MaxScale/server/modules/monitor/mariadbmon/mariadbserver.hh

#pragma once

/*
 * 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.
 */
#include "mariadbmon_common.hh"
#include <string>
#include <memory>
#include <maxscale/monitor.h>
#include "gtid.hh"

enum print_repl_warnings_t
{
    WARNINGS_ON,
    WARNINGS_OFF
};

class QueryResult;
class MariaDBServer;
// Server pointer array
typedef std::vector<MariaDBServer*> ServerArray;

// Contains data returned by one row of SHOW ALL SLAVES STATUS
class SlaveStatus
{
public:
    enum slave_io_running_t
    {
        SLAVE_IO_YES,
        SLAVE_IO_CONNECTING,
        SLAVE_IO_NO,
    };

    std::string name;               /**< Slave connection name. Must be unique. */
    int64_t master_server_id;       /**< The master's server_id value. Valid ids are 32bit unsigned. -1 is
                                     *   unread/error. */
    std::string master_host;        /**< Master server host name. */
    int master_port;                /**< Master server port. */
    slave_io_running_t slave_io_running; /**< Slave I/O thread running state: "Yes", "Connecting" or "No" */
    bool slave_sql_running;         /**< Slave SQL thread running state, true if "Yes" */
    GtidList gtid_io_pos;           /**< Gtid I/O position of the slave thread. */
    std::string last_error;         /**< Last IO or SQL error encountered. */

    SlaveStatus();
    std::string to_string() const;
    static slave_io_running_t slave_io_from_string(const std::string& str);
    static std::string slave_io_to_string(slave_io_running_t slave_io);
};

// 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)
    {}
};

/**
 * Data required for checking replication topology cycles. Not all of the listed data is used yet.
 */
struct NodeData
{
    static const int INDEX_NOT_VISITED = 0;

    int index;           /* Marks the order in which this node was visited. */
    int lowest_index;    /* The lowest index node this node has in its subtree. */
    int cycle;           /* Which cycle is this node part of, if any. */
    bool in_stack;       /* Is this node currently is the search stack. */
    ServerArray parents; /* Which nodes is this node replicating from. External masters excluded. */
    ServerArray children;/* Which nodes are replicating from this node. */
    std::vector<int64_t> external_masters; /* Server id:s of external masters. */

    NodeData();

    /**
     * Reset the data to default values
     */
    void reset();
};

/**
 * Monitor specific information about a server. Eventually, this will be the primary data structure handled
 * by the monitor. These are initialized in @c init_server_info.
 */
class MariaDBServer
{
public:
    typedef std::vector<SlaveStatus> SlaveStatusArray;
    enum class version
    {
        UNKNOWN,            /* Anything older than 5.5. These are no longer supported by the monitor. */
        MARIADB_MYSQL_55,   /* MariaDB 5.5 series or MySQL 5.5 and later. Does not have gtid (on MariaDB) so
                             * all gtid-related features (failover etc.) are disabled. */
        MARIADB_100,        /* MariaDB 10.0 and greater. In practice though, 10.0.2 or greater is assumed.
                             * All monitor features are on. */
        BINLOG_ROUTER       /* MaxScale binlog server. Requires special handling. */
    };

    MXS_MONITORED_SERVER* m_server_base;    /**< Monitored server base class/struct. MariaDBServer does not
                                              *  own the struct, it is not freed (or connection closed) when
                                              *  a MariaDBServer is destroyed. Can be const on gcc 4.8 */
    bool            m_print_update_errormsg;/**< Should an update error be printed. */
    version         m_version;              /**< Server version/type. */
    int64_t         m_server_id;            /**< Value of @@server_id. Valid values are 32bit unsigned. */

    bool            m_read_only;            /**< Value of @@read_only */
    size_t          m_n_slaves_running;     /**< Number of running slave connections */
    int             m_n_slave_heartbeats;   /**< Number of received heartbeats */
    double          m_heartbeat_period;     /**< The time interval between heartbeats */
    time_t          m_latest_event;         /**< Time when latest event was received from the master */
    int64_t         m_gtid_domain_id;       /**< The value of gtid_domain_id, the domain which is used for
                                              *  new non-replicated events. */
    GtidList        m_gtid_current_pos;     /**< Gtid of latest event. */
    GtidList        m_gtid_binlog_pos;      /**< Gtid of latest event written to binlog. */
    SlaveStatusArray m_slave_status;        /**< Data returned from SHOW SLAVE STATUS */
    ReplicationSettings m_rpl_settings;     /**< Miscellaneous replication related settings */

