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Refactor preparations to failover

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The two operations are quite similar so the code should look
similar as well and use shared functions.
This commit is contained in:
Esa Korhonen
2018-08-03 18:43:43 +03:00
parent ac57b4f71f
commit 17c84a22c7
6 changed files with 299 additions and 297 deletions
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96
server/modules/monitor/mariadbmon/mariadbserver.cc
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@ -960,13 +960,7 @@ bool MariaDBServer::sstatus_arrays_topology_equal(const SlaveStatusArray& lhs, c
return rval;
}
/**
* Check if the server can be demoted.
*
* @param reason_out Output for the reason server cannot be demoted
* @return True, if suggested new master is a viable demotion candidate
*/
bool MariaDBServer::can_be_demoted(string* reason_out)
bool MariaDBServer::can_be_demoted_switchover(string* reason_out)
{
bool demotable = false;
string reason;
@ -1001,32 +995,63 @@ bool MariaDBServer::can_be_demoted(string* reason_out)
return demotable;
}
/**
* Check if the server can be promoted.
*
* @param demotion_target The server this should be promoted to
* @param reason_out Output for the reason server cannot be promoted
* @return True, if suggested new master is a viable promotion candidate
*/
bool MariaDBServer::can_be_promoted(const MariaDBServer* demotion_target, std::string* reason_out)
bool MariaDBServer::can_be_demoted_failover(string* reason_out)
{
bool demotable = false;
string reason;
if (is_master())
{
reason = "it is a running master.";
}
else if (is_running())
{
reason = "it is running.";
}
else if (m_gtid_binlog_pos.empty())
{
reason = "it does not have a 'gtid_binlog_pos'.";
}
else
{
demotable = true;
}
if (!demotable && reason_out)
{
*reason_out = reason;
}
return demotable;
}
bool MariaDBServer::can_be_promoted(ClusterOperation op,
const MariaDBServer* demotion_target,
std::string* reason_out)
{
bool promotable = false;
string reason;
string query_error;
auto sstatus = slave_connection_status(demotion_target);
if (is_master())
{
reason = "it is already the master.";
}
// TODO: Check that the correct slave connection is working properly in case of switchover.
// For failover the connection may be in CONNECTING-stage.
else if (!is_replicating_from(demotion_target))
else if (sstatus == NULL)
{
reason = string_printf("it is not replicating from '%s'.", demotion_target->name());
}
else if (sstatus->gtid_io_pos.empty())
{
reason = string_printf("its slave connection to '%s' is not using gtid.", demotion_target->name());
}
else if (op == ClusterOperation::SWITCHOVER && sstatus->slave_io_running != SlaveStatus::SLAVE_IO_YES)
{
reason = string_printf("its slave connection to '%s' is broken.", demotion_target->name());
}
else if (!update_replication_settings(&query_error))
{
string_printf("it could not be queried: '%s'.", query_error.c_str());
reason = string_printf("it could not be queried: '%s'.", query_error.c_str());
}
else if (!binlog_on())
{
@ -1044,10 +1069,37 @@ bool MariaDBServer::can_be_promoted(const MariaDBServer* demotion_target, std::s
return promotable;
}
bool MariaDBServer::is_replicating_from(const MariaDBServer* target)
const SlaveStatus* MariaDBServer::slave_connection_status(const MariaDBServer* target)
{
// Not properly implemented yet, TODO
return is_slave();
// The slave node may have several slave connections, need to find the one that is
// connected to the parent. This section is quite similar to the one in
// 'build_replication_graph', although here we require that the sql thread is running.
auto master_server_id = target->m_server_id;
SlaveStatus* rval = NULL;
for (SlaveStatus& ss : m_slave_status)
{
auto master_id = ss.master_server_id;
auto io_running = ss.slave_io_running;
// Should this check 'Master_Host' and 'Master_Port' instead of server id:s?
if (master_id > 0 && master_id == master_server_id && ss.slave_sql_running)
{
if (io_running == SlaveStatus::SLAVE_IO_YES)
{
rval = &ss;
break;
}
else if (io_running == SlaveStatus::SLAVE_IO_CONNECTING && had_status(SERVER_WAS_SLAVE))
{
// Stale connection. TODO: The SERVER_WAS_SLAVE check above is not enough in
// several situations. The previously observed live slave connections
// need to be saved distinctly to avoid a SERVER_WAS_SLAVE bit from one
// connection from affecting another.
rval = &ss;
break;
}
}
}
return rval;
}
string SlaveStatus::to_string() const