Improve performance of ExpressionExtensions.MakeTupleAccess method

Author: AlexUstinov

Orm/Xtensive.Orm/Linq/ExpressionExtensions.cs

@@ -5,6 +5,7 @@
 // Created:    2009.04.21
 
 using System;
+using System.Collections.Concurrent;
 using System.Linq;
 using System.Linq.Expressions;
 using System.Reflection;
@@ -20,7 +21,10 @@ namespace Xtensive.Linq
   /// </summary>
   public static class ExpressionExtensions
   {
-    private static readonly MethodInfo TupleGenericAccessor;
+    private static readonly ConcurrentDictionary<Type, MethodInfo> valueAccessors =
+      new ConcurrentDictionary<Type, MethodInfo>();
+
+    private static readonly Func<Type, MethodInfo> TupleValueAccessorFactory;
 
     ///<summary>
     /// Makes <see cref="Tuples.Tuple.GetValueOrDefault{T}"/> method call.
@@ -29,15 +33,12 @@ public static class ExpressionExtensions
     ///<param name="accessorType">Type of accessor.</param>
     ///<param name="index">Tuple field index.</param>
     ///<returns><see cref="MethodCallExpression"/></returns>
-    public static MethodCallExpression MakeTupleAccess(this Expression target, Type accessorType, int index)
-    {
-      return Expression.Call(
+    public static MethodCallExpression MakeTupleAccess(this Expression target, Type accessorType, int index) =>
+      Expression.Call(
         target,
-        TupleGenericAccessor.MakeGenericMethod(accessorType),
+        valueAccessors.GetOrAdd(accessorType, TupleValueAccessorFactory),
         Expression.Constant(index)
-        );
-    }
-
+      );
 
     /// <summary>
     /// Makes <c>IsNull</c> condition expression.
@@ -46,41 +47,38 @@ public static MethodCallExpression MakeTupleAccess(this Expression target, Type
     /// <param name="ifNull">Result expression if <paramref name="target"/> is <see langword="null" />.</param>
     /// <param name="ifNotNull">Result expression if <paramref name="target"/> is not <see langword="null" />.</param>
     /// <returns><see cref="ConditionalExpression"/></returns>
-    public static ConditionalExpression MakeIsNullCondition(this Expression target, Expression ifNull, Expression ifNotNull)
-    {
-      return Expression.Condition(
+    public static ConditionalExpression MakeIsNullCondition(
+      this Expression target, Expression ifNull, Expression ifNotNull) =>
+      Expression.Condition(
         Expression.Equal(target, Expression.Constant(null, target.Type)),
-        ifNull, ifNotNull
-        );
-    }
+        ifNull,
+        ifNotNull
+      );
 
     /// <summary>
     /// Converts expression type to nullable type (for value types).
     /// </summary>
     /// <param name="expression">The expression.</param>
-    public static Expression LiftToNullable(this Expression expression)
-    {
-      return expression.Type.IsNullable() 
-               ? expression 
-               : Expression.Convert(expression, expression.Type.ToNullable());
-    }
+    public static Expression LiftToNullable(this Expression expression) =>
+      expression.Type.IsNullable()
+        ? expression
+        : Expression.Convert(expression, expression.Type.ToNullable());
 
     /// <summary>
     /// Converts specified <see cref="Expression"/> to <see cref="ExpressionTree"/>.
     /// </summary>
     /// <param name="expression">The expression to convert.</param>
     /// <returns>Expression tree that wraps <paramref name="expression"/>.</returns>
-    public static ExpressionTree ToExpressionTree(this Expression expression)
-    {
-      return new ExpressionTree(expression);
-    }
+    public static ExpressionTree ToExpressionTree(this Expression expression) => new ExpressionTree(expression);
 
 
     // Type initializer
 
     static ExpressionExtensions()
     {
-      TupleGenericAccessor = typeof (Tuple).GetMethods().Single(mi => mi.Name==WellKnown.Tuple.GetValueOrDefault && mi.IsGenericMethod);
+      var tupleGenericAccessor = typeof(Tuple).GetMethods()
+        .Single(mi => mi.Name == WellKnown.Tuple.GetValueOrDefault && mi.IsGenericMethod);
+      TupleValueAccessorFactory = type => tupleGenericAccessor.MakeGenericMethod(type);
     }
   }
 }