public function touch($key, $expire)
{
if (isset($this->keys[$key]) && isset($this->keys[$key][2]['expire'])) {
// changing expiration time of a value we're already storing in
// this transaction - might as well just set new expiration time
// right away
$this->keys[$key][2]['expire'] = $expire;
} else {
$args = array('key' => $key, 'expire' => $expire);
$this->keys[$key] = array(__FUNCTION__, array($this->cache, __FUNCTION__), $args);
}
}