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MXS-1883 Remove locking during monitor loop

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Since the admin cannot modify server states any more, the locks are not
required.
This commit is contained in:
Esa Korhonen
2018-05-28 17:11:52 +03:00
parent 37841183b3
commit 7cd19a12a2
5 changed files with 64 additions and 139 deletions
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85
server/core/monitor.cc
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@ -136,7 +136,7 @@ MXS_MONITOR* monitor_create(const char *name, const char *module)
mon->journal_max_age = DEFAULT_JOURNAL_MAX_AGE;
mon->script_timeout = DEFAULT_SCRIPT_TIMEOUT;
mon->parameters = NULL;
mon->server_pending_changes = false;
mon->check_maintenance_flag = MAINTENANCE_FLAG_NOCHECK;
memset(mon->journal_hash, 0, sizeof(mon->journal_hash));
mon->disk_space_threshold = NULL;
mon->disk_space_check_interval = 0;
@ -1712,73 +1712,35 @@ void mon_report_query_error(MXS_MONITORED_SERVER* db)
db->server->port, mysql_error(db->con));
}
/**
* Acquire locks on all servers monitored by this monitor. There should
* only be max 1 monitor per server.
* @param monitor The target monitor
*/
void lock_monitor_servers(MXS_MONITOR *monitor)
{
MXS_MONITORED_SERVER *ptr = monitor->monitored_servers;
while (ptr)
{
spinlock_acquire(&ptr->server->lock);
ptr = ptr->next;
}
}
/**
* Release locks on all servers monitored by this monitor. There should
* only be max 1 monitor per server.
* @param monitor The target monitor
*/
void release_monitor_servers(MXS_MONITOR *monitor)
{
MXS_MONITORED_SERVER *ptr = monitor->monitored_servers;
while (ptr)
{
spinlock_release(&ptr->server->lock);
ptr = ptr->next;
}
}
/**
* Check if admin is requesting setting or clearing maintenance status on the server and act accordingly.
* Should be called at the beginning of a monitor loop.
*
* @param monitor The target monitor
*/
void servers_status_pending_to_current(MXS_MONITOR *monitor)
void monitor_check_maintenance_requests(MXS_MONITOR *monitor)
{
MXS_MONITORED_SERVER *ptr = monitor->monitored_servers;
while (ptr)
/* In theory, the admin may be modifying the server maintenance status during this function. The overall
* maintenance flag should be read-written atomically to prevent missing a value. */
int flags_changed = atomic_exchange_int(&monitor->check_maintenance_flag, MAINTENANCE_FLAG_NOCHECK);
if (flags_changed != MAINTENANCE_FLAG_NOCHECK)
{
// The only server status bit the admin may change is the [Maintenance] bit.
int admin_msg = atomic_exchange_int(&ptr->server->maint_request, MAINTENANCE_NO_CHANGE);
if (admin_msg == MAINTENANCE_ON)
MXS_MONITORED_SERVER *ptr = monitor->monitored_servers;
while (ptr)
{
// TODO: Change to writing MONITORED_SERVER->pending status instead once cleanup done.
server_set_status_nolock(ptr->server, SERVER_MAINT);
// The only server status bit the admin may change is the [Maintenance] bit.
int admin_msg = atomic_exchange_int(&ptr->server->maint_request, MAINTENANCE_NO_CHANGE);
if (admin_msg == MAINTENANCE_ON)
{
// TODO: Change to writing MONITORED_SERVER->pending status instead once cleanup done.
server_set_status_nolock(ptr->server, SERVER_MAINT);
}
else if (admin_msg == MAINTENANCE_OFF)
{
server_clear_status_nolock(ptr->server, SERVER_MAINT);
}
ptr = ptr->next;
}
else if (admin_msg == MAINTENANCE_OFF)
{
server_clear_status_nolock(ptr->server, SERVER_MAINT);
}
ptr = ptr->next;
}
monitor->server_pending_changes = false;
}
/**
* Sets the pending status of all servers monitored by this monitor to
* the current status. This should only be called at the end of
* a monitor loop, before the servers are released.
* @param monitor The target monitor
*/
void servers_status_current_to_pending(MXS_MONITOR *monitor)
{
MXS_MONITORED_SERVER *ptr = monitor->monitored_servers;
while (ptr)
{
ptr = ptr->next;
}
}
@ -2778,8 +2740,7 @@ void MonitorInstance::main()
while (!m_shutdown)
{
lock_monitor_servers(m_monitor);
servers_status_pending_to_current(m_monitor);
monitor_check_maintenance_requests(m_monitor);
tick();
@ -2790,15 +2751,13 @@ void MonitorInstance::main()
mon_process_state_changes(m_monitor, m_script.empty() ? NULL : m_script.c_str(), m_events);
mon_hangup_failed_servers(m_monitor);
servers_status_current_to_pending(m_monitor);
store_server_journal(m_monitor, m_master);
release_monitor_servers(m_monitor);
/** Sleep until the next monitoring interval */
unsigned int ms = 0;
while (ms < m_monitor->interval && !m_shutdown)
{
if (m_monitor->server_pending_changes)
if (atomic_load_int(&m_monitor->check_maintenance_flag) != MAINTENANCE_FLAG_NOCHECK)
{
// Admin has changed something, skip sleep
break;