hcq/MaxScale
hcq/MaxScale
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

Handle the situation where the previous master is reselected

Browse Source
This commit is contained in:
Esa Korhonen 2018-07-20 18:05:13 +03:00
parent f8898a1562
commit 27084f1368
1 changed files with 21 additions and 5 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

26
server/modules/monitor/mariadbmon/cluster_discovery.cc
View File

@ -810,7 +810,7 @@ bool MariaDBMonitor::master_is_valid(std::string* reason_out)
*reason_out = string_printf("it has been down over %d (failcount) monitor updates and failover "
"is not on", m_failcount);
}
// 3) The master was a non-replicating master (not in a cycle) but now has a slave connection.
// 4) The master was a non-replicating master (not in a cycle) but now has a slave connection.
else if (m_master_cycle_status.cycle_id == NodeData::CYCLE_NONE)
{
// The master should not have a master of its own.
@ -820,7 +820,7 @@ bool MariaDBMonitor::master_is_valid(std::string* reason_out)
*reason_out = "it has started replicating from another server in the cluster";
}
}
// 4) The master was part of a cycle but is no longer, or one of the servers in the cycle is
// 5) The master was part of a cycle but is no longer, or one of the servers in the cycle is
// replicating from a server outside the cycle.
else
{
@ -828,7 +828,7 @@ bool MariaDBMonitor::master_is_valid(std::string* reason_out)
* if the cycle is still the best multimaster group. */
int current_cycle_id = m_master->m_node.cycle;
// 4a) The master is no longer in a cycle.
// 5a) The master is no longer in a cycle.
if (current_cycle_id == NodeData::CYCLE_NONE)
{
rval = false;
@ -836,7 +836,7 @@ bool MariaDBMonitor::master_is_valid(std::string* reason_out)
string server_names_old = monitored_servers_to_string(old_members);
*reason_out = "it is no longer in the multimaster group (" + server_names_old + ")";
}
// 4b) The master is still in a cycle but the cycle has gained a master outside of the cycle.
// 5b) The master is still in a cycle but the cycle has gained a master outside of the cycle.
else
{
ServerArray& current_members = m_cycles[current_cycle_id];
@ -909,6 +909,8 @@ void MariaDBMonitor::update_topology()
// If the 'master_candidate' is a valid server but different from the current master,
// a change may be necessary. It will only happen if the current master is no longer usable.
bool have_better = (master_candidate && master_candidate != m_master);
bool current_still_best = (master_candidate && master_candidate == m_master);
// Check if current master is still valid.
string reason_not_valid;
bool current_is_ok = master_is_valid(&reason_not_valid);
@ -962,6 +964,20 @@ void MariaDBMonitor::update_topology()
// Change the master, even though this may break replication.
assign_new_master(master_candidate);
}
else if (current_still_best)
{
// Tried to find another master but the current one is still the best.
MXS_WARNING("Attempted to find a replacement for the current master server '%s' because %s, "
"but '%s' is still the best master server.",
m_master->name(), reason_not_valid.c_str(), m_master->name());
if (!topology_messages.empty())
{
MXS_WARNING("%s", topology_messages.c_str());
}
// The following updates some data on the master.
assign_new_master(master_candidate);
}
else
{
// No alternative master. Keep current status and print warnings.
@ -972,7 +988,7 @@ void MariaDBMonitor::update_topology()
{
ss_dassert(!reason_not_valid.empty());
MXS_WARNING("The current master server '%s' is no longer valid because %s, "
"but there is no better alternative to swap to.",
"but there is no valid alternative to swap to.",
m_master->name(), reason_not_valid.c_str());
}
else