/* * Copyright (c) 2016 MariaDB Corporation Ab * * Use of this software is governed by the Business Source License included * in the LICENSE.TXT file and at www.mariadb.com/bsl11. * * Change Date: 2020-01-01 * * On the date above, in accordance with the Business Source License, use * of this software will be governed by version 2 or later of the General * Public License. */ /** * @file mysql_mon.c - A MySQL replication cluster monitor */ #define MXS_MODULE_NAME "mysqlmon" #include "../mysqlmon.h" #include #include #include #include #include #include #include #include #include #include #include #include #include // TODO: For monitorAddParameters #include "../../../core/maxscale/monitor.h" /** Column positions for SHOW SLAVE STATUS */ #define MYSQL55_STATUS_MASTER_LOG_POS 5 #define MYSQL55_STATUS_MASTER_LOG_FILE 6 #define MYSQL55_STATUS_IO_RUNNING 10 #define MYSQL55_STATUS_SQL_RUNNING 11 #define MYSQL55_STATUS_MASTER_ID 39 /** Column positions for SHOW SLAVE STATUS */ #define MARIA10_STATUS_MASTER_LOG_FILE 7 #define MARIA10_STATUS_MASTER_LOG_POS 8 #define MARIA10_STATUS_IO_RUNNING 12 #define MARIA10_STATUS_SQL_RUNNING 13 #define MARIA10_STATUS_MASTER_ID 41 #define MARIA10_STATUS_HEARTBEATS 55 #define MARIA10_STATUS_HEARTBEAT_PERIOD 56 #define MARIA10_STATUS_SLAVE_GTID 57 /** Column positions for SHOW SLAVE HOSTS */ #define SLAVE_HOSTS_SERVER_ID 0 #define SLAVE_HOSTS_HOSTNAME 1 #define SLAVE_HOSTS_PORT 2 using std::string; typedef std::vector ServerVector; typedef std::vector StringVector; class MySqlServerInfo; static void monitorMain(void *); static void *startMonitor(MXS_MONITOR *, const MXS_CONFIG_PARAMETER*); static void stopMonitor(MXS_MONITOR *); static bool stop_monitor(MXS_MONITOR *); static void diagnostics(DCB *, const MXS_MONITOR *); static json_t* diagnostics_json(const MXS_MONITOR *); static MXS_MONITORED_SERVER *getServerByNodeId(MXS_MONITORED_SERVER *, long); static MXS_MONITORED_SERVER *getSlaveOfNodeId(MXS_MONITORED_SERVER *, long); static MXS_MONITORED_SERVER *get_replication_tree(MXS_MONITOR *, int); static void set_master_heartbeat(MYSQL_MONITOR *, MXS_MONITORED_SERVER *); static void set_slave_heartbeat(MXS_MONITOR *, MXS_MONITORED_SERVER *); static int add_slave_to_master(long *, int, long); static bool isMySQLEvent(mxs_monitor_event_t event); void check_maxscale_schema_replication(MXS_MONITOR *monitor); static bool mon_process_failover(MYSQL_MONITOR* monitor, const char* failover_script, uint32_t failover_timeout); static bool do_failover(MYSQL_MONITOR* mon); static bool update_gtid_slave_pos(MXS_MONITORED_SERVER *database, int64_t domain, MySqlServerInfo* info); static bool update_replication_settings(MXS_MONITORED_SERVER *database, MySqlServerInfo* info); static bool report_version_err = true; static const char* hb_table_name = "maxscale_schema.replication_heartbeat"; static const char CN_FAILOVER[] = "failover"; static const char CN_FAILOVER_SCRIPT[] = "failover_script"; static const char CN_FAILOVER_TIMEOUT[] = "failover_timeout"; static const char CN_SWITCHOVER[] = "switchover"; static const char CN_SWITCHOVER_SCRIPT[] = "switchover_script"; static const char CN_SWITCHOVER_TIMEOUT[] = "switchover_timeout"; // Parameters for master failure verification and timeout static const char CN_VERIFY_MASTER_FAILURE[] = "verify_master_failure"; static const char CN_MASTER_FAILURE_TIMEOUT[] = "master_failure_timeout"; // Replication credentials parameters for failover static const char CN_REPLICATION_USER[] = "replication_user"; static const char CN_REPLICATION_PASSWORD[] = "replication_password"; /** Default failover timeout */ #define DEFAULT_FAILOVER_TIMEOUT "90" /** Default switchover timeout */ #define DEFAULT_SWITCHOVER_TIMEOUT "90" /** Default master failure verification timeout */ #define DEFAULT_MASTER_FAILURE_TIMEOUT "10" // TODO: Specify the real default failover script. static const char DEFAULT_FAILOVER_SCRIPT[] = "/usr/bin/echo INITIATOR=$INITIATOR " "PARENT=$PARENT CHILDREN=$CHILDREN EVENT=$EVENT " "CREDENTIALS=$CREDENTIALS NODELIST=$NODELIST " "LIST=$LIST MASTERLIST=$MASTERLIST " "SLAVELIST=$SLAVELIST SYNCEDLIST=$SYNCEDLIST"; // TODO: Specify the real default switchover script. static const char DEFAULT_SWITCHOVER_SCRIPT[] = "/usr/bin/echo CURRENT_MASTER=$CURRENT_MASTER NEW_MASTER=$NEW_MASTER " "INITIATOR=$INITIATOR " "PARENT=$PARENT CHILDREN=$CHILDREN EVENT=$EVENT " "CREDENTIALS=$CREDENTIALS NODELIST=$NODELIST " "LIST=$LIST MASTERLIST=$MASTERLIST " "SLAVELIST=$SLAVELIST SYNCEDLIST=$SYNCEDLIST"; /** * Check whether specified current master is acceptable. * * @param current_master The specified current master. * @param monitored_server The server to check against. * @param monitored_current_master On output, @c monitored_server, if @c monitored_server * is the same server as @c current_master. * @param error On output, error object if function failed. * * @return False, if there is some error with the specified current master, * True otherwise. */ bool mysql_switchover_check_current(SERVER* current_master, MXS_MONITORED_SERVER* monitored_server, MXS_MONITORED_SERVER** monitored_current_master, json_t** error) { bool rv = true; bool is_master = SERVER_IS_MASTER(monitored_server->server); if (current_master == monitored_server->server) { if (is_master) { *monitored_current_master = monitored_server; } else { *error = mxs_json_error("Specified %s is a server, but not the current master.", current_master->unique_name); rv = false; } } else if (is_master) { *error = mxs_json_error("Current master not specified, even though there is " "a master (%s).", monitored_server->server->unique_name); rv = false; } return rv; } /** * Check whether specified new master is acceptable. * * @param new_master The specified new master. * @param monitored_server The server to check against. * @param monitored_new_master On output, @c monitored_server, if @c monitored_server * is the same server as @c new_master. * @param error On output, error object if function failed. * * @return False, if there is some error with the specified current master, * True otherwise. */ bool mysql_switchover_check_new(SERVER* new_master, MXS_MONITORED_SERVER* monitored_server, MXS_MONITORED_SERVER** monitored_new_master, json_t** error) { bool rv = true; bool is_master = SERVER_IS_MASTER(monitored_server->server); if (new_master == monitored_server->server) { if (!is_master) { *monitored_new_master = monitored_server; } else { *error = mxs_json_error("Specified new master %s is already the current master.", new_master->unique_name); rv = false; } } return rv; } /** * Check whether specified current and new master are acceptable. * * @param mon The monitor. * @param new_master The specified new master. * @param current_master The specifiec current master (may be NULL). * @param monitored_new_master On output, the monitored server corresponding to * @c new_master. * @param monitored_current_master On output, the monitored server corresponding to * @c current_master. * @param error On output, error object if function failed. * * @return True if switchover can proceeed, false otherwise. */ bool mysql_switchover_check(MXS_MONITOR* mon, SERVER* new_master, SERVER* current_master, MXS_MONITORED_SERVER** monitored_new_master, MXS_MONITORED_SERVER** monitored_current_master, json_t** error) { bool rv = true; *monitored_new_master = NULL; *monitored_current_master = NULL; *error = NULL; MXS_MONITORED_SERVER* monitored_server = mon->monitored_servers; while (rv && !*monitored_current_master && !*monitored_new_master && monitored_server) { if (!*monitored_current_master) { rv = mysql_switchover_check_current(current_master, monitored_server, monitored_current_master, error); } if (rv) { rv = mysql_switchover_check_new(new_master, monitored_server, monitored_new_master, error); } monitored_server = monitored_server->next; } if (rv && ((current_master && !*monitored_current_master) || !*monitored_new_master)) { if (current_master && !*monitored_current_master) { *error = mxs_json_error("Specified current master %s is not found amongst " "existing servers.", current_master->unique_name); } if (!*monitored_new_master) { *error = mxs_json_error_append(*error, "Specified new master %s is not found amongst " "existing servers.", new_master->unique_name); } rv = false; } return rv; } bool mysql_switchover_perform(MXS_MONITOR* mon, MXS_MONITORED_SERVER* monitored_new_master, MXS_MONITORED_SERVER* monitored_current_master, json_t** result) { MYSQL_MONITOR* mysql_mon = static_cast(mon->handle); SERVER* new_master = monitored_new_master->server; SERVER* current_master = monitored_current_master ? monitored_current_master->server : NULL; const char* switchover_script = mysql_mon->switchover_script; if (!switchover_script) { switchover_script = DEFAULT_SWITCHOVER_SCRIPT; } int rv = -1; EXTERNCMD* cmd = externcmd_allocate(switchover_script, mysql_mon->switchover_timeout); if (cmd) { if (externcmd_matches(cmd, "$CURRENT_MASTER")) { char address[(current_master ? strlen(current_master->name) : 0) + 24]; // Extra space for port if (current_master) { snprintf(address, sizeof(address), "[%s]:%d", current_master->name, current_master->port); } else { strcpy(address, "none"); } externcmd_substitute_arg(cmd, "[$]CURRENT_MASTER", address); } if (externcmd_matches(cmd, "$NEW_MASTER")) { char address[strlen(new_master->name) + 24]; // Extra space for port snprintf(address, sizeof(address), "[%s]:%d", new_master->name, new_master->port); externcmd_substitute_arg(cmd, "[$]NEW_MASTER", address); } // TODO: We behave as if the specified new master would be the server that causes the // TODO: event, although that's not really the case. rv = monitor_launch_command(mon, monitored_new_master, cmd); } else { *result = mxs_json_error("Failed to initialize script '%s'. See log-file for the " "cause of this failure.", switchover_script); } return rv == 0 ? true : false; } /** * Handle switchover * * @mon The monitor. * @new_master The specified new master. * @current_master The specified current master. * @output Pointer where to place output object. * * @return True, if switchover was performed, false otherwise. */ bool mysql_switchover(MXS_MONITOR* mon, SERVER* new_master, SERVER* current_master, json_t** output) { bool rv = true; MYSQL_MONITOR *handle = static_cast(mon->handle); *output = NULL; bool stopped = stop_monitor(mon); if (stopped) { MXS_NOTICE("Stopped the monitor %s for the duration of switchover.", mon->name); } else { MXS_NOTICE("Monitor %s already stopped, switchover can proceed.", mon->name); } MXS_MONITORED_SERVER* monitored_new_master = NULL; MXS_MONITORED_SERVER* monitored_current_master = NULL; rv = mysql_switchover_check(mon, new_master, current_master, &monitored_new_master, &monitored_current_master, output); if (rv) { bool failover = config_get_bool(mon->parameters, CN_FAILOVER); rv = mysql_switchover_perform(mon, monitored_new_master, monitored_current_master, output); if (rv) { MXS_NOTICE("Switchover %s -> %s performed.", current_master->unique_name ? current_master->unique_name : "none", new_master->unique_name); if (stopped) { startMonitor(mon, mon->parameters); } } else { if (failover) { // TODO: There could be a more convenient way for this. MXS_CONFIG_PARAMETER p = {}; p.name = const_cast(CN_FAILOVER); p.value = const_cast("false"); monitorAddParameters(mon, &p); MXS_ALERT("Switchover %s -> %s failed, failover has been disabled.", current_master->unique_name ? current_master->unique_name : "none", new_master->unique_name); } else { MXS_ERROR("Switchover %s -> %s failed.", current_master->unique_name ? current_master->unique_name : "none", new_master->unique_name); } } } else { if (stopped) { startMonitor(mon, mon->parameters); } } return rv; } /** * Command handler for 'switchover' * * @param args The provided arguments. * @param output Pointer where to place output object. * * @return True, if the command was executed, false otherwise. */ bool mysql_handle_switchover(const MODULECMD_ARG* args, json_t** output) { ss_dassert((args->argc == 2) || (args->argc == 3)); ss_dassert(MODULECMD_GET_TYPE(&args->argv[0].type) == MODULECMD_ARG_MONITOR); ss_dassert(MODULECMD_GET_TYPE(&args->argv[1].type) == MODULECMD_ARG_SERVER); ss_dassert((args->argc == 2) || (MODULECMD_GET_TYPE(&args->argv[2].type) == MODULECMD_ARG_SERVER)); MXS_MONITOR* mon = args->argv[0].value.monitor; MYSQL_MONITOR* mysql_mon = static_cast(mon->handle); SERVER* new_master = args->argv[1].value.server; SERVER* current_master = (args->argc == 3) ? args->argv[2].value.server : NULL; bool rv = false; if (!config_get_global_options()->passive) { if (mysql_mon->switchover) { rv = mysql_switchover(mon, new_master, current_master, output); } else { MXS_WARNING("Attempt to perform switchover %s -> %s, even though " "switchover is not enabled.", current_master ? current_master->unique_name : "none", new_master->unique_name); *output = mxs_json_error("Switchover %s -> %s not performed, as switchover is not enabled.", current_master ? current_master->unique_name : "none", new_master->unique_name); } } else { MXS_WARNING("Attempt to perform switchover %s -> %s, even though " "MaxScale is in passive mode.", current_master ? current_master->unique_name : "none", new_master->unique_name); *output = mxs_json_error("Switchover %s -> %s not performed, as MaxScale is in passive mode.", current_master ? current_master->unique_name : "none", new_master->unique_name); } return rv; } /** * The module entry point routine. It is this routine that * must populate the structure that is referred to as the * "module object", this is a structure with the set of * external entry points for this module. * * @return The module object */ extern "C" { MXS_MODULE* MXS_CREATE_MODULE() { MXS_NOTICE("Initialise the MySQL Monitor module."); static modulecmd_arg_type_t switchover_argv[] = { { MODULECMD_ARG_MONITOR | MODULECMD_ARG_NAME_MATCHES_DOMAIN, "MySQL Monitor name (from configuration file)" }, { MODULECMD_ARG_SERVER, "New master" }, { MODULECMD_ARG_SERVER | MODULECMD_ARG_OPTIONAL, "Current master (obligatory if exists)" } }; modulecmd_register_command(MXS_MODULE_NAME, "switchover", MODULECMD_TYPE_ACTIVE, mysql_handle_switchover, MXS_ARRAY_NELEMS(switchover_argv), switchover_argv, "Perform master switchover"); static MXS_MONITOR_OBJECT MyObject = { startMonitor, stopMonitor, diagnostics, diagnostics_json }; static MXS_MODULE info = { MXS_MODULE_API_MONITOR, MXS_MODULE_GA, MXS_MONITOR_VERSION, "A MySQL Master/Slave replication monitor", "V1.5.0", MXS_NO_MODULE_CAPABILITIES, &MyObject, NULL, /* Process init. */ NULL, /* Process finish. */ NULL, /* Thread init. */ NULL, /* Thread finish. */ { {"detect_replication_lag", MXS_MODULE_PARAM_BOOL, "false"}, {"detect_stale_master", MXS_MODULE_PARAM_BOOL, "true"}, {"detect_stale_slave", MXS_MODULE_PARAM_BOOL, "true"}, {"mysql51_replication", MXS_MODULE_PARAM_BOOL, "false"}, {"multimaster", MXS_MODULE_PARAM_BOOL, "false"}, {"detect_standalone_master", MXS_MODULE_PARAM_BOOL, "false"}, {"failcount", MXS_MODULE_PARAM_COUNT, "5"}, {"allow_cluster_recovery", MXS_MODULE_PARAM_BOOL, "true"}, {"allow_external_slaves", MXS_MODULE_PARAM_BOOL, "true"}, { "script", MXS_MODULE_PARAM_PATH, NULL, MXS_MODULE_OPT_PATH_X_OK }, { "events", MXS_MODULE_PARAM_ENUM, MXS_MONITOR_EVENT_DEFAULT_VALUE, MXS_MODULE_OPT_NONE, mxs_monitor_event_enum_values }, {CN_FAILOVER, MXS_MODULE_PARAM_BOOL, "false"}, { CN_FAILOVER_SCRIPT, MXS_MODULE_PARAM_PATH, NULL, MXS_MODULE_OPT_PATH_X_OK }, {CN_FAILOVER_TIMEOUT, MXS_MODULE_PARAM_COUNT, DEFAULT_FAILOVER_TIMEOUT}, {CN_SWITCHOVER, MXS_MODULE_PARAM_BOOL, "false"}, { CN_SWITCHOVER_SCRIPT, MXS_MODULE_PARAM_PATH, NULL, MXS_MODULE_OPT_PATH_X_OK }, {CN_SWITCHOVER_TIMEOUT, MXS_MODULE_PARAM_COUNT, DEFAULT_SWITCHOVER_TIMEOUT}, {CN_REPLICATION_USER, MXS_MODULE_PARAM_STRING}, {CN_REPLICATION_PASSWORD, MXS_MODULE_PARAM_STRING}, {CN_VERIFY_MASTER_FAILURE, MXS_MODULE_PARAM_BOOL, "true"}, {CN_MASTER_FAILURE_TIMEOUT, MXS_MODULE_PARAM_COUNT, DEFAULT_MASTER_FAILURE_TIMEOUT}, {MXS_END_MODULE_PARAMS} } }; return &info; } } class Gtid { public: uint32_t domain; uint32_t server_id; uint64_t sequence; Gtid() : domain(0) , server_id(0) , sequence(0) {} /** * Parse a Gtid-triplet from a string. In case of a multi-triplet value, only the triplet with the given domain * is returned. * * @param str Gtid string * @param search_domain The Gtid domain whose triplet should be returned. Negative domain means autoselect, * which is only allowed when the string contains one triplet. */ Gtid(const char* str, int64_t search_domain = -1) : domain(0) , server_id(0) , sequence(0) { // Autoselect only allowed with one triplet ss_dassert(search_domain >= 0 || strchr(str, ',') == NULL); parse_triplet(str); if (search_domain >= 0 && domain != search_domain) { // Search for the correct triplet. bool found = false; for (const char* next_triplet = strchr(str, ','); next_triplet != NULL && !found; next_triplet = strchr(next_triplet, ',')) { parse_triplet(++next_triplet); if (domain == search_domain) { found = true; } } ss_dassert(found); } } bool operator == (const Gtid& rhs) const { return domain == rhs.domain && server_id == rhs.server_id && sequence == rhs.sequence; } private: void parse_triplet(const char* str) { ss_debug(int rv =) sscanf(str, "%" PRIu32 "-%" PRIu32 "-%" PRIu64, &domain, &server_id, &sequence); ss_dassert(rv == 3); } }; // Contains data returned by one row of SHOW ALL SLAVES STATUS class SlaveStatusInfo { public: int master_server_id; /**< The master's server_id value. */ bool slave_io_running; /**< Whether the slave I/O thread is running and connected. */ bool slave_sql_running; /**< Whether or not the SQL thread is running. */ string master_log_file; /**< Name of the master binary log file that the I/O thread is currently reading from. */ uint64_t read_master_log_pos; /**< Position up to which the I/O thread has read in the current master * binary log file. */ Gtid gtid_io_pos; /**< Gtid I/O position of the slave thread. */ SlaveStatusInfo() : master_server_id(0), slave_io_running(false), slave_sql_running(false), read_master_log_pos(0) {} }; // This class groups some miscellaneous replication related settings together. class ReplicationSettings { public: bool gtid_strict_mode; /**< Enable additional checks for replication */ bool log_bin; /**< Is binary logging enabled */ bool log_slave_updates;/**< Does the slave log replicated events to binlog */ ReplicationSettings() : gtid_strict_mode(false) , log_bin(false) , log_slave_updates(false) {} }; /** * Monitor specific information about a server * * Note: These are initialized in @c init_server_info */ class MySqlServerInfo { public: int server_id; /**< Value of @@server_id */ int group; /**< Multi-master group where this server belongs, 0 for servers not in groups */ bool read_only; /**< Value of @@read_only */ bool slave_configured; /**< Whether SHOW SLAVE STATUS returned rows */ bool binlog_relay; /** Server is a Binlog Relay */ int n_slaves_configured; /**< Number of configured slave connections*/ int n_slaves_running; /**< Number of running slave connections */ int slave_heartbeats; /**< Number of received heartbeats */ double heartbeat_period; /**< The time interval between heartbeats */ time_t latest_event; /**< Time when latest event was received from the master */ Gtid gtid_slave_pos; /**< Gtid of latest replicated event. Only shows the triplet with the * same domain as Gtid_IO_Pos. */ SlaveStatusInfo slave_status; /**< Data returned from SHOW SLAVE STATUS */ ReplicationSettings rpl_settings; /**< Miscellaneous replication related settings */ MySqlServerInfo() : server_id(0), group(0), read_only(false), slave_configured(false), binlog_relay(false), n_slaves_configured(0), n_slaves_running(0), slave_heartbeats(0), heartbeat_period(0), latest_event(0) {} /** * Calculate how many events are left in relay log. * * @return Number of events in relay log according to latest queried info. */ int64_t relay_log_events() { return slave_status.gtid_io_pos.sequence - gtid_slave_pos.sequence; } }; void* info_copy_func(const void *val) { ss_dassert(val); MySqlServerInfo *old_val = (MySqlServerInfo*)val; MySqlServerInfo *new_val = new (std::nothrow) MySqlServerInfo; if (new_val) { *new_val = *old_val; } return new_val; } void info_free_func(void *val) { if (val) { MySqlServerInfo *old_val = (MySqlServerInfo*)val; delete old_val; } } /** * @brief Helper function that initializes the server info hashtable * * @param handle MySQL monitor handle * @param database List of monitored databases * @return True on success, false if initialization failed. At the moment * initialization can only fail if memory allocation fails. */ bool init_server_info(MYSQL_MONITOR *handle, MXS_MONITORED_SERVER *database) { bool rval = true; MySqlServerInfo info; while (database) { /** Delete any existing structures and replace them with empty ones */ hashtable_delete(handle->server_info, database->server->unique_name); if (!hashtable_add(handle->server_info, database->server->unique_name, &info)) { rval = false; break; } database = database->next; } return rval; } static MySqlServerInfo* get_server_info(const MYSQL_MONITOR* handle, const MXS_MONITORED_SERVER* db) { void* value = hashtable_fetch(handle->server_info, db->server->unique_name); ss_dassert(value); return static_cast(value); } static bool set_replication_credentials(MYSQL_MONITOR *handle, const MXS_CONFIG_PARAMETER* params) { bool rval = false; const char* repl_user = config_get_string(params, CN_REPLICATION_USER); const char* repl_pw = config_get_string(params, CN_REPLICATION_PASSWORD); if (!*repl_user && !