channel_observation_manager.h

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/* Copyright (c) 2015, 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.
 
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   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
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   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
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   Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301  USA */
 
#ifndef CHANNEL_OBSERVATION_MANAGER_INCLUDE
#define CHANNEL_OBSERVATION_MANAGER_INCLUDE
 
#include <mysql/group_replication_priv.h>
#include <list>
 
#include "my_inttypes.h"
#include "mysql/plugin.h"
 
class Channel_observation_manager;
 
/**
  A interface class to code channel state response methods
*/
class Channel_state_observer {
 public:
  virtual ~Channel_state_observer() = 0;
  virtual int thread_start(Binlog_relay_IO_param *param) = 0;
  virtual int thread_stop(Binlog_relay_IO_param *param) = 0;
  virtual int applier_start(Binlog_relay_IO_param *param) = 0;
  virtual int applier_stop(Binlog_relay_IO_param *param, bool aborted) = 0;
  virtual int before_request_transmit(Binlog_relay_IO_param *param,
                                      uint32 flags) = 0;
  virtual int after_read_event(Binlog_relay_IO_param *param, const char *packet,
                               unsigned long len, const char **event_buf,
                               unsigned long *event_len) = 0;
  virtual int after_queue_event(Binlog_relay_IO_param *param,
                                const char *event_buf, unsigned long event_len,
                                uint32 flags) = 0;
  virtual int after_reset_slave(Binlog_relay_IO_param *param) = 0;
  virtual int applier_log_event(Binlog_relay_IO_param *param,
                                Trans_param *trans_param, int &out) = 0;
};
 
/**
  A class to hold different channel observation manager.
 
  @note Slave channels observation and group replication channel observation
        serves different purposes and can interfere with one another.
        For that reason they are separated here.
*/
class Channel_observation_manager_list {
 public:
  /**
    Constructor.
    Initializes the given number of channel observation manager
    and register an observer in the server.
 
    @param plugin_info  The plugin info to register the hooks
    @param num_managers The number of channel observation manager instantiated
  */
  Channel_observation_manager_list(MYSQL_PLUGIN plugin_info, uint num_managers);
 
  /**
    Destructor.
    Unregister the server observer
    and deletes all the channel observation manager.
  */
  ~Channel_observation_manager_list();
 
  /**
    A method to add channel observation manager to the
    channel_observation_manager list.
 
    @param manager A channel observation manager implementation.
  */
  void add_channel_observation_manager(Channel_observation_manager *manager);
 
  /**
    A method to remove a channel observation manager from
    channel_observation_manager list.
 
    @param manager A channel observation manager implementation.
  */
  void remove_channel_observation_manager(Channel_observation_manager *manager);
 
  /**
    Get all the channel observation manager
 
    @return The list of all channel observation manager
  */
  std::list<Channel_observation_manager *>
      &get_channel_observation_manager_list();
 
  /**
    Get particular channel observation manager
 
    @param  position get iterator value at position
    @return The channel observation manager
  */
  Channel_observation_manager *get_channel_observation_manager(
      uint position = 0);
 
 private:
  /** Server relay log observer struct */
  Binlog_relay_IO_observer server_channel_state_observers;
 
  /** server plugin handle */
  MYSQL_PLUGIN group_replication_plugin_info;
 
  /** list of channel observation manager */
  std::list<Channel_observation_manager *> channel_observation_manager;
};
 
/**
  A class to register observers for channel state events.
*/
class Channel_observation_manager {
 public:
  /**
    Initialize the class.
  */
  Channel_observation_manager();
 
  /**
    Destructor.
    Deletes all the channel state observers.
  */
  ~Channel_observation_manager();
 
  /**
    A method to register observers to the events that come from the server.
 
    @param observer A channel state observer implementation.
  */
  void register_channel_observer(Channel_state_observer *observer);
 
  /**
    A method to remove a channel state observer.
 
    @param observer A channel state observer implementation.
  */
  void unregister_channel_observer(Channel_state_observer *observer);
 
  /**
    Get all registered observers
 
    @note to get the list and while using it, you should take a read lock from
    channel_list_lock (you can use the read_lock_channel_list method)
 
    @return The list of all registered observers
  */
  std::list<Channel_state_observer *> &get_channel_state_observers();
 
  /** Locks the observer list for reads */
  void read_lock_channel_list();
  /** Locks the observer list for writes */
  void write_lock_channel_list();
  /** Unlocks the observer list */
  void unlock_channel_list();
 
 private:
  /** list of channel state observer */
  std::list<Channel_state_observer *> channel_observers;
 
  // run conditions and locks
  Checkable_rwlock *channel_list_lock;
};
 
#endif /* CHANNEL_OBSERVATION_MANAGER_INCLUDE */