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

MXS-1937 Enable server events on new master during switchover and failover

Browse Source 
Combined some of the shared code in enable/disable_events(). Also disables
events on a joining standalone server.
This commit is contained in:
Esa Korhonen
2018-09-03 16:29:43 +03:00
parent 7e6ce2d13f
commit f3fbb297a4
3 changed files with 126 additions and 46 deletions
Download Patch File Download Diff File Expand all files Collapse all files

2
server/modules/monitor/mariadbmon/cluster_manipulation.cc
View File

@ -311,7 +311,7 @@ uint32_t MariaDBMonitor::do_rejoin(const ServerArray& joinable_servers, json_t**
else
{
MXS_NOTICE("Directing standalone server '%s' to replicate from '%s'.", name, master_name);
op_success = joinable->join_cluster(change_cmd);
op_success = joinable->join_cluster(change_cmd, m_handle_event_scheduler);
}
}
else

159
server/modules/monitor/mariadbmon/mariadbserver.cc
View File

@ -651,7 +651,7 @@ bool MariaDBServer::redirect_one_slave(const string& change_cmd)
return success;
}
bool MariaDBServer::join_cluster(const string& change_cmd)
bool MariaDBServer::join_cluster(const string& change_cmd, bool disable_server_events)
{
/* Server does not have slave connections. This operation can fail, or the resulting
* replication may end up broken. */
@ -660,6 +660,13 @@ bool MariaDBServer::join_cluster(const string& change_cmd)
const char* query = "SET GLOBAL read_only=1;";
if (mxs_mysql_query(server_conn, query) == 0)
{
if (disable_server_events)
{
// This is unlikely to change anything, since a restarted server does not have event scheduler
// ON. If it were on and events were running while the server was standalone, its data would have
// diverged from the rest of the cluster.
disable_events();
}
query = "CHANGE MASTER TO ..."; // Don't show the real query as it contains a password.
if (mxs_mysql_query(server_conn, change_cmd.c_str()) == 0)
{
@ -1067,25 +1074,118 @@ const SlaveStatus* MariaDBServer::slave_connection_status(const MariaDBServer* t
bool MariaDBServer::disable_events()
{
string error_msg;
ManipulatorFunc disabler = [this](const string& db_name,
const string& event_name,
const string& event_definer,
const string& event_status) -> bool
{
bool rval = true;
string error_msg;
if (event_status == "ENABLED")
{
// Found an enabled event. Disable it. Must first switch to the correct database.
string use_db_query = string_printf("USE %s;", db_name.c_str());
if (execute_cmd(use_db_query, &error_msg))
{
// An ALTER EVENT by default changes the definer (owner) of the event to the monitor user.
// This causes problems if the monitor user does not have privileges to run
// the event contents. Prevent this by setting definer explicitly.
string alter_event_query = string_printf("ALTER DEFINER = %s EVENT %s DISABLE ON SLAVE;",
event_definer.c_str(), event_name.c_str());
if (execute_cmd(alter_event_query, &error_msg))
{
MXS_NOTICE("Event '%s' of database '%s' disabled on '%s'.",
event_name.c_str(), db_name.c_str(), name());
}
else
{
rval = false;
MXS_ERROR("Could not disable event '%s' of database '%s' on '%s': %s",
event_name.c_str(), db_name.c_str(), name() , error_msg.c_str());
}
}
else
{
rval = false;
MXS_ERROR("Could not switch to database '%s' on '%s': %s Event '%s' not disabled.",
db_name.c_str(), name(), event_name.c_str(), error_msg.c_str());
}
}
return rval;
};
// Events only need to be disabled if the event scheduler is ON. The comparison to 'localhost'
// excludes normal users with the username 'event_scheduler'.
warn_event_scheduler();
return events_foreach(disabler);
// TODO: For better error handling, this function should try to re-enable any disabled events if a later
// disable fails.
}
bool MariaDBServer::enable_events()
{
ManipulatorFunc enabler = [this](const string& db_name,
const string& event_name,
const string& event_definer,
const string& event_status) -> bool
{
bool rval = true;
string error_msg;
if (event_status == "SLAVESIDE_DISABLED")
{
// Found a disabled event. Enable it. Must first switch to the correct database.
string use_db_query = string_printf("USE %s;", db_name.c_str());
if (execute_cmd(use_db_query, &error_msg))
{
string alter_event_query = string_printf("ALTER DEFINER = %s EVENT %s ENABLE;",
event_definer.c_str(), event_name.c_str());
if (execute_cmd(alter_event_query, &error_msg))
{
MXS_NOTICE("Event '%s' of database '%s' enabled on '%s'.",
event_name.c_str(), db_name.c_str(), name());
}
else
{
rval = false;
MXS_ERROR("Could not enable event '%s' of database '%s' on '%s': %s",
event_name.c_str(), db_name.c_str(), name() , error_msg.c_str());
}
}
else
{
rval = false;
MXS_ERROR("Could not switch to database '%s' on '%s': %s Event '%s' not enabled.",
db_name.c_str(), name(), event_name.c_str(), error_msg.c_str());
}
}
return rval;
};
warn_event_scheduler();
return events_foreach(enabler);
}
void MariaDBServer::warn_event_scheduler()
{
string error_msg;
const string scheduler_query = "SELECT * FROM information_schema.PROCESSLIST "
"WHERE User = 'event_scheduler' AND Host = 'localhost';";
"WHERE User = 'event_scheduler' AND Command = 'Daemon';";
auto proc_list = execute_query(scheduler_query, &error_msg);
if (proc_list.get() == NULL)
{
MXS_ERROR("Could not query the event scheduler status of '%s': %s", name(), error_msg.c_str());
return false;
}
else if (proc_list->get_row_count() < 1)
else
{
// This is ok, though unexpected since user should have event handling activated for a reason.
MXS_NOTICE("Event scheduler is inactive on '%s', not disabling events.", name());
return true;
if (proc_list->get_row_count() < 1)
{
// This is ok, though unexpected since user should have event handling activated for a reason.
MXS_WARNING("Event scheduler is inactive on '%s'.", name());
}
}
}
bool MariaDBServer::events_foreach(ManipulatorFunc& func)
{
string error_msg;
// Get info about all scheduled events on the server.
auto event_info = execute_query("SELECT * FROM information_schema.EVENTS;", &error_msg);
if (event_info.get() == NULL)
@ -1096,52 +1196,23 @@ bool MariaDBServer::disable_events()
auto db_name_ind = event_info->get_col_index("EVENT_SCHEMA");
auto event_name_ind = event_info->get_col_index("EVENT_NAME");
auto event_definer_ind = event_info->get_col_index("DEFINER");
auto event_status_ind = event_info->get_col_index("STATUS");
mxb_assert(db_name_ind > 0 && event_name_ind > 0 && event_status_ind > 0);
mxb_assert(db_name_ind > 0 && event_name_ind > 0 && event_definer_ind > 0 && event_status_ind > 0);
int errors = 0;
while (event_info->next_row())
{
string db_name = event_info->get_string(db_name_ind);
string event_name = event_info->get_string(event_name_ind);
string event_definer = event_info->get_string(event_definer_ind);
string event_status = event_info->get_string(event_status_ind);
if (event_status == "ENABLED")
if (!func(db_name, event_name, event_definer, event_status))
{
// Found an enabled event. Disable it. Must first switch to the correct database.
string use_db_query = string_printf("USE %s;", db_name.c_str());
if (execute_cmd(use_db_query, &error_msg))
{
string alter_event_query = string_printf("ALTER EVENT %s DISABLE ON SLAVE;",
event_name.c_str());
if (execute_cmd(alter_event_query, &error_msg))
{
MXS_NOTICE("Event '%s' of database '%s' disabled on '%s'.",
event_name.c_str(), db_name.c_str(), name());
}
else
{
errors++;
MXS_ERROR("Could not disable event '%s' of database '%s' on '%s': %s",
event_name.c_str(), db_name.c_str(), name() , error_msg.c_str());
}
}
else
{
errors++;
MXS_ERROR("Could not switch to database '%s' on '%s': %s Event '%s' not disabled.",
db_name.c_str(), name(), event_name.c_str(), error_msg.c_str());
}
errors++;
}
}
return errors == 0;
// TODO: For better error handling, this function should try to re-enable any disabled events if a later
// disable fails.
}
bool MariaDBServer::enable_events()
{
// TODO:
return true;
}
string SlaveStatus::to_string() const

11
server/modules/monitor/mariadbmon/mariadbserver.hh
View File

@ -13,6 +13,7 @@
#pragma once
#include "mariadbmon_common.hh"
#include <chrono>
#include <functional>
#include <string>
#include <memory>
#include <maxscale/monitor.h>
@ -402,9 +403,10 @@ public:
* Joins this standalone server to the cluster.
*
* @param change_cmd Change master command
* @param disable_server_events Should events be disabled on the server
* @return True if commands were accepted by server
*/
bool join_cluster(const std::string& change_cmd);
bool join_cluster(const std::string& change_cmd, bool disable_server_events);
/**
* Check if the server can be demoted by switchover.
@ -473,9 +475,16 @@ public:
bool enable_events();
private:
typedef std::function<bool (const std::string& db_name,
const std::string& event_name,
const std::string& event_definer,
const std::string& event_status)> ManipulatorFunc;
bool update_slave_status(std::string* errmsg_out = NULL);
bool sstatus_array_topology_equal(const SlaveStatusArray& new_slave_status);
const SlaveStatus* sstatus_find_previous_row(const SlaveStatus& new_row, size_t guess);
void warn_event_scheduler();
bool events_foreach(ManipulatorFunc& func);
};
/**