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

Author: alobakov

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

@@ -0,0 +1,45 @@
+using System;
+
+namespace NHibernate.Test.NHSpecificTest.NH3985
+{
+	public partial class Process
+	{
+		#region Extensibility Method Definitions
+
+		public override bool Equals(object obj)
+		{
+			Process toCompare = obj as Process;
+			if (toCompare == null)
+			{
+				return false;
+			}
+
+			if (Object.Equals(this.ProcessID, default(long)) &&
+				Object.Equals(toCompare.ProcessID, default(long)))
+				return ReferenceEquals(this, toCompare);
+
+			if (!Object.Equals(this.ProcessID, toCompare.ProcessID))
+				return false;
+
+			return true;
+		}
+
+		public override int GetHashCode()
+		{
+			int hashCode = 13;
+
+			// on transient objects, use the basic GetHashCode()
+			if (Object.Equals(this.ProcessID, default(long)))
+				return base.GetHashCode();
+
+			hashCode = (hashCode * 7) + ProcessID.GetHashCode();
+			return hashCode;
+		}
+
+		#endregion
+
+		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(new TestDelegate(() => { 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

@@ -741,6 +741,8 @@
     <Compile Include="NHSpecificTest\EntityWithUserTypeCanHaveLinqGenerators\FooExample.cs" />
     <Compile Include="NHSpecificTest\EntityWithUserTypeCanHaveLinqGenerators\IExample.cs" />
     <Compile Include="Insertordering\NH3931Entities.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" />
@@ -3248,6 +3250,9 @@
     <EmbeddedResource Include="NHSpecificTest\NH1291AnonExample\Mappings.hbm.xml" />
   </ItemGroup>
   <ItemGroup>
+    <EmbeddedResource Include="NHSpecificTest\NH3985\Mappings.hbm.xml">
+      <SubType>Designer</SubType>
+    </EmbeddedResource>
     <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

@@ -2221,7 +2221,10 @@ public ISession GetChildSession()
 
 				CheckAndUpdateSessionStatus();
 
-				if (_childSession == null)
+				var childImpl = _childSession as SessionImpl;
+
+				// if child session never existed or has already been disposed, create new
+				if (childImpl == null || childImpl.IsAlreadyDisposed)
 				{
 					log.Debug("Creating child session.");
 					_childSession = new SessionImpl(this);