Disable caching for DML queries

Author: bahusoid

src/NHibernate/Engine/Query/QueryPlanCache.cs

@@ -62,7 +62,7 @@ public IQueryExpressionPlan GetHQLQueryPlan(IQueryExpression queryExpression, bo
 				}
 				plan = new QueryExpressionPlan(queryExpression, shallow, enabledFilters, factory);
 				// 6.0 TODO: add "CanCachePlan { get; }" to IQueryExpression interface
-				if (!(queryExpression is NhLinqExpression linqExpression) || linqExpression.CanCachePlan)
+				if (!(queryExpression is ICacheableQueryExpression linqExpression) || linqExpression.CanCachePlan)
 					planCache.Put(key, plan);
 				else
 					log.Debug("Query plan not cacheable");
@@ -117,7 +117,7 @@ public IQueryExpressionPlan GetFilterQueryPlan(IQueryExpression queryExpression,
 				log.Debug("unable to locate collection-filter query plan in cache; generating ({0} : {1})", collectionRole, queryExpression.Key);
 				plan = new FilterQueryPlan(queryExpression, collectionRole, shallow, enabledFilters, factory);
 				// 6.0 TODO: add "CanCachePlan { get; }" to IQueryExpression interface
-				if (!(queryExpression is NhLinqExpression linqExpression) || linqExpression.CanCachePlan)
+				if (!(queryExpression is ICacheableQueryExpression linqExpression) || linqExpression.CanCachePlan)
 					planCache.Put(key, plan);
 				else
 					log.Debug("Query plan not cacheable");

src/NHibernate/IQueryExpression.cs

@@ -5,11 +5,17 @@
 
 namespace NHibernate
 {
+	//TODO 6.0: Merge into IQueryExpression
+	internal interface ICacheableQueryExpression
+	{
+		bool CanCachePlan { get; }
+	}
+
 	public interface IQueryExpression
 	{
 		IASTNode Translate(ISessionFactoryImplementor sessionFactory, bool filter);
 		string Key { get; }
 		System.Type Type { get; }
 		IList<NamedParameterDescriptor> ParameterDescriptors { get; }
 	}
-}
+}

src/NHibernate/Impl/ExpressionQueryImpl.cs

@@ -150,7 +150,7 @@ public override object[] ValueArray()
 		}
 	}
 
-	internal class ExpandedQueryExpression : IQueryExpression
+	internal class ExpandedQueryExpression : IQueryExpression, ICacheableQueryExpression
 	{
 		private readonly IASTNode _tree;
 
@@ -160,6 +160,7 @@ public ExpandedQueryExpression(IQueryExpression queryExpression, IASTNode tree,
 			Key = key;
 			Type = queryExpression.Type;
 			ParameterDescriptors = queryExpression.ParameterDescriptors;
+			CanCachePlan = (queryExpression as ICacheableQueryExpression)?.CanCachePlan ?? true;
 		}
 
 		#region IQueryExpression Members
@@ -176,6 +177,8 @@ public IASTNode Translate(ISessionFactoryImplementor sessionFactory, bool filter
 		public IList<NamedParameterDescriptor> ParameterDescriptors { get; private set; }
 
 		#endregion
+
+		public bool CanCachePlan { get; }
 	}
 
 	internal class ParameterExpander

src/NHibernate/Linq/NhLinqDmlExpression.cs

@@ -17,6 +17,10 @@ public NhLinqDmlExpression(QueryMode queryMode, Expression expression, ISessionF
 		{
 			Key = $"{queryMode.ToString().ToUpperInvariant()} {Key}";
 			QueryMode = queryMode;
+
+			//For DML queries parameters check doesn't really work (queries are either not cached or cached incorrectly - see GH-2222 and GH-2298)
+			//So for now disable caching for DML queries
+			CanCachePlan = false;
 		}
 	}
 }

src/NHibernate/Linq/NhLinqExpression.cs

@@ -11,11 +11,11 @@
 
 namespace NHibernate.Linq
 {
-	public class NhLinqExpression : IQueryExpression
+	public class NhLinqExpression : IQueryExpression, ICacheableQueryExpression
 	{
 		public string Key { get; protected set; }
 
-		public bool CanCachePlan { get; private set; } = true;
+		public bool CanCachePlan { get; protected set; } = true;
 
 		public System.Type Type { get; private set; }