Remove variable from changes list

in case If variable created and removed in same transaction level

Author: CherkashinSergey

expected/pg_variables_trans.out

@@ -1859,6 +1859,27 @@ SELECT pgv_insert('vars4', 'r1', row('str1', 'str1'));
 ERROR:  could not identify a hash function for type unknown
 SELECT pgv_select('vars4', 'r1', 0);
 ERROR:  unrecognized variable "r1"
+-- If variable created and removed in same transaction level,
+-- it should be totally removed and should not be present
+-- in changes list and cache.
+BEGIN;
+SELECT pgv_set('vars', 'any1', 'some value'::text, true);
+ pgv_set 
+---------
+ 
+(1 row)
+
+SAVEPOINT comm;
+SELECT pgv_remove('vars', 'any1');
+ pgv_remove 
+------------
+ 
+(1 row)
+
+RELEASE comm;
+SELECT pgv_get('vars', 'any1',NULL::text);
+ERROR:  unrecognized variable "any1"
+COMMIT;
 SELECT pgv_free();
  pgv_free 
 ----------

pg_variables.c

@@ -73,7 +73,7 @@ static bool isObjectChangedInUpperTrans(TransObject *object);
 
 static void addToChangesStack(TransObject *object, TransObjectType type);
 static void pushChangesStack(void);
-static void removeFromChangedVars(Package *package);
+static void removeFromChangesStack(TransObject *transObj, TransObjectType type);
 
 /* Constructors */
 static void makePackHTAB(Package *package, bool is_trans);
@@ -1658,16 +1658,16 @@ removeObject(TransObject *object, TransObjectType type)
 	bool		found;
 	HTAB	   *hash;
 
+	/*
+	 * Delete an object from the change history of the overlying
+	 * transaction level (head of 'changesStack' at this point).
+	 */
+	if (!dlist_is_empty(changesStack))
+			removeFromChangesStack(object, type);
 	if (type == TRANS_PACKAGE)
 	{
 		Package    *package = (Package *) object;
 
-		/*
-		 * Delete a variable from the change history of the overlying
-		 * transaction level (head of 'changesStack' at this point)
-		 */
-		if (!dlist_is_empty(changesStack))
-			removeFromChangedVars(package);
 		/* Regular variables had already removed */
 		MemoryContextDelete(package->hctxTransact);
 		hash = packagesHash;
@@ -1939,33 +1939,40 @@ addToChangesStack(TransObject *transObj, TransObjectType type)
  * Remove from the changes list a deleted package
  */
 static void
-removeFromChangedVars(Package *package)
+removeFromChangesStack(TransObject *object, TransObjectType type)
 {
 	dlist_mutable_iter var_miter,
-				pack_miter;
-	dlist_head *changedVarsList,
-			   *changedPacksList;
+					   pack_miter;
+	dlist_head		  *changesList;
+	ChangesStackNode  *csn = get_actual_changes_list();
 
-	/* First remove corresponding variables from changedVarsList */
-	changedVarsList = get_actual_changes_list()->changedVarsList;
-	dlist_foreach_modify(var_miter, changedVarsList)
+	/*
+	 * If we remove package, we should remove corresponding variables
+	 * from changedVarsList first.
+	 */
+	if (type == TRANS_PACKAGE)
 	{
-		ChangedObject *co_cur = dlist_container(ChangedObject, node,
-												var_miter.cur);
-		Variable   *var = (Variable *) co_cur->object;
+		changesList = csn->changedVarsList;
+		dlist_foreach_modify(var_miter, changesList)
+		{
+			ChangedObject *co_cur = dlist_container(ChangedObject, node,
+													var_miter.cur);
+			Variable   *var = (Variable *) co_cur->object;
 
-		if (var->package == package)
-			dlist_delete(&co_cur->node);
+			if (var->package == (Package *)object)
+				dlist_delete(&co_cur->node);
+		}
 	}
-	/* Now remove package itself from changedPacksList */
-	changedPacksList = get_actual_changes_list()->changedPacksList;
-	dlist_foreach_modify(pack_miter, changedPacksList)
+	/* Now remove object itself from changes list */
+	changesList = (type == TRANS_PACKAGE ? csn->changedPacksList :
+										   csn->changedVarsList);
+	dlist_foreach_modify(pack_miter, changesList)
 	{
 		ChangedObject *co_cur = dlist_container(ChangedObject, node,
 												pack_miter.cur);
-		Package    *pack = (Package *) co_cur->object;
+		TransObject *obj = co_cur->object;
 
-		if (pack == package)
+		if (obj == object)
 		{
 			dlist_delete(&co_cur->node);
 			break;

sql/pg_variables_trans.sql

@@ -471,4 +471,15 @@ SELECT pgv_insert('package', 'errs',row(1), true);
 SELECT pgv_insert('vars4', 'r1', row('str1', 'str1'));
 SELECT pgv_select('vars4', 'r1', 0);
 
+-- If variable created and removed in same transaction level,
+-- it should be totally removed and should not be present
+-- in changes list and cache.
+BEGIN;
+SELECT pgv_set('vars', 'any1', 'some value'::text, true);
+SAVEPOINT comm;
+SELECT pgv_remove('vars', 'any1');
+RELEASE comm;
+SELECT pgv_get('vars', 'any1',NULL::text);
+COMMIT;
+
 SELECT pgv_free();