text: /* BGP Keepalives.
   * Implements a producer thread to generate BGP keepalives for peers.
   * Copyright (C) 2017 Cumulus Networks, Inc.
   * Quentin Young
   *
   * This file is part of FRRouting.
   *
   * FRRouting is free software; you can redistribute it and/or modify it under
   * the terms of the GNU General Public License as published by the Free
   * Software Foundation; either version 2, or (at your option) any later
   * version.
   *
   * FRRouting 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 for more
   * details.
   *
   * You should have received a copy of the GNU General Public License along
   * with this program; see the file COPYING; if not, write to the Free Software
   * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
   */
  
  #ifndef _FRR_BGP_KEEPALIVES_H
  #define _FRR_BGP_KEEPALIVES_H
  
  #include "frr_pthread.h"
  #include "bgpd.h"
  
  /**
   * Turns on keepalives for a peer.
   *
   * This function adds the peer to an internal list of peers to generate
   * keepalives for.
   *
   * At set intervals, a BGP KEEPALIVE packet is generated and placed on
   * peer->obuf. This operation is thread-safe with respect to peer->obuf.
   *
   * peer->v_keepalive determines the interval. Changing this value before
   * unregistering this peer with bgp_keepalives_off() results in undefined
   * behavior.
   *
   * If the peer is already registered for keepalives via this function, nothing
   * happens.
   */
  extern void bgp_keepalives_on(struct peer *);
  
  /**
   * Turns off keepalives for a peer.
   *
   * Removes the peer from the internal list of peers to generate keepalives for.
   *
   * If the peer is already unregistered for keepalives, nothing happens.
   */
  extern void bgp_keepalives_off(struct peer *);
  
  /**
   * Pre-run initialization function for keepalives pthread.
   *
   * Initializes synchronization primitives. This should be called before
   * anything else to avoid race conditions.
   */
  extern void bgp_keepalives_init(void);
  
  /**
   * Entry function for keepalives pthread.
   *
   * This function loops over an internal list of peers, generating keepalives at
   * regular intervals as determined by each peer's keepalive timer.
   *
   * See bgp_keepalives_on() for additional details.
   *
   * @param arg pthread arg, not used
   */
  extern void *bgp_keepalives_start(void *arg);
  
  /**
   * Poking function for keepalives pthread.
   *
   * Under normal circumstances the pthread will automatically wake itself
   * whenever it is necessary to do work. This function may be used to force the
   * thread to wake up and see if there is any work to do, or if it is time to
   * die.
   *
   * It is not necessary to call this after bgp_keepalives_on().
   */
  extern void bgp_keepalives_wake(void);
  
  /**
   * Stops the thread and blocks until it terminates.
   */
  int bgp_keepalives_stop(struct frr_pthread *fpt, void **result);
  
  #endif /* _FRR_BGP_KEEPALIVES_H */
  