*repl_pw) { // No replication credentials defined, use monitor credentials repl_user = handle->monitor->user; repl_pw = handle->monitor->password; } if (*repl_user && *repl_pw) { handle->replication_user = MXS_STRDUP_A(repl_user); handle->replication_password = decrypt_password(repl_pw); rval = true; } return rval; } /*lint +e14 */ /** * Start the instance of the monitor, returning a handle on the monitor. * * This function creates a thread to execute the actual monitoring. * * @param arg The current handle - NULL if first start * @param opt Configuration parameters * @return A handle to use when interacting with the monitor */ static void * startMonitor(MXS_MONITOR *monitor, const MXS_CONFIG_PARAMETER* params) { MYSQL_MONITOR *handle = (MYSQL_MONITOR*) monitor->handle; if (handle) { handle->shutdown = 0; MXS_FREE(handle->script); MXS_FREE(handle->switchover_script); MXS_FREE(handle->replication_user); MXS_FREE(handle->replication_password); } else { handle = (MYSQL_MONITOR *) MXS_MALLOC(sizeof(MYSQL_MONITOR)); HASHTABLE *server_info = hashtable_alloc(MAX_NUM_SLAVES, hashtable_item_strhash, hashtable_item_strcmp); if (handle == NULL || server_info == NULL) { MXS_FREE(handle); hashtable_free(server_info); return NULL; } hashtable_memory_fns(server_info, hashtable_item_strdup, info_copy_func, hashtable_item_free, info_free_func); handle->server_info = server_info; handle->shutdown = 0; handle->id = config_get_global_options()->id; handle->warn_set_standalone_master = true; handle->monitor = monitor; } /** This should always be reset to NULL */ handle->master = NULL; handle->detectStaleMaster = config_get_bool(params, "detect_stale_master"); handle->detectStaleSlave = config_get_bool(params, "detect_stale_slave"); handle->replicationHeartbeat = config_get_bool(params, "detect_replication_lag"); handle->multimaster = config_get_bool(params, "multimaster"); handle->detect_standalone_master = config_get_bool(params, "detect_standalone_master"); handle->failcount = config_get_integer(params, "failcount"); handle->allow_cluster_recovery = config_get_bool(params, "allow_cluster_recovery"); handle->mysql51_replication = config_get_bool(params, "mysql51_replication"); handle->script = config_copy_string(params, "script"); handle->events = config_get_enum(params, "events", mxs_monitor_event_enum_values); handle->allow_external_slaves = config_get_bool(params, "allow_external_slaves"); handle->failover = config_get_bool(params, CN_FAILOVER); handle->failover_script = config_copy_string(params, CN_FAILOVER_SCRIPT); handle->failover_timeout = config_get_integer(params, CN_FAILOVER_TIMEOUT); handle->switchover = config_get_bool(params, CN_SWITCHOVER); handle->switchover_script = config_copy_string(params, CN_SWITCHOVER_SCRIPT); handle->switchover_timeout = config_get_integer(params, CN_SWITCHOVER_TIMEOUT); handle->verify_master_failure = config_get_bool(params, CN_VERIFY_MASTER_FAILURE); handle->master_failure_timeout = config_get_integer(params, CN_MASTER_FAILURE_TIMEOUT); bool error = false; if (!set_replication_credentials(handle, params)) { MXS_ERROR("Both '%s' and '%s' must be defined", CN_REPLICATION_USER, CN_REPLICATION_PASSWORD); error = true; } if (!check_monitor_permissions(monitor, "SHOW SLAVE STATUS")) { MXS_ERROR("Failed to start monitor. See earlier errors for more information."); error = true; } if (!init_server_info(handle, monitor->monitored_servers)) { error = true; } if (error) { hashtable_free(handle->server_info); MXS_FREE(handle->switchover_script); MXS_FREE(handle->script); MXS_FREE(handle); handle = NULL; } else { handle->status = MXS_MONITOR_RUNNING; if (thread_start(&handle->thread, monitorMain, handle, 0) == NULL) { MXS_ERROR("Failed to start monitor thread for monitor '%s'.", monitor->name); hashtable_free(handle->server_info); MXS_FREE(handle->switchover_script); MXS_FREE(handle->script); MXS_FREE(handle); handle = NULL; } } return handle; } /** * Stop a running monitor * * @param mon The monitor that should be stopped. */ static void stopMonitor(MXS_MONITOR *mon) { MYSQL_MONITOR *handle = (MYSQL_MONITOR *) mon->handle; handle->shutdown = 1; thread_wait(handle->thread); } /** * Stop a running monitor * * @param mon The monitor that should be stopped. * * @return True, if the monitor had to be stopped. * False, if the monitor already was stopped. */ static bool stop_monitor(MXS_MONITOR* mon) { // There should be no race here as long as admin operations are performed // with the single admin lock locked. bool actually_stopped = false; MYSQL_MONITOR *handle = static_cast(mon->handle); if (handle->status == MXS_MONITOR_RUNNING) { stopMonitor(mon); actually_stopped = true; } return actually_stopped; } /** * Daignostic interface * * @param dcb DCB to print diagnostics * @param arg The monitor handle */ static void diagnostics(DCB *dcb, const MXS_MONITOR *mon) { const MYSQL_MONITOR *handle = (const MYSQL_MONITOR *)mon->handle; dcb_printf(dcb, "Failover:\t%s\n", handle->failover ? "Enabled" : "Disabled"); dcb_printf(dcb, "Failover Timeout:\t%u\n", handle->failover_timeout); dcb_printf(dcb, "Switchover:\t%s\n", handle->switchover ? "Enabled" : "Disabled"); dcb_printf(dcb, "Switchover Timeout:\t%u\n", handle->switchover_timeout); dcb_printf(dcb, "MaxScale MonitorId:\t%lu\n", handle->id); dcb_printf(dcb, "Replication lag:\t%s\n", (handle->replicationHeartbeat == 1) ? "enabled" : "disabled"); dcb_printf(dcb, "Detect Stale Master:\t%s\n", (handle->detectStaleMaster == 1) ? "enabled" : "disabled"); dcb_printf(dcb, "Server information\n\n"); for (MXS_MONITORED_SERVER *db = mon->monitored_servers; db; db = db->next) { MySqlServerInfo *serv_info = get_server_info(handle, db); dcb_printf(dcb, "Server: %s\n", db->server->unique_name); dcb_printf(dcb, "Server ID: %d\n", serv_info->server_id); dcb_printf(dcb, "Read only: %s\n", serv_info->read_only ? "ON" : "OFF"); dcb_printf(dcb, "Slave configured: %s\n", serv_info->slave_configured ? "YES" : "NO"); dcb_printf(dcb, "Slave IO running: %s\n", serv_info->slave_status.slave_io_running ? "YES" : "NO"); dcb_printf(dcb, "Slave SQL running: %s\n", serv_info->slave_status.slave_sql_running ? "YES" : "NO"); dcb_printf(dcb, "Master ID: %d\n", serv_info->slave_status.master_server_id); dcb_printf(dcb, "Master binlog file: %s\n", serv_info->slave_status.master_log_file.c_str()); dcb_printf(dcb, "Master binlog position: %lu\n", serv_info->slave_status.read_master_log_pos); if (handle->multimaster) { dcb_printf(dcb, "Master group: %d\n", serv_info->group); } dcb_printf(dcb, "\n"); } } /** * Diagnostic interface * * @param arg The monitor handle */ static json_t* diagnostics_json(const MXS_MONITOR *mon) { json_t* rval = json_object(); const MYSQL_MONITOR *handle = (const MYSQL_MONITOR *)mon->handle; json_object_set_new(rval, "monitor_id", json_integer(handle->id)); json_object_set_new(rval, "detect_stale_master", json_boolean(handle->detectStaleMaster)); json_object_set_new(rval, "detect_stale_slave", json_boolean(handle->detectStaleSlave)); json_object_set_new(rval, "detect_replication_lag", json_boolean(handle->replicationHeartbeat)); json_object_set_new(rval, "multimaster", json_boolean(handle->multimaster)); json_object_set_new(rval, "detect_standalone_master", json_boolean(handle->detect_standalone_master)); json_object_set_new(rval, "failcount", json_integer(handle->failcount)); json_object_set_new(rval, "allow_cluster_recovery", json_boolean(handle->allow_cluster_recovery)); json_object_set_new(rval, "mysql51_replication", json_boolean(handle->mysql51_replication)); json_object_set_new(rval, CN_FAILOVER, json_boolean(handle->failover)); json_object_set_new(rval, CN_FAILOVER_TIMEOUT, json_integer(handle->failover_timeout)); json_object_set_new(rval, CN_SWITCHOVER, json_boolean(handle->switchover)); json_object_set_new(rval, CN_SWITCHOVER_TIMEOUT, json_integer(handle->switchover_timeout)); if (handle->switchover_script) { json_object_set_new(rval, CN_SWITCHOVER_SCRIPT, json_string(handle->script)); } if (handle->script) { json_object_set_new(rval, "script", json_string(handle->script)); } if (mon->monitored_servers) { json_t* arr = json_array(); for (MXS_MONITORED_SERVER *db = mon->monitored_servers; db; db = db->next) { json_t* srv = json_object(); MySqlServerInfo *serv_info = get_server_info(handle, db); json_object_set_new(srv, "name", json_string(db->server->unique_name)); json_object_set_new(srv, "server_id", json_integer(serv_info->server_id)); json_object_set_new(srv, "master_id", json_integer(serv_info->slave_status.master_server_id)); json_object_set_new(srv, "read_only", json_boolean(serv_info->read_only)); json_object_set_new(srv, "slave_configured", json_boolean(serv_info->slave_configured)); json_object_set_new(srv, "slave_io_running", json_boolean(serv_info->slave_status.slave_io_running)); json_object_set_new(srv, "slave_sql_running", json_boolean(serv_info->slave_status.slave_sql_running)); json_object_set_new(srv, "master_binlog_file", json_string(serv_info->slave_status.master_log_file.c_str())); json_object_set_new(srv, "master_binlog_position", json_integer(serv_info->slave_status.read_master_log_pos)); if (handle->multimaster) { json_object_set_new(srv, "master_group", json_integer(serv_info->group)); } json_array_append_new(arr, srv); } json_object_set_new(rval, "server_info", arr); } return rval; } enum mysql_server_version { MYSQL_SERVER_VERSION_100, MYSQL_SERVER_VERSION_55, MYSQL_SERVER_VERSION_51 }; static enum mysql_server_version get_server_version(MXS_MONITORED_SERVER* db) { unsigned long server_version = mysql_get_server_version(db->con); if (server_version >= 100000) { return MYSQL_SERVER_VERSION_100; } else if (server_version >= 5 * 10000 + 5 * 100) { return MYSQL_SERVER_VERSION_55; } return MYSQL_SERVER_VERSION_51; } static bool do_show_slave_status(MySqlServerInfo* serv_info, MXS_MONITORED_SERVER* database, enum mysql_server_version server_version) { bool rval = true; unsigned int columns; int i_slave_io_running, i_slave_sql_running, i_read_master_log_pos, i_master_server_id, i_master_log_file; const char *query; if (server_version == MYSQL_SERVER_VERSION_100) { columns = 42; query = "SHOW ALL SLAVES STATUS"; i_slave_io_running = MARIA10_STATUS_IO_RUNNING; i_slave_sql_running = MARIA10_STATUS_SQL_RUNNING; i_master_log_file = MARIA10_STATUS_MASTER_LOG_FILE; i_read_master_log_pos = MARIA10_STATUS_MASTER_LOG_POS; i_master_server_id = MARIA10_STATUS_MASTER_ID; } else { columns = server_version == MYSQL_SERVER_VERSION_55 ? 40 : 38; query = "SHOW SLAVE STATUS"; i_slave_io_running = MYSQL55_STATUS_IO_RUNNING; i_slave_sql_running = MYSQL55_STATUS_SQL_RUNNING; i_master_log_file = MYSQL55_STATUS_MASTER_LOG_FILE; i_read_master_log_pos = MYSQL55_STATUS_MASTER_LOG_POS; i_master_server_id = MYSQL55_STATUS_MASTER_ID; } MYSQL_RES* result; int master_server_id = -1; int nconfigured = 0; int nrunning = 0; if (mxs_mysql_query(database->con, query) == 0 && (result = mysql_store_result(database->con)) != NULL) { if (mysql_field_count(database->con) < columns) { mysql_free_result(result); MXS_ERROR("\"%s\" returned less than the expected amount of columns. " "Expected %u columns.", query, columns); return false; } MYSQL_ROW row = mysql_fetch_row(result); if (row) { serv_info->slave_configured = true; do { /* get Slave_IO_Running and Slave_SQL_Running values*/ serv_info->slave_status.slave_io_running = strncmp(row[i_slave_io_running], "Yes", 3) == 0; serv_info->slave_status.slave_sql_running = strncmp(row[i_slave_sql_running], "Yes", 3) == 0; if (serv_info->slave_status.slave_io_running && serv_info->slave_status.slave_sql_running) { if (nrunning == 0) { /** Only check binlog name for the first running slave */ uint64_t read_master_log_pos = atol(row[i_read_master_log_pos]); char* master_log_file = row[i_master_log_file]; if (serv_info->slave_status.master_log_file != master_log_file || read_master_log_pos != serv_info->slave_status.read_master_log_pos) { // IO thread is reading events from the master serv_info->latest_event = time(NULL); } serv_info->slave_status.master_log_file = master_log_file; serv_info->slave_status.read_master_log_pos = read_master_log_pos; } nrunning++; } /* If Slave_IO_Running = Yes, assign the master_id to current server: this allows building * the replication tree, slaves ids will be added to master(s) and we will have at least the * root master server. * Please note, there could be no slaves at all if Slave_SQL_Running == 'No' */ if (serv_info->slave_status.slave_io_running && server_version != MYSQL_SERVER_VERSION_51) { /* Get Master_Server_Id */ master_server_id = atoi(row[i_master_server_id]); if (master_server_id == 0) { master_server_id = -1; } } if (server_version == MYSQL_SERVER_VERSION_100) { const char* beats = mxs_mysql_get_value(result, row, "Slave_received_heartbeats"); const char* period = mxs_mysql_get_value(result, row, "Slave_heartbeat_period"); const char* gtid_io_pos = mxs_mysql_get_value(result, row, "Gtid_IO_Pos"); ss_dassert(beats && period); int heartbeats = atoi(beats); if (serv_info->slave_heartbeats < heartbeats) { serv_info->latest_event = time(NULL); serv_info->slave_heartbeats = heartbeats; serv_info->heartbeat_period = atof(period); } serv_info->slave_status.gtid_io_pos = (serv_info->slave_status.slave_sql_running && gtid_io_pos) ? Gtid(gtid_io_pos) : Gtid(); } nconfigured++; row = mysql_fetch_row(result); } while (row); } else { /** Query returned no rows, replication is not configured */ serv_info->slave_configured = false; serv_info->slave_heartbeats = 0; serv_info->slave_status = SlaveStatusInfo(); } serv_info->slave_status.master_server_id = master_server_id; mysql_free_result(result); } else { mon_report_query_error(database); } serv_info->n_slaves_configured = nconfigured; serv_info->n_slaves_running = nrunning; return rval; } static bool update_slave_status(MYSQL_MONITOR* handle, MXS_MONITORED_SERVER* db) { void* value = hashtable_fetch(handle->server_info,db->server->unique_name); ss_dassert(value); MySqlServerInfo* info = static_cast(value); enum mysql_server_version version = get_server_version(db); return do_show_slave_status(info, db, version); } static inline bool master_maybe_dead(MYSQL_MONITOR* handle) { return handle->verify_master_failure && handle->master && SERVER_IS_DOWN(handle->master->server); } static bool master_still_alive(MYSQL_MONITOR* handle) { bool rval = true; if (handle->master && SERVER_IS_DOWN(handle->master->server)) { // We have a master and it appears to be dead rval = false; for (MXS_MONITORED_SERVER* s = handle->monitor->monitored_servers; s; s = s->next) { MySqlServerInfo* info = get_server_info(handle, s); if (info->slave_configured && info->slave_status.master_server_id == handle->master->server->node_id && difftime(time(NULL), info->latest_event) < handle->master_failure_timeout) { /** * The slave is still connected to the correct master and has * received events. This means that the master is not dead, but * we just can't connect to it. */ rval = true; break; } } } return rval; } static inline void monitor_mysql_db(MXS_MONITORED_SERVER* database, MySqlServerInfo *serv_info, enum mysql_server_version server_version) { /** Clear old states */ monitor_clear_pending_status(database, SERVER_SLAVE | SERVER_MASTER | SERVER_RELAY_MASTER | SERVER_STALE_STATUS | SERVER_SLAVE_OF_EXTERNAL_MASTER); if (do_show_slave_status(serv_info, database, server_version)) { /* If all configured slaves are running set this node as slave */ if (serv_info->slave_configured && serv_info->n_slaves_running > 0 && serv_info->n_slaves_running == serv_info->n_slaves_configured) { monitor_set_pending_status(database, SERVER_SLAVE); } /** Store master_id of current node. For MySQL 5.1 it will be set at a later point. */ database->server->master_id = serv_info->slave_status.master_server_id; } } /** * Build the replication tree for a MySQL 5.1 cluster * * This function queries each server with SHOW SLAVE HOSTS to determine which servers * have slaves replicating from them. * @param mon Monitor * @return Lowest server ID master in the monitor */ static MXS_MONITORED_SERVER *build_mysql51_replication_tree(MXS_MONITOR *mon) { MXS_MONITORED_SERVER* database = mon->monitored_servers; MXS_MONITORED_SERVER *ptr, *rval = NULL; int i; MYSQL_MONITOR *handle = static_cast(mon->handle); while (database) { bool ismaster = false; MYSQL_RES* result; MYSQL_ROW row; int nslaves = 0; if (database->con) { if (mxs_mysql_query(database->con, "SHOW SLAVE HOSTS") == 0 && (result = mysql_store_result(database->con)) != NULL) { if (mysql_field_count(database->con) < 4) { mysql_free_result(result); MXS_ERROR("\"SHOW SLAVE HOSTS\" " "returned less than the expected amount of columns. " "Expected 4 columns."); return NULL; } if (mysql_num_rows(result) > 0) { ismaster = true; while (nslaves < MAX_NUM_SLAVES && (row = mysql_fetch_row(result))) { /* get Slave_IO_Running and Slave_SQL_Running values*/ database->server->slaves[nslaves] = atol(row[SLAVE_HOSTS_SERVER_ID]); nslaves++; MXS_DEBUG("Found slave at %s:%s", row[SLAVE_HOSTS_HOSTNAME], row[SLAVE_HOSTS_PORT]); } database->server->slaves[nslaves] = 0; } mysql_free_result(result); } else { mon_report_query_error(database); } /* Set the Slave Role */ if (ismaster) { handle->master = database; MXS_DEBUG("Master server found at [%s]:%d with %d slaves", database->server->name, database->server->port, nslaves); monitor_set_pending_status(database, SERVER_MASTER); database->server->depth = 0; // Add Depth 0 for Master if (rval == NULL || rval->server->node_id > database->server->node_id) { rval = database; } } } database = database->next; } database = mon->monitored_servers; /** Set master server IDs */ while (database) { ptr = mon->monitored_servers; while (ptr) { for (i = 0; ptr->server->slaves[i]; i++) { if (ptr->server->slaves[i] == database->server->node_id) { database->server->master_id = ptr->server->node_id; database->server->depth = 1; // Add Depth 1 for Slave break; } } ptr = ptr->next; } if (SERVER_IS_SLAVE(database->server) && (database->server->master_id <= 0 || database->server->master_id != handle->master->server->node_id)) { if (handle->allow_external_slaves) { monitor_set_pending_status(database, SERVER_SLAVE); } else { monitor_clear_pending_status(database, SERVER_SLAVE); } monitor_set_pending_status(database, SERVER_SLAVE_OF_EXTERNAL_MASTER); } database = database->next; } return rval; } /** * Monitor an individual server * * @param handle The MySQL Monitor object * @param database The database to probe */ static void monitorDatabase(MXS_MONITOR *mon, MXS_MONITORED_SERVER *database) { MYSQL_MONITOR* handle = static_cast(mon->handle); MYSQL_ROW row; MYSQL_RES *result; unsigned long int server_version = 0; char *server_string; /* Don't probe servers in maintenance mode */ if (SERVER_IN_MAINT(database->server)) { return; } /** Store previous status */ database->mon_prev_status = database->server->status; mxs_connect_result_t rval = mon_ping_or_connect_to_db(mon, database); if (rval == MONITOR_CONN_OK) { server_clear_status_nolock(database->server, SERVER_AUTH_ERROR); monitor_clear_pending_status(database, SERVER_AUTH_ERROR); } else { /* The current server is not running * * Store server NOT running in server and monitor server pending struct * */ if (mysql_errno(database->con) == ER_ACCESS_DENIED_ERROR) { server_set_status_nolock(database->server, SERVER_AUTH_ERROR); monitor_set_pending_status(database, SERVER_AUTH_ERROR); } server_clear_status_nolock(database->server, SERVER_RUNNING); monitor_clear_pending_status(database, SERVER_RUNNING); /* Also clear M/S state in both server and monitor server pending struct */ server_clear_status_nolock(database->server, SERVER_SLAVE); server_clear_status_nolock(database->server, SERVER_MASTER); server_clear_status_nolock(database->server, SERVER_RELAY_MASTER); monitor_clear_pending_status(database, SERVER_SLAVE); monitor_clear_pending_status(database, SERVER_MASTER); monitor_clear_pending_status(database, SERVER_RELAY_MASTER); /* Clean addition status too */ server_clear_status_nolock(database->server, SERVER_SLAVE_OF_EXTERNAL_MASTER); server_clear_status_nolock(database->server, SERVER_STALE_STATUS); server_clear_status_nolock(database->server, SERVER_STALE_SLAVE); monitor_clear_pending_status(database, SERVER_SLAVE_OF_EXTERNAL_MASTER); monitor_clear_pending_status(database, SERVER_STALE_STATUS); monitor_clear_pending_status(database, SERVER_STALE_SLAVE); /* Log connect failure only once */ if (mon_status_changed(database) && mon_print_fail_status(database)) { mon_log_connect_error(database, rval); } return; } /* Store current status in both server and monitor server pending struct */ server_set_status_nolock(database->server, SERVER_RUNNING); monitor_set_pending_status(database, SERVER_RUNNING); /* get server version from current server */ server_version = mysql_get_server_version(database->con); /* get server version string */ mxs_mysql_set_server_version(database->con, database->server); server_string = database->server->version_string; MySqlServerInfo *serv_info = get_server_info(handle, database); /* Check whether current server is MaxScale Binlog Server */ if (mxs_mysql_query(database->con, "SELECT @@maxscale_version") == 0 && (result = mysql_store_result(database->con)) != NULL) { serv_info->binlog_relay = true; mysql_free_result(result); } else { serv_info->binlog_relay = false; } /* Get server_id and read_only from current node */ if (mxs_mysql_query(database->con, "SELECT @@server_id, @@read_only") == 0 && (result = mysql_store_result(database->con)) != NULL) { long server_id = -1; if (mysql_field_count(database->con) != 2) { mysql_free_result(result); MXS_ERROR("Unexpected result for 'SELECT @@server_id, @@read_only'. Expected 2 columns." " MySQL Version: %s", server_string); return; } while ((row = mysql_fetch_row(result))) { server_id = strtol(row[0], NULL, 10); if ((errno == ERANGE && (server_id == LONG_MAX || server_id == LONG_MIN)) || (errno != 0 && server_id == 0)) { server_id = -1; } database->server->node_id = server_id; serv_info->server_id = server_id; serv_info->read_only = (row[1] && strcmp(row[1], "1") == 0); } mysql_free_result(result); } else { mon_report_query_error(database); } /* Check first for MariaDB 10.x.x and get status for multi-master replication */ if (server_version >= 100000) { monitor_mysql_db(database, serv_info, MYSQL_SERVER_VERSION_100); } else if (server_version >= 5 * 10000 + 5 * 100) { monitor_mysql_db(database, serv_info, MYSQL_SERVER_VERSION_55); } else { if (handle->mysql51_replication) { monitor_mysql_db(database, serv_info, MYSQL_SERVER_VERSION_51); } else if (report_version_err) { report_version_err = false; MXS_ERROR("MySQL version is lower than 5.5 and 'mysql51_replication' option is " "not enabled, replication tree cannot be resolved. To enable MySQL 5.1 replication " "detection, add 'mysql51_replication=true' to the monitor section."); } } } /** * @brief A node in a graph */ struct graph_node { int index; int lowest_index; int cycle; bool active; struct graph_node *parent; MySqlServerInfo *info; MXS_MONITORED_SERVER *db; }; /** * @brief Visit a node in the graph * * This function is the main function used to determine whether the node is a * part of a cycle. It is an implementation of the Tarjan's strongly connected * component algorithm. All one node cycles are ignored since normal * master-slave monitoring handles that. * * Tarjan's strongly connected component algorithm: * * https://en.wikipedia.org/wiki/Tarjan%27s_strongly_connected_components_algorithm */ static void visit_node(struct graph_node *node, struct graph_node **stack, int *stacksize, int *index, int *cycle) { /** Assign an index to this node */ node->lowest_index = node->index = *index; node->active = true; *index += 