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Only write to SERVER->status at the end of a monitoring loop

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This makes the code clearer and reduces race conditions, as the monitor
could be writing SERVER->status while a router is reading it. Also,
the time during which the SERVER struct is locked drops to a fraction.
This commit is contained in:
Esa Korhonen
2018-05-17 14:27:16 +03:00
parent 715b8a6f1d
commit 3ec449339f
6 changed files with 183 additions and 118 deletions
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30
server/modules/monitor/mariadbmon/cluster_manipulation.cc
View File

@ -1203,7 +1203,7 @@ bool MariaDBMonitor::switchover_check_current(const MXS_MONITORED_SERVER* sugges
mon_serv != NULL && extra_master == NULL;
mon_serv = mon_serv->next)
{
if (SERVER_IS_MASTER(mon_serv->server))
if (SRV_MASTER_STATUS(mon_serv->pending_status))
{
if (mon_serv == suggested_curr_master)
{
@ -1237,22 +1237,20 @@ bool MariaDBMonitor::switchover_check_current(const MXS_MONITORED_SERVER* sugges
*
* @return True, if suggested new master is a viable promotion candidate.
*/
bool MariaDBMonitor::switchover_check_new(const MXS_MONITORED_SERVER* monitored_server, json_t** error)
bool MariaDBMonitor::switchover_check_new(const MariaDBServer* new_master_cand, json_t** error)
{
SERVER* server = monitored_server->server;
const char* name = server->name;
bool is_master = SERVER_IS_MASTER(server);
bool is_slave = SERVER_IS_SLAVE(server);
bool is_master = new_master_cand->is_master();
bool is_slave = new_master_cand->is_slave();
if (is_master)
{
const char IS_MASTER[] = "Specified new master '%s' is already the current master.";
PRINT_MXS_JSON_ERROR(error, IS_MASTER, name);
PRINT_MXS_JSON_ERROR(error, IS_MASTER, new_master_cand->name());
}
else if (!is_slave)
{
const char NOT_SLAVE[] = "Specified new master '%s' is not a slave.";
PRINT_MXS_JSON_ERROR(error, NOT_SLAVE, name);
PRINT_MXS_JSON_ERROR(error, NOT_SLAVE, new_master_cand->name());
}
return !is_master && is_slave;
@ -1274,7 +1272,7 @@ bool MariaDBMonitor::failover_check(json_t** error_out)
for (auto iter = m_servers.begin(); iter != m_servers.end(); iter++)
{
MariaDBServer* server = *iter;
uint64_t status_bits = server->m_server_base->server->status;
uint64_t status_bits = server->m_server_base->pending_status;
uint64_t master_up = (SERVER_MASTER | SERVER_RUNNING);
if ((status_bits & master_up) == master_up)
{
@ -1509,13 +1507,17 @@ bool MariaDBMonitor::switchover_check(SERVER* new_master, SERVER* current_master
new_master_ok = false;
PRINT_MXS_JSON_ERROR(error_out, NO_SERVER, new_master->name, m_monitor_base->name);
}
else if (!switchover_check_new(mon_new_master, error_out))
{
new_master_ok = false;
}
else
{
*new_master_out = get_server_info(mon_new_master);
MariaDBServer* found_new_master = get_server_info(mon_new_master);
if (switchover_check_new(found_new_master, error_out))
{
*new_master_out = found_new_master;
}
else
{
new_master_ok = false;
}
}
}