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

[Yunkai Zhang]

On Tue, May 8, 2012 at 11:36 PM, Christoph Hellwig <hch at infradead.org> wrote:
> On Tue, May 08, 2012 at 11:20:18PM +0800, Yunkai Zhang wrote:
>> On Tue, May 8, 2012 at 11:06 PM, Christoph Hellwig <hch at infradead.org> wrote:
>> > On Tue, May 08, 2012 at 11:01:53PM +0800, Yunkai Zhang wrote:
>> >> It works well now, I don't know what you worry about?
>> >
>> > It works most of the time, but not always. ?Even worse the reace is
>> > small enough that you won't find it during most testing, and only run
>> > into it on some heavily loaded production system once in a while.
>>
>> Producer: watcher thread
>> Consumer: main thread
>>
>> 1) watcher thread:
>> When sheep leave, /sheepdog/member/<nodeid_to_str> was deleted by
>> zookeeper server, watcher() will forge an LEAVE event, and:
>> atomic_add_and_return(&nr_zk_levents, 1)
>>
>> 2) main thread:
>> Check if atomic_read(&nr_zk_levents) > 0; if so, call
>> atomic_sub_and_return(&nr_zk_levents, 1), and processes this LEAVE
>> event.
>>
>> What is the problem you worry about? Can you give me an example?
>
> You're right - there is a strict relation.  Care to add the above
> explanation as a comment?
It is a good idea, CC Liu Yuan

>



-- 
Yunkai Zhang
Work at Taobao