Fix unfetched lazy property issue #3731

src/NHibernate.Test/Async/CacheTest/JsonSerializerCacheFixture.cs

@@ -30,7 +30,8 @@ public class JsonSerializerCacheFixtureAsync : TestCase
 		protected override string[] Mappings => new[]
 		{
 			"CacheTest.ReadOnly.hbm.xml",
-			"CacheTest.ReadWrite.hbm.xml"
+			"CacheTest.ReadWrite.hbm.xml",
+			"CacheTest.NonStrictReadWrite.hbm.xml"
 		};
 
 		protected override string MappingsAssembly => "NHibernate.Test";
@@ -46,7 +47,7 @@ protected override void Configure(Configuration configuration)
 			serializer.RegisterType(typeof(Tuple<string, object>), "tso");
 			CoreDistributedCacheProvider.DefaultSerializer = serializer;
 		}
-
+		
 		protected override void OnSetUp()
 		{
 			using (var s = Sfi.OpenSession())
@@ -55,36 +56,27 @@ protected override void OnSetUp()
 				var totalItems = 6;
 				for (var i = 1; i <= totalItems; i++)
 				{
-					var parent = new ReadOnly
-					{
-						Name = $"Name{i}"
-					};
+					var parent = new ReadOnly { Name = $"Name{i}" };
 					for (var j = 1; j <= totalItems; j++)
 					{
-						var child = new ReadOnlyItem
-						{
-							Parent = parent
-						};
-						parent.Items.Add(child);
+						parent.Items.Add(new ReadOnlyItem { Parent = parent });
 					}
 					s.Save(parent);
 				}
 				for (var i = 1; i <= totalItems; i++)
 				{
-					var parent = new ReadWrite
-					{
-						Name = $"Name{i}"
-					};
+					var parent = new ReadWrite { Name = $"Name{i}" };
 					for (var j = 1; j <= totalItems; j++)
 					{
-						var child = new ReadWriteItem
-						{
-							Parent = parent
-						};
-						parent.Items.Add(child);
+						parent.Items.Add(new ReadWriteItem { Parent = parent });
 					}
 					s.Save(parent);
 				}
+				for (var i = 1; i <= totalItems; i++)
+				{
+					var parent = new NonStrictReadWrite() { Name = $"Name{i}" };
+					s.Save(parent);
+				}
 				tx.Commit();
 			}
 		}
@@ -98,12 +90,13 @@ protected override void OnTearDown()
 				s.CreateQuery("delete from ReadWriteItem").ExecuteUpdate();
 				s.CreateQuery("delete from ReadOnly").ExecuteUpdate();
 				s.CreateQuery("delete from ReadWrite").ExecuteUpdate();
+				s.CreateQuery("delete from NonStrictReadWrite").ExecuteUpdate();
 				tx.Commit();
 			}
 			// Must rebuild the session factory, CoreDistribted cache being not clearable.
 			RebuildSessionFactory();
 		}
-
+		
 		[Test]
 		public async Task CacheableScalarSqlQueryWithTransformerAsync()
 		{
@@ -532,5 +525,22 @@ public async Task QueryFetchEntityBatchCacheTestAsync(bool future)
 			Assert.That(Sfi.Statistics.QueryCacheMissCount, Is.EqualTo(0), "Unexpected cache miss count");
 			Assert.That(Sfi.Statistics.QueryCacheHitCount, Is.EqualTo(future ? 2 : 1), "Unexpected cache hit count");
 		}
+
+		[Test]
+		public async Task LazyFormulaTestAsync()
+		{
+			using (var s = OpenSession())
+			using (var t = s.BeginTransaction())
+			{
+				var l = await (s.Query<NonStrictReadWrite>().ToListAsync());
+				foreach (var item in l)
+				{
+					// The lazy formula will puke if equality is not correct (due to comparison of deserialized
+					// UnfetchedLazyProperty vs LazyPropertyInitializer.UnfetchedProperty
+					Assert.AreEqual(1, item.Count);
+				}
+				await (t.CommitAsync());
+			}
+		}
 	}
 }

src/NHibernate.Test/CacheTest/CacheEntity.cs

@@ -0,0 +1,11 @@
+namespace NHibernate.Test.CacheTest;
+
+public abstract class CacheEntity
+{
+	public virtual int Id { get; protected set; }
+}
+
+public abstract class NamedCacheEntity : CacheEntity
+{
+	public virtual string Name { get; set; }
+}

src/NHibernate.Test/CacheTest/JsonSerializerCacheFixture.cs

@@ -19,7 +19,8 @@ public class JsonSerializerCacheFixture : TestCase
 		protected override string[] Mappings => new[]
 		{
 			"CacheTest.ReadOnly.hbm.xml",
-			"CacheTest.ReadWrite.hbm.xml"
+			"CacheTest.ReadWrite.hbm.xml",
+			"CacheTest.NonStrictReadWrite.hbm.xml"
 		};
 
