[Bug libstdc++/41861] [DR 887][C++0x] <condition_variable> does not use monotonic_clock

["mac at mcrowe dot com" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=41861

--- Comment #15 from Mike Crowe <mac at mcrowe dot com> ---
(In reply to Mike Crowe from comment #14)
> I submitted an RFC glibc patch last year:
> http://patchwork.ozlabs.org/project/glibc/list/?submitter=66786

I submitted an updated version earlier this year:

 https://sourceware.org/ml/libc-alpha/2017-06/msg01111.html

There are a few minor niggles to address, but it seems that the greater hurdle
now is that two respondents have requested that I raise this with the Austin
Group. So, I have done so at:

 http://austingroupbugs.net/view.php?id=1164

If this attempt fails, then I think it would be preferable to switch libstdc++
std::condition_variable to use std::chrono::steady_clock as its primary clock
(along with the necessary changes in gthreads to support creating a condition
variable using CLOCK_MONOTONIC) and convert all other clocks to that clock. I
personally think it's more surprising that:

 cv.wait_for(std::chrono::seconds(2));

risks waiting for potentially huge amount of time if someone changes the system
clock, than

 cv.wait_until(std::chrono::system_clock::now() + std::chrono::seconds(2));

waiting for two seconds if someone changes the system clock just afterwards so
that the wait should return immediately.