Fix #50: High CPU usage on complete/hover app path

This change fixes an issue which causes high CPU usage and a delay when an
application path is completed or hovered over.  This is due to an
unnecesary call to Get-Help which takes some time before it returns in
this case.

Author: daviwil

src/PowerShellEditorServices.Host/LanguageServer.cs

@@ -427,13 +427,10 @@ protected async Task HandleCompletionResolveRequest(
                         completionItem.Label,
                         runspaceHandle.Runspace);
 
-                if (commandInfo != null)
-                {
-                    completionItem.Documentation =
-                        CommandHelpers.GetCommandSynopsis(
-                            commandInfo,
-                            runspaceHandle.Runspace);
-                }
+                completionItem.Documentation =
+                    CommandHelpers.GetCommandSynopsis(
+                        commandInfo,
+                        runspaceHandle.Runspace);
 
                 runspaceHandle.Dispose();
             }

src/PowerShellEditorServices/Language/CommandHelpers.cs

@@ -52,25 +52,31 @@ public static string GetCommandSynopsis(
 
             PSObject helpObject = null;
 
-            using (PowerShell powerShell = PowerShell.Create())
-            {
-                powerShell.Runspace = runspace;
-                powerShell.AddCommand("Get-Help");
-                powerShell.AddArgument(commandInfo);
-                helpObject = powerShell.Invoke<PSObject>().FirstOrDefault();
-            }
-
-            if (helpObject != null)
+            if (commandInfo != null &&
+                (commandInfo.CommandType == CommandTypes.Cmdlet ||
+                 commandInfo.CommandType == CommandTypes.Function ||
+                 commandInfo.CommandType == CommandTypes.Filter))
             {
-                // Extract the synopsis string from the object
-                synopsisString = 
-                    (string)helpObject.Properties["synopsis"].Value ?? 
-                    string.Empty;
+                using (PowerShell powerShell = PowerShell.Create())
+                {
+                    powerShell.Runspace = runspace;
+                    powerShell.AddCommand("Get-Help");
+                    powerShell.AddArgument(commandInfo);
+                    helpObject = powerShell.Invoke<PSObject>().FirstOrDefault();
+                }
 
-                // Ignore the placeholder value for this field
-                if (string.Equals(synopsisString, "SHORT DESCRIPTION", System.StringComparison.InvariantCultureIgnoreCase))
+                if (helpObject != null)
                 {
-                    synopsisString = string.Empty;
+                    // Extract the synopsis string from the object
+                    synopsisString =
+                        (string)helpObject.Properties["synopsis"].Value ??
+                        string.Empty;
+
+                    // Ignore the placeholder value for this field
+                    if (string.Equals(synopsisString, "SHORT DESCRIPTION", System.StringComparison.InvariantCultureIgnoreCase))
+                    {
+                        synopsisString = string.Empty;
+                    }
                 }
             }
 

src/PowerShellEditorServices/Language/SymbolDetails.cs

@@ -51,12 +51,29 @@ internal SymbolDetails(
                         symbolReference.SymbolName,
                         runspace);
 
-                this.Documentation =
-                    CommandHelpers.GetCommandSynopsis(
-                        commandInfo, 
-                        runspace);
+                if (commandInfo != null)
+                {
+                    this.Documentation =
+                        CommandHelpers.GetCommandSynopsis(
+                            commandInfo,
+                            runspace);
 
-                this.DisplayString = "function " + symbolReference.SymbolName;
+                    if (commandInfo.CommandType == CommandTypes.Application)
+                    {
+                        this.DisplayString = "(application) " + symbolReference.SymbolName;
+                    }
+                    else
+                    {
+                        this.DisplayString = "function " + symbolReference.SymbolName;
+                    }
+                }
+                else
+                {
+                    // Command information can't be loaded.  This is likely due to
+                    // the symbol being a function that is defined in a file that
+                    // hasn't been loaded in the runspace yet.
+                    this.DisplayString = "function " + symbolReference.SymbolName;
+                }
             }
             else if (symbolReference.SymbolType == SymbolType.Parameter)
             {