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/*
** Zabbix
** Copyright (C) 2001-2020 Zabbix SIA
**
** This program is free software; you can redistribute it and/or modify
** it under the terms of the GNU General Public License as published by
** the Free Software Foundation; either version 2 of the License, or
** (at your option) any later version.
**
** This program is distributed in the hope that it will be useful,
** but WITHOUT ANY WARRANTY; without even the implied warranty of
** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
** GNU General Public License for more details.
**
** You should have received a copy of the GNU General Public License
** along with this program; if not, write to the Free Software
** Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
**/
#include "common.h"
#include "db.h"
/******************************************************************************
* *
* Function: zbx_db_lock_maintenanceids *
* *
* Purpose: lock maintenances in database *
* *
* Parameters: maintenanceids - [IN/OUT] a vector of unique maintenance ids *
* IN - the maintenances to lock *
* OUT - the locked maintenance ids (sorted) *
* *
* Return value: SUCCEED - at least one maintenance was locked *
* FAIL - no maintenances were locked (all target *
* maintenances were removed by user and *
* configuration cache was not yet updated) *
* *
* Comments: This function locks maintenances in database to avoid foreign *
* key errors when a maintenance is removed in the middle of *
* processing. *
* The output vector might contain less values than input vector if *
* a maintenance was removed before lock attempt. *
* *
******************************************************************************/
int zbx_db_lock_maintenanceids(zbx_vector_uint64_t *maintenanceids)
{
char *sql = NULL;
size_t sql_alloc = 0, sql_offset = 0;
zbx_uint64_t maintenanceid;
int i;
DB_RESULT result;
DB_ROW row;
zbx_vector_uint64_sort(maintenanceids, ZBX_DEFAULT_UINT64_COMPARE_FUNC);
zbx_strcpy_alloc(&sql, &sql_alloc, &sql_offset, "select maintenanceid from maintenances where");
DBadd_condition_alloc(&sql, &sql_alloc, &sql_offset, "maintenanceid", maintenanceids->values,
maintenanceids->values_num);
#if defined(HAVE_MYSQL)
zbx_strcpy_alloc(&sql, &sql_alloc, &sql_offset, " order by maintenanceid lock in share mode");
#elif defined(HAVE_ORACLE)
/* Row level shared locks are not supported in Oracle. Table lock in share mode leads to deadlock on */
/* event_suppress insertion due to locking that occurs in order to satisfy foreign key constraint. */
zbx_strcpy_alloc(&sql, &sql_alloc, &sql_offset, " order by maintenanceid" ZBX_FOR_UPDATE);
#else
/* For PostgreSQL table level locks are used because row level shared locks have reader preference which */
/* could lead to theoretical situation when server blocks out frontend from maintenances updates. */
DBexecute("lock table maintenances in share mode");
zbx_strcpy_alloc(&sql, &sql_alloc, &sql_offset, " order by maintenanceid");
#endif
result = DBselect("%s", sql);
zbx_free(sql);
for (i = 0; NULL != (row = DBfetch(result)); i++)
{
ZBX_STR2UINT64(maintenanceid, row[0]);
while (maintenanceid != maintenanceids->values[i])
zbx_vector_uint64_remove(maintenanceids, i);
}
DBfree_result(result);
while (i != maintenanceids->values_num)
zbx_vector_uint64_remove_noorder(maintenanceids, i);
return (0 != maintenanceids->values_num ? SUCCEED : FAIL);
}
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