/* 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 */