NH-3413 - Linq - use original expression and parameters after getting QueryExpression from cache

Author: hazzik

src/NHibernate.Test/Linq/WhereTests.cs

@@ -1,7 +1,10 @@
 using System;
+using System.Collections;
 using System.Collections.Generic;
+using System.Collections.ObjectModel;
 using System.Linq;
 using System.Linq.Expressions;
+using NHibernate.Engine.Query;
 using NHibernate.Linq;
 using NHibernate.DomainModel.Northwind.Entities;
 using NUnit.Framework;
@@ -415,6 +418,34 @@ where names.Contains(user.Name)
 			Assert.AreEqual(2, query.Count);
 		}
 
+		[Test, Description("NH-3413")]
+		public void UsersWithListContains_MutatingListDoesNotBreakOtherSessions()
+		{
+			{
+				var names = new List<string> { "ayende", "rahien" };
+
+				var query = (from user in db.Users
+							 where names.Contains(user.Name)
+							 select user).ToList();
+
+				Assert.AreEqual(2, query.Count); 
+
+				names.Clear();
+			}
+
+			{
+				var names = new List<string> { "ayende" };
+
+				var query = (from user in db.Users
+							 where names.Contains(user.Name)
+							 select user).ToList();
+
+				// This line fails with Expected: 1 But was: 0
+				// The SQL in NHProf shows that the where clause was executed as WHERE 1 = 0 as if names were empty
+				Assert.AreEqual(1, query.Count);
+			}
+		}
+
 		[Test]
 		public void UsersWithEmptyList_NH2400()
 		{

src/NHibernate/Engine/Query/QueryPlanCache.cs

@@ -3,6 +3,7 @@
 using Iesi.Collections.Generic;
 
 using NHibernate.Engine.Query.Sql;
+using NHibernate.Linq;
 using NHibernate.Util;
 
 namespace NHibernate.Engine.Query
@@ -94,6 +95,16 @@ public IQueryExpressionPlan GetHQLQueryPlan(IQueryExpression queryExpression, bo
 				{
 					log.Debug("located HQL query plan in cache (" + expressionStr + ")");
 				}
+				var planExpression = plan.QueryExpression as NhLinqExpression;
+				var expression = queryExpression as NhLinqExpression;
+				if (planExpression != null && expression != null)
+				{
+					//NH-3413
+					//Here we have to use original expression.
+					//TODO: cache only required parts of QueryExpression
+					planExpression._expression = expression._expression;
+					planExpression._constantToParameterMap = expression._constantToParameterMap;
+				}
 			}
 
 			return plan;

src/NHibernate/Impl/ExpressionQueryImpl.cs

@@ -109,17 +109,18 @@ protected internal IQueryExpression ExpandParameters(IDictionary<string, TypedVa
 				map.Add(name, aliases);
 			}
 
+			//TODO: Do we need to translate expression one more time here?
 			IASTNode newTree = ParameterExpander.Expand(QueryExpression.Translate(Session.Factory), map);
 			var key = new StringBuilder(QueryExpression.Key);
 
 			map.Aggregate(key, (sb, kvp) =>
-			                   {
-			                   	sb.Append(' ');
-			                   	sb.Append(kvp.Key);
-			                   	sb.Append(':');
-			                   	kvp.Value.Aggregate(sb, (sb2, str) => sb2.Append(str));
-			                   	return sb;
-			                   });
+							   {
+								sb.Append(' ');
+								sb.Append(kvp.Key);
+								sb.Append(':');
+								kvp.Value.Aggregate(sb, (sb2, str) => sb2.Append(str));
+								return sb;
+							   });
 
 			return new ExpandedQueryExpression(QueryExpression, newTree, key.ToString());
 		}

src/NHibernate/Linq/NhLinqExpression.cs

@@ -24,8 +24,8 @@ public class NhLinqExpression : IQueryExpression
 
 		public ExpressionToHqlTranslationResults ExpressionToHqlTranslationResults { get; private set; }
 
-		private readonly Expression _expression;
-		private readonly IDictionary<ConstantExpression, NamedParameter> _constantToParameterMap;
+		internal Expression _expression;
+		internal IDictionary<ConstantExpression, NamedParameter> _constantToParameterMap;
 
 		public NhLinqExpression(Expression expression, ISessionFactory sessionFactory)
 		{