Revert "Revert "Optimize BuildMaterializer()"" (#218)

This reverts commit 442e8ef.

Author: SergeiPavlov

Orm/Xtensive.Orm/Orm/Internals/TypeMapping.cs

@@ -8,24 +8,12 @@
 using Xtensive.Tuples.Transform;
 using Xtensive.Orm.Model;
 
-namespace Xtensive.Orm.Internals
-{
-  internal readonly struct TypeMapping
-  {
-    public readonly TypeInfo Type;
-    public readonly MapTransform KeyTransform;
-    public readonly IReadOnlyList<ColNum> KeyIndexes;
-    public readonly MapTransform Transform;
+namespace Xtensive.Orm.Internals;
 
-
-    // Constructors
-
-    public TypeMapping(TypeInfo type, MapTransform keyTransform, MapTransform transform, IReadOnlyList<ColNum> keyIndexes)
-    {
-      Type = type;
-      KeyTransform = keyTransform;
-      Transform = transform;
-      KeyIndexes = keyIndexes;
-    }
-  }
-}
+internal readonly record struct TypeMapping
+(
+  TypeInfo Type,
+  MapTransform KeyTransform,
+  MapTransform Transform,
+  IReadOnlyList<ColNum> KeyIndexes
+);

Orm/Xtensive.Orm/Orm/Linq/Materialization/MaterializationContext.cs

@@ -60,13 +60,11 @@ public TypeIdRegistry TypeIdRegistry
 
     public TypeMapping GetTypeMapping(int entityIndex, TypeInfo approximateType, int typeId, IReadOnlyList<Pair<ColNum>> columns)
     {
-      TypeMapping result;
       ref var cache = ref entityMappings[entityIndex];
-      if (cache.SingleItem != null) {
-        if (typeId != ResolveTypeToNodeSpecificTypeIdentifier(cache.SingleItem?.Type)) {
-          throw new ArgumentOutOfRangeException("typeId");
-        }
-        return cache.SingleItem.Value;
+      if (cache.SingleItem is TypeMapping result) {
+        return typeId == ResolveTypeToNodeSpecificTypeIdentifier(result.Type)
+          ? result
+          : throw new ArgumentOutOfRangeException("typeId");
       }
       if (cache.Items.TryGetValue(typeId, out result))
         return result;
@@ -90,8 +88,8 @@ public TypeMapping GetTypeMapping(int entityIndex, TypeInfo approximateType, int
         typeColumnMap = newColumns;
       }
 
-      ArraySegment<ColNum> allIndexes = MaterializationHelper.CreateSingleSourceMap(descriptor.Count, typeColumnMap);
-      ArraySegment<ColNum> keyIndexes = allIndexes.Slice(0, keyInfo.TupleDescriptor.Count);
+      var allIndexes = MaterializationHelper.CreateSingleSourceMap(descriptor.Count, typeColumnMap);
+      var keyIndexes = allIndexes.Take(keyInfo.TupleDescriptor.Count).ToArray();
 
       var transform    = new MapTransform(true, descriptor, allIndexes);
       var keyTransform = new MapTransform(true, keyInfo.TupleDescriptor, keyIndexes);

Orm/Xtensive.Orm/Orm/Linq/Materialization/MaterializationInfo.cs

@@ -6,17 +6,6 @@
 
 using System.Linq.Expressions;
 
-namespace Xtensive.Orm.Linq.Materialization
-{
-  internal sealed class MaterializationInfo
-  {
-    public int EntitiesInRow { get; private set; }
-    public LambdaExpression Expression { get; private set; }
+namespace Xtensive.Orm.Linq.Materialization;
 
-    public MaterializationInfo(int entitiesInRow, LambdaExpression expression)
-    {
-      EntitiesInRow = entitiesInRow;
-      Expression = expression;
-    }
-  }
-}
+internal readonly record struct MaterializationInfo(int EntitiesInRow, LambdaExpression Expression);

Orm/Xtensive.Orm/Orm/Linq/Translator.Materialization.cs

@@ -127,14 +127,19 @@ private Materializer BuildMaterializer(ProjectionExpression projection, IReadOnl
       var materializationInfo = itemProjector.Materialize(context, tupleParameters);
       var elementType = itemProjector.Item.Type;
       var materializeMethod = MaterializationHelper.MaterializeMethodInfo.CachedMakeGenericMethod(elementType);
-      var itemMaterializerFactoryMethod =
-        elementType.IsNullable()
-          ? MaterializationHelper.CreateNullableItemMaterializerMethodInfo.CachedMakeGenericMethod(
-            elementType.GetGenericArguments()[0])
+
+#if NET8_0_OR_GREATER
+      var itemMaterializerFactoryMethod = elementType.IsNullable()
+          ? MaterializationHelper.CreateNullableItemMaterializerMethodInfo.CachedMakeGenericMethodInvoker(elementType.GetGenericArguments()[0])
+          : MaterializationHelper.CreateItemMaterializerMethodInfo.CachedMakeGenericMethodInvoker(elementType);
+      var itemMaterializer = itemMaterializerFactoryMethod.Invoke(null, materializationInfo.Expression, itemProjector.AggregateType);
+#else
+      var itemMaterializerFactoryMethod = elementType.IsNullable()
+          ? MaterializationHelper.CreateNullableItemMaterializerMethodInfo.CachedMakeGenericMethod(elementType.GetGenericArguments()[0])
           : MaterializationHelper.CreateItemMaterializerMethodInfo.CachedMakeGenericMethod(elementType);
+      var itemMaterializer = itemMaterializerFactoryMethod.Invoke(null, [materializationInfo.Expression, itemProjector.AggregateType]);
+#endif
 
-      var itemMaterializer = itemMaterializerFactoryMethod.Invoke(
-        null, new object[] { materializationInfo.Expression, itemProjector.AggregateType });
       Expression<Func<Session, int, MaterializationContext>> materializationContextCtor =
         (s, entityCount) => new MaterializationContext(s, entityCount);
       var materializationContextExpression = materializationContextCtor

Orm/Xtensive.Orm/Orm/Linq/TranslatorContext.cs

@@ -82,13 +82,23 @@ public IReadOnlyList<string> GetMainQueryTags() =>
         ? applyParameters.Keys.OfType<TagProvider>().Select(p => p.Tag).ToList()
         : Array.Empty<string>();
 
-    public IDisposable DisableSessionTags()
+    internal readonly struct TagsRestorer : IDisposable
     {
-      var originalTags = SessionTags;
-      SessionTags = null;
-      return new Disposable((b) => SessionTags = originalTags);
+      private readonly TranslatorContext context;
+      private readonly IReadOnlyList<string> originalTags;
+
+      public void Dispose() => context.SessionTags = originalTags;
+
+      internal TagsRestorer(TranslatorContext context)
+      {
+        this.context = context;
+        originalTags = context.SessionTags;
+        context.SessionTags = null;
+      }
     }
 
+    public TagsRestorer DisableSessionTags() => new(this);
+
     public void RebindApplyParameter(CompilableProvider old, CompilableProvider @new)
     {
       if (applyParameters.TryGetValue(old, out var parameter)) {