Constrain use of ConcurrentDictionary to CommandHelpers

Which is where it might be accessed concurrently as a cache, but we can
use `IDictionary` (and return a copy of the caches) to the rest of the
users.

Author: andyleejordan

Diff for: src/PowerShellEditorServices/Services/PowerShell/Utility/CommandHelpers.cs

@@ -177,16 +177,10 @@ public static async Task<string> GetCommandSynopsisAsync(
         /// Gets all aliases found in the runspace
         /// </summary>
         /// <param name="executionService"></param>
-        public static async Task<(ConcurrentDictionary<string, List<string>>, ConcurrentDictionary<string, string>)> GetAliasesAsync(IInternalPowerShellExecutionService executionService)
+        public static async Task<(Dictionary<string, List<string>>, Dictionary<string, string>)> GetAliasesAsync(IInternalPowerShellExecutionService executionService)
         {
             Validate.IsNotNull(nameof(executionService), executionService);
 
-            // TODO: Should we return the caches if they're not empty, or always update?
-            // if (!s_cmdletToAliasCache.IsEmpty || !s_aliasToCmdletCache.IsEmpty)
-            // {
-            //     return (s_cmdletToAliasCache, s_aliasToCmdletCache);
-            // }
-
             IEnumerable<CommandInfo> aliases = await executionService.ExecuteDelegateAsync<IEnumerable<CommandInfo>>(
                 nameof(GetAliasesAsync),
                 Execution.ExecutionOptions.Default,
@@ -209,7 +203,8 @@ public static async Task<string> GetCommandSynopsisAsync(
                 s_aliasToCmdletCache.TryAdd(aliasInfo.Name, aliasInfo.Definition);
             }
 
-            return (s_cmdletToAliasCache, s_aliasToCmdletCache);
+            return (new Dictionary<string, List<string>>(s_cmdletToAliasCache),
+                new Dictionary<string, string>(s_aliasToCmdletCache));
         }
     }
 }

Diff for: src/PowerShellEditorServices/Services/Symbols/SymbolsService.cs

@@ -189,7 +189,7 @@ public async Task<List<SymbolReference>> FindReferencesOfSymbol(
                 return null;
             }
 
-            (ConcurrentDictionary<string, List<string>> cmdletToAliases, ConcurrentDictionary<string, string> aliasToCmdlets) = await CommandHelpers.GetAliasesAsync(_executionService).ConfigureAwait(false);
+            (Dictionary<string, List<string>> cmdletToAliases, Dictionary<string, string> aliasToCmdlets) = await CommandHelpers.GetAliasesAsync(_executionService).ConfigureAwait(false);
 
             // We want to look for references first in referenced files, hence we use ordered dictionary
             // TODO: File system case-sensitivity is based on filesystem not OS, but OS is a much cheaper heuristic

Diff for: src/PowerShellEditorServices/Services/Symbols/Vistors/AstOperations.cs

@@ -2,7 +2,6 @@
 // Licensed under the MIT License.
 
 using System;
-using System.Collections.Concurrent;
 using System.Collections.Generic;
 using System.Diagnostics;
 using System.Linq;
@@ -160,8 +159,8 @@ public static SymbolReference FindCommandAtPosition(Ast scriptAst, int lineNumbe
         public static IEnumerable<SymbolReference> FindReferencesOfSymbol(
             Ast scriptAst,
             SymbolReference symbolReference,
-            ConcurrentDictionary<string, List<string>> cmdletToAliasDictionary = default,
-            ConcurrentDictionary<string, string> aliasToCmdletDictionary = default)
+            IDictionary<string, List<string>> cmdletToAliasDictionary = default,
+            IDictionary<string, string> aliasToCmdletDictionary = default)
         {
             // find the symbol evaluators for the node types we are handling
             FindReferencesVisitor referencesVisitor = new(

Diff for: src/PowerShellEditorServices/Services/Symbols/Vistors/FindReferencesVisitor.cs

@@ -2,7 +2,6 @@
 // Licensed under the MIT License.
 
 using System;
-using System.Collections.Concurrent;
 using System.Collections.Generic;
 using System.Management.Automation.Language;
 
@@ -14,8 +13,8 @@ namespace Microsoft.PowerShell.EditorServices.Services.Symbols
     internal class FindReferencesVisitor : AstVisitor
     {
         private readonly SymbolReference _symbolRef;
-        private readonly ConcurrentDictionary<string, List<string>> _cmdletToAliasDictionary;
-        private readonly ConcurrentDictionary<string, string> _aliasToCmdletDictionary;
+        private readonly IDictionary<string, List<string>> _cmdletToAliasDictionary;
+        private readonly IDictionary<string, string> _aliasToCmdletDictionary;
         private readonly string _symbolRefCommandName;
         private readonly bool _needsAliases;
 
@@ -29,8 +28,8 @@ internal class FindReferencesVisitor : AstVisitor
         /// <param name="aliasToCmdletDictionary">Dictionary maping aliases to cmdlets for finding alias references</param>
         public FindReferencesVisitor(
             SymbolReference symbolReference,
-            ConcurrentDictionary<string, List<string>> cmdletToAliasDictionary = default,
-            ConcurrentDictionary<string, string> aliasToCmdletDictionary = default)
+            IDictionary<string, List<string>> cmdletToAliasDictionary = default,
+            IDictionary<string, string> aliasToCmdletDictionary = default)
         {
             _symbolRef = symbolReference;
             FoundReferences = new List<SymbolReference>();