Simple rate-limiting algorithm?

OK let me propose another solution. Once you hit the limit a 60 second timeout begins and gets refreshed on each attempt. Also not exactly what Marco wanted, but workable.

public function allow_hit($id, $limit_per_minute)
{
    $key = md5($id);
    $count = intval(Cache::get('rate-limiter', $key));
    if ($count > $limit_per_minute) {
      Cache::replace('rate-limiter', $key, $count + 1, 60);
      return false;
    }
    if ($count) {
      Cache::increment('rate-limiter', $key, 1);
    } else {
      Cache::set('rate-limiter', $key, 1, /* ttl */ 60);
    }
    return true;
}

Posted: 2009-03-12 13:02