b434c94563
If a monitor is started and stopped before the external monitoring thread has had time to start, a deadlock will occur. The first thing that the monitoring threads do is read the monitor handle from the monitor object. This handle is given as the return value of startMonitor and it is stored in the monitor object. As this can still be NULL when the monitor thread starts, the threads use locks to prevent this. The correct way to prevent this is to pass the handle as the thread parameter so that no locks are required.
384 lines
10 KiB
C
384 lines
10 KiB
C
/*
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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: 2019-07-01
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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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/**
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* @file ndbcluster_mon.c - A MySQL cluster SQL node monitor
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*
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* @verbatim
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* Revision History
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*
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* Date Who Description
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* 25/07/14 Massimiliano Pinto Initial implementation
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* 10/11/14 Massimiliano Pinto Added setNetworkTimeout for connect,read,write
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* 08/05/15 Markus Makela Addition of launchable scripts
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*
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* @endverbatim
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*/
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#define MXS_MODULE_NAME "ndbclustermon"
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#include "../mysqlmon.h"
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#include <maxscale/alloc.h>
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static void monitorMain(void *);
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/* @see function load_module in load_utils.c for explanation of the following
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* lint directives.
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*/
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/*lint -e14 */
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/*lint +e14 */
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static void *startMonitor(MXS_MONITOR *, const MXS_CONFIG_PARAMETER *params);
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static void stopMonitor(MXS_MONITOR *);
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static void diagnostics(DCB *, const MXS_MONITOR *);
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static json_t* diagnostics_json(const MXS_MONITOR *);
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bool isNdbEvent(mxs_monitor_event_t event);
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/**
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* The module entry point routine. It is this routine that
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* must populate the structure that is referred to as the
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* "module object", this is a structure with the set of
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* external entry points for this module.
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*
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* @return The module object
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*/
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MXS_MODULE* MXS_CREATE_MODULE()
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{
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MXS_NOTICE("Initialise the MySQL Cluster Monitor module.");
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static MXS_MONITOR_OBJECT MyObject =
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{
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startMonitor,
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stopMonitor,
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diagnostics,
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diagnostics_json
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};
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static MXS_MODULE info =
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{
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MXS_MODULE_API_MONITOR,
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MXS_MODULE_BETA_RELEASE,
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MXS_MONITOR_VERSION,
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"A MySQL cluster SQL node monitor",
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"V2.1.0",
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MXS_NO_MODULE_CAPABILITIES,
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&MyObject,
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NULL, /* Process init. */
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NULL, /* Process finish. */
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NULL, /* Thread init. */
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NULL, /* Thread finish. */
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{
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{
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"script",
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MXS_MODULE_PARAM_PATH,
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NULL,
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MXS_MODULE_OPT_PATH_X_OK
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},
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{
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"events",
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MXS_MODULE_PARAM_ENUM,
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MXS_MONITOR_EVENT_DEFAULT_VALUE,
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MXS_MODULE_OPT_NONE,
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mxs_monitor_event_enum_values
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},
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{MXS_END_MODULE_PARAMS} // No parameters
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}
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};
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return &info;
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}
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/*lint +e14 */
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/**
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* Start the instance of the monitor, returning a handle on the monitor.
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*
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* This function creates a thread to execute the actual monitoring.
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*
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* @return A handle to use when interacting with the monitor
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*/
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static void *
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startMonitor(MXS_MONITOR *mon, const MXS_CONFIG_PARAMETER *params)
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{
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MYSQL_MONITOR *handle = mon->handle;
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bool have_events = false, script_error = false;
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if (handle != NULL)
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{
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handle->shutdown = 0;
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MXS_FREE(handle->script);
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}
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else
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{
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if ((handle = (MYSQL_MONITOR *) MXS_MALLOC(sizeof(MYSQL_MONITOR))) == NULL)
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{
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return NULL;
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}
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handle->shutdown = 0;
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handle->id = MXS_MONITOR_DEFAULT_ID;
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handle->master = NULL;
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handle->monitor = mon;
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}
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handle->script = config_copy_string(params, "script");
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handle->events = config_get_enum(params, "events", mxs_monitor_event_enum_values);
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/** SHOW STATUS doesn't require any special permissions */
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if (!check_monitor_permissions(mon, "SHOW STATUS LIKE 'Ndb_number_of_ready_data_nodes'"))
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{
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MXS_ERROR("Failed to start monitor. See earlier errors for more information.");
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MXS_FREE(handle->script);
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MXS_FREE(handle);
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return NULL;
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}
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if (thread_start(&handle->thread, monitorMain, handle) == NULL)
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{
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MXS_ERROR("Failed to start monitor thread for monitor '%s'.", mon->name);
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MXS_FREE(handle->script);
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MXS_FREE(handle);
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return NULL;
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}
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return handle;
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}
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/**
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* Stop a running monitor
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*
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* @param arg Handle on thr running monior
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*/
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static void
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stopMonitor(MXS_MONITOR *mon)
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{
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MYSQL_MONITOR *handle = (MYSQL_MONITOR *) mon->handle;
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handle->shutdown = 1;
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thread_wait(handle->thread);
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}
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/**
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* Diagnostic interface
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*
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* @param dcb DCB to send output
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* @param arg The monitor handle
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*/
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static void
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diagnostics(DCB *dcb, const MXS_MONITOR *mon)
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{
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}
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/**
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* Diagnostic interface
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*
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* @param dcb DCB to send output
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* @param arg The monitor handle
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*/
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static json_t* diagnostics_json(const MXS_MONITOR *mon)
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{
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return NULL;
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}
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/**
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* Monitor an individual server
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*
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* @param database The database to probe
