/*********************************************************************************************************
* Software License Agreement (BSD License)                                                               *
* Author: Thomas Klausner <tk@giga.or.at>                                                                *
*                                                                                                        *
* Copyright (c) 2013, Thomas Klausner                                                                    *
* All rights reserved.                                                                                   *
*                                                                                                        *
* Written under contract by nfotex IT GmbH, http://nfotex.com/                                           *
*                                                                                                        *
* Redistribution and use of this software in source and binary forms, with or without modification, are  *
* permitted provided that the following conditions are met:                                              *
*                                                                                                        *
* * Redistributions of source code must retain the above                                                 *
*   copyright notice, this list of conditions and the                                                    *
*   following disclaimer.                                                                                *
*                                                                                                        *
* * Redistributions in binary form must reproduce the above                                              *
*   copyright notice, this list of conditions and the                                                    *
*   following disclaimer in the documentation and/or other                                               *
*   materials provided with the distribution.                                                            *
*                                                                                                        *
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED *
* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A *
* PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR *
* ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT     *
* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS    *
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR *
* TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF   *
* ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.                                                             *
*********************************************************************************************************/

#include <freeDiameter/extension.h>

/*
 * Load balancing extension. Send request to least-loaded node.
 */

/* The callback for load balancing the requests across the peers */
static int rt_load_balancing(void * cbdata, struct msg ** pmsg, struct fd_list * candidates)
{
	struct fd_list *lic;
	struct msg * msg = *pmsg;
	
	TRACE_ENTRY("%p %p %p", cbdata, msg, candidates);
	
	CHECK_PARAMS(msg && candidates);
	
	/* Check if it is worth processing the message */
	if (FD_IS_LIST_EMPTY(candidates))
		return 0;

	/* load balancing */
	for (lic = candidates->next; lic != candidates; lic = lic->next) {
		struct rtd_candidate * cand = (struct rtd_candidate *) lic;
		struct peer_hdr *peer;
		long to_receive, to_send, load;
		int score;
		CHECK_FCT(fd_peer_getbyid(cand->diamid, cand->diamidlen, 0, &peer));
		CHECK_FCT(fd_peer_get_load_pending(peer, &to_receive, &to_send));
                load = to_receive + to_send;
		score = cand->score;
		if (load > 5)
			cand->score -= 5;
		else
			cand->score -= load;
		TRACE_DEBUG(INFO, "evaluated peer `%.*s', score was %d, now %d", (int)cand->diamidlen, cand->diamid, score, cand->score);
	}

	return 0;
}

/* handler */
static struct fd_rt_out_hdl * rt_load_balancing_hdl = NULL;

/* entry point */
static int rt_load_balance_entry(char * conffile)
{
	/* Register the callback */
	CHECK_FCT(fd_rt_out_register(rt_load_balancing, NULL, 10, &rt_load_balancing_hdl));

	TRACE_DEBUG(INFO, "Extension 'Load Balancing' initialized");
	return 0;
}

/* Unload */
void fd_ext_fini(void)
{
	/* Unregister the callbacks */
	CHECK_FCT_DO(fd_rt_out_unregister(rt_load_balancing_hdl, NULL), /* continue */);
	return ;
}

EXTENSION_ENTRY("rt_load_balance", rt_load_balance_entry);