/*********************************************************************************************************
* Software License Agreement (BSD License)                                                               *
* Author: Sebastien Decugis <sdecugis@nict.go.jp>							 *
*													 *
* Copyright (c) 2009, WIDE Project and NICT								 *
* All rights reserved.											 *
* 													 *
* 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.								 *
* 													 *
* * Neither the name of the WIDE Project or NICT nor the 						 *
*   names of its contributors may be used to endorse or 						 *
*   promote products derived from this software without 						 *
*   specific prior written permission of WIDE Project and 						 *
*   NICT.												 *
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED *
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*********************************************************************************************************/

#include "fD.h"

static pthread_t       exp_thr;
static struct fd_list  exp_list = FD_LIST_INITIALIZER( exp_list );
static pthread_cond_t  exp_cnd  = PTHREAD_COND_INITIALIZER;
static pthread_mutex_t exp_mtx  = PTHREAD_MUTEX_INITIALIZER;

static void * exp_th_fct(void * arg)
{
	fd_log_threadname ( "Peers/expire" );
	TRACE_ENTRY( "" );
	
	CHECK_POSIX_DO( pthread_mutex_lock(&exp_mtx),  goto error );
	pthread_cleanup_push( fd_cleanup_mutex, &exp_mtx );
	
	do {
		struct timespec	now;
		struct fd_peer * first;
		
		/* Check if there are expiring sessions available */
		if (FD_IS_LIST_EMPTY(&exp_list)) {
			/* Just wait for a change or cancelation */
			CHECK_POSIX_DO( pthread_cond_wait( &exp_cnd, &exp_mtx ), goto error );
			/* Restart the loop on wakeup */
			continue;
		}
		
		/* Get the pointer to the peer that expires first */
		first = (struct fd_peer *)(exp_list.next->o);
		ASSERT( CHECK_PEER(first) );
		
		/* Get the current time */
		CHECK_SYS_DO(  clock_gettime(CLOCK_REALTIME, &now),  goto error  );

		/* If first peer is not expired, we just wait until it happens */
		if ( TS_IS_INFERIOR( &now, &first->p_exp_timer ) ) {
			
			CHECK_POSIX_DO2(  pthread_cond_timedwait( &exp_cnd, &exp_mtx, &first->p_exp_timer ),  
					ETIMEDOUT, /* ETIMEDOUT is a normal error, continue */,
					/* on other error, */ goto error );
	
			/* on wakeup, loop */
			continue;
		}
		
		/* Now, the first peer in the list is expired; signal it */
		fd_list_unlink( &first->p_expiry );
		CHECK_FCT_DO( fd_event_send(first->p_events, FDEVP_TERMINATE, NULL), goto error );
		
	} while (1);
	
	pthread_cleanup_pop( 1 );
error:
	TRACE_DEBUG(INFO, "An error occurred in peers module! Expiry thread is terminating...");
	ASSERT(0);
	CHECK_FCT_DO(fd_event_send(fd_g_config->cnf_main_ev, FDEV_TERMINATE, NULL), );
	return NULL;
}

/* Initialize peers expiry mechanism */
int fd_p_expi_init(void)
{
	TRACE_ENTRY();
	CHECK_FCT( pthread_create( &exp_thr, NULL, exp_th_fct, NULL ) );
	return 0;
}

/* Finish peers expiry mechanism */
int fd_p_expi_fini(void)
{
	CHECK_FCT_DO( fd_thr_term(&exp_thr), );
	CHECK_POSIX( pthread_mutex_lock(&exp_mtx) );
	
	while (!FD_IS_LIST_EMPTY(&exp_list)) {
		struct fd_peer * peer = (struct fd_peer *)(exp_list.next->o);
		fd_list_unlink(&peer->p_expiry );
	}
	
	CHECK_POSIX( pthread_mutex_unlock(&exp_mtx) );
	return 0;
}

/* Add / requeue a peer in the expiry list */
int fd_p_expi_update(struct fd_peer * peer )
{
	TRACE_ENTRY("%p", peer);
	CHECK_PARAMS( CHECK_PEER(peer) );
	
	CHECK_POSIX( pthread_mutex_lock(&exp_mtx) );
	
	fd_list_unlink(&peer->p_expiry );
	
	/* if peer expires */
	if (peer->p_hdr.info.pi_flags.exp) {
		struct fd_list * li;
		
		/* update the p_exp_timer value */
		CHECK_SYS(  clock_gettime(CLOCK_REALTIME, &peer->p_exp_timer)  );
		peer->p_exp_timer.tv_sec += peer->p_hdr.info.pi_lft;
		
		/* add to the expiry list in appropriate position (probably around the end) */
		for (li = exp_list.prev; li != &exp_list; li = li->prev) {
			struct fd_peer * p = (struct fd_peer *)(li->o);
			if (TS_IS_INFERIOR( &p->p_exp_timer, &peer->p_exp_timer ) )
				break;
		}
		
		fd_list_insert_after(li, &peer->p_expiry);
		
		/* signal the expiry thread if we added in first position */
		if (li == &exp_list) {
			CHECK_POSIX( pthread_cond_signal(&exp_cnd) );
		}
	}
	
	CHECK_POSIX( pthread_mutex_unlock(&exp_mtx) );
	return 0;
}