 		protected override string MappingsAssembly => "NHibernate.Test";
@@ -35,7 +36,7 @@ protected override void Configure(Configuration configuration)
 			serializer.RegisterType(typeof(Tuple<string, object>), "tso");
 			CoreDistributedCacheProvider.DefaultSerializer = serializer;
 		}
-
+		
 		protected override void OnSetUp()
 		{
 			using (var s = Sfi.OpenSession())
@@ -44,36 +45,27 @@ protected override void OnSetUp()
 				var totalItems = 6;
 				for (var i = 1; i <= totalItems; i++)
 				{
-					var parent = new ReadOnly
-					{
-						Name = $"Name{i}"
-					};
+					var parent = new ReadOnly { Name = $"Name{i}" };
 					for (var j = 1; j <= totalItems; j++)
 					{
-						var child = new ReadOnlyItem
-						{
-							Parent = parent
-						};
-						parent.Items.Add(child);
+						parent.Items.Add(new ReadOnlyItem { Parent = parent });
 					}
 					s.Save(parent);
 				}
 				for (var i = 1; i <= totalItems; i++)
 				{
-					var parent = new ReadWrite
-					{
-						Name = $"Name{i}"
-					};
+					var parent = new ReadWrite { Name = $"Name{i}" };
 					for (var j = 1; j <= totalItems; j++)
 					{
-						var child = new ReadWriteItem
-						{
-							Parent = parent
-						};
-						parent.Items.Add(child);
+						parent.Items.Add(new ReadWriteItem { Parent = parent });
 					}
 					s.Save(parent);
 				}
+				for (var i = 1; i <= totalItems; i++)
+				{
+					var parent = new NonStrictReadWrite() { Name = $"Name{i}" };
+					s.Save(parent);
+				}
 				tx.Commit();
 			}
 		}
@@ -87,12 +79,13 @@ protected override void OnTearDown()
 				s.CreateQuery("delete from ReadWriteItem").ExecuteUpdate();
 				s.CreateQuery("delete from ReadOnly").ExecuteUpdate();
 				s.CreateQuery("delete from ReadWrite").ExecuteUpdate();
+				s.CreateQuery("delete from NonStrictReadWrite").ExecuteUpdate();
 				tx.Commit();
 			}
 			// Must rebuild the session factory, CoreDistribted cache being not clearable.
 			RebuildSessionFactory();
 		}
-
+		
 		[Test]
 		public void CacheableScalarSqlQueryWithTransformer()
 		{
@@ -521,5 +514,22 @@ public void QueryFetchEntityBatchCacheTest(bool future)
 			Assert.That(Sfi.Statistics.QueryCacheMissCount, Is.EqualTo(0), "Unexpected cache miss count");
 			Assert.That(Sfi.Statistics.QueryCacheHitCount, Is.EqualTo(future ? 2 : 1), "Unexpected cache hit count");
 		}
+
+		[Test]
+		public void LazyFormulaTest()
+		{
+			using (var s = OpenSession())
+			using (var t = s.BeginTransaction())
+			{
+				var l = s.Query<NonStrictReadWrite>().ToList();
+				foreach (var item in l)
+				{
+					// The lazy formula will puke if equality is not correct (due to comparison of deserialized
+					// UnfetchedLazyProperty vs LazyPropertyInitializer.UnfetchedProperty
+					Assert.AreEqual(1, item.Count);
+				}
+				t.Commit();
+			}
+		}
 	}
 }

src/NHibernate.Test/CacheTest/NonStrictReadWrite.cs

@@ -0,0 +1,7 @@
+namespace NHibernate.Test.CacheTest
+{
+	public class NonStrictReadWrite : NamedCacheEntity
+	{
+		public virtual int Count { get; set; }
+	}
+}

src/NHibernate.Test/CacheTest/NonStrictReadWrite.hbm.xml

@@ -0,0 +1,15 @@
+<?xml version="1.0" encoding="utf-8" ?>
+<hibernate-mapping xmlns="urn:nhibernate-mapping-2.2" 
+				   assembly="NHibernate.Test"
+				   namespace="NHibernate.Test.CacheTest">
+
+  <class name="NonStrictReadWrite" batch-size="3">
+    <cache usage="nonstrict-read-write" />
+    <id name="Id" unsaved-value="0">
+      <generator class="native"/>
+    </id>
+    <property name="Name" />
+    <property name="Count" formula="(select count(*) from NonStrictReadWrite x where x.Id = Id)" lazy="true"/>
+  </class>
+
+</hibernate-mapping>

src/NHibernate.Test/CacheTest/ReadOnly.cs

@@ -1,25 +1,14 @@
-using System;
-using System.Collections.Generic;
-using System.Linq;
-using System.Text;
-using System.Threading.Tasks;
+using System.Collections.Generic;
 
 namespace NHibernate.Test.CacheTest
 {
-	public class ReadOnly : CacheEntity
+	public class ReadOnly : NamedCacheEntity
 	{
-		public virtual string Name { get; set; }
-
 		public virtual ISet<ReadOnlyItem> Items { get; set; } = new HashSet<ReadOnlyItem>();
 	}
 
 	public class ReadOnlyItem : CacheEntity
 	{
 		public virtual ReadOnly Parent { get; set; }
 	}
-
-	public abstract class CacheEntity
-	{
-		public virtual int Id { get; protected set; }
-	}
 }

