extensions/rt_redirect/redir_expiry.c

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* Software License Agreement (BSD License)                                                               *
* Author: Sebastien Decugis <sdecugis@freediameter.net>							 *
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#include "rt_redir.h"

/* Expiration management */


/* Entries by their ascending expiration date, to accelerate the work of the expire thread */
static struct fd_list  expire_list = FD_LIST_INITIALIZER(expire_list);
static pthread_cond_t  exp_cnd  = PTHREAD_COND_INITIALIZER;

pthread_mutex_t redir_exp_peer_lock = PTHREAD_MUTEX_INITIALIZER;

/* The thread that handles expired entries cleanup. */
void * redir_exp_thr_fct(void * arg)
{
	fd_log_threadname ( "Redirects/expire" );
	TRACE_ENTRY( "" );

	CHECK_POSIX_DO( pthread_mutex_lock(&redir_exp_peer_lock),  goto fatal_error );
	pthread_cleanup_push( fd_cleanup_mutex, &redir_exp_peer_lock );

	do {
		struct timespec	now;
		struct redir_entry * first;
again:
		/* Check if there are expiring entries available */
		if (FD_IS_LIST_EMPTY(&expire_list)) {
			/* Just wait for a change or cancelation */
			CHECK_POSIX_DO( pthread_cond_wait( &exp_cnd, &redir_exp_peer_lock ), break /* this might not pop the cleanup handler, but since we ASSERT(0), it is not the big issue... */ );
			/* Restart the loop on wakeup */
			goto again;
		}

		/* Get the pointer to the entry that expires first */
		first = (struct redir_entry *)(expire_list.next->o);

		/* Get the current time */
		CHECK_SYS_DO(  clock_gettime(CLOCK_REALTIME, &now),  break  );

		/* If first session is not expired, we just wait until it happens */
		if ( TS_IS_INFERIOR( &now, &first->timeout ) ) {

			CHECK_POSIX_DO2(  pthread_cond_timedwait( &exp_cnd, &redir_exp_peer_lock, &first->timeout ),
					ETIMEDOUT, /* ETIMEDOUT is a normal error, continue */,
					/* on other error, */ break );

			/* on wakeup, loop */
			goto again;
		}

		/* Now, the first entry in the list is expired; destroy it */

		CHECK_FCT_DO( redir_entry_destroy( first ), break );

	} while (1);

	pthread_cleanup_pop( 0 );
	CHECK_POSIX_DO( pthread_mutex_unlock(&redir_exp_peer_lock),  );

fatal_error:
	TRACE_DEBUG(INFO, "A system error occurred in redirect module! Expiry thread is terminating...");
	ASSERT(0);
	return NULL;
}

/* Sets the timeout value & link in expiry list. The mutex must be held on calling */
int redir_exp_set(struct redir_entry * e, uint32_t duration)
{
	struct fd_list * li;
	TRACE_ENTRY("%p %d", e, duration);
	CHECK_PARAMS(e && (e->eyec == REDIR_ENTRY_EYEC) && duration );

	/* Unlink in case it was already set before */
	fd_list_unlink(&e->exp_list);

	/* Get current time */
	CHECK_SYS(  clock_gettime(CLOCK_REALTIME, &e->timeout)  );

	/* Add the duration */
	e->timeout.tv_sec += duration;

	/* now search the next element in the list */
	for (li = expire_list.next; li != &expire_list; li = li->next) {
		struct redir_entry * n = li->o;

		if ( TS_IS_INFERIOR( &e->timeout, &n->timeout ) )
			break;

	}

	/* Insert before this element */
	fd_list_insert_before(li, &e->exp_list);

	/* Signal the expiry thread if needed */
	if (e->exp_list.prev == &expire_list) { /* it is the first element */
		CHECK_POSIX( pthread_cond_signal(&exp_cnd) );
	}

	/* Done */
	return 0;
}