1; stack[*stacksize] = node; *stacksize += 1; if (node->parent == NULL) { /** This node does not connect to another node, it can't be a part of a cycle */ node->lowest_index = -1; } else if (node->parent->index == 0) { /** Node has not been visited */ visit_node(node->parent, stack, stacksize, index, cycle); if (node->parent->lowest_index < node->lowest_index) { /** The parent connects to a node with a lower index, this node could be a part of a cycle. */ node->lowest_index = node->parent->lowest_index; } } else if (node->parent->active) { /** This node could be a root node of the cycle */ if (node->parent->index < node->lowest_index) { /** Root node found */ node->lowest_index = node->parent->index; } } else { /** Node connects to an already connected cycle, it can't be a part of it */ node->lowest_index = -1; } if (node->active && node->parent && node->lowest_index > 0) { if (node->lowest_index == node->index && node->lowest_index == node->parent->lowest_index) { /** * Found a multi-node cycle from the graph. The cycle is formed from the * nodes with a lowest_index value equal to the lowest_index value of the * current node. Rest of the nodes on the stack are not part of a cycle * and can be discarded. */ *cycle += 1; while (*stacksize > 0) { struct graph_node *top = stack[(*stacksize) - 1]; top->active = false; if (top->lowest_index == node->lowest_index) { top->cycle = *cycle; } *stacksize -= 1; } } } else { /** Pop invalid nodes off the stack */ node->active = false; if (*stacksize > 0) { *stacksize -= 1; } } } /** * @brief Find the strongly connected components in the replication tree graph * * Each replication cluster is a directed graph made out of replication * trees. If this graph has strongly connected components (more generally * cycles), it is considered a multi-master cluster due to the fact that there * are multiple nodes where the data can originate. * * Detecting the cycles in the graph allows this monitor to better understand * the relationships between the nodes. All nodes that are a part of a cycle can * be labeled as master nodes. This information will later be used to choose the * right master where the writes should go. * * This function also populates the MYSQL_SERVER_INFO structures group * member. Nodes in a group get a positive group ID where the nodes not in a * group get a group ID of 0. */ void find_graph_cycles(MYSQL_MONITOR *handle, MXS_MONITORED_SERVER *database, int nservers) { struct graph_node graph[nservers]; struct graph_node *stack[nservers]; int nodes = 0; for (MXS_MONITORED_SERVER *db = database; db; db = db->next) { graph[nodes].info = get_server_info(handle, db); graph[nodes].db = db; graph[nodes].index = graph[nodes].lowest_index = 0; graph[nodes].cycle = 0; graph[nodes].active = false; graph[nodes].parent = NULL; nodes++; } /** Build the graph */ for (int i = 0; i < nservers; i++) { if (graph[i].info->slave_status.master_server_id > 0) { /** Found a connected node */ for (int k = 0; k < nservers; k++) { if (graph[k].info->server_id == graph[i].info->slave_status.master_server_id) { graph[i].parent = &graph[k]; break; } } } } int index = 1; int cycle = 0; int stacksize = 0; for (int i = 0; i < nservers; i++) { if (graph[i].index == 0) { /** Index is 0, this node has not yet been visited */ visit_node(&graph[i], stack, &stacksize, &index, &cycle); } } for (int i = 0; i < nservers; i++) { graph[i].info->group = graph[i].cycle; if (graph[i].cycle > 0) { /** We have at least one cycle in the graph */ if (graph[i].info->read_only) { monitor_set_pending_status(graph[i].db, SERVER_SLAVE); monitor_clear_pending_status(graph[i].db, SERVER_MASTER); } else { monitor_set_pending_status(graph[i].db, SERVER_MASTER); monitor_clear_pending_status(graph[i].db, SERVER_SLAVE); } } else if (handle->detectStaleMaster && cycle == 0 && graph[i].db->server->status & SERVER_MASTER && (graph[i].db->pending_status & SERVER_MASTER) == 0) { /** * Stale master detection is handled here for multi-master mode. * * If we know that no cycles were found from the graph and that a * server once had the master status, replication has broken * down. These masters are assigned the stale master status allowing * them to be used as masters even if they lose their slaves. A * slave in this case can be either a normal slave or another * master. */ if (graph[i].info->read_only) { /** The master is in read-only mode, set it into Slave state */ monitor_set_pending_status(graph[i].db, SERVER_SLAVE); monitor_clear_pending_status(graph[i].db, SERVER_MASTER | SERVER_STALE_STATUS); } else { monitor_set_pending_status(graph[i].db, SERVER_MASTER | SERVER_STALE_STATUS); monitor_clear_pending_status(graph[i].db, SERVER_SLAVE); } } } } /** * @brief Check whether standalone master conditions have been met * * This function checks whether all the conditions to use a standalone master have * been met. For this to happen, only one server must be available and * other servers must have passed the configured tolerance level of failures. * * @param handle Monitor instance * @param db Monitor servers * * @return True if standalone master should be used */ bool standalone_master_required(MYSQL_MONITOR *handle, MXS_MONITORED_SERVER *db) { int candidates = 0; while (db) { if (SERVER_IS_RUNNING(db->server)) { candidates++; MySqlServerInfo *server_info = get_server_info(handle, db); if (server_info->read_only || server_info->slave_configured || candidates > 1) { return false; } } else if (db->mon_err_count < handle->failcount) { return false; } db = db->next; } return candidates == 1; } /** * @brief Use standalone master * * This function assigns the last remaining server the master status and sets all other * servers into maintenance mode. By setting the servers into maintenance mode, we * prevent any possible conflicts when the failed servers come back up. * * @param handle Monitor instance * @param db Monitor servers */ void set_standalone_master(MYSQL_MONITOR *handle, MXS_MONITORED_SERVER *db) { while (db) { if (SERVER_IS_RUNNING(db->server)) { if (!SERVER_IS_MASTER(db->server) && handle->warn_set_standalone_master) { MXS_WARNING("Setting standalone master, server '%s' is now the master.%s", db->server->unique_name, handle->allow_cluster_recovery ? "" : " All other servers are set into maintenance mode."); handle->warn_set_standalone_master = false; } server_clear_set_status(db->server, SERVER_SLAVE, SERVER_MASTER | SERVER_STALE_STATUS); monitor_set_pending_status(db, SERVER_MASTER | SERVER_STALE_STATUS); monitor_clear_pending_status(db, SERVER_SLAVE); handle->master = db; } else if (!handle->allow_cluster_recovery) { server_set_status_nolock(db->server, SERVER_MAINT); monitor_set_pending_status(db, SERVER_MAINT); } db = db->next; } } bool failover_not_possible(MYSQL_MONITOR* handle) { bool rval = false; for (MXS_MONITORED_SERVER* s = handle->monitor->monitored_servers; s; s = s->next) { MySqlServerInfo* info = get_server_info(handle, s); if (info->n_slaves_configured > 1) { MXS_ERROR("Server '%s' is configured to replicate from multiple " "masters, failover is not possible.", s->server->unique_name); rval = true; } } return rval; } /** * The entry point for the monitoring module thread * * @param arg The handle of the monitor */ static void monitorMain(void *arg) { MYSQL_MONITOR *handle = (MYSQL_MONITOR *) arg; MXS_MONITOR* mon = handle->monitor; MXS_MONITORED_SERVER *ptr; int replication_heartbeat; bool detect_stale_master; int num_servers = 0; MXS_MONITORED_SERVER *root_master = NULL; size_t nrounds = 0; int log_no_master = 1; bool heartbeat_checked = false; replication_heartbeat = handle->replicationHeartbeat; detect_stale_master = handle->detectStaleMaster; if (mysql_thread_init()) { MXS_ERROR("mysql_thread_init failed in monitor module. Exiting."); handle->status = MXS_MONITOR_STOPPED; return; } load_server_journal(mon, &handle->master); while (1) { if (handle->shutdown) { handle->status = MXS_MONITOR_STOPPING; mysql_thread_end(); handle->status = MXS_MONITOR_STOPPED; return; } /** Wait base interval */ thread_millisleep(MXS_MON_BASE_INTERVAL_MS); if (handle->replicationHeartbeat && !heartbeat_checked) { check_maxscale_schema_replication(mon); heartbeat_checked = true; } /** * Calculate how far away the monitor interval is from its full * cycle and if monitor interval time further than the base * interval, then skip monitoring checks. Excluding the first * round. */ if (nrounds != 0 && (((nrounds * MXS_MON_BASE_INTERVAL_MS) % mon->interval) >= MXS_MON_BASE_INTERVAL_MS) && (!mon->server_pending_changes)) { nrounds += 1; continue; } nrounds += 1; /* reset num_servers */ num_servers = 0; lock_monitor_servers(mon); servers_status_pending_to_current(mon); /* start from the first server in the list */ ptr = mon->monitored_servers; while (ptr) { ptr->mon_prev_status = ptr->server->status; /* copy server status into monitor pending_status */ ptr->pending_status = ptr->server->status; /* monitor current node */ monitorDatabase(mon, ptr); /* reset the slave list of current node */ memset(&ptr->server->slaves, 0, sizeof(ptr->server->slaves)); num_servers++; if (mon_status_changed(ptr)) { if (SRV_MASTER_STATUS(ptr->mon_prev_status)) { /** Master failed, can't recover */ MXS_NOTICE("Server [%s]:%d lost the master status.", ptr->server->name, ptr->server->port); } } if (mon_status_changed(ptr)) { #if defined(SS_DEBUG) MXS_INFO("Backend server [%s]:%d state : %s", ptr->server->name, ptr->server->port, STRSRVSTATUS(ptr->server)); #else MXS_DEBUG("Backend server [%s]:%d state : %s", ptr->server->name, ptr->server->port, STRSRVSTATUS(ptr->server)); #endif } if (SERVER_IS_DOWN(ptr->server)) { /** Increase this server'e error count */ ptr->mon_err_count += 1; } else { /** Reset this server's error count */ ptr->mon_err_count = 0; } ptr = ptr->next; } ptr = mon->monitored_servers; /* if only one server is configured, that's is Master */ if (num_servers == 1) { if (SERVER_IS_RUNNING(ptr->server)) { ptr->server->depth = 0; /* status cleanup */ monitor_clear_pending_status(ptr, SERVER_SLAVE); /* master status set */ monitor_set_pending_status(ptr, SERVER_MASTER); ptr->server->depth = 0; handle->master = ptr; root_master = ptr; } } else { /* Compute the replication tree */ if (handle->mysql51_replication) { root_master = build_mysql51_replication_tree(mon); } else { root_master = get_replication_tree(mon, num_servers); } } if (handle->multimaster && num_servers > 0) { /** Find all the master server cycles in the cluster graph. If multiple masters are found, the servers with the read_only variable set to ON will be assigned the slave status. */ find_graph_cycles(handle, mon->monitored_servers, num_servers); } ptr = mon->monitored_servers; while (ptr) { MySqlServerInfo *serv_info = get_server_info(handle, ptr); ss_dassert(serv_info); if (ptr->server->node_id > 0 && ptr->server->master_id > 0 && getSlaveOfNodeId(mon->monitored_servers, ptr->server->node_id) && getServerByNodeId(mon->monitored_servers, ptr->server->master_id) && (!handle->multimaster || serv_info->group == 0)) { /** This server is both a slave and a master i.e. a relay master */ monitor_set_pending_status(ptr, SERVER_RELAY_MASTER); monitor_clear_pending_status(ptr, SERVER_MASTER); } /* Remove SLAVE status if this server is a Binlog Server relay */ if (serv_info->binlog_relay) { monitor_clear_pending_status(ptr, SERVER_SLAVE); } ptr = ptr->next; } /* Update server status from monitor pending status on that server*/ ptr = mon->monitored_servers; while (ptr) { if (!SERVER_IN_MAINT(ptr->server)) { MySqlServerInfo *serv_info = get_server_info(handle, ptr); /** If "detect_stale_master" option is On, let's use the previous master. * * Multi-master mode detects the stale masters in find_graph_cycles(). */ if (detect_stale_master && root_master && !handle->multimaster && (strcmp(ptr->server->name, root_master->server->name) == 0 && ptr->server->port == root_master->server->port) && (ptr->server->status & SERVER_MASTER) && !