    NodeData        m_node;                 /**< Replication topology data */
    MariaDBServer(MXS_MONITORED_SERVER* monitored_server);

    /**
     * Calculate how many events are left in the relay log.
     *
     * @return Number of events in relay log according to latest queried info.
     */
    int64_t relay_log_events();

    /**
     * Execute a query which returns data. The results are returned as an auto-pointer to a QueryResult
     * object.
     *
     * @param query The query
     * @param errmsg_out Where to store an error message if query fails. Can be null.
     * @return Pointer to query results, or an empty auto-ptr on failure. Currently, the column names of the
     * results are assumed unique.
     */
    std::auto_ptr<QueryResult> execute_query(const std::string& query, std::string* errmsg_out = NULL);

    /**
     * Update server slave connection information.
     *
     * @param gtid_domain Which gtid domain should be parsed.
     * @param errmsg_out Where to store an error message if query fails. Can be null.
     * @return True on success
     */
    bool do_show_slave_status(std::string* errmsg_out = NULL);

    /**
     * Query gtid_current_pos and gtid_binlog_pos and save the values to the server.
     *
     * @param errmsg_out Where to store an error message if query fails. Can be null.
     * @return True if successful
     */
    bool update_gtids(std::string* errmsg_out = NULL);

    /**
     * Query a few miscellaneous replication settings.
     *
     * @return True on success
     */
    bool update_replication_settings();

    /**
     * Query and save server_id, read_only and (if 10.X) gtid_domain_id.
     *
     * @param errmsg_out Where to store an error message if query fails. Can be null.
     * @return True on success.
     */
    bool read_server_variables(std::string* errmsg_out = NULL);

    /**
     * Check if server has binary log enabled. Print warnings if gtid_strict_mode or log_slave_updates is off.
     *
     * @param print_on Print warnings or not
     * @return True if log_bin is on
     */
    bool check_replication_settings(print_repl_warnings_t print_warnings = WARNINGS_ON);

    /**
     * Wait until server catches up to the target gtid. Only considers gtid domains common to this server
     * and the target gtid. The gtid compared is the gtid_binlog_pos if this server has both log_bin and
     * log_slave_updates on, and gtid_current_pos otherwise.
     *
     * @param target Which gtid must be reached
     * @param timeout Maximum wait time in seconds
     * @param err_out json object for error printing. Can be NULL.
     * @return True, if target gtid was reached within allotted time
     */
    bool wait_until_gtid(const GtidList& target, int timeout, json_t** err_out);

    /**
     * Convenience method for SERVER_IS_MASTER
     *
     * @return True if server is a master
     */
    bool is_master() const;

    /**
     * Convenience method for SERVER_IS_SLAVE
     *
     * @return True if server is a slave
     */
    bool is_slave() const;

    /**
     * Convenience method for SERVER_IS_RUNNING
     *
     * @return True if server is running
     */
    bool is_running() const;

    /**
     * Convenience method for SERVER_IS_DOWN
     *
     * @return True if server is down
     */
    bool is_down() const;

    /**
     * Convenience method for SERVER_IN_MAINT
     */
    bool is_in_maintenance() const;

    /**
     * Convenience method for SERVER_IS_RELAY_SERVER
     */
    bool is_relay_server() const;

    /**
     * Returns the server name.
     *
     * @return Server unique name
     */
    const char* name() const;

    /**
     * Print server information to a json object.
     *
     * @param multimaster Print multimaster group
     * @return Json diagnostics object
     */
    json_t* diagnostics_json(bool multimaster) const;

    /**
     * Print server information to a string.
     *
     * @param multimaster Print multimaster group
     * @return Diagnostics string
     */
    std::string diagnostics(bool multimaster) const;

    /**
     * Check if server is using gtid replication.
     *
     * @param error_out Error output
     * @return True if using gtid-replication. False if not, or if server is not a slave or otherwise does
     * not have a gtid_IO_Pos.
     */
    bool uses_gtid(json_t** error_out);

