PGPRO-2601: Remove LastHSeqStatus and add test a cursor with the hash table

Author: Arthur Zakirov

expected/pg_variables.out

@@ -730,7 +730,8 @@ SELECT pgv_select('vars3', 'r1', 1);
 
 (1 row)
 
-SELECT pgv_select('vars3', 'r1') LIMIT 2;
+SELECT pgv_select('vars3', 'r1') LIMIT 2; -- warning
+WARNING:  leaked hash_seq_search scan for hash table 0x561738129110
  pgv_select 
 ------------
  (,strNULL)
@@ -743,8 +744,34 @@ SELECT pgv_select('vars3', 'r1') LIMIT 2 OFFSET 2;
  (0,str00)
 (1 row)
 
+-- PGPRO-2601 - Test a cursor with the hash table
+BEGIN;
+DECLARE r1_cur CURSOR FOR SELECT pgv_select('vars3', 'r1');
+FETCH 1 in r1_cur;
+ pgv_select 
+------------
+ (,strNULL)
+(1 row)
+
+SELECT pgv_select('vars3', 'r1');
+ pgv_select 
+------------
+ (,strNULL)
+ (2,)
+ (0,str00)
+(3 rows)
+
+FETCH 1 in r1_cur;
+ pgv_select 
+------------
+ (2,)
+(1 row)
+
+CLOSE r1_cur;
+COMMIT; -- warning
+WARNING:  leaked hash_seq_search scan for hash table 0x561738129110
 -- Clean memory after unsuccessful creation of a variable
-SELECT pgv_insert('vars4', 'r1', row('str1', 'str1'));
+SELECT pgv_insert('vars4', 'r1', row('str1', 'str1')); -- fail
 ERROR:  could not identify a hash function for type unknown
 SELECT package FROM pgv_stats() WHERE package = 'vars4';
  package 

pg_variables.c

@@ -108,14 +108,6 @@ static Variable *LastVariable = NULL;
 /* Recent row type id */
 static Oid LastTypeId = InvalidOid;
 
-/*
- * Cache sequentially search through hash table status.  It is necessary for
- * clean up if hash_seq_term() wasn't called or if we didn't scan the whole
- * table. In this case we need to manually call hash_seq_term() within
- * variable_ExecutorEnd().
- */
-static HASH_SEQ_STATUS *LastHSeqStatus = NULL;
-
 /* Saved hook values for recall */
 static ExecutorEnd_hook_type prev_ExecutorEnd = NULL;
 
@@ -615,8 +607,6 @@ variable_select(PG_FUNCTION_ARGS)
 		MemoryContextSwitchTo(oldcontext);
 		PG_FREE_IF_COPY(package_name, 0);
 		PG_FREE_IF_COPY(var_name, 1);
-
-		LastHSeqStatus = rstat;
 	}
 
 	funcctx = SRF_PERCALL_SETUP();
@@ -633,7 +623,6 @@ variable_select(PG_FUNCTION_ARGS)
 	}
 	else
 	{
-		LastHSeqStatus = NULL;
 		pfree(rstat);
 		SRF_RETURN_DONE(funcctx);
 	}
@@ -1212,8 +1201,6 @@ get_packages_stats(PG_FUNCTION_ARGS)
 			hash_seq_init(pstat, packagesHash);
 
 			funcctx->user_fctx = pstat;
-
-			LastHSeqStatus = pstat;
 		}
 		else
 			funcctx->user_fctx = NULL;
@@ -1260,7 +1247,6 @@ get_packages_stats(PG_FUNCTION_ARGS)
 	}
 	else
 	{
-		LastHSeqStatus = NULL;
 		pfree(pstat);
 		SRF_RETURN_DONE(funcctx);
 	}
@@ -2126,7 +2112,6 @@ pgvSubTransCallback(SubXactEvent event, SubTransactionId mySubid,
 				break;
 		}
 	}
-	LastHSeqStatus = NULL;
 }
 
 /*
@@ -2155,7 +2140,6 @@ pgvTransCallback(XactEvent event, void *arg)
 				break;
 		}
 	}
-	LastHSeqStatus = NULL;
 }
 
 /*
@@ -2164,11 +2148,6 @@ pgvTransCallback(XactEvent event, void *arg)
 static void
 variable_ExecutorEnd(QueryDesc *queryDesc)
 {
-	if (LastHSeqStatus)
-	{
-		hash_seq_term(LastHSeqStatus);
-		LastHSeqStatus = NULL;
-	}
 	if (prev_ExecutorEnd)
 		prev_ExecutorEnd(queryDesc);
 	else

sql/pg_variables.sql

@@ -207,11 +207,20 @@ $$BEGIN
 END$$;
 -- Check that the hash table was cleaned up after rollback
 SELECT pgv_select('vars3', 'r1', 1);
-SELECT pgv_select('vars3', 'r1') LIMIT 2;
+SELECT pgv_select('vars3', 'r1') LIMIT 2; -- warning
 SELECT pgv_select('vars3', 'r1') LIMIT 2 OFFSET 2;
 
+-- PGPRO-2601 - Test a cursor with the hash table
+BEGIN;
+DECLARE r1_cur CURSOR FOR SELECT pgv_select('vars3', 'r1');
+FETCH 1 in r1_cur;
+SELECT pgv_select('vars3', 'r1');
+FETCH 1 in r1_cur;
+CLOSE r1_cur;
+COMMIT; -- warning
+
 -- Clean memory after unsuccessful creation of a variable
-SELECT pgv_insert('vars4', 'r1', row('str1', 'str1'));
+SELECT pgv_insert('vars4', 'r1', row('str1', 'str1')); -- fail
 SELECT package FROM pgv_stats() WHERE package = 'vars4';
 
 -- Remove package if it is empty