14e38e4e08
Previously, if the server had no gtid:s, the method would fail leading to a confusing error message. This could even totally stop the monitor from working if a recent server version (10.X) did not have any gtid events.
550 lines
20 KiB
C++
550 lines
20 KiB
C++
/*
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* Copyright (c) 2018 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: 2022-01-01
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*
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* On the date above, in accordance with the Business Source License, use
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* of this software will be governed by version 2 or later of the General
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* Public License.
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*/
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#pragma once
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#include "mariadbmon_common.hh"
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#include <functional>
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#include <string>
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#include <memory>
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#include <maxscale/monitor.h>
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#include <maxbase/stopwatch.hh>
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#include "server_utils.hh"
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class QueryResult;
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class MariaDBServer;
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// Server pointer array
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typedef std::vector<MariaDBServer*> ServerArray;
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/**
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* Data required for checking replication topology cycles and other graph algorithms. This data is mostly
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* used by the monitor object, as the data only makes sense in relation to other nodes.
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*/
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struct NodeData
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{
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// Default values for index parameters
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static const int INDEX_NOT_VISITED = 0;
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static const int INDEX_FIRST = 1;
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// Default values for the cycle
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static const int CYCLE_NONE = 0;
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static const int CYCLE_FIRST = 1;
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// Default value for reach
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static const int REACH_UNKNOWN = -1;
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// Bookkeeping for graph searches. May be overwritten by multiple algorithms.
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int index; /* Marks the order in which this node was visited. */
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int lowest_index; /* The lowest index node this node has in its subtree. */
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bool in_stack; /* Is this node currently is the search stack. */
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// Results from algorithm runs. Should only be overwritten when server data has been queried.
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int cycle; /* Which cycle is this node part of, if any. */
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int reach; /* How many servers replicate from this server or its children. */
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ServerArray parents; /* Which nodes is this node replicating from. External masters
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* excluded. */
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ServerArray children; /* Which nodes are replicating from this node. */
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std::vector<int64_t> external_masters; /* Server id:s of external masters. */
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NodeData();
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/**
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* Reset result data to default values. Should be ran when starting an iteration.
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*/
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void reset_results();
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/**
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* Reset index data. Should be ran before an algorithm run.
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*/
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void reset_indexes();
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};
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/**
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* Monitor specific information about a server. Eventually, this will be the primary data structure handled
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* by the monitor. These are initialized in @c init_server_info.
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*/
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class MariaDBServer
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{
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public:
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enum class version
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{
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UNKNOWN, /* Totally unknown. Server has not been connected to yet. */
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OLD, /* Anything older than 5.5. These are no longer supported by the monitor. */
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MARIADB_MYSQL_55, /* MariaDB 5.5 series or MySQL 5.5 and later. Does not have gtid (on MariaDB) so
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* all gtid-related features (failover etc.) are disabled. */
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MARIADB_100, /* MariaDB 10.0 and greater. In practice though, 10.0.2 or greater is assumed.
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* All monitor features are on. */
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BINLOG_ROUTER /* MaxScale binlog server. Requires special handling. */
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};
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enum class BinlogMode
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{
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BINLOG_ON,
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BINLOG_OFF
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};
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// This class groups some miscellaneous replication related settings together.
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class ReplicationSettings
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{
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public:
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bool gtid_strict_mode = false; /* Enable additional checks for replication */
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bool log_bin = false; /* Is binary logging enabled? */
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bool log_slave_updates = false; /* Does the slave write replicated events to binlog? */
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};
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/* Monitored server base class/struct. MariaDBServer does not own the struct, it is not freed
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* (or connection closed) when a MariaDBServer is destroyed. */
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MXS_MONITORED_SERVER* m_server_base = NULL;
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/* What position this server has in the monitor config? Used for tiebreaking between servers. */
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int m_config_index = 0;
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version m_version = version::UNKNOWN; /* Server version/type. */
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int64_t m_server_id = SERVER_ID_UNKNOWN; /* Value of @@server_id. Valid values are
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* 32bit unsigned. */
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int64_t m_gtid_domain_id = GTID_DOMAIN_UNKNOWN; /* The value of gtid_domain_id, the domain which is used
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* for new non-replicated events. */
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bool m_read_only = false; /* Value of @@read_only */
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GtidList m_gtid_current_pos; /* Gtid of latest event. */
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GtidList m_gtid_binlog_pos; /* Gtid of latest event written to binlog. */
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SlaveStatusArray m_slave_status; /* Data returned from SHOW (ALL) SLAVE(S) STATUS */
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NodeData m_node; /* Replication topology data */
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/* Replication lag of the server. Used during calculation so that the actual SERVER struct is
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* only written to once. */
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int m_replication_lag = MXS_RLAG_UNDEFINED;
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/* Has anything that could affect replication topology changed this iteration?
