Codigniter and MySQL GET_LOCK

gistfile1.php

<?php

/*

 - codeigniter, by default, uses persistent database connections, this is problematic in that the 
lock is never automatically released on connection termination (what else is to expect with persistent 
connections). However after a script ends you also never can RELEASE_LOCK() anymore, at least it didn't 
work overhere while testing. The script really has to make sure to release the lock before ending 
(shutdown_function) if it uses persistent DB connections.

 - Due to a bug in mysql < 5.5.3 any script that tries to get a lock that already is in use, will wait 
until timeout has expired, and still report 0 (cannot get lock). The script should use IS_FREE_LOCK() 
and/or IS_USED_LOCK() before trying to get a lock.

*/
	// what is the lock status
	$sql = 'SELECT IS_FREE_LOCK("ci_cron_lock") as lockstatus';
	$query = $this->db->query($sql);
	$row = $query->row();
	if ($row->lockstatus == 0)
	{
		// lock not free, wait and try again? exit?
	}
	else
	{
		// try to get a lock for 60 seconds
		$sql = 'SELECT GET_LOCK("ci_cron_lock", 60) as lockstatus';
		$query = $this->db->query($sql);
		$row = $query->row();
		if ($row->lockstatus == 0)
		{
			// could not get a lock, exit
		}
		else
		{
			/* 
			 * cron tasks go here
			 *
			 */
			
			$sql = 'SELECT RELEASE_LOCK("ci_cron_lock") as lockstatus';
			$query = $this->db->query($sql);
			$row = $query->row();
			if ($row->lockstatus == 0)
			{
				// could not release lock
			}
			else
			{
				// lock released
			}
		}
	}