    /**
     * Update replication settings, gtid:s and slave status of the server.
     *
     * @param server Slave to update
     * @return True on success. False on error, or if server is not a slave (slave SQL not running).
     */
    bool update_slave_info();

    /**
     * Checks if this server can replicate from master. Only considers gtid:s and only detects obvious errors.
     * The non-detected errors will mostly be detected once the slave tries to start replicating.
     *
     * @param master_info Master server
     * @return True if slave can replicate from master
     */
    bool can_replicate_from(MariaDBServer* master);

    /**
     * Redirect one slave server to another master
     *
     * @param change_cmd Change master command, usually generated by generate_change_master_cmd()
     * @return True if slave accepted all commands
     */
    bool redirect_one_slave(const std::string& change_cmd);

    /**
     * Joins this standalone server to the cluster.
     *
     * @param change_cmd Change master command
     * @return True if commands were accepted by server
     */
    bool join_cluster(const std::string& change_cmd);

    /**
     * Waits until this server has processed all its relay log, or time is up.
     *
     * @param seconds_remaining How much time left
     * @param err_out Json error output
     * @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(int seconds_remaining, json_t** err_out);

    /**
     * Read the file contents and send them as sql queries to the server. Any data returned by the queries is
     * discarded.
     *
     * @param server Server to send queries to
     * @param path Text file path.
     * @param error_out Error output
     * @return True if file was read and all commands were completed successfully
     */
    bool run_sql_from_file(const std::string& path, json_t** error_out);

    /**
     * Query and update information of this server. Sets some values for status bits,
     * but these may be added or overridden by later methods.
     *
     * @param base_monitor The base monitor object monitoring this server. Required for connection settings.
     */
    void update_server(MXS_MONITOR* base_monitor);

    /**
     * Clear server pending status flags.
     *
     * @param bits Which flags to clear
     */
    void clear_status(uint64_t bits);

    /**
     * Set server pending status flags.
     *
     * @param bits Which flags to set
     */
    void set_status(uint64_t bits);

private:
    void monitor_server(MXS_MONITOR* base_monitor);
    bool update_slave_status(std::string* errmsg_out = NULL);
    void update_server_info();
};

/**
 * Helper class for simplifying working with resultsets. Used in MariaDBServer.
 */
class QueryResult
{
    // These need to be banned to avoid premature destruction.
    QueryResult(const QueryResult&) = delete;
    QueryResult& operator = (const QueryResult&) = delete;

public:
    QueryResult(MYSQL_RES* resultset = NULL);
    ~QueryResult();

    /**
     * Advance to next row. Affects all result returning functions.
     *
     * @return True if the next row has data, false if the current row was the last one.
     */
    bool next_row();

    /**
     * Get the index of the current row.
     *
     * @return Current row index, or -1 if no data or next_row() has not been called yet.
     */
    int64_t get_row_index() const;

    /**
     * How many columns the result set has.
     *
     * @return Column count, or -1 if no data.
     */
    int64_t get_column_count() const;

    /**
     * Get a numeric index for a column name. May give wrong results if column names are not unique.
     *
     * @param col_name Column name
     * @return Index or -1 if not found.
     */
    int64_t get_col_index(const std::string& col_name) const;

    /**
     * Read a string value from the current row and given column. Empty string and (null) are both interpreted
     * as the empty string.
     *
     * @param column_ind Column index
     * @return Value as string
     */
    std::string get_string(int64_t column_ind) const;

    /**
     * Read a non-negative integer value from the current row and given column.
     *
     * @param column_ind Column index
     * @return Value as integer. 0 or greater indicates success, -1 is returned on error.
     */
    int64_t get_uint(int64_t column_ind) const;

    /**
     * Read a boolean value from the current row and given column.
     *
     * @param column_ind Column index
     * @return Value as boolean. Returns true if the text is either 'Y' or '1'.
     */
    bool get_bool(int64_t column_ind) const;

private:
    MYSQL_RES* m_resultset; // Underlying result set, freed at dtor.
    std::tr1::unordered_map<std::string, int64_t> m_col_indexes; // Map of column name -> index
    int64_t m_columns;     // How many columns does the data have. Usually equal to column index map size.
    MYSQL_ROW m_rowdata;   // Data for current row
    int64_t m_current_row; // Index of current row
};