Fix assigning subtransaction logical xids

cloudnepal · Nov 29, 2024 · b3555db · b3555db
1 parent 18c749d
commit b3555db
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Showing 4 changed files with 52 additions and 2 deletions.
diff --git a/expected/subtransactions.out b/expected/subtransactions.out
@@ -770,6 +770,29 @@ FETCH FROM abc;
 -------
 (0 rows)
 
+ROLLBACK;
+-- Check for logical xid overflow
+BEGIN;
+DO $$
+BEGIN
+    FOR i IN 1..1000 LOOP
+        BEGIN
+	    RAISE reading_sql_data_not_permitted;
+	EXCEPTION WHEN reading_sql_data_not_permitted THEN END;
+    END LOOP;
+END;$$;
+ROLLBACK;
+BEGIN;
+DO $$
+BEGIN
+    FOR i IN 1..100000 LOOP
+        BEGIN
+	    RAISE reading_sql_data_not_permitted;
+	EXCEPTION WHEN reading_sql_data_not_permitted THEN END;
+    END LOOP;
+END;$$;
+ERROR:  not enough logical xids
+CONTEXT:  PL/pgSQL function inline_code_block line 4 during statement block entry
 ROLLBACK;
 DROP EXTENSION orioledb CASCADE;
 NOTICE:  drop cascades to table o_subtrans

diff --git a/sql/subtransactions.sql b/sql/subtransactions.sql
@@ -413,6 +413,28 @@ ROLLBACK TO s1;
 FETCH FROM abc;
 ROLLBACK;
 
+-- Check for logical xid overflow
+BEGIN;
+DO $$
+BEGIN
+    FOR i IN 1..1000 LOOP
+        BEGIN
+	    RAISE reading_sql_data_not_permitted;
+	EXCEPTION WHEN reading_sql_data_not_permitted THEN END;
+    END LOOP;
+END;$$;
+ROLLBACK;
+BEGIN;
+DO $$
+BEGIN
+    FOR i IN 1..100000 LOOP
+        BEGIN
+	    RAISE reading_sql_data_not_permitted;
+	EXCEPTION WHEN reading_sql_data_not_permitted THEN END;
+    END LOOP;
+END;$$;
+ROLLBACK;
+
 DROP EXTENSION orioledb CASCADE;
 DROP SCHEMA subtransactions CASCADE;
 RESET search_path;
diff --git a/src/transam/oxid.c b/src/transam/oxid.c
@@ -260,6 +260,7 @@ acquire_logical_xid(void)
 				if (nloops > 16)
 					elog(ERROR, "not enough logical xids");
 			}
+			continue;
 		}
 		bitnum = pg_ceil_log2_32(bit);
 		Assert(bit == (1 << bitnum));
@@ -312,6 +313,10 @@ release_logical_xid(TransactionId xid)
 void
 assign_subtransaction_logical_xid(void)
 {
+	TransactionId nextLogicalXid;
+
+	nextLogicalXid = acquire_logical_xid();
+
 	if (TransactionIdIsValid(logicalXid))
 	{
 		MemoryContext mcxt = MemoryContextSwitchTo(TopMemoryContext);
@@ -324,7 +329,7 @@ assign_subtransaction_logical_xid(void)
 		MemoryContextSwitchTo(mcxt);
 	}
 
-	logicalXid = acquire_logical_xid();
+	logicalXid = nextLogicalXid;
 }
 
 /*

diff --git a/src/transam/undo.c b/src/transam/undo.c
@@ -1565,9 +1565,9 @@ undo_subxact_callback(SubXactEvent event, SubTransactionId mySubid,
 	{
 		case SUBXACT_EVENT_START_SUB:
 			(void) get_current_oxid();
+			add_subxact_undo_item(parentSubid);
 			prentLogicalXid = get_current_logical_xid();
 			assign_subtransaction_logical_xid();
-			add_subxact_undo_item(parentSubid);
 			add_savepoint_wal_record(parentSubid, prentLogicalXid);
 			break;
 		case SUBXACT_EVENT_COMMIT_SUB: