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MXS-1937 Disable server events on master during switchover

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The feature is behind a config setting.
This commit is contained in:
Esa Korhonen
2018-08-31 18:14:50 +03:00
parent a0ea37b2c5
commit 7e6ce2d13f
5 changed files with 217 additions and 53 deletions
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142
server/modules/monitor/mariadbmon/mariadbserver.cc
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@ -86,7 +86,7 @@ std::unique_ptr<QueryResult> MariaDBServer::execute_query(const string& query, s
{
auto conn = m_server_base->con;
std::unique_ptr<QueryResult> rval;
MYSQL_RES *result = NULL;
MYSQL_RES* result = NULL;
if (mxs_mysql_query(conn, query.c_str()) == 0 && (result = mysql_store_result(conn)) != NULL)
{
rval = std::unique_ptr<QueryResult>(new QueryResult(result));
@ -98,6 +98,32 @@ std::unique_ptr<QueryResult> MariaDBServer::execute_query(const string& query, s
return rval;
}
bool MariaDBServer::execute_cmd(const string& cmd, std::string* errmsg_out)
{
bool rval = false;
auto conn = m_server_base->con;
if (mxs_mysql_query(conn, cmd.c_str()) == 0)
{
MYSQL_RES* result = mysql_store_result(conn);
if (result == NULL)
{
rval = true;
}
else if (errmsg_out)
{
int cols = mysql_num_fields(result);
int rows = mysql_num_rows(result);
*errmsg_out = string_printf("Query '%s' returned %d columns and %d rows of data when none "
"was expected.", cmd.c_str(), cols, rows);
}
}
else if (errmsg_out)
{
*errmsg_out = string_printf("Query '%s' failed: '%s'.", cmd.c_str(), mysql_error(conn));
}
return rval;
}
bool MariaDBServer::do_show_slave_status(string* errmsg_out)
{
unsigned int columns = 0;
@ -125,10 +151,10 @@ bool MariaDBServer::do_show_slave_status(string* errmsg_out)
{
return false;
}
else if(result->get_column_count() < columns)
else if (result->get_col_count() < columns)
{
MXS_ERROR("'%s' returned less than the expected amount of columns. Expected %u columns, "
"got %" PRId64 ".", query.c_str(), columns, result->get_column_count());
"got %" PRId64 ".", query.c_str(), columns, result->get_col_count());
return false;
}
@ -1039,6 +1065,85 @@ const SlaveStatus* MariaDBServer::slave_connection_status(const MariaDBServer* t
return rval;
}
bool MariaDBServer::disable_events()
{
string error_msg;
// Events only need to be disabled if the event scheduler is ON. The comparison to 'localhost'
// excludes normal users with the username 'event_scheduler'.
const string scheduler_query = "SELECT * FROM information_schema.PROCESSLIST "
"WHERE User = 'event_scheduler' AND Host = 'localhost';";
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)
{
// 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;
}
// 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)
{
MXS_ERROR("Could not query event status of '%s': %s", name(), error_msg.c_str());
return false;
}
auto db_name_ind = event_info->get_col_index("EVENT_SCHEMA");
auto event_name_ind = event_info->get_col_index("EVENT_NAME");
auto event_status_ind = event_info->get_col_index("STATUS");
mxb_assert(db_name_ind > 0 && event_name_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_status = event_info->get_string(event_status_ind);
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))
{
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());
}
}
}
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
{
// Print all of this on the same line to make things compact. Are the widths reasonable? The format is
@ -1115,15 +1220,12 @@ string SlaveStatus::slave_io_to_string(SlaveStatus::slave_io_running_t slave_io)
QueryResult::QueryResult(MYSQL_RES* resultset)
: m_resultset(resultset)
, m_columns(-1)
, m_rowdata(NULL)
, m_current_row(-1)
{
if (m_resultset)
{
m_columns = mysql_num_fields(m_resultset);
auto columns = mysql_num_fields(m_resultset);
MYSQL_FIELD* field_info = mysql_fetch_fields(m_resultset);
for (int64_t column_index = 0; column_index < m_columns; column_index++)
for (int64_t column_index = 0; column_index < columns; column_index++)
{
string key(field_info[column_index].name);
// TODO: Think of a way to handle duplicate names nicely. Currently this should only be used
@ -1144,23 +1246,29 @@ QueryResult::~QueryResult()
bool QueryResult::next_row()
{
mxb_assert(m_resultset);
m_rowdata = mysql_fetch_row(m_resultset);
if (m_rowdata != NULL)
if (m_rowdata)
{
m_current_row++;
m_current_row_ind++;
return true;
}
return false;
}
int64_t QueryResult::get_row_index() const
int64_t QueryResult::get_current_row_index() const
{
return m_current_row;
return m_current_row_ind;
}
int64_t QueryResult::get_column_count() const
int64_t QueryResult::get_col_count() const
{
return m_columns;
return m_resultset ? mysql_num_fields(m_resultset): -1;
}
int64_t QueryResult::get_row_count() const
{
return m_resultset ? mysql_num_rows(m_resultset) : -1;
}
int64_t QueryResult::get_col_index(const string& col_name) const
@ -1171,14 +1279,14 @@ int64_t QueryResult::get_col_index(const string& col_name) const
string QueryResult::get_string(int64_t column_ind) const
{
mxb_assert(column_ind < m_columns && column_ind >= 0);
mxb_assert(column_ind < get_col_count() && column_ind >= 0);
char* data = m_rowdata[column_ind];
return data ? data : "";
}
int64_t QueryResult::get_uint(int64_t column_ind) const
{
mxb_assert(column_ind < m_columns && column_ind >= 0);
mxb_assert(column_ind < get_col_count() && column_ind >= 0);
char* data = m_rowdata[column_ind];
int64_t rval = -1;
if (data && *data)
@ -1196,7 +1304,7 @@ int64_t QueryResult::get_uint(int64_t column_ind) const
bool QueryResult::get_bool(int64_t column_ind) const
{
mxb_assert(column_ind < m_columns && column_ind >= 0);
mxb_assert(column_ind < get_col_count() && column_ind >= 0);
char* data = m_rowdata[column_ind];
return data ? (strcmp(data,"Y") == 0 || strcmp(data, "1") == 0) : false;
}