Fix collection (locking and getting next value).
Fix collection (locking and getting next value).

oblank/captcha,dchest/captcha,msn217/captcha,rainyear/captcha,ZiRo-/captcha,gotomypc/captcha,ZiRo-/captcha,kaz8/go-captcha,eleme/fork_captcha,thomasmodeneis/captcha,zj8487/captcha