NH-3606 - A method to create a child stateless session

src/NHibernate.Test/Linq/StatelessSessionQueringTest.cs

@@ -8,6 +8,77 @@ namespace NHibernate.Test.Linq
 {
 	public class StatelessSessionQueringTest : LinqTestCase
 	{
+		[Test]
+		public void CanQueryChildStatelessSession()
+		{
+			//NH-3606
+			using (var session = this.OpenSession())
+			{
+				Assert.AreEqual(0, session.GetSessionImplementation().PersistenceContext.EntityEntries.Count);
+
+				using (var statelessSession = session.GetStatelessSession())
+				{
+					var results = statelessSession.Query<Customer>().ToList();
+
+					Assert.IsNotEmpty(results);
+				}
+
+				Assert.AreEqual(0, session.GetSessionImplementation().PersistenceContext.EntityEntries.Count);
+			}
+		}
+
+		[Test]
+		public void CanCreateStatelessSessions()
+		{
+			//NH-3606
+			using (var session = OpenSession())
+			using (session.BeginTransaction())
+			{
+				Assert.IsTrue(session.Transaction.IsActive);
+
+				using (var statelessSession = session.GetStatelessSession())
+				{
+					Assert.IsTrue(statelessSession.Transaction.IsActive);
+
+					statelessSession.Transaction.Rollback();
+				}
+
+				Assert.IsFalse(session.Transaction.IsActive);
+			}
+		}
+
+		[Test]
+		public void CanApplyAsStatelessExtensionMethod()
+		{
+			//NH-3606
+			using (var session = OpenSession())
+			{
+				Assert.AreEqual(0, session.GetSessionImplementation().PersistenceContext.EntityEntries.Count);
+
+				var results = session.Query<Customer>().AsStateless().ToList();
+
+				Assert.IsNotEmpty(results);
+
+				Assert.AreEqual(0, session.GetSessionImplementation().PersistenceContext.EntityEntries.Count);
+			}
+		}
+
+		[Test]
+		public void ExplicitlyFetchedLazyMembersAreNotCached()
+		{
+			//NH-3606
+			using (var session = OpenSession())
+			{
+				Assert.AreEqual(0, session.GetSessionImplementation().PersistenceContext.EntityEntries.Count);
+
+				var results = session.Query<Customer>().AsStateless().Fetch(x => x.Orders).ToList();
+
+				Assert.IsNotEmpty(results);
+
+				Assert.AreEqual(0, session.GetSessionImplementation().PersistenceContext.EntityEntries.Count);
+			}
+		}
+
 		[Test]
 		public void WhenQueryThroughStatelessSessionThenDoesNotThrows()
 		{

src/NHibernate/AdoNet/ConnectionManager.cs

@@ -34,7 +34,7 @@ public interface Callback
 		private bool ownConnection;
 
 		[NonSerialized]
-		private ITransaction transaction;
+		internal ITransaction transaction;
 
 		[NonSerialized]
 		private IBatcher batcher;

src/NHibernate/Impl/SessionImpl.cs

@@ -78,6 +78,10 @@ public sealed class SessionImpl : AbstractSessionImpl, IEventSource, ISerializab
 		[NonSerialized]
 		ISession _childSession;
 
+		//NH-3606
+		[NonSerialized]
+		private IStatelessSession childStatelessSession;
+
 		[NonSerialized]
 		private readonly bool flushBeforeCompletionEnabled;
 		[NonSerialized]
@@ -359,12 +363,20 @@ public DbConnection Close()
 				{
 					try
 					{
+						//NH-3606
+						if (childStatelessSession != null)
+						{
+							childStatelessSession.Close();
+							childStatelessSession = null;
+						}
+
 						if (_childSession != null)
 						{
 							if (_childSession.IsOpen)
 							{
 								_childSession.Close();
 							}
+							_childSession = null;
 						}
 					}
 					catch
@@ -2210,6 +2222,27 @@ public ISessionImplementor GetSessionImplementation()
 			return this;
 		}
 
+		//NH-3606
+		public IStatelessSession GetStatelessSession()
+		{
+			using (new SessionIdLoggingContext(SessionId))
+			{
+				if (rootSession != null)
+				{
+					return rootSession.GetStatelessSession();
+				}
+
+				if (childStatelessSession == null)
+				{
+					childStatelessSession = new StatelessSessionImpl(Connection, SessionFactory as SessionFactoryImpl);
+
+					(childStatelessSession as StatelessSessionImpl).ConnectionManager.transaction = Transaction;
+				}
+
+				return childStatelessSession;
+			}
+		}
+
 		public ISession GetChildSession()
 		{
 			using (new SessionIdLoggingContext(SessionId))

src/NHibernate/Linq/DefaultQueryProvider.cs

@@ -28,7 +28,7 @@ public DefaultQueryProvider(ISessionImplementor session)
 			_session = new WeakReference(session, true);
 		}
 
-		protected virtual ISessionImplementor Session
+		protected internal virtual ISessionImplementor Session
 		{
 			get { return _session.Target as ISessionImplementor; }
 		}

src/NHibernate/Linq/LinqExtensionMethods.cs

@@ -13,6 +13,14 @@ namespace NHibernate.Linq
 {
 	public static class LinqExtensionMethods
 	{
+		public static IQueryable<T> AsStateless<T>(this IQueryable<T> query)
+		{
+			var session = (query.Provider as DefaultQueryProvider).Session;
+			var statelessSession = (session as SessionImpl).GetStatelessSession();
+
+			return new DefaultQueryProvider(statelessSession.GetSessionImplementation()).CreateQuery<T>(query.Expression);
+		}
+
 		public static IQueryable<T> Query<T>(this ISession session)
 		{
 			return new NhQueryable<T>(session.GetSessionImplementation());

src/NHibernate/NHibernate.csproj

@@ -620,6 +620,7 @@
     <Compile Include="Proxy\DynProxyTypeValidator.cs" />
     <Compile Include="QueryException.cs" />
     <Compile Include="ReplicationMode.cs" />
+    <Compile Include="SessionExtensions.cs" />
     <Compile Include="SqlCommand\Alias.cs" />
     <Compile Include="SqlCommand\ANSICaseFragment.cs" />
     <Compile Include="SqlCommand\ANSIJoinFragment.cs" />

src/NHibernate/SessionExtensions.cs

@@ -0,0 +1,16 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using NHibernate.Impl;
+
+namespace NHibernate
+{
+	public static class SessionExtensions
+	{
+		public static IStatelessSession GetStatelessSession(this ISession session)
+		{
+			return (session.GetSessionImplementation() as SessionImpl).GetStatelessSession();
+		}
+	}
+}