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* Causes: server id, slave connections, read-only. */
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bool m_topology_changed = true;
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/* Miscellaneous replication related settings. These are not normally queried from the server, call
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* 'update_replication_settings' before use. */
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ReplicationSettings m_rpl_settings;
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bool m_print_update_errormsg = true; /* Should an update error be printed? */
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MariaDBServer(MXS_MONITORED_SERVER* monitored_server, int config_index);
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/**
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* Print server information to a json object.
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*
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* @return Json diagnostics object
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*/
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json_t* to_json() const;
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/**
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* Print server information to a string.
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*
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* @return Diagnostics string
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*/
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std::string diagnostics() const;
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/**
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* Query this server.
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*/
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void monitor_server();
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/**
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* Update server version. This method should be called after (re)connecting to a
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* backend. Calling this every monitoring loop is overkill.
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*/
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void update_server_version();
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/**
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* Checks monitor permissions on the server. Sets/clears the SERVER_AUTH_ERROR bit.
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*/
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void check_permissions();
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/**
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* Calculate how many events are left in the relay log of the slave connection.
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*
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* @param slave_conn The slave connection to calculate for
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* @return Number of events in relay log. Always 0 or greater.
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*/
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uint64_t relay_log_events(const SlaveStatus& slave_conn);
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/**
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* Execute a query which returns data. The results are returned as a unique pointer to a QueryResult
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* object. The column names of the results are assumed unique.
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*
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* @param query The query
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* @param errmsg_out Where to store an error message if query fails. Can be null.
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* @return Pointer to query results, or an empty pointer on failure
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*/
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std::unique_ptr<QueryResult> execute_query(const std::string& query, std::string* errmsg_out = NULL);
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/**
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* execute_cmd_ex with query retry ON.
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*/
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bool execute_cmd(const std::string& cmd, std::string* errmsg_out = NULL);
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/**
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* execute_cmd_ex with query retry OFF.
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*/
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bool execute_cmd_no_retry(const std::string& cmd,
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std::string* errmsg_out = NULL, unsigned int* errno_out = NULL);
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/**
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* Update server slave connection information.
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*
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* @param gtid_domain Which gtid domain should be parsed.
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* @param errmsg_out Where to store an error message if query fails. Can be null.
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* @return True on success
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*/
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bool do_show_slave_status(std::string* errmsg_out = NULL);
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/**
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* Query gtid_current_pos and gtid_binlog_pos and save the values to the server.
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*
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* @param errmsg_out Where to store an error message if query fails. Can be null.
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* @return True if query succeeded
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*/
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bool update_gtids(std::string* errmsg_out = NULL);
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/**
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* Query a few miscellaneous replication settings.
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*
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* @param error_out Query error output
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* @return True on success
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*/
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bool update_replication_settings(std::string* error_out = NULL);
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/**
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* Query and save server_id, read_only and (if 10.X) gtid_domain_id.
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*
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* @param errmsg_out Where to store an error message if query fails. Can be null.
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* @return True on success.
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*/
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bool read_server_variables(std::string* errmsg_out = NULL);
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/**
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* Print warnings if gtid_strict_mode or log_slave_updates is off. Does not query the server,
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* so 'update_replication_settings' should have been called recently to update the values.
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*/
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void warn_replication_settings() const;
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/**
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* Wait until server catches up to demotion target. Only considers gtid domains common
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* to this server and the target. The gtid compared to on the demotion target is 'gtid_binlog_pos'.
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* It is not updated during this method.
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*
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* The gtid used for comparison on this server is 'gtid_binlog_pos' if this server has both 'log_bin'
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* and 'log_slave_updates' on, and 'gtid_current_pos' otherwise. This server is updated during the
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* method.
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*
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* @return True, if target server gtid was reached within allotted time
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*/
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bool catchup_to_master(GeneralOpData& op, const GtidList& target);
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/**
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* Find slave connection to the target server. If the IO thread is trying to connect
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* ("Connecting"), the connection is only accepted if the 'Master_Server_Id' is known to be correct.
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* If the IO or the SQL thread is stopped, the connection is not returned.
