344 lines
11 KiB
C++
344 lines
11 KiB
C++
#pragma once
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/*
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* Copyright (c) 2016 MariaDB Corporation Ab
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*
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* Use of this software is governed by the Business Source License included
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* in the LICENSE.TXT file and at www.mariadb.com/bsl11.
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*
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* Change Date: 2020-01-01
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*
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* On the date above, in accordance with the Business Source License, use
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* of this software will be governed by version 2 or later of the General
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* Public License.
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*/
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#include <maxscale/cppdefs.hh>
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#include <maxscale/monitor.h>
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#include <maxscale/semaphore.hh>
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#include <maxscale/thread.h>
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namespace maxscale
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{
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class MonitorInstance : public MXS_MONITOR_INSTANCE
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{
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public:
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MonitorInstance(const MonitorInstance&) = delete;
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MonitorInstance& operator = (const MonitorInstance&) = delete;
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virtual ~MonitorInstance();
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/**
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* @brief Current state of the monitor.
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*
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* Note that in principle the state of the monitor may already have
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* changed when the current state is returned. The state can be fully
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* trusted only if it is asked in a context when it is known that nobody
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* else can affect it.
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*
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* @return @c MXS_MONITOR_RUNNING if the monitor is running,
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* @c MXS_MONITOR_STOPPING if the monitor is stopping, and
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* @c MXS_MONITOR_STOPPED of the monitor is stopped.
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*/
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int32_t state() const;
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/**
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* @brief Find out whether the monitor is running.
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*
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* @return True, if the monitor is running, false otherwise.
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*
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* @see state().
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*/
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bool is_running() const
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{
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return state() == MXS_MONITOR_RUNNING;
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}
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/**
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* @brief Starts the monitor.
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*
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* - Calls @c has_sufficient_permissions(), if it has not been done earlier.
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* - Updates the 'script' and 'events' configuration paramameters.
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* - Calls @c configure().
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* - Starts the monitor thread.
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*
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* - Once the monitor thread starts, it will
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* - Load the server journal and update @c m_master.
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* - Call @c pre_loop().
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* - Enter a loop where it, until told to shut down, will
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* - Check whether there are maintenance requests.
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* - Call @c tick().
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* - Call @c process_state_changes()
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* - Hang up failed servers.
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* - Store the server journal (@c m_master assumed to reflect the current situation).
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* - Sleep until time for next @c tick().
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* - Call @c post_loop().
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*
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* @param param The parameters of the monitor.
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*
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* @return True, if the monitor started, false otherwise.
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*/
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bool start(const MXS_CONFIG_PARAMETER* params);
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/**
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* @brief Stops the monitor.
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*
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* When the function returns, the monitor has stopped.
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*/
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void stop();
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/**
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* @brief Write diagnostics
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*
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* The implementation should write diagnostic information to the
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* provided dcb. The default implementation writes nothing.
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*
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* @param dcb The dcb to write to.
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*/
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virtual void diagnostics(DCB* dcb) const;
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/**
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* @brief Obtain diagnostics
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*
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* The implementation should create a JSON object and fill it with diagnostics
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* information. The default implementation returns an object that is populated
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* with the keys 'script' and 'events' if they have been set, otherwise the
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* object is empty.
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*
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* @return An object, if there is information to return, NULL otherwise.
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*/
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virtual json_t* diagnostics_json() const;
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protected:
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MonitorInstance(MXS_MONITOR* pMonitor);
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const std::string& script() const { return m_script; }
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uint64_t events() const { return m_events; }
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/**
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* @brief Should the monitor shut down?
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*
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* @return True, if the monitor should shut down, false otherwise.
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*/
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bool should_shutdown() const
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{
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return atomic_load_int32(&m_shutdown) != 0;
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}
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/**
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* @brief Should the disk space status be updated.
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*
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* @param pMonitored_server The monitored server in question.
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*
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* @return True, if the disk space should be checked, false otherwise.
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*/
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bool should_update_disk_space_status(const MXS_MONITORED_SERVER* pMonitored_server) const;
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/**
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* @brief Update the disk space status of a server.
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*
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* After the call, the bit @c SERVER_DISK_SPACE_EXHAUSTED will be set on
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* @c pMonitored_server->pending_status if the disk space is exhausted
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* or cleared if it is not.
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*/
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void update_disk_space_status(MXS_MONITORED_SERVER* pMonitored_server);
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static int64_t get_time_ms();
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/**
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* @brief Configure the monitor.
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*
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* When the monitor is started, this function will be called in order
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* to allow the concrete implementation to configure itself from
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* configuration parameters. The default implementation returns true.
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*
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* @return True, if the monitor could be configured, false otherwise.
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*
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* @note If false is returned, then the monitor will not be started.
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*/
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virtual bool configure(const MXS_CONFIG_PARAMETER* pParams);
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/**
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* @brief Check whether the monitor has sufficient rights
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*
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* The implementation should check whether the monitor user has sufficient
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* rights to access the servers. The default implementation returns True.
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*
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* @return True, if the monitor user has sufficient rights, false otherwise.
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*/
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virtual bool has_sufficient_permissions() const;
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/**
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* @brief Flush pending server status to each server.
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*
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* This function is expected to flush the pending status to each server.
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* The default implementation simply copies monitored_server->pending_status
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* to server->status.
