Minor optimizations (#59)

* Make QueryTranslationResult readonly struct

* Make QueryRequest readonly struct

* Don't load string resource until necessary

* improve is/as usages

* Optimize PrefetchHelper && make Fetcher readonluy struct

* Optimize BatchingCommandProcessor.PutTasksForExecution

* Refactor PrefetchManager.GetGraphContainer() to avoid unnecessary allocation

* Avoid double HashSet-search in TypeRegistry.Register()

* Improving refactoring of TypeDefCollection

* Use Queue.TryDequeue()

* Avoid ReadOnly-wrapping of Empty arrays. They are always immutable

* Avoid double dictionary search when removing

* Make BuildBatch() to accept IReadOnlyList<string> arg to avoid conversions

* Make ColumnInfoRef readonly struct

* Refactor ColumnCollection

* Make TypeReference readonly struct

* Make ColumnGroup readonly struct

* Make TypeInfoRef readonly struct

Author: SergeiPavlov

Extensions/Xtensive.Orm.BulkOperations/Internals/BulkDeleteOperation.cs

@@ -51,10 +51,10 @@ protected async override Task<int> ExecuteInternalAsync(CancellationToken token
       }
     }
 
-    private QueryCommand CreateCommand(QueryTranslationResult request)
+    private QueryCommand CreateCommand(in QueryTranslationResult request)
     {
       var delete = SqlDml.Delete(SqlDml.TableRef(PrimaryIndexes[0].Table));
-      Join(delete, (SqlSelect) request.Query);
+      Join(delete, request.Query);
       return ToCommand(delete);
     }
 

Extensions/Xtensive.Orm.BulkOperations/Internals/BulkUpdateOperation.cs

@@ -54,11 +54,11 @@ protected async override Task<int> ExecuteInternalAsync(CancellationToken token
       }
     }
 
-    private QueryCommand CreateCommand(QueryTranslationResult request)
+    private QueryCommand CreateCommand(in QueryTranslationResult request)
     {
       var update = SqlDml.Update(SqlDml.TableRef(PrimaryIndexes[0].Table));
       setOperation.Statement = SetStatement.Create(update);
-      Join(update, (SqlSelect) request.Query);
+      Join(update, request.Query);
       setOperation.AddValues();
       return ToCommand(update);
     }

Extensions/Xtensive.Orm.BulkOperations/Internals/SetOperation.cs

@@ -103,7 +103,7 @@ private void AddComputedStaticExpression(AddValueContext addContext)
         all,
         addContext.Lambda);
       QueryTranslationResult request = parent.GetRequest(parent.QueryProvider.CreateQuery<T>(selectExpression));
-      var sqlSelect = ((SqlSelect)request.Query);
+      var sqlSelect = request.Query;
       SqlExpression ex = sqlSelect.OrderBy[0].Expression;
       var placeholder = ex as SqlPlaceholder;
       if (placeholder == null)
@@ -133,7 +133,7 @@ private void AddComputedExpression(AddValueContext addContext)
         all,
         addContext.Lambda);
       QueryTranslationResult request = parent.GetRequest(parent.QueryProvider.CreateQuery<T>(selectExpression));
-      var sqlSelect = ((SqlSelect) request.Query);
+      var sqlSelect = request.Query;
       SqlExpression ex = sqlSelect.OrderBy[0].Expression;
       parent.Bindings.AddRange(request.ParameterBindings);
 
@@ -217,7 +217,7 @@ private void AddEntityValue(AddValueContext addContext)
             QueryTranslationResult request = parent.GetRequest(field.ValueType, q);
             parent.Bindings.AddRange(request.ParameterBindings);
             SqlTableColumn c = SqlDml.TableColumn(addContext.Statement.Table, addContext.Field.Columns[i].Name);
-            addContext.Statement.AddValue(c, SqlDml.SubQuery((ISqlQueryExpression) request.Query));
+            addContext.Statement.AddValue(c, SqlDml.SubQuery(request.Query));
           }
           return;
         }

Orm/Xtensive.Orm.Tests/Storage/QueryBuilderTest.cs

@@ -56,7 +56,7 @@ public void ModifyQueryTest()
         Assert.That(translated.Query, Is.Not.Null);
         Assert.That(translated.ParameterBindings, Is.Not.Null);
 
-        var select = (SqlSelect) translated.Query;
+        var select = translated.Query;
         select.Columns.Clear();
         select.Columns.Add(SqlDml.Count());
         var compiled = builder.CompileQuery(translated.Query);

Orm/Xtensive.Orm/Caching/WeakestCache.cs

@@ -236,9 +236,7 @@ public override TItem Add(TItem item, bool replaceIfExists)
     public override void RemoveKey(TKey key)
     {
       ArgumentValidator.EnsureArgumentNotNull(key, "key");
-      WeakEntry entry;
-      if (items.TryGetValue(key, out entry)) {
-        items.Remove(key);
+      if (items.Remove(key, out var entry)) {
         entry.Dispose();
       }
     }

Orm/Xtensive.Orm/Collections/ExtensionCollection.cs

@@ -153,12 +153,13 @@ public ExtensionCollection(IExtensionCollection source)
       ArgumentValidator.EnsureArgumentNotNull(source, "source");
       if (source.Count==0)
         return;
-      var sourceLikeMe = source as ExtensionCollection;
-      if (sourceLikeMe!=null)
+      if (source is ExtensionCollection sourceLikeMe) {
         extensions = new Dictionary<Type, object>(sourceLikeMe.extensions);
-      else
+      }
+      else {
         foreach (Type extensionType in source)
           Set(extensionType, source.Get(extensionType));
+      }
     }
   }
 }

