NH-3985 - Fix for subsequent child sessions being returned in disposed state

Author: alobakov

src/NHibernate.Test/NHSpecificTest/NH3985/Entity.cs

@@ -0,0 +1,10 @@
+using System;
+
+namespace NHibernate.Test.NHSpecificTest.NH3985
+{
+	public partial class Process
+	{
+		public virtual Guid ProcessID { get; set; }
+		public virtual string Name { get; set; }
+	}
+}

src/NHibernate.Test/NHSpecificTest/NH3985/Fixture.cs

@@ -0,0 +1,28 @@
+using NUnit.Framework;
+using System;
+
+namespace NHibernate.Test.NHSpecificTest.NH3985
+{
+	/// <summary>
+	/// The test verifies that subsequent child sessions are not issued in already-disposed state.
+	/// </summary>
+	[TestFixture]
+	public class Fixture : BugTestCase
+	{
+		[Test]
+		public void GetChildSession_ShouldReturnNonDisposedInstance()
+		{
+			using (var rootSession = OpenSession())
+			{
+				using (var childSession1 = rootSession.GetChildSession())
+				{
+				}
+
+				using (var childSession2 = rootSession.GetChildSession())
+				{
+					Assert.DoesNotThrow(() => { childSession2.Get<Process>(Guid.NewGuid()); });
+				}
+			}
+		}
+	}
+}

src/NHibernate.Test/NHSpecificTest/NH3985/Mappings.hbm.xml

@@ -0,0 +1,7 @@
+<?xml version="1.0" encoding="utf-8" ?>
+<hibernate-mapping xmlns="urn:nhibernate-mapping-2.2" assembly="NHibernate.Test" namespace="NHibernate.Test.NHSpecificTest.NH3985">
+	<class name="Process">
+		<id name="ProcessID" generator="guid.comb" />
+		<property name="Name" />
+	</class>
+</hibernate-mapping>

src/NHibernate.Test/NHibernate.Test.csproj

@@ -743,6 +743,8 @@
     <Compile Include="NHSpecificTest\EntityWithUserTypeCanHaveLinqGenerators\IExample.cs" />
     <Compile Include="Insertordering\NH3931Entities.cs" />
     <Compile Include="NHSpecificTest\NH1904\StructFixture.cs" />
+    <Compile Include="NHSpecificTest\NH3985\Entity.cs" />
+    <Compile Include="NHSpecificTest\NH3985\Fixture.cs" />
     <Compile Include="NHSpecificTest\NH3247\Entity.cs" />
     <Compile Include="NHSpecificTest\NH3247\Fixture.cs" />
     <Compile Include="NHSpecificTest\NH3386\Entity.cs" />
@@ -2668,6 +2670,7 @@
     <EmbeddedResource Include="NHSpecificTest\NH2195\Mappings.hbm.xml" />
     <EmbeddedResource Include="NHSpecificTest\NH3187\Mappings.hbm.xml" />
     <EmbeddedResource Include="NHSpecificTest\NH3932\Model\Mappings.hbm.xml" />
+    <EmbeddedResource Include="NHSpecificTest\NH3985\Mappings.hbm.xml" />
     <EmbeddedResource Include="TypedManyToOne\Customer.hbm.xml" />
   </ItemGroup>
   <ItemGroup>
@@ -3253,6 +3256,10 @@
   </ItemGroup>
   <ItemGroup>
     <EmbeddedResource Include="NHSpecificTest\NH1904\StructMappings.hbm.xml" />
+    <EmbeddedResource Include="NHSpecificTest\NH3985\Mappings.hbm.xml">
+      <SubType>Designer</SubType>
+    </EmbeddedResource>
+    <EmbeddedResource Include="NHSpecificTest\NH3985\Mappings.hbm.xml" />
     <EmbeddedResource Include="Insertordering\FamilyModel\Mappings.hbm.xml" />
     <EmbeddedResource Include="Insertordering\AnimalModel\Mappings.hbm.xml" />
     <EmbeddedResource Include="NHSpecificTest\NH3247\Mappings.hbm.xml" />

src/NHibernate/Impl/SessionImpl.cs

@@ -6,6 +6,7 @@
 using System.Linq.Expressions;
 using System.Runtime.Serialization;
 using System.Security;
+using System.Threading;
 using NHibernate.AdoNet;
 using NHibernate.Collection;
 using NHibernate.Criterion;
@@ -73,7 +74,7 @@ public sealed class SessionImpl : AbstractSessionImpl, IEventSource, ISerializab
 		private readonly StatefulPersistenceContext persistenceContext;
 
 		[NonSerialized]
-		private readonly ISession rootSession;
+		private readonly SessionImpl rootSession;
 
 		[NonSerialized]
 		ISession _childSession;
@@ -1681,6 +1682,9 @@ private void Dispose(bool isDisposing)
 				// free unmanaged resources here
 
 				IsAlreadyDisposed = true;
+
+				rootSession?.RemoveChildSession(this);
+
 				// nothing for Finalizer to do - so tell the GC to ignore it
 				GC.SuppressFinalize(this);
 			}
@@ -2604,5 +2608,10 @@ public override IEntityPersister GetEntityPersister(string entityName, object ob
 				}
 			}
 		}
+
+		void RemoveChildSession(ISession session)
+		{
+			Interlocked.CompareExchange(ref _childSession, null, session);
+		}
 	}
 }