(ptr->pending_status & SERVER_MASTER) && !serv_info->read_only) { /** * In this case server->status will not be updated from pending_status * Set the STALE bit for this server in server struct */ server_set_status_nolock(ptr->server, SERVER_STALE_STATUS | SERVER_MASTER); ptr->pending_status |= SERVER_STALE_STATUS | SERVER_MASTER; /** Log the message only if the master server didn't have * the stale master bit set */ if ((ptr->mon_prev_status & SERVER_STALE_STATUS) == 0) { MXS_WARNING("All slave servers under the current master " "server have been lost. Assigning Stale Master" " status to the old master server '%s' (%s:%i).", ptr->server->unique_name, ptr->server->name, ptr->server->port); } } if (handle->detectStaleSlave) { unsigned bits = SERVER_SLAVE | SERVER_RUNNING; if ((ptr->mon_prev_status & bits) == bits && root_master && SERVER_IS_MASTER(root_master->server)) { /** Slave with a running master, assign stale slave candidacy */ if ((ptr->pending_status & bits) == bits) { ptr->pending_status |= SERVER_STALE_SLAVE; } /** Server lost slave when a master is available, remove * stale slave candidacy */ else if ((ptr->pending_status & bits) == SERVER_RUNNING) { ptr->pending_status &= ~SERVER_STALE_SLAVE; } } /** If this server was a stale slave candidate, assign * slave status to it */ else if (ptr->mon_prev_status & SERVER_STALE_SLAVE && ptr->pending_status & SERVER_RUNNING && // Master is down (!root_master || !SERVER_IS_MASTER(root_master->server) || // Master just came up (SERVER_IS_MASTER(root_master->server) && (root_master->mon_prev_status & SERVER_MASTER) == 0))) { ptr->pending_status |= SERVER_SLAVE; } else if (root_master == NULL && serv_info->slave_configured) { ptr->pending_status |= SERVER_SLAVE; } } ptr->server->status = ptr->pending_status; } ptr = ptr->next; } /** Now that all servers have their status correctly set, we can check if we need to use standalone master. */ if (handle->detect_standalone_master) { if (standalone_master_required(handle, mon->monitored_servers)) { /** Other servers have died, set last remaining server as master */ set_standalone_master(handle, mon->monitored_servers); } else { handle->warn_set_standalone_master = true; } } /** * After updating the status of all servers, check if monitor events * need to be launched. */ mon_process_state_changes(mon, handle->script, handle->events); if (handle->failover) { const char* failover_script = handle->failover_script; if (!failover_script) { failover_script = DEFAULT_FAILOVER_SCRIPT; } if (failover_not_possible(handle)) { MXS_ERROR("Failover is not possible due to one or more problems in " "the replication configuration, disabling failover. " "Failover should only be enabled after the replication " "configuration has been fixed. To re-enable failover " "functionality, manually set '%s' to 'true' for monitor " "'%s' via MaxAdmin or the REST API.", CN_FAILOVER, mon->name); handle->failover = false; } else if (master_maybe_dead(handle) && master_still_alive(handle)) { MXS_INFO("Master failure not yet confirmed by slaves, delaying failover."); } else if (!mon_process_failover(handle, failover_script, handle->failover_timeout)) { MXS_ALERT("Failed to perform failover, disabling failover functionality. " "To enable failover functionality, manually set 'failover' to " "'true' for monitor '%s' via MaxAdmin or the REST API.", mon->name); mon_alter_parameter(handle->monitor, CN_FAILOVER, "false"); handle->failover = false; } } /* log master detection failure of first master becomes available after failure */ if (root_master && mon_status_changed(root_master) && !(root_master->server->status & SERVER_STALE_STATUS)) { if (root_master->pending_status & (SERVER_MASTER) && SERVER_IS_RUNNING(root_master->server)) { if (!(root_master->mon_prev_status & SERVER_STALE_STATUS) && !(root_master->server->status & SERVER_MAINT)) { MXS_NOTICE("A Master Server is now available: %s:%i", root_master->server->name, root_master->server->port); } } else { MXS_ERROR("No Master can be determined. Last known was %s:%i", root_master->server->name, root_master->server->port); } log_no_master = 1; } else { if (!root_master && log_no_master) { MXS_ERROR("No Master can be determined"); log_no_master = 0; } } /* Do now the heartbeat replication set/get for MySQL Replication Consistency */ if (replication_heartbeat && root_master && (SERVER_IS_MASTER(root_master->server) || SERVER_IS_RELAY_SERVER(root_master->server))) { set_master_heartbeat(handle, root_master); ptr = mon->monitored_servers; while (ptr) { MySqlServerInfo *serv_info = get_server_info(handle, ptr); if ((!SERVER_IN_MAINT(ptr->server)) && SERVER_IS_RUNNING(ptr->server)) { if (ptr->server->node_id != root_master->server->node_id && (SERVER_IS_SLAVE(ptr->server) || SERVER_IS_RELAY_SERVER(ptr->server)) && !serv_info->binlog_relay) // No select lag for Binlog Server { set_slave_heartbeat(mon, ptr); } } ptr = ptr->next; } } mon_hangup_failed_servers(mon); servers_status_current_to_pending(mon); store_server_journal(mon, handle->master); release_monitor_servers(mon); } /*< while (1) */ } /** * Fetch a MySQL node by node_id * * @param ptr The list of servers to monitor * @param node_id The MySQL server_id to fetch * @return The server with the required server_id */ static MXS_MONITORED_SERVER * getServerByNodeId(MXS_MONITORED_SERVER *ptr, long node_id) { SERVER *current; while (ptr) { current = ptr->server; if (current->node_id == node_id) { return ptr; } ptr = ptr->next; } return NULL; } /** * Fetch a MySQL slave node from a node_id * * @param ptr The list of servers to monitor * @param node_id The MySQL server_id to fetch * @return The slave server of this node_id */ static MXS_MONITORED_SERVER * getSlaveOfNodeId(MXS_MONITORED_SERVER *ptr, long node_id) { SERVER *current; while (ptr) { current = ptr->server; if (current->master_id == node_id) { return ptr; } ptr = ptr->next; } return NULL; } /******* * This function sets the replication heartbeat * into the maxscale_schema.replication_heartbeat table in the current master. * The inserted values will be seen from all slaves replication from this master. * * @param handle The monitor handle * @param database The number database server */ static void set_master_heartbeat(MYSQL_MONITOR *handle, MXS_MONITORED_SERVER *database) { unsigned long id = handle->id; time_t heartbeat; time_t purge_time; char heartbeat_insert_query[512] = ""; char heartbeat_purge_query[512] = ""; MYSQL_RES *result; long returned_rows; if (handle->master == NULL) { MXS_ERROR("set_master_heartbeat called without an available Master server"); return; } /* check if the maxscale_schema database and replication_heartbeat table exist */ if (mxs_mysql_query(database->con, "SELECT table_name FROM information_schema.tables " "WHERE table_schema = 'maxscale_schema' AND table_name = 'replication_heartbeat'")) { MXS_ERROR( "Error checking for replication_heartbeat in Master server" ": %s", mysql_error(database->con)); database->server->rlag = MAX_RLAG_NOT_AVAILABLE; } result = mysql_store_result(database->con); if (result == NULL) { returned_rows = 0; } else { returned_rows = mysql_num_rows(result); mysql_free_result(result); } if (0 == returned_rows) { /* create repl_heartbeat table in maxscale_schema database */ if (mxs_mysql_query(database->con, "CREATE TABLE IF NOT EXISTS " "maxscale_schema.replication_heartbeat " "(maxscale_id INT NOT NULL, " "master_server_id INT NOT NULL, " "master_timestamp INT UNSIGNED NOT NULL, " "PRIMARY KEY ( master_server_id, maxscale_id ) )")) { MXS_ERROR("Error creating maxscale_schema.replication_heartbeat " "table in Master server: %s", mysql_error(database->con)); database->server->rlag = MAX_RLAG_NOT_AVAILABLE; } } /* auto purge old values after 48 hours*/ purge_time = time(0) - (3600 * 48); sprintf(heartbeat_purge_query, "DELETE FROM maxscale_schema.replication_heartbeat WHERE master_timestamp < %lu", purge_time); if (mxs_mysql_query(database->con, heartbeat_purge_query)) { MXS_ERROR("Error deleting from maxscale_schema.replication_heartbeat " "table: [%s], %s", heartbeat_purge_query, mysql_error(database->con)); } heartbeat = time(0); /* set node_ts for master as time(0) */ database->server->node_ts = heartbeat; sprintf(heartbeat_insert_query, "UPDATE maxscale_schema.replication_heartbeat " "SET master_timestamp = %lu WHERE master_server_id = %li AND maxscale_id = %lu", heartbeat, handle->master->server->node_id, id); /* Try to insert MaxScale timestamp into master */ if (mxs_mysql_query(database->con, heartbeat_insert_query)) { database->server->rlag = MAX_RLAG_NOT_AVAILABLE; MXS_ERROR("Error updating maxscale_schema.replication_heartbeat table: [%s], %s", heartbeat_insert_query, mysql_error(database->con)); } else { if (mysql_affected_rows(database->con) == 0) { heartbeat = time(0); sprintf(heartbeat_insert_query, "REPLACE INTO maxscale_schema.replication_heartbeat " "(master_server_id, maxscale_id, master_timestamp ) VALUES ( %li, %lu, %lu)", handle->master->server->node_id, id, heartbeat); if (mxs_mysql_query(database->con, heartbeat_insert_query)) { database->server->rlag = MAX_RLAG_NOT_AVAILABLE; MXS_ERROR("Error inserting into " "maxscale_schema.replication_heartbeat table: [%s], %s", heartbeat_insert_query, mysql_error(database->con)); } else { /* Set replication lag to 0 for the master */ database->server->rlag = 0; MXS_DEBUG("heartbeat table inserted data for %s:%i", database->server->name, database->server->port); } } else { /* Set replication lag as 0 for the master */ database->server->rlag = 0; MXS_DEBUG("heartbeat table updated for Master %s:%i", database->server->name, database->server->port); } } } /******* * This function gets the replication heartbeat * from the maxscale_schema.replication_heartbeat table in the current slave * and stores the timestamp and replication lag in the slave server struct * * @param handle The monitor handle * @param database The number database server */ static void set_slave_heartbeat(MXS_MONITOR* mon, MXS_MONITORED_SERVER *database) { MYSQL_MONITOR *handle = (MYSQL_MONITOR*) mon->handle; unsigned long id = handle->id; time_t heartbeat; char select_heartbeat_query[256] = ""; MYSQL_ROW row; MYSQL_RES *result; if (handle->master == NULL) { MXS_ERROR("set_slave_heartbeat called without an available Master server"); return; } /* Get the master_timestamp value from maxscale_schema.replication_heartbeat table */ sprintf(select_heartbeat_query, "SELECT master_timestamp " "FROM maxscale_schema.replication_heartbeat " "WHERE maxscale_id = %lu AND master_server_id = %li", id, handle->master->server->node_id); /* if there is a master then send the query to the slave with master_id */ if (handle->master != NULL && (mxs_mysql_query(database->con, select_heartbeat_query) == 