            return Task.Factory.StartNew(action, default(CancellationToken), TaskCreationOptions.HideScheduler, scheduler);
-        }
-
         class AwaitableWrapper : IAwaitable
         {
             Func<IAwaiter> getAwaiter;

src/GitHub.InlineReviews/InlineReviewsPackage.cs

@@ -2,13 +2,13 @@
 using System.ComponentModel.Design;
 using System.Runtime.InteropServices;
 using System.Threading;
-using GitHub.Helpers;
 using GitHub.Commands;
 using GitHub.InlineReviews.Views;
 using GitHub.Services.Vssdk.Commands;
 using GitHub.VisualStudio;
 using Microsoft.VisualStudio.ComponentModelHost;
 using Microsoft.VisualStudio.Shell;
+using Microsoft.VisualStudio.Threading;
 using Task = System.Threading.Tasks.Task;
 
 namespace GitHub.InlineReviews
@@ -28,10 +28,15 @@ protected override async Task InitializeAsync(
             var componentModel = (IComponentModel)(await GetServiceAsync(typeof(SComponentModel)));
             var exports = componentModel.DefaultExportProvider;
 
-            await ThreadingHelper.SwitchToMainThreadAsync();
-            menuService.AddCommands(
-                exports.GetExportedValue<INextInlineCommentCommand>(),
-                exports.GetExportedValue<IPreviousInlineCommentCommand>());
+            // Avoid delays when there is ongoing UI activity.
+            // See: https://github.com/github/VisualStudio/issues/1537
+            await JoinableTaskFactory.RunAsync(VsTaskRunContext.UIThreadNormalPriority, async () =>
+            {
+                await JoinableTaskFactory.SwitchToMainThreadAsync();
+                menuService.AddCommands(
+                    exports.GetExportedValue<INextInlineCommentCommand>(),
+                    exports.GetExportedValue<IPreviousInlineCommentCommand>());
+            });
         }
     }
 }

src/GitHub.InlineReviews/PullRequestStatusBarPackage.cs

@@ -28,14 +28,13 @@ protected override async Task InitializeAsync(CancellationToken cancellationToke
             var serviceProvider = (IGitHubServiceProvider)await GetServiceAsync(typeof(IGitHubServiceProvider));
             var barManager = new PullRequestStatusBarManager(usageTracker, serviceProvider);
 
-            // Unfortunately this doesn't return until after the GitHub pane has finnished refreshing.
-            //log.Information("SwitchToMainThreadAsync");
-            //await JoinableTaskFactory
-            //   .WithPriority(VsTaskRunContext.UIThreadNormalPriority)
-            //   .SwitchToMainThreadAsync();
-
-            // Posting a task like this seems to work.            
-            await ThreadingHelper.RunOnMainThreadNormalPriority(() => barManager.StartShowingStatus());
+            // Avoid delays when there is ongoing UI activity.
+            // See: https://github.com/github/VisualStudio/issues/1537
+            await JoinableTaskFactory.RunAsync(VsTaskRunContext.UIThreadNormalPriority, async () =>
+            {
+                await JoinableTaskFactory.SwitchToMainThreadAsync();
+                barManager.StartShowingStatus();
+            });
         }
 
     }

src/GitHub.VisualStudio/GitHubPackage.cs

@@ -59,16 +59,21 @@ async Task InitializeMenus()
             var componentModel = (IComponentModel)(await GetServiceAsync(typeof(SComponentModel)));
             var exports = componentModel.DefaultExportProvider;
 
-            await ThreadingHelper.SwitchToMainThreadAsync();
-            menuService.AddCommands(
-                exports.GetExportedValue<IAddConnectionCommand>(),
-                exports.GetExportedValue<IBlameLinkCommand>(),
-                exports.GetExportedValue<ICopyLinkCommand>(),
-                exports.GetExportedValue<ICreateGistCommand>(),
-                exports.GetExportedValue<IOpenLinkCommand>(),
-                exports.GetExportedValue<IOpenPullRequestsCommand>(),
-                exports.GetExportedValue<IShowCurrentPullRequestCommand>(),
-                exports.GetExportedValue<IShowGitHubPaneCommand>());
+            // Avoid delays when there is ongoing UI activity.
+            // See: https://github.com/github/VisualStudio/issues/1537
+            await JoinableTaskFactory.RunAsync(VsTaskRunContext.UIThreadNormalPriority, async () =>
+            {
+                await JoinableTaskFactory.SwitchToMainThreadAsync();
+                menuService.AddCommands(
+                    exports.GetExportedValue<IAddConnectionCommand>(),
+                    exports.GetExportedValue<IBlameLinkCommand>(),
+                    exports.GetExportedValue<ICopyLinkCommand>(),
+                    exports.GetExportedValue<ICreateGistCommand>(),
+                    exports.GetExportedValue<IOpenLinkCommand>(),
+                    exports.GetExportedValue<IOpenPullRequestsCommand>(),
+                    exports.GetExportedValue<IShowCurrentPullRequestCommand>(),
+                    exports.GetExportedValue<IShowGitHubPaneCommand>());
+            });
         }
 
         async Task EnsurePackageLoaded(Guid packageGuid)