Function lookupProcCallback

src/backend/catalog/pg_proc_callback.c:127–172

--------------------- * lookupProcCallback() - Find a specified callback for a specified function * * Parameters: * profnoid - oid of the function that has a callback * promethod - which callback to find * --------------------- */

 * ---------------------
 */
Oid  
lookupProcCallback(Oid profnoid, char promethod)
{
	Relation	rel;
	ScanKeyData skey[2];
	SysScanDesc scan;
	HeapTuple	tup;
	Oid         result;

	Assert(OidIsValid(profnoid));

	/* open pg_proc_callback */
	rel = heap_open(ProcCallbackRelationId, AccessShareLock);

	/* Lookup (profnoid, promethod) from index */
	/* (profnoid, promethod) is guaranteed unique by the index */
	ScanKeyInit(&skey[0],
				Anum_pg_proc_callback_profnoid,
				BTEqualStrategyNumber, F_OIDEQ,
				ObjectIdGetDatum(profnoid));
	ScanKeyInit(&skey[1],
				Anum_pg_proc_callback_promethod,
				BTEqualStrategyNumber, F_CHAREQ,
				CharGetDatum(promethod));
	scan = systable_beginscan(rel, ProcCallbackProfnoidPromethodIndexId, true,
							  NULL, 2, skey);
	tup = systable_getnext(scan);
	if (HeapTupleIsValid(tup))
	{
		Datum		d;
		bool		isnull;

		d = heap_getattr(tup, Anum_pg_proc_callback_procallback,
						 RelationGetDescr(rel), &isnull);
		Assert(!isnull);

		result = DatumGetObjectId(d);
	}
	else
		result = InvalidOid;

	systable_endscan(scan);
	heap_close(rel, AccessShareLock);

	return result;
}