Improve performance of EntityFieldExpression.CreateEntityField method

Author: AlexUstinov

Orm/Xtensive.Orm/Orm/Linq/Expressions/EntityFieldExpression.cs

@@ -161,16 +161,22 @@ public override FieldExpression RemoveOwner()
 
     public static EntityFieldExpression CreateEntityField(FieldInfo entityField, int offset)
     {
-      if (!entityField.IsEntity)
-        throw new ArgumentException(string.Format(Strings.ExFieldXIsNotEntity, entityField.Name), "entityField");
+      if (!entityField.IsEntity) {
+        throw new ArgumentException(string.Format(Strings.ExFieldXIsNotEntity, entityField.Name), nameof(entityField));
+      }
+
       var entityType = entityField.ValueType;
       var persistentType = entityField.ReflectedType.Model.Types[entityType];
-      var mapping = new Segment<int>(entityField.MappingInfo.Offset + offset, entityField.MappingInfo.Length);
-      var fields = new List<PersistentFieldExpression>();
-      var keyExpression = KeyExpression.Create(persistentType, offset + entityField.MappingInfo.Offset);
-      fields.Add(keyExpression);
-      foreach (var keyField in persistentType.Fields.Where(f => f.IsPrimaryKey))
-        fields.Add(BuildNestedFieldExpression(keyField, offset + entityField.MappingInfo.Offset));
+
+      ref var mappingInfo = ref entityField.mappingInfo;
+      var mapping = new Segment<int>(mappingInfo.Offset + offset, mappingInfo.Length);
+      var keyFields = persistentType.Key.Fields;
+      var keyExpression = KeyExpression.Create(persistentType, offset + mappingInfo.Offset);
+      var fields = new List<PersistentFieldExpression>(keyFields.Count + 1) {keyExpression};
+      foreach (var field in keyFields) {
+        fields.Add(BuildNestedFieldExpression(field, offset + mappingInfo.Offset));
+      }
+
       return new EntityFieldExpression(persistentType, entityField, fields, mapping, keyExpression, null, null, false);
     }
 

Orm/Xtensive.Orm/Orm/Linq/Expressions/FieldExpression.cs

@@ -119,9 +119,12 @@ public virtual FieldExpression RemoveOwner()
 
     public static FieldExpression CreateField(FieldInfo field, int offset)
     {
-      if (!field.IsPrimitive)
+      if (!field.IsPrimitive) {
         throw new ArgumentException(string.Format(Strings.ExFieldXIsNotPrimitive, field.Name), "field");
-      var mapping = new Segment<int>(field.MappingInfo.Offset + offset, field.MappingInfo.Length);
+      }
+
+      ref var mappingInfo = ref field.mappingInfo;
+      var mapping = new Segment<int>(mappingInfo.Offset + offset, mappingInfo.Length);
       return new FieldExpression(ExtendedExpressionType.Field, field, mapping, null, false);
     }
 

Orm/Xtensive.Orm/Orm/Model/FieldInfo.cs

@@ -60,7 +60,7 @@ public sealed class FieldInfo : MappedNode,
     private int? cachedHashCode;
 
     private IList<IPropertyValidator> validators;
-    private Segment<int> mappingInfo;
+    internal Segment<int> mappingInfo;
 
     #region IsXxx properties
 
@@ -720,14 +720,14 @@ private void CreateMappingInfo()
           mappingInfo = new Segment<int>(primaryIndex.Columns.IndexOf(indexColumn), 1);
         }
       }
-      else 
-        if (Fields.Count > 0)
-          mappingInfo = new Segment<int>(
-            Fields.First().MappingInfo.Offset, Fields.Sum(f => f.IsPrimitive ? f.MappingInfo.Length : 0));
+      else if (Fields.Count > 0) {
+        mappingInfo = new Segment<int>(
+          Fields[0].mappingInfo.Offset, Fields.Sum(f => f.IsPrimitive ? f.mappingInfo.Length : 0));
+      }
 
       if (IsEntity || IsStructure) {
         valueExtractor = new SegmentTransform(
-          false, reflectedType.TupleDescriptor, new Segment<int>(MappingInfo.Offset, MappingInfo.Length));
+          false, reflectedType.TupleDescriptor, new Segment<int>(mappingInfo.Offset, mappingInfo.Length));
       }
     }