connection_acceptor.h

/*
   Copyright (c) 2013, 2022, 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 also distributed 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 included with MySQL.

   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 CONNECTION_ACCEPTOR_INCLUDED
#define CONNECTION_ACCEPTOR_INCLUDED

#include "sql/conn_handler/channel_info.h"                // Channel_info
#include "sql/conn_handler/connection_handler_manager.h"  // Connection_handler_manager

/**
  This class presents a generic interface to initialize and run
  a connection event loop for different types of listeners and
  a callback functor to call on the connection event from the
  listener that listens for connection. Listener type should
  be a class providing methods setup_listener, listen_for_
  connection_event and close_listener. The Connection event
  callback functor object would on receiving connection event
  from the client to process the connection.
*/
template <typename Listener>
class Connection_acceptor {
  Listener *m_listener;

 public:
  Connection_acceptor(Listener *listener) : m_listener(listener) {}

  ~Connection_acceptor() { delete m_listener; }

  /**
    Initialize a connection acceptor.

    @retval   return true if initialization failed, else false.
  */
  bool init_connection_acceptor() { return m_listener->setup_listener(); }

  /**
    Connection acceptor loop to accept connections from clients.
  */
  void connection_event_loop() {
    Connection_handler_manager *mgr =
        Connection_handler_manager::get_instance();
    while (!connection_events_loop_aborted()) {
      Channel_info *channel_info = m_listener->listen_for_connection_event();
      if (channel_info != nullptr) mgr->process_new_connection(channel_info);
    }
  }

  /**
     Spawn admin connection handler to accept admin connections from clients if
     create-admin-listener-thread is specified by user on commandline.

    @return true unable to spawn admin connection handler thread else false.
  */
  bool check_and_spawn_admin_connection_handler_thread() const {
    return m_listener->check_and_spawn_admin_connection_handler_thread();
  }

  /**
    Close the listener.
  */
  void close_listener() { m_listener->close_listener(); }
};
#endif  // CONNECTION_ACCEPTOR_INCLUDED