self-increasing counter

Self-increasing counter based on redis, generating self-increasing numbers

/**
 * Generate self-increasing number
 *
 * @param string $key cache key
 * @param int $step self-increasing step size
 * @param int $expires cache expiration time, unit seconds
 *
 * @return int $num ;
 * @author leeyi
*/
function incr_num($key='ddg', $step=1, $expires=0) {
 // The link redis is encapsulated in OrgRedis()
 $redis = new OrgRedis();
 $cache_key = 'incrnum:'.$key;
 $num = $redis->handler->incrBy($cache_key, (int)$step);

 $millisecond = $expires> 0 ? $expires*1000 : (get_time_235959()*1000+999);

 $redis->handler->pexpireAt($cache_key, $millisecond); // Set expiration time

 return $num;
}