Create JumpList in background thread to improve performance (#6985)

bergmeister · iSazonov · commit f54085f8a394 · 2018-06-05T17:44:45.000+05:00
* Perform JumpList creation in background thread to improve performance when pwsh owns the window (i.e. when the Jumplist has to be created) * Move JumpList creation to a later stage to allow for more code that might make it exit earlier as suggested in PR review by @iSazonov
diff --git a/src/Microsoft.PowerShell.ConsoleHost/WindowsTaskbarJumpList/TaskbarJumpList.cs b/src/Microsoft.PowerShell.ConsoleHost/WindowsTaskbarJumpList/TaskbarJumpList.cs
@@ -12,7 +12,8 @@ internal static class TaskbarJumpList
     {
         internal static void CreateElevatedEntry(string title)
         {
-            // check startupInfo to know if the current shell owns a window before proceeding
+            // Check startupInfo first to know if the current shell is interactive and owns a window before proceeding
+            // This check is fast (less than 1ms) and allows for quick-exit
             GetStartupInfo(out StartUpInfo startupInfo);
             var STARTF_USESHOWWINDOW = 0x00000001;
             var SW_HIDE = 0;
diff --git a/src/Microsoft.PowerShell.ConsoleHost/host/msh/ConsoleHost.cs b/src/Microsoft.PowerShell.ConsoleHost/host/msh/ConsoleHost.cs
@@ -26,6 +26,7 @@
 using Dbg = System.Management.Automation.Diagnostics;
 using ConsoleHandle = Microsoft.Win32.SafeHandles.SafeFileHandle;
 using System.Management.Automation.Tracing;
+using System.Threading.Tasks;
 #if LEGACYTELEMETRY
 using Microsoft.PowerShell.Telemetry.Internal;
 #endif
@@ -120,10 +121,6 @@ internal static int Start(
             }
 #endif
 
-#if !UNIX
-            Microsoft.PowerShell.TaskbarJumpList.CreateElevatedEntry(ConsoleHostStrings.RunAsAdministrator);
-#endif
-
             // put PSHOME in front of PATH so that calling `powershell` within `powershell` always starts the same running version
             string path = Environment.GetEnvironmentVariable("PATH");
             if (path != null)
@@ -214,6 +211,16 @@ internal static int Start(
                     return ExitCodeBadCommandLineParameter;
                 }
 
+#if !UNIX
+                // Creating a JumpList entry takes around 55ms when the PowerShell process is interactive and
+                // owns the current window (otherwise it does a fast exit anyway). Since there is no 'GET' like API,
+                // we always have to execute this call because we do not know if it has been created yet.
+                // The JumpList does persist as long as the filepath of the executable does not change but there
+                // could be disruptions to it like e.g. the bi-annual Windows update, we decided to
+                // not over-optimize this and always create the JumpList as a non-blocking background task instead.
+                Task.Run(() => TaskbarJumpList.CreateElevatedEntry(ConsoleHostStrings.RunAsAdministrator));
+#endif
+
                 // First check for and handle PowerShell running in a server mode.
                 if (s_cpp.ServerMode)
                 {

Original file line number	Diff line number	Diff line change
`@@ -12,7 +12,8 @@ internal static class TaskbarJumpList`
`12`	`12`	`{`
`13`	`13`	`internal static void CreateElevatedEntry(string title)`
`14`	`14`	`{`
`15`		`- // check startupInfo to know if the current shell owns a window before proceeding`
	`15`	`+ // Check startupInfo first to know if the current shell is interactive and owns a window before proceeding`
	`16`	`+ // This check is fast (less than 1ms) and allows for quick-exit`
`16`	`17`	`GetStartupInfo(out StartUpInfo startupInfo);`
`17`	`18`	`var STARTF_USESHOWWINDOW = 0x00000001;`
`18`	`19`	`var SW_HIDE = 0;`