0 && (result = mysql_store_result(database->con)) != NULL)) { int rows_found = 0; while ((row = mysql_fetch_row(result))) { int rlag = MAX_RLAG_NOT_AVAILABLE; time_t slave_read; rows_found = 1; heartbeat = time(0); slave_read = strtoul(row[0], NULL, 10); if ((errno == ERANGE && (slave_read == LONG_MAX || slave_read == LONG_MIN)) || (errno != 0 && slave_read == 0)) { slave_read = 0; } if (slave_read) { /* set the replication lag */ rlag = heartbeat - slave_read; } /* set this node_ts as master_timestamp read from replication_heartbeat table */ database->server->node_ts = slave_read; if (rlag >= 0) { /* store rlag only if greater than monitor sampling interval */ database->server->rlag = ((unsigned int)rlag > (mon->interval / 1000)) ? rlag : 0; } else { database->server->rlag = MAX_RLAG_NOT_AVAILABLE; } MXS_DEBUG("Slave %s:%i has %i seconds lag", database->server->name, database->server->port, database->server->rlag); } if (!rows_found) { database->server->rlag = MAX_RLAG_NOT_AVAILABLE; database->server->node_ts = 0; } mysql_free_result(result); } else { database->server->rlag = MAX_RLAG_NOT_AVAILABLE; database->server->node_ts = 0; if (handle->master->server->node_id < 0) { MXS_ERROR("error: replication heartbeat: " "master_server_id NOT available for %s:%i", database->server->name, database->server->port); } else { MXS_ERROR("error: replication heartbeat: " "failed selecting from hearthbeat table of %s:%i : [%s], %s", database->server->name, database->server->port, select_heartbeat_query, mysql_error(database->con)); } } } /******* * This function computes the replication tree * from a set of MySQL Master/Slave monitored servers * and returns the root server with SERVER_MASTER bit. * The tree is computed even for servers in 'maintenance' mode. * * @param handle The monitor handle * @param num_servers The number of servers monitored * @return The server at root level with SERVER_MASTER bit */ static MXS_MONITORED_SERVER *get_replication_tree(MXS_MONITOR *mon, int num_servers) { MYSQL_MONITOR* handle = (MYSQL_MONITOR*) mon->handle; MXS_MONITORED_SERVER *ptr; MXS_MONITORED_SERVER *backend; SERVER *current; int depth = 0; long node_id; int root_level; ptr = mon->monitored_servers; root_level = num_servers; while (ptr) { /* The server could be in SERVER_IN_MAINT * that means SERVER_IS_RUNNING returns 0 * Let's check only for SERVER_IS_DOWN: server is not running */ if (SERVER_IS_DOWN(ptr->server)) { ptr = ptr->next; continue; } depth = 0; current = ptr->server; node_id = current->master_id; if (node_id < 1) { MXS_MONITORED_SERVER *find_slave; find_slave = getSlaveOfNodeId(mon->monitored_servers, current->node_id); if (find_slave == NULL) { current->depth = -1; ptr = ptr->next; continue; } else { current->depth = 0; } } else { depth++; } while (depth <= num_servers) { /* set the root master at lowest depth level */ if (current->depth > -1 && current->depth < root_level) { root_level = current->depth; handle->master = ptr; } backend = getServerByNodeId(mon->monitored_servers, node_id); if (backend) { node_id = backend->server->master_id; } else { node_id = -1; } if (node_id > 0) { current->depth = depth + 1; depth++; } else { MXS_MONITORED_SERVER *master; current->depth = depth; master = getServerByNodeId(mon->monitored_servers, current->master_id); if (master && master->server && master->server->node_id > 0) { add_slave_to_master(master->server->slaves, sizeof(master->server->slaves), current->node_id); master->server->depth = current->depth - 1; if (handle->master && master->server->depth < handle->master->server->depth) { /** A master with a lower depth was found, remove the master status from the previous master. */ monitor_clear_pending_status(handle->master, SERVER_MASTER); } MySqlServerInfo* info = get_server_info(handle, master); if (SERVER_IS_RUNNING(master->server)) { /** Only set the Master status if read_only is disabled */ monitor_set_pending_status(master, info->read_only ? SERVER_SLAVE : SERVER_MASTER); } handle->master = master; } else { if (current->master_id > 0) { if (handle->allow_external_slaves) { monitor_set_pending_status(ptr, SERVER_SLAVE); } else { monitor_clear_pending_status(ptr, SERVER_SLAVE); } monitor_set_pending_status(ptr, SERVER_SLAVE_OF_EXTERNAL_MASTER); } } break; } } ptr = ptr->next; } /* * Return the root master */ if (handle->master != NULL) { /* If the root master is in MAINT, return NULL */ if (SERVER_IN_MAINT(handle->master->server)) { return NULL; } else { return handle->master; } } else { return NULL; } } /******* * This function add a slave id into the slaves server field * of its master server * * @param slaves_list The slave list array of the master server * @param list_size The size of the slave list * @param node_id The node_id of the slave to be inserted * @return 1 for inserted value and 0 otherwise */ static int add_slave_to_master(long *slaves_list, int list_size, long node_id) { for (int i = 0; i < list_size; i++) { if (slaves_list[i] == 0) { slaves_list[i] = node_id; return 1; } } return 0; } /** * Check if replicate_ignore_table is defined and if maxscale_schema.replication_hearbeat * table is in the list. * @param database Server to check * @return False if the table is not replicated or an error occurred when querying * the server */ bool check_replicate_ignore_table(MXS_MONITORED_SERVER* database) { MYSQL_RES *result; bool rval = true; if (mxs_mysql_query(database->con, "show variables like 'replicate_ignore_table'") == 0 && (result = mysql_store_result(database->con)) && mysql_num_fields(result) > 1) { MYSQL_ROW row; while ((row = mysql_fetch_row(result))) { if (strlen(row[1]) > 0 && strcasestr(row[1], hb_table_name)) { MXS_WARNING("'replicate_ignore_table' is " "defined on server '%s' and '%s' was found in it. ", database->server->unique_name, hb_table_name); rval = false; } } mysql_free_result(result); } else { MXS_ERROR("Failed to query server %s for " "'replicate_ignore_table': %s", database->server->unique_name, mysql_error(database->con)); rval = false; } return rval; } /** * Check if replicate_do_table is defined and if maxscale_schema.replication_hearbeat * table is not in the list. * @param database Server to check * @return False if the table is not replicated or an error occurred when querying * the server */ bool check_replicate_do_table(MXS_MONITORED_SERVER* database) { MYSQL_RES *result; bool rval = true; if (mxs_mysql_query(database->con, "show variables like 'replicate_do_table'") == 0 && (result = mysql_store_result(database->con)) && mysql_num_fields(result) > 1) { MYSQL_ROW row; while ((row = mysql_fetch_row(result))) { if (strlen(row[1]) > 0 && strcasestr(row[1], hb_table_name) == NULL) { MXS_WARNING("'replicate_do_table' is " "defined on server '%s' and '%s' was not found in it. ", database->server->unique_name, hb_table_name); rval = false; } } mysql_free_result(result); } else { MXS_ERROR("Failed to query server %s for " "'replicate_do_table': %s", database->server->unique_name, mysql_error(database->con)); rval = false; } return rval; } /** * Check if replicate_wild_do_table is defined and if it doesn't match * maxscale_schema.replication_heartbeat. * @param database Database server * @return False if the table is not replicated or an error occurred when trying to * query the server. */ bool check_replicate_wild_do_table(MXS_MONITORED_SERVER* database) { MYSQL_RES *result; bool rval = true; if (mxs_mysql_query(database->con, "show variables like 'replicate_wild_do_table'") == 0 && (result = mysql_store_result(database->con)) && mysql_num_fields(result) > 1) { MYSQL_ROW row; while ((row = mysql_fetch_row(result))) { if (strlen(row[1]) > 0) { mxs_pcre2_result_t rc = modutil_mysql_wildcard_match(row[1], hb_table_name); if (rc == MXS_PCRE2_NOMATCH) { MXS_WARNING("'replicate_wild_do_table' is " "defined on server '%s' and '%s' does not match it. ", database->server->unique_name, hb_table_name); rval = false; } } } mysql_free_result(result); } else { MXS_ERROR("Failed to query server %s for " "'replicate_wild_do_table': %s", database->server->unique_name, mysql_error(database->con)); rval = false; } return rval; } /** * Check if replicate_wild_ignore_table is defined and if it matches * maxscale_schema.replication_heartbeat. * @param database Database server * @return False if the table is not replicated or an error occurred when trying to * query the server. */ bool check_replicate_wild_ignore_table(MXS_MONITORED_SERVER* database) { MYSQL_RES *result; bool rval = true; if (mxs_mysql_query(database->con, "show variables like 'replicate_wild_ignore_table'") == 0 && (result = mysql_store_result(database->con)) && mysql_num_fields(result) > 1) { MYSQL_ROW row; while ((row = mysql_fetch_row(result))) { if (strlen(row[1]) > 0) { mxs_pcre2_result_t rc = modutil_mysql_wildcard_match(row[1], hb_table_name); if (rc == MXS_PCRE2_MATCH) { MXS_WARNING("'replicate_wild_ignore_table' is " "defined on server '%s' and '%s' matches it. ", database->server->unique_name, hb_table_name); rval = false; } } } mysql_free_result(result); } else { MXS_ERROR("Failed to query server %s for " "'replicate_wild_do_table': %s", database->server->unique_name, mysql_error(database->con)); rval = false; } return rval; } /** * Check if the maxscale_schema.replication_heartbeat table is replicated on all * servers and log a warning if problems were found. * @param monitor Monitor structure */ void check_maxscale_schema_replication(MXS_MONITOR *monitor) { MXS_MONITORED_SERVER* database = monitor->monitored_servers; bool err = false; while (database) { mxs_connect_result_t rval = mon_ping_or_connect_to_db(monitor, database); if (rval == MONITOR_CONN_OK) { if (!check_replicate_ignore_table(database) || !check_replicate_do_table(database) || !check_replicate_wild_do_table(database) || !check_replicate_wild_ignore_table(database)) { err = true; } } else { mon_log_connect_error(database, rval); } database = database->next; } if (err) { MXS_WARNING("Problems were encountered when checking if '%s' is replicated. Make sure that " "the table is replicated to all slaves.", hb_table_name); } } /** * @brief Process possible failover event * * If a master failure has occurred and MaxScale is configured with failover * functionality, this fuction executes an external failover program to elect * a new master server. * * This function should be called immediately after @c mon_process_state_changes. * * @param monitor Monitor whose cluster is processed * @param failover_script The script to be used for performing the failover. * @param failover_timeout Timeout in seconds for the failover * * @return True on success, false on error * * @todo Currently this only works with flat replication topologies and * needs to be moved inside mysqlmon as it is MariaDB specific code. */ bool mon_process_failover(MYSQL_MONITOR* monitor, const char* failover_script, uint32_t failover_timeout) { bool rval = true; MXS_CONFIG* cnf = config_get_global_options(); MXS_MONITORED_SERVER* failed_master = NULL; for (MXS_MONITORED_SERVER *ptr = monitor->monitor->monitored_servers; ptr; ptr = ptr->next) { if (ptr->new_event && !cnf->passive && ptr->server->last_event == MASTER_DOWN_EVENT) { if (failed_master) { MXS_ALERT("Multiple failed master servers detected: " "'%s' is the first master to fail but server " "'%s' has