src/NHibernate.Test/CacheTest/ReadWrite.cs

@@ -1,15 +1,9 @@
-using System;
-using System.Collections.Generic;
-using System.Linq;
-using System.Text;
-using System.Threading.Tasks;
+using System.Collections.Generic;
 
 namespace NHibernate.Test.CacheTest
 {
-	public class ReadWrite : CacheEntity
+	public class ReadWrite : NamedCacheEntity
 	{
-		public virtual string Name { get; set; }
-
 		public virtual ISet<ReadWriteItem> Items { get; set; } = new HashSet<ReadWriteItem>();
 	}
 

src/NHibernate.Test/NHibernate.Test.csproj

@@ -52,6 +52,7 @@
     <Compile Remove="**\NHSpecificTest\NH2484\**" />
     <Compile Remove="**\NHSpecificTest\NH2188\**" />
     <Compile Remove="**\NHSpecificTest\NH3121\**" />
+    <Compile Remove="CacheTest\EntityWithLazyFormula.cs" />
   </ItemGroup>
   <ItemGroup>
     <PackageReference Include="log4net" Version="3.0.2" />

src/NHibernate/Engine/IPersistenceContext.cs

@@ -457,7 +457,7 @@ public static EntityEntry AddEntity(
 				existsInDatabase,
 				persister,
 				disableVersionIncrement,
-				loadedState?.Any(o => o == LazyPropertyInitializer.UnfetchedProperty) == true);
+				loadedState?.Any(o => Equals(o, LazyPropertyInitializer.UnfetchedProperty)) == true);
 #pragma warning restore 618
 		}
 
@@ -505,7 +505,7 @@ public static EntityEntry AddEntry(
 				existsInDatabase,
 				persister,
 				disableVersionIncrement,
-				loadedState?.Any(o => o == LazyPropertyInitializer.UnfetchedProperty) == true);
+				loadedState?.Any(o => Equals(o, LazyPropertyInitializer.UnfetchedProperty)) == true);
 #pragma warning restore 618
 		}
 	}

src/NHibernate/Intercept/ILazyPropertyInitializer.cs

@@ -4,8 +4,14 @@
 namespace NHibernate.Intercept
 {
 	[Serializable]
-	public struct UnfetchedLazyProperty
+	public struct UnfetchedLazyProperty : IEquatable<UnfetchedLazyProperty>
 	{
+		/// <summary>As long as the other instance is the same type, it's considered equal. This
+		/// avoids the issue where a deserialized value fails the base Object.Equals() check due to
+		/// both objects being different references.</summary>
+		public bool Equals(UnfetchedLazyProperty other) => true;
+		public override bool Equals(object obj) => obj is UnfetchedLazyProperty;
+		public override int GetHashCode() => typeof(UnfetchedLazyProperty).GetHashCode();
 	}
 
 	public struct LazyPropertyInitializer
@@ -20,4 +26,4 @@ public interface ILazyPropertyInitializer
 		/// <summary> Initialize the property, and return its new value</summary>
 		object InitializeLazyProperty(string fieldName, object entity, ISessionImplementor session);
 	}
-}
+}

src/NHibernate/Persister/Entity/AbstractEntityPersister.cs

@@ -1396,7 +1396,7 @@ public virtual object InitializeLazyProperty(string fieldName, object entity, IS
 				{
 					CacheEntry cacheEntry = (CacheEntry)CacheEntryStructure.Destructure(ce, factory);
 					var initializedValue = InitializeLazyPropertiesFromCache(fieldName, entity, session, entry, cacheEntry, uninitializedLazyProperties);
-					if (initializedValue != LazyPropertyInitializer.UnfetchedProperty)
+					if (!Equals(initializedValue, LazyPropertyInitializer.UnfetchedProperty))
 					{
 						// NOTE EARLY EXIT!!!
 						return initializedValue;
@@ -1567,7 +1567,7 @@ private object InitializeLazyPropertiesFromCache(
 			for (int j = 0; j < lazyPropertyNames.Length; j++)
 			{
 				var cachedValue = disassembledValues[lazyPropertyNumbers[j]];
-				if (cachedValue == LazyPropertyInitializer.UnfetchedProperty)
+				if (Equals(cachedValue, LazyPropertyInitializer.UnfetchedProperty))
 				{
 					if (fieldName == lazyPropertyNames[j])
 					{

src/NHibernate/Tuple/Entity/BytecodeEnhancementMetadataPocoImpl.cs

@@ -202,7 +202,7 @@ public ISet<string> GetUninitializedLazyProperties(object[] entityState)
 			var uninitializedProperties = new HashSet<string>();
 			foreach (var propertyDescriptor in LazyPropertiesMetadata.LazyPropertyDescriptors)
 			{
-				if (entityState[propertyDescriptor.PropertyIndex] == LazyPropertyInitializer.UnfetchedProperty)
+				if (Equals(entityState[propertyDescriptor.PropertyIndex], LazyPropertyInitializer.UnfetchedProperty))
 				{
 					uninitializedProperties.Add(propertyDescriptor.Name);
 				}