Optimization: avoid Lambda JITing for typical case of invoking Bulk .Set() with value

Author: SergeiPavlov

Extensions/Xtensive.Orm.BulkOperations/BulkExtensions.cs

@@ -78,8 +78,11 @@ public static IUpdatable<T> Set<T, TResult>(this IUpdatable<T> query, Expression
     /// <returns>Instance of <see cref=" IUpdatable&lt;T&gt;"/>.</returns>
     [Pure]
     public static IUpdatable<T> Set<T, TResult>(this IQueryable<T> query, Expression<Func<T, TResult>> field,
-      TResult value) where T: IEntity =>
-      Set(query, field, a => value);
+        TResult value) where T: IEntity =>
+      Set(query,
+        field,
+        Expression.Lambda<Func<T, TResult>>(Expression.Constant(value), Expression.Parameter(typeof(T), "a"))   // Manually constructed expression is simpler than `a => value`
+      );
 
     /// <summary>
     /// Executes bulk update of entities specified by the query.

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

@@ -136,7 +136,7 @@ private void AddComputedExpression(AddValueContext addContext)
       var sqlSelect = request.Query;
       SqlExpression ex = sqlSelect.OrderBy[0].Expression;
       parent.Bindings.AddRange(request.ParameterBindings);
-      
+
       if(parent.JoinedTableRef!=null)
         ex.AcceptVisitor(new ComputedExpressionSqlVisitor(sqlSelect.From, parent.JoinedTableRef));
 
@@ -146,10 +146,14 @@ private void AddComputedExpression(AddValueContext addContext)
     private void AddConstantValue(AddValueContext addContext)
     {
       SqlTableColumn column = SqlDml.TableColumn(addContext.Statement.Table, addContext.Field.Column.Name);
+      var constant =
+        addContext.Lambda.Body is ConstantExpression ce
+          ? ce.Value
+          : FastExpression.Lambda(addContext.Lambda.Body).Compile().DynamicInvoke();
       SqlExpression value;
-      object constant = FastExpression.Lambda(addContext.Lambda.Body).Compile().DynamicInvoke();
-      if (constant==null)
+      if (constant == null) {
         value = SqlDml.Null;
+      }
       else {
         QueryParameterBinding binding = parent.QueryBuilder.CreateParameterBinding(constant.GetType(), context => constant);
         parent.Bindings.Add(binding);