Re: [boost] Probably bug in condition::timed_wait()

From: Peter Dimov (pdimov_at_[hidden])
Date: 2006-10-08 08:16:18

Alexander Terekhov wrote:
> Peter Dimov wrote:
>>
>> Pavel Syomin wrote:
>>
>>> This is solve my problems, but why there is nothing about spurious
>>> wakeup in boost documentation?...
>>
>> The older documentation
>>
>> http://web.archive.org/web/20041024220516/boost.org/libs/thread/doc/condition.html
>>
>> does have a few sentences that mention spurious wakeups; I've no
>> idea how they got lost. I'll CC: the dev list.
>
> The docu might tell something not only about spurious wakeups but
> also about the fact that return of timedout status doesn't preclude
> consumption of a signal issued concurrently (note that thread
> cancel delivery does preclude it).

Hey!

Does this mean that timed_wait( lock, xt, pred ) has a bug? Instead of

while (!pred()) { if (!timed_wait(lock, xt)) return false; } return true;

it needs to be

while (!pred()) { if (!timed_wait(lock, xt)) return pred(); } return true;

otherwise a 'false' return can consume a signal meant for someone else 
without notifying the caller to handle the pred() == true case?

I probably have the same subtle bug in at least a few places...