Re: [boost] Boost Threads Condition may block forever on clockchange

From: Peter Dimov (pdimov_at_[hidden])
Date: 2007-11-27 13:41:16

Anthony Williams:

>> We should probably think of a way to enable the use of a monotonic clock
>> with the absolute timeout overloads. It doesn't feel right to make the
>> relative overloads the only way to access the functionality.
>
> Yes, we should. However, absolute time is always going to have issues with
> clock changes --- if I schedule for something now (2007-11-27 18:23:15 UTC 
> by
> the current clock) to run tomorrow (2007-11-28 18:23:15 UTC), does it 
> schedule
> for 24-hours from now, or for when-the-clock-reads the right time?

These are UTC times. The monotonic clock (CLOCK_MONOTONIC) is not 
user-settable and for it, now+K always occurs after K seconds. For 
CLOCK_REALTIME, it schedules for the given time.

http://www.opengroup.org/onlinepubs/009695399/functions/pthread_condattr_getclock.html
http://www.opengroup.org/onlinepubs/000095399/functions/clock_getres.html