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*
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* @param target Immediate master or relay server
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* @return The slave status info of the slave thread, or NULL if not found or not accepted
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*/
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const SlaveStatus* slave_connection_status(const MariaDBServer* target) const;
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/**
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* Find slave connection to the target server. Only considers host and port when selecting
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* the connection. A matching connection is accepted even if its IO or SQL thread is stopped.
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*
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* @param target Immediate master or relay server
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* @return The slave status info of the slave thread, or NULL if not found
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*/
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const SlaveStatus* slave_connection_status_host_port(const MariaDBServer* target) const;
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/**
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* Checks if this server can replicate from master. Only considers gtid:s and only detects obvious errors.
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* The non-detected errors will mostly be detected once the slave tries to start replicating.
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*
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* @param master_info Master server
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* @param error_out Details the reason for a negative result
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* @return True if slave can replicate from master
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*/
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bool can_replicate_from(MariaDBServer* master, std::string* error_out);
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/**
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* Redirect one slave server to another master
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*
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* @param change_cmd Change master command, usually generated by generate_change_master_cmd()
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* @return True if slave accepted all commands
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*/
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bool redirect_one_slave(const std::string& change_cmd);
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/**
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* Check if the server can be demoted by switchover.
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*
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* @param reason_out Output explaining why server cannot be demoted
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* @return True if server can be demoted
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*/
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bool can_be_demoted_switchover(std::string* reason_out);
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/**
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* Check if the server can be demoted by failover.
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*
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* @param operation Switchover or failover
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* @param reason_out Output explaining why server cannot be demoted
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* @return True if server can be demoted
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*/
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bool can_be_demoted_failover(std::string* reason_out);
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/**
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* Check if the server can be promoted by switchover or failover.
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*
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* @param op Switchover or failover
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* @param demotion_target The server this should be promoted to
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* @param reason_out Output for the reason server cannot be promoted
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* @return True, if suggested new master is a viable promotion candidate
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*/
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bool can_be_promoted(OperationType op, const MariaDBServer* demotion_target, std::string* reason_out);
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/**
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* Read the file contents and send them as sql queries to the server. Any data
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* returned by the queries is discarded.
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*
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* @param server Server to send queries to
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* @param path Text file path.
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* @param error_out Error output
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* @return True if file was read and all commands were completed successfully
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*/
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bool run_sql_from_file(const std::string& path, json_t** error_out);
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/**
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* Enable any "SLAVESIDE_DISABLED" events. Event scheduler is not touched.
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*
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* @param error_out Error output
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* @return True if all SLAVESIDE_DISABLED events were enabled
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*/
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bool enable_events(json_t** error_out);
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/**
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* Disable any "ENABLED" events. Event scheduler is not touched.
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*
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* @param binlog_mode If OFF, binlog event creation is disabled for the session during method execution.
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* @param error_out Error output
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* @return True if all ENABLED events were disabled
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*/
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bool disable_events(BinlogMode binlog_mode, json_t** error_out);
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/**
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* Stop and delete all slave connections.
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*
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* @param error_out Error output
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* @return True if successful. If false, some connections may have been successfully deleted.
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*/
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bool reset_all_slave_conns(json_t** error_out);
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/**
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* Promote this server to take role of demotion target. Remove slave connections from this server.
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* If target is/was a master, set read-only to OFF. Copy slave connections from target.
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*
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* @param op Cluster operation descriptor
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* @return True if successful
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*/
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bool promote(GeneralOpData& op, ServerOperation& promotion, OperationType type,
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const MariaDBServer* demotion_target);
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/**
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* Demote this server. Removes all slave connections. If server was master, sets read_only.
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*
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* @param op Cluster operation descriptor
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* @return True if successful
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*/
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bool demote(GeneralOpData& general, ServerOperation& op);
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/**
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* Redirect the slave connection going to old master to replicate from new master.
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*
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* @param op Operation descriptor
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* @param old_conn The connection which is redirected
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* @param new_master The new master for the redirected connection
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* @return True on success
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*/
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bool redirect_existing_slave_conn(GeneralOpData& op, const SlaveStatus& old_conn,
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const MariaDBServer* new_master);
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/**
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* Copy slave connections to this server. This is usually needed during switchover promotion and on
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* the demoted server. It is assumed that all slave connections of this server have
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* been stopped & removed so there will be no conflicts with existing connections.