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*/
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virtual void flush_server_status();
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/**
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* @brief Monitor the servers
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*
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* This function is called once per monitor round, and the concrete
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* implementation should probe all servers and set server status bits.
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*/
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virtual void tick() = 0;
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/**
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* @brief Called before the monitor loop is started
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*
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* The default implementation does nothing.
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*/
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virtual void pre_loop();
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/**
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* @brief Called after the monitor loop has ended.
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*
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* The default implementation does nothing.
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*/
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virtual void post_loop();
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/**
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* @brief Called after tick returns
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*
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* The default implementation will call @mon_process_state_changes.
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*/
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virtual void process_state_changes();
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MXS_MONITOR* m_monitor; /**< The generic monitor structure. */
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MXS_MONITORED_SERVER* m_master; /**< Master server */
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private:
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int32_t m_state; /**< The current state of the monitor. */
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THREAD m_thread; /**< The thread handle of the monitoring thread. */
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int32_t m_shutdown; /**< Non-zero if the monitor should shut down. */
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bool m_checked; /**< Whether server access has been checked. */
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std::string m_script; /**< Launchable script. */
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uint64_t m_events; /**< Enabled monitor events. */
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Semaphore m_semaphore; /**< Semaphore for synchronizing with monitor thread. */
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void main();
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static void main(void* pArg);
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void sleep_until_next_tick(int64_t tick_start_ms);
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};
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class MonitorInstanceSimple : public MonitorInstance
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{
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public:
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MonitorInstanceSimple(const MonitorInstanceSimple&) = delete;
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MonitorInstanceSimple& operator = (const MonitorInstanceSimple&) = delete;
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protected:
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MonitorInstanceSimple(MXS_MONITOR* pMonitor)
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: MonitorInstance(pMonitor)
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{
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}
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/**
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* @brief Update server information
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*
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* The implementation should probe the server in question and update
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* the server status bits.
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*/
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virtual void update_server_status(MXS_MONITORED_SERVER* pMonitored_server) = 0;
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/**
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* @brief Called right at the beginning of @c tick().
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*
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* The default implementation does nothing.
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*/
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virtual void pre_tick();
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/**
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* @brief Called right before the end of @c tick().
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*
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* The default implementation does nothing.
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*/
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virtual void post_tick();
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private:
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/**
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* @brief Monitor the servers
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*
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* This function is called once per monitor round and will for each server:
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*
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* - Do nothing, if the server is in maintenance.
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* - Store the previous status of the server.
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* - Set the pending status of the monitored server object
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* to the status of the corresponding server object.
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* - Ensure that there is a connection to the server.
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* If there is, @c update_server_status() is called.
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* If there is not, the pending status will be updated accordingly and
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* @c update_server_status() will *not* be called.
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* - After the call, update the error count of the server if it is down.
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*/
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void tick(); // final
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};
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/**
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* The purpose of the template MonitorApi is to provide an implementation
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* of the monitor C-API. The template is instantiated with a class that
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* provides the actual behaviour of a monitor.
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*/
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template<class MonitorInstance>
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class MonitorApi
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{
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public:
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MonitorApi() = delete;
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MonitorApi(const MonitorApi&) = delete;
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MonitorApi& operator = (const MonitorApi&) = delete;
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static MXS_MONITOR_INSTANCE* createInstance(MXS_MONITOR* pMonitor)
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{
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MonitorInstance* pInstance = NULL;
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MXS_EXCEPTION_GUARD(pInstance = MonitorInstance::create(pMonitor));
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return pInstance;
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}
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static void destroyInstance(MXS_MONITOR_INSTANCE* pInstance)
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{
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MXS_EXCEPTION_GUARD(delete static_cast<MonitorInstance*>(pInstance));
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}
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static bool startMonitor(MXS_MONITOR_INSTANCE* pInstance,
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const MXS_CONFIG_PARAMETER* pParams)
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{
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bool started = false;
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MXS_EXCEPTION_GUARD(started = static_cast<MonitorInstance*>(pInstance)->start(pParams));
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return started;
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}
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static void stopMonitor(MXS_MONITOR_INSTANCE* pInstance)
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{
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MXS_EXCEPTION_GUARD(static_cast<MonitorInstance*>(pInstance)->stop());
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}
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static void diagnostics(const MXS_MONITOR_INSTANCE* pInstance, DCB* pDcb)
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{
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MXS_EXCEPTION_GUARD(static_cast<const MonitorInstance*>(pInstance)->diagnostics(pDcb));
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}
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static json_t* diagnostics_json(const MXS_MONITOR_INSTANCE* pInstance)
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{
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json_t* pJson = NULL;
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MXS_EXCEPTION_GUARD(pJson = static_cast<const MonitorInstance*>(pInstance)->diagnostics_json());
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return pJson;
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}
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static MXS_MONITOR_API s_api;
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};
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template<class MonitorInstance>
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MXS_MONITOR_API MonitorApi<MonitorInstance>::s_api =
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{
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&MonitorApi<MonitorInstance>::createInstance,
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&MonitorApi<MonitorInstance>::destroyInstance,
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&MonitorApi<MonitorInstance>::startMonitor,
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&MonitorApi<MonitorInstance>::stopMonitor,
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&MonitorApi<MonitorInstance>::diagnostics,
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&MonitorApi<MonitorInstance>::diagnostics_json,
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};
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}
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