[Sheepdog] [PATCH] zookeeper: switch gcc atomic builtins to atomic helpers

[Yunkai Zhang]

On Tue, May 8, 2012 at 8:24 PM, Liu Yuan <namei.unix at gmail.com> wrote:
> On 05/08/2012 08:21 PM, Yunkai Zhang wrote:
>
>>> > The combination of a read and an atomic_sub later looks racy to me, what
>>> > prevents nr_zk_levents from changing between the two calls?
>> The watcher function was executed in another thread(create by
>> zookeeper_init() ), we should use atomic function to read/wirte
>> nr_zk_levents in any time.
>>
>
>
> Maybe you don't get Christoph.
>
>        if (!uatomic_read(&zk_notify_blocked) &&
>             uatomic_read(&nr_zk_levents)) {
>                nr_levents = uatomic_sub_return(&nr_zk_levents, 1) + 1;
>
> I guess he means the possible race between uatomic_read() and
> uatomic_sub_return() on the same value.

I have explained - when we are trying to subtract nr_zk_levents, it
will be added by watcher() in another thread.

>
> Thanks,
> Yuan



-- 
Yunkai Zhang
Work at Taobao