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*/
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static void
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monitorDatabase(MXS_MONITOR_SERVERS *database, char *defaultUser, char *defaultPasswd, MXS_MONITOR *mon)
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{
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MYSQL_ROW row;
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MYSQL_RES *result;
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int isjoined = 0;
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char *server_string;
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/* Don't even probe server flagged as in maintenance */
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if (SERVER_IN_MAINT(database->server))
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{
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return;
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}
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mxs_connect_result_t rval = mon_ping_or_connect_to_db(mon, database);
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if (rval != MONITOR_CONN_OK)
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{
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server_clear_status_nolock(database->server, SERVER_RUNNING);
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if (mysql_errno(database->con) == ER_ACCESS_DENIED_ERROR)
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{
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server_set_status_nolock(database->server, SERVER_AUTH_ERROR);
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}
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database->server->node_id = -1;
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if (mon_status_changed(database) && mon_print_fail_status(database))
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{
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mon_log_connect_error(database, rval);
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}
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return;
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}
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server_clear_status_nolock(database->server, SERVER_AUTH_ERROR);
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/* If we get this far then we have a working connection */
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server_set_status_nolock(database->server, SERVER_RUNNING);
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/* get server version string */
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server_string = (char *) mysql_get_server_info(database->con);
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if (server_string)
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{
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server_set_version_string(database->server, server_string);
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}
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/* Check if the the SQL node is able to contact one or more data nodes */
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if (mysql_query(database->con, "SHOW STATUS LIKE 'Ndb_number_of_ready_data_nodes'") == 0
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&& (result = mysql_store_result(database->con)) != NULL)
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{
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if (mysql_field_count(database->con) < 2)
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{
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mysql_free_result(result);
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MXS_ERROR("Unexpected result for \"SHOW STATUS LIKE "
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"'Ndb_number_of_ready_data_nodes'\". Expected 2 columns."
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" MySQL Version: %s", server_string);
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return;
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}
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while ((row = mysql_fetch_row(result)))
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{
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if (atoi(row[1]) > 0)
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{
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isjoined = 1;
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}
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}
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mysql_free_result(result);
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}
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/* Check the the SQL node id in the MySQL cluster */
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if (mysql_query(database->con, "SHOW STATUS LIKE 'Ndb_cluster_node_id'") == 0
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&& (result = mysql_store_result(database->con)) != NULL)
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{
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if (mysql_field_count(database->con) < 2)
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{
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mysql_free_result(result);
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MXS_ERROR("Unexpected result for \"SHOW STATUS LIKE 'Ndb_cluster_node_id'\". "
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"Expected 2 columns."
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" MySQL Version: %s", server_string);
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return;
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}
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long cluster_node_id = -1;
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while ((row = mysql_fetch_row(result)))
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{
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cluster_node_id = strtol(row[1], NULL, 10);
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if ((errno == ERANGE && (cluster_node_id == LONG_MAX
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|| cluster_node_id == LONG_MIN)) || (errno != 0 && cluster_node_id == 0))
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{
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cluster_node_id = -1;
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}
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database->server->node_id = cluster_node_id;
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}
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mysql_free_result(result);
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}
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if (isjoined)
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{
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server_set_status_nolock(database->server, SERVER_NDB);
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database->server->depth = 0;
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}
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else
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{
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server_clear_status_nolock(database->server, SERVER_NDB);
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database->server->depth = -1;
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}
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}
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/**
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* The entry point for the monitoring module thread
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*
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* @param arg The handle of the monitor
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*/
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static void
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monitorMain(void *arg)
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{
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MYSQL_MONITOR *handle = (MYSQL_MONITOR*)arg;
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MXS_MONITOR* mon = handle->monitor;
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MXS_MONITOR_SERVERS *ptr;
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size_t nrounds = 0;
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if (mysql_thread_init())
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{
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MXS_ERROR("Fatal : mysql_thread_init failed in monitor module. Exiting.");
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return;
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}
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handle->status = MXS_MONITOR_RUNNING;
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while (1)
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{
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if (handle->shutdown)
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{
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handle->status = MXS_MONITOR_STOPPING;
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mysql_thread_end();
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handle->status = MXS_MONITOR_STOPPED;
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return;
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}
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/** Wait base interval */
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thread_millisleep(MXS_MON_BASE_INTERVAL_MS);
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/**
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* Calculate how far away the monitor interval is from its full
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* cycle and if monitor interval time further than the base
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* interval, then skip monitoring checks. Excluding the first
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* round.
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*/
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if (nrounds != 0 &&
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((nrounds * MXS_MON_BASE_INTERVAL_MS) % mon->interval) >=
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MXS_MON_BASE_INTERVAL_MS)
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{
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nrounds += 1;
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continue;
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}
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nrounds += 1;
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lock_monitor_servers(mon);
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servers_status_pending_to_current(mon);
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ptr = mon->databases;
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while (ptr)
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{
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ptr->mon_prev_status = ptr->server->status;
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monitorDatabase(ptr, mon->user, mon->password, mon);
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if (ptr->server->status != ptr->mon_prev_status ||
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SERVER_IS_DOWN(ptr->server))
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{
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MXS_DEBUG("Backend server [%s]:%d state : %s",
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ptr->server->name,
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ptr->server->port,
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STRSRVSTATUS(ptr->server));
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}
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ptr = ptr->next;
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}
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/**
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* After updating the status of all servers, check if monitor events
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* need to be launched.
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*/
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mon_process_state_changes(mon, handle->script, handle->events);
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mon_hangup_failed_servers(mon);
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servers_status_current_to_pending(mon);
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release_monitor_servers(mon);
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}
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}
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