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* A special rule is applied to a connection which points to this server itself: that connection
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* is directed towards the 'replacement'. This is required to properly handle connections between
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* the promotion and demotion targets.
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*
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* @param op Operation descriptor
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* @params conns_to_copy The connections to add to the server
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* @params replacement Which server should rep
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* @return True on success
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*/
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bool copy_slave_conns(GeneralOpData& op, const SlaveStatusArray& conns_to_copy,
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const MariaDBServer* replacement);
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/**
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* Create a new slave connection on the server and start it.
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*
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* @param op Operation descriptor
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* @param slave_conn Existing connection to emulate
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* @return True on success
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*/
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bool create_start_slave(GeneralOpData& op, const SlaveStatus& slave_conn);
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/**
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* Is binary log on? 'update_replication_settings' should be ran before this function to query the data.
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*
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* @return True if server has binary log enabled
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*/
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bool binlog_on() const;
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/**
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* Check if server is a running master.
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*
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* @return True if server is a master
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*/
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bool is_master() const;
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/**
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* Check if server is a running slave.
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*
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* @return True if server is a slave
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*/
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bool is_slave() const;
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/**
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* Check if server is a slave of an external server.
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*
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* @return True if server is a slave of an external server
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*/
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bool is_slave_of_ext_master() const;
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/**
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* Check if server is running and not in maintenance.
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*
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* @return True if server is usable
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*/
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bool is_usable() const;
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/**
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* Check if server is running.
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*
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* @return True if server is running
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*/
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bool is_running() const;
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/**
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* Check if server is down.
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*
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* @return True if server is down
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*/
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bool is_down() const;
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/**
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* Check if server is in maintenance.
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*/
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bool is_in_maintenance() const;
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/**
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* Is the server a relay master.
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*/
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bool is_relay_master() const;
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/**
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* Is the server low on disk space?
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*/
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bool is_low_on_disk_space() const;
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/**
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* Check if server has the given bits on in 'pending_status'.
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*
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* @param bits Bits to check
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* @return True if all given bits are on
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*/
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bool has_status(uint64_t bits) const;
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/**
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* Check if server has the given bits on in 'mon_prev_status'.
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*
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* @param bits Bits to check
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* @return True if all given bits are on
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*/
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bool had_status(uint64_t bits) const;
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/**
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* Getter for m_read_only.
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*
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* @return True if server is in read_only mode
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*/
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bool is_read_only() const;
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/**
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* Returns the server name.
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*
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* @return Server unique name
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*/
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const char* name() const;
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/**
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* Clear server pending status flags.
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*
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* @param bits Which flags to clear
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*/
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void clear_status(uint64_t bits);
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/**
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* Set server pending status flags.
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*
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* @param bits Which flags to set
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*/
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void set_status(uint64_t bits);
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private:
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class EventInfo;
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typedef std::function<void (const EventInfo&, json_t** error_out)> ManipulatorFunc;
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enum class StopMode
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{
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STOP_ONLY,
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RESET,
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RESET_ALL
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};
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enum class QueryRetryMode
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{
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ENABLED,
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DISABLED
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};
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enum class ReadOnlySetting
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{
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ENABLE,
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DISABLE
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};
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bool update_slave_status(std::string* errmsg_out = NULL);
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bool sstatus_array_topology_equal(const SlaveStatusArray& new_slave_status);
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const SlaveStatus* sstatus_find_previous_row(const SlaveStatus& new_row, size_t guess);
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void warn_event_scheduler();
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bool events_foreach(ManipulatorFunc& func, json_t** error_out);
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bool alter_event(const EventInfo& event, const std::string& target_status,
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json_t** error_out);
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bool stop_slave_conn(const std::string& conn_name, StopMode mode, maxbase::Duration time_limit,
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json_t** error_out);
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bool remove_slave_conns(GeneralOpData& op, const SlaveStatusArray& conns_to_remove);
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bool execute_cmd_ex(const std::string& cmd, QueryRetryMode mode,
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std::string* errmsg_out = NULL, unsigned int* errno_out = NULL);
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bool execute_cmd_time_limit(const std::string& cmd, maxbase::Duration time_limit,
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std::string* errmsg_out);
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bool set_read_only(ReadOnlySetting value, maxbase::Duration time_limit, json_t** error_out);
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bool merge_slave_conns(GeneralOpData& op, const SlaveStatusArray& conns_to_merge);
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std::string generate_change_master_cmd(GeneralOpData& op, const SlaveStatus& slave_conn);
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};
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