Fix CORE-5252

Author: aafemt

src/jrd/exe.cpp

@@ -1016,7 +1016,14 @@ static void execute_looper(thread_db* tdbb,
 	if (!(request->req_flags & req_proc_fetch) && request->req_transaction)
 	{
 		if (transaction && !(transaction->tra_flags & TRA_system))
-			transaction->startSavepoint();
+		{
+			if (request->req_savepoints)
+			{
+				request->req_savepoints = request->req_savepoints->moveToStack(transaction->tra_save_point);
+			}
+			else
+				transaction->startSavepoint();
+		}
 	}
 
 	request->req_flags &= ~req_stall;
@@ -1033,8 +1040,12 @@ static void execute_looper(thread_db* tdbb,
 			transaction->tra_save_point->isSystem() &&
 			!transaction->tra_save_point->isChanging())
 		{
+			Savepoint* savepoint = transaction->tra_save_point;
 			// Forget about any undo for this verb
 			transaction->rollforwardSavepoint(tdbb);
+			// Preserve savepoint for reuse
+			fb_assert(savepoint == transaction->tra_save_free);
+			transaction->tra_save_free = savepoint->moveToStack(request->req_savepoints);
 		}
 	}
 }

src/jrd/req.h

@@ -246,6 +246,7 @@ class jrd_req : public pool_alloc<type_req>
 	ExtEngineManager::ResultSet*	req_ext_resultset;	// external result set
 	USHORT		req_label;				// label for leave
 	ULONG		req_flags;				// misc request flags
+	Savepoint*	req_savepoints;			// Looper savepoint list
 	Savepoint*	req_proc_sav_point;		// procedure savepoint list
 	Firebird::TimeStamp	req_timestamp;	// Start time of request
 

src/jrd/tra.cpp

@@ -143,7 +143,13 @@ void TRA_attach_request(Jrd::jrd_tra* transaction, Jrd::jrd_req* request)
 void TRA_detach_request(Jrd::jrd_req* request)
 {
 	if (!request->req_transaction)
+	{
+		fb_assert(!request->req_savepoints);
 		return;
+	}
+
+	// Release stored looper savepoints
+	Savepoint::destroy(request->req_savepoints);
 
 	// Remove request from the doubly linked list
 	if (request->req_tra_next)