semisync_replica.h

/*
   Copyright (c) 2006, 2025, Oracle and/or its affiliates.

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License, version 2.0,
   as published by the Free Software Foundation.

   This program is designed to work with certain software (including
   but not limited to OpenSSL) that is licensed under separate terms,
   as designated in a particular file or component or in included license
   documentation.  The authors of MySQL hereby grant you an additional
   permission to link the program and your derivative works with the
   separately licensed software that they have either included with
   the program or referenced in the documentation.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License, version 2.0, for more details.

   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software
   Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301  USA */

#ifndef SEMISYNC_REPLICA_H
#define SEMISYNC_REPLICA_H

#include "my_inttypes.h"
#include "plugin/semisync/semisync.h"

/**
   The extension class for the slave of semi-synchronous replication
*/
class ReplSemiSyncSlave : public ReplSemiSyncBase {
 public:
  ReplSemiSyncSlave() : slave_enabled_(false) {}
  ~ReplSemiSyncSlave() = default;

  void setTraceLevel(unsigned long trace_level) { trace_level_ = trace_level; }

  /* Initialize this class after MySQL parameters are initialized. this
   * function should be called once at bootstrap time.
   */
  int initObject();

  bool getSlaveEnabled() { return slave_enabled_; }
  void setSlaveEnabled(bool enabled) { slave_enabled_ = enabled; }

  /* A slave reads the semi-sync packet header and separate the metadata
   * from the payload data.
   *
   * Input:
   *  header      - (IN)  packet header pointer
   *  total_len   - (IN)  total packet length: metadata + payload
   *  need_reply  - (IN)  whether the master is waiting for the reply
   *  payload     - (IN)  payload: the replication event
   *  payload_len - (IN)  payload length
   *
   * Return:
   *  0: success;  non-zero: error
   */
  int slaveReadSyncHeader(const char *header, unsigned long total_len,
                          bool *need_reply, const char **payload,
                          unsigned long *payload_len);

  /* A slave replies to the master indicating its replication process.  It
   * indicates that the slave has received all events before the specified
   * binlog position.
   *
   * Input:
   *  mysql            - (IN)  the mysql network connection
   *  binlog_filename  - (IN)  the reply point's binlog file name
   *  binlog_filepos   - (IN)  the reply point's binlog file offset
   *
   * Return:
   *  0: success;  non-zero: error
   */
  int slaveReply(MYSQL *mysql, const char *binlog_filename,
                 my_off_t binlog_filepos);

  int slaveStart(Binlog_relay_IO_param *param);
  int slaveStop(Binlog_relay_IO_param *param);

 private:
  /* True when initObject has been called */
  bool init_done_ = false;
  bool slave_enabled_ = false;  /* semi-sycn is enabled on the slave */
  MYSQL *mysql_reply = nullptr; /* connection to send reply */
};

/* System and status variables for the slave component */
extern bool rpl_semi_sync_replica_enabled;
extern unsigned long rpl_semi_sync_replica_trace_level;
extern char rpl_semi_sync_replica_status;

#endif /* SEMISYNC_REPLICA_H */