Merge pull request PowerShell#430 from daviwil/avoid-completion-slowness

Temporarily mitigate intermittent IntelliSense slowness

Author: daviwil

src/PowerShellEditorServices.Protocol/Server/LanguageServer.cs

@@ -758,10 +758,13 @@ await CommandHelpers.GetCommandInfo(
                         completionItem.Label,
                         this.editorSession.PowerShellContext);
 
-                completionItem.Documentation =
-                    await CommandHelpers.GetCommandSynopsis(
-                        commandInfo,
-                        this.editorSession.PowerShellContext);
+                if (commandInfo != null)
+                {
+                    completionItem.Documentation =
+                        await CommandHelpers.GetCommandSynopsis(
+                            commandInfo,
+                            this.editorSession.PowerShellContext);
+                }
             }
 
             // Send back the updated CompletionItem

src/PowerShellEditorServices/Language/CommandHelpers.cs

@@ -3,6 +3,8 @@
 // Licensed under the MIT license. See LICENSE file in the project root for full license information.
 //
 
+using Microsoft.PowerShell.EditorServices.Utility;
+using System.Collections.Generic;
 using System.Linq;
 using System.Management.Automation;
 using System.Threading.Tasks;
@@ -14,6 +16,20 @@ namespace Microsoft.PowerShell.EditorServices
     /// </summary>
     public class CommandHelpers
     {
+        private static HashSet<string> NounBlackList =
+            new HashSet<string>
+            {
+                "Module",
+                "Script",
+                "Package",
+                "PackageProvider",
+                "PackageSource",
+                "InstalledModule",
+                "InstalledScript",
+                "ScriptFileInfo",
+                "PSRepository"
+            };
+
         /// <summary>
         /// Gets the CommandInfo instance for a command with a particular name.
         /// </summary>
@@ -24,6 +40,18 @@ public static async Task<CommandInfo> GetCommandInfo(
             string commandName,
             PowerShellContext powerShellContext)
         {
+            Validate.IsNotNull(nameof(commandName), commandName);
+
+            // Make sure the command's noun isn't blacklisted.  This is
+            // currently necessary to make sure that Get-Command doesn't
+            // load PackageManagement or PowerShellGet because they cause
+            // a major slowdown in IntelliSense.
+            var commandParts = commandName.Split('-');
+            if (commandParts.Length == 2 && NounBlackList.Contains(commandParts[1]))
+            {
+                return null;
+            }
+
             PSCommand command = new PSCommand();
             command.AddCommand(@"Microsoft.PowerShell.Core\Get-Command");
             command.AddArgument(commandName);