Orm/Xtensive.Orm/Collections/Graphs/TopologicalSorter.cs

@@ -1,4 +1,4 @@
-// Copyright (C) 2003-2012 Xtensive LLC.
+// Copyright (C) 2003-2012 Xtensive LLC.
 // All rights reserved.
 // For conditions of distribution and use, see license.
 // Created by: Alex Yakunin
@@ -41,10 +41,8 @@ public T Pop()
 
       public void Remove(T item)
       {
-        LinkedListNode<T> node;
-        if (map.TryGetValue(item, out node)) {
+        if (map.Remove(item, out var node)) {
           list.Remove(node);
-          map.Remove(item);
         }
       }
 
@@ -104,8 +102,7 @@ public static TopologicalSortResult<TNode, TEdge> Sort<TNode, TEdge>(Graph<TNode
 
     restart:
       // Sorting
-      while (nodesWithoutIncomingEdges.Count!=0) {
-        var node = nodesWithoutIncomingEdges.Dequeue();
+      while (nodesWithoutIncomingEdges.TryDequeue(out var node)) {
         if (unsortedNodes!=null) // Break edges
           unsortedNodes.Remove(node);
         else
@@ -126,8 +123,7 @@ public static TopologicalSortResult<TNode, TEdge> Sort<TNode, TEdge>(Graph<TNode
       if (unsortedNodes!=null) { // Break edges
         if (unsortedNodes.Count != 0) {
           // Trying to break edges (collection is always empty when breakEdges==false)
-          while (breakableEdges.Count != 0) {
-            var edge = breakableEdges.Dequeue();
+          while (breakableEdges.TryDequeue(out var edge)) {
             if (!edge.IsAttached || !edgeBreaker(edge))
               continue;
             result.BrokenEdges.Add(edge);

Orm/Xtensive.Orm/Collections/TopDeque.cs

@@ -253,10 +253,8 @@ public void AddToBottom(K key, V value)
     /// <inheritdoc/>
     public void Remove(K key)
     {
-      LinkedListNode<Pair<K, V>> valueContainer;
-      if (map.TryGetValue(key, out valueContainer)) {
+      if (map.Remove(key, out var valueContainer)) {
         list.Remove(valueContainer);
-        map.Remove(key);
       }
     }
 

Orm/Xtensive.Orm/Collections/TypeRegistry.cs

@@ -61,12 +61,9 @@ public void Register(Type type)
       ArgumentValidator.EnsureArgumentNotNull(type, "type");
       if (!isProcessingPendingActions)
         Register(new TypeRegistration(type));
-      else {
-        if (typeSet.Contains(type))
-          return;
+      else if (typeSet.Add(type)) {
         serviceRegistrations = null;
         types.Add(type);
-        typeSet.Add(type);
         assemblies.Add(type.Assembly);
       }
     }

Orm/Xtensive.Orm/Modelling/Comparison/Comparer.cs

@@ -296,11 +296,13 @@ protected virtual void CompareProperties(Node source, Node target, NodeDifferenc
             continue;
 
           if (any.Nesting.PropertyInfo != null && accessor.DependencyRootType==any.Nesting.PropertyInfo.PropertyType) {
-            if (propertyDifference is NodeDifference)
-              ((NodeDifference) propertyDifference).IsDependentOnParent = true;
-            else if (propertyDifference is NodeCollectionDifference)
-              ((NodeCollectionDifference) propertyDifference).ItemChanges
+            if (propertyDifference is NodeDifference nodeDifference) {
+              nodeDifference.IsDependentOnParent = true;
+            }
+            else if (propertyDifference is NodeCollectionDifference nodeCollectionDifference) {
+              nodeCollectionDifference.ItemChanges
                 .ForEach(item=>item.IsDependentOnParent = true);
+            }
           }
           difference.PropertyChanges.Add(property.Name, propertyDifference);
         }
@@ -411,12 +413,12 @@ protected virtual Difference VisitNodeCollection(NodeCollection source, NodeColl
         return difference.ItemChanges.Count != 0 ? difference : null;
       }
     }
-    
+
     // Sort by items only with source, then by (target ?? source).Index then with source and target and then only with target
     private static int CompareNodeDifference(NodeDifference curr, NodeDifference other)
     {
-      var currType = curr.Source != null && curr.Target != null ? 1 : curr.Source == null ? 3 : 0; 
-      var otherType = other.Source != null && other.Target != null ? 1 : other.Source == null ? 3 : 0; 
+      var currType = curr.Source != null && curr.Target != null ? 1 : curr.Source == null ? 3 : 0;
+      var otherType = other.Source != null && other.Target != null ? 1 : other.Source == null ? 3 : 0;
       var typeIsNot0Comparison = (currType != 0).CompareTo(otherType != 0);
       if (typeIsNot0Comparison != 0) {
         return typeIsNot0Comparison;
@@ -590,10 +592,10 @@ protected virtual bool IsImmutable(Node node)
     /// <returns>Comparison key for the specified node.</returns>
     protected virtual string GetNodeComparisonKey(Node node)
     {
-      if (!(node is INodeReference))
+      if (!(node is INodeReference nodeReference))
         return GetTargetName(node);
 
-      var targetNode = ((INodeReference) node).Value;
+      var targetNode = nodeReference.Value;
       return targetNode==null ? null : GetTargetPath(targetNode);
     }