also triggered a master_down event.", failed_master->server->unique_name, ptr->server->unique_name); return false; } if (ptr->server->active_event) { // MaxScale was active when the event took place failed_master = ptr; ptr->new_event = false; } else if (monitor->monitor->master_has_failed) { /** * If a master_down event was triggered when this MaxScale was * passive, we need to execute the failover script again if no new * masters have appeared. */ int64_t timeout = SEC_TO_HB(failover_timeout); int64_t t = hkheartbeat - ptr->server->triggered_at; if (t > timeout) { MXS_WARNING("Failover of server '%s' did not take place within " "%u seconds, failover needs to be re-triggered", ptr->server->unique_name, failover_timeout); failed_master = ptr; ptr->new_event = false; } } } } if (failed_master) { MXS_NOTICE("Performing automatic failover to replace failed master '%s'.", failed_master->server->unique_name); rval = do_failover(monitor); } return rval; } /** * Selects a new master. Also adds slaves which should be redirected to an array. * * @param mon The monitor * @param out_slaves Vector for storing slave servers, can be NULL * @return The found master, or NULL if not found */ MXS_MONITORED_SERVER* failover_select_new_master(MYSQL_MONITOR* mon, ServerVector* out_slaves) { /* Select a new master candidate. Selects the one with the latest event in relay log. * If multiple slaves have same number of events, select the one with most processed events. */ MXS_MONITORED_SERVER* new_master = NULL; MySqlServerInfo* new_master_info = NULL; int master_vector_index = -1; for (MXS_MONITORED_SERVER *mon_server = mon->monitor->monitored_servers; mon_server; mon_server = mon_server->next) { MySqlServerInfo* cand_info = get_server_info(mon, mon_server); if (cand_info->slave_status.slave_sql_running && update_replication_settings(mon_server, cand_info) && update_gtid_slave_pos(mon_server, cand_info->slave_status.gtid_io_pos.domain, cand_info)) { if (out_slaves) { out_slaves->push_back(mon_server); } if (cand_info->rpl_settings.log_bin == false) { MXS_WARNING("Failover: Slave '%s' has binary log disabled and is not a valid promotion " "candidate.", mon_server->server->unique_name); continue; } if (cand_info->rpl_settings.gtid_strict_mode == false) { MXS_WARNING("Failover: Slave '%s' has gtid_strict_mode disabled. Enabling this setting is " "recommended. For more information, see " "https://mariadb.com/kb/en/library/gtid/#gtid_strict_mode", mon_server->server->unique_name); } if (cand_info->rpl_settings.log_slave_updates == false) { MXS_WARNING("Failover: Slave '%s' has log_slave_updates disabled. It is a valid candidate " "but replication will break for lagging slaves if '%s' is promoted.", mon_server->server->unique_name, mon_server->server->unique_name); } bool select_this = false; // If no candidate yet, accept any. if (new_master == NULL) { select_this = true; } else { uint64_t cand_io = cand_info->slave_status.gtid_io_pos.sequence; uint64_t cand_processed = cand_info->gtid_slave_pos.sequence; uint64_t master_io = new_master_info->slave_status.gtid_io_pos.sequence; uint64_t master_processed = new_master_info->gtid_slave_pos.sequence; bool cand_updates = cand_info->rpl_settings.log_slave_updates; bool master_updates = new_master_info->rpl_settings.log_slave_updates; // Otherwise accept a slave with a later event in relay log. if (cand_io > master_io || // If io sequences are identical, the slave with more events processed wins. (cand_io == master_io && (cand_processed > master_processed || // Finally, if binlog positions are identical, prefer a slave with log_slave_updates. (cand_processed == master_processed && cand_updates && !master_updates)))) { select_this = true; } } if (select_this) { new_master = mon_server; new_master_info = cand_info; if (out_slaves) { master_vector_index = out_slaves->size() - 1; } } } } if (new_master && out_slaves) { // Remove the selected master from the vector. ServerVector::iterator remove_this = out_slaves->begin(); remove_this += master_vector_index; out_slaves->erase(remove_this); } return new_master; } /** * Waits until the new master has processed all its relay log, or time is up. * * @param mon The monitor * @param new_master The new master * @return True if relay log was processed within time limit, or false if time ran out or an error occurred. */ bool failover_wait_relay_log(MYSQL_MONITOR* mon, MXS_MONITORED_SERVER* new_master) { MySqlServerInfo* master_info = get_server_info(mon, new_master); time_t begin = time(NULL); bool query_ok = true; bool io_pos_changed = false; while (master_info->relay_log_events() > 0 && query_ok && !io_pos_changed && difftime(time(NULL), begin) < mon->failover_timeout) { MXS_NOTICE("Failover: Relay log of server '%s' not yet empty, waiting to clear %" PRId64 " events.", new_master->server->unique_name, master_info->relay_log_events()); thread_millisleep(1000); // Sleep for a while before querying server again. // Todo: check server version before entering failover. Gtid old_gtid_io_pos = master_info->slave_status.gtid_io_pos; query_ok = do_show_slave_status(master_info, new_master, MYSQL_SERVER_VERSION_100) && update_gtid_slave_pos(new_master, old_gtid_io_pos.domain, master_info); io_pos_changed = (old_gtid_io_pos == master_info->slave_status.gtid_io_pos); } bool rval = false; if (master_info->relay_log_events() == 0) { rval = true; } else { const char* reason = "Timeout"; if (!query_ok) { reason = "Query error"; } else if (io_pos_changed) { reason = "Old master sent new event(s)"; } MXS_ERROR("Failover: %s while waiting for server '%s' to process relay log. Cancelling failover.", reason, new_master->server->unique_name); rval = false; } return rval; } /** * Prepares a server for the replication master role. * * @param mon The monitor * @param new_master The new master server * @return True if successful */ bool failover_promote_new_master(MYSQL_MONITOR* mon, MXS_MONITORED_SERVER* new_master) { MXS_NOTICE("Failover: Promoting server '%s' to master.", new_master->server->unique_name); if (mxs_mysql_query(new_master->con, "STOP SLAVE;") == 0 && mxs_mysql_query(new_master->con, "RESET SLAVE ALL;") == 0 && mxs_mysql_query(new_master->con, "SET GLOBAL read_only=0;") == 0) { return true; } else { MXS_WARNING("Failover: Promotion failed: '%s'.", mysql_error(new_master->con)); return false; } } /** * Redirects slaves to replicate from another master server. * * @param mon The monitor * @param slaves An array of slaves * @param new_master The replication master * @return True, if even one slave was redirected, or if there was none to redirect */ bool failover_redirect_slaves(MYSQL_MONITOR* mon, ServerVector& slaves, MXS_MONITORED_SERVER* new_master) { MXS_NOTICE("Failover: Redirecting slaves to new master."); std::stringstream change_cmd_temp; change_cmd_temp << "CHANGE MASTER TO MASTER_HOST = '" << new_master->server->name << "', "; change_cmd_temp << "MASTER_PORT = " << new_master->server->port << ", "; change_cmd_temp << "MASTER_USE_GTID = slave_pos, "; change_cmd_temp << "MASTER_USER = '" << mon->replication_user << "', "; const char MASTER_PW[] = "MASTER_PASSWORD = '"; const char END[] = "';"; #if defined(SS_DEBUG) std::stringstream change_cmd_nopw; change_cmd_nopw << change_cmd_temp.str(); change_cmd_nopw << MASTER_PW << "******" << END;; MXS_DEBUG("Failover: Change master command is '%s'.", change_cmd_nopw.str().c_str()); #endif change_cmd_temp << MASTER_PW << mon->replication_password << END; std::string change_cmd = change_cmd_temp.str(); int fails = 0; int successes = 0; for (ServerVector::const_iterator iter = slaves.begin(); iter != slaves.end(); iter++) { MXS_MONITORED_SERVER* mon_server = *iter; if (mxs_mysql_query(mon_server->con, "STOP SLAVE;") == 0 && mxs_mysql_query(mon_server->con, change_cmd.c_str()) == 0 && mxs_mysql_query(mon_server->con, "START SLAVE;") == 0) { successes++; MXS_NOTICE("Failover: Slave '%s' redirected to new master.", mon_server->server->unique_name); } else { fails++; MXS_ERROR("Failover: Slave '%s' redirection failed: '%s'.", mon_server->server->unique_name, mysql_error(mon_server->con)); } } return (successes + fails) == 0 || successes > 0; } /** * Performs failover for a simple topology (1 master, N slaves, no intermediate masters). * * @param mon Server cluster monitor * @return True if successful */ static bool do_failover(MYSQL_MONITOR* mon) { // Topology has already been tested to be simple. // Step 1: Select new master. Also populate a vector with all slaves not the selected master. ServerVector redirect_slaves; MXS_MONITORED_SERVER* new_master = failover_select_new_master(mon, &redirect_slaves); if (new_master == NULL) { MXS_ERROR("Failover: No suitable promotion candidate found, cancelling."); return false; } // Step 2: Wait until relay log consumed. if (failover_wait_relay_log(mon, new_master) && // Step 3: Stop and reset slave, set read-only to 0. failover_promote_new_master(mon, new_master) && // Step 4: Redirect slaves. failover_redirect_slaves(mon, redirect_slaves, new_master)) { return true; } return false; } /** * Query one row of results, save strings to array. Any additional rows are ignored. * * @param database The database to query. * @param query The query to execute. * @param expected_cols How many columns the result should have. * @param output The output array to populate. * @return True on success. */ static bool query_one_row(MXS_MONITORED_SERVER *database, const char* query, unsigned int expected_cols, StringVector* output) { bool rval = false; MYSQL_RES *result; if (mxs_mysql_query(database->con, query) == 0 && (result = mysql_store_result(database->con)) != NULL) { unsigned int columns = mysql_field_count(database->con); if (columns != expected_cols) { mysql_free_result(result); MXS_ERROR("Unexpected result for '%s'. Expected %d columns, got %d. MySQL Version: %s", query, expected_cols, columns, database->server->version_string); } else { MYSQL_ROW row = mysql_fetch_row(result); if (row) { for (unsigned int i = 0; i < columns; i++) { output->push_back((row[i] != NULL) ? row[i] : ""); } rval = true; } else { MXS_ERROR("Query '%s' returned no rows.", query); } mysql_free_result(result); } } else { mon_report_query_error(database); } return rval; } /** * Query a few miscellaneous replication settings. * * @param database The slave server to query * @param info Where to save results * @return True on success */ static bool update_replication_settings(MXS_MONITORED_SERVER *database, MySqlServerInfo* info) { StringVector row; bool ok = query_one_row(database, "SELECT @@gtid_strict_mode, @@log_bin, @@log_slave_updates;", 3, &row); if (ok) { info->rpl_settings.gtid_strict_mode = (row[0] == "1"); info->rpl_settings.log_bin = (row[1] == "1"); info->rpl_settings.log_slave_updates = (row[2] == "1"); } return ok; } /** * Query gtid_slave_pos and save it to the server info object. * * @param database The server to query. * @param domain Which gtid domain should be saved. * @param info Server info structure for saving result. * @return True if successful */ static bool update_gtid_slave_pos(MXS_MONITORED_SERVER *database, int64_t domain, MySqlServerInfo* info) { StringVector row; bool rval = query_one_row(database, "SELECT @@gtid_slave_pos;", 1, &row); if (rval) { info->gtid_slave_pos = Gtid(row.front().c_str(), domain); } return rval; }