Re: [RFC 2/2] Add steady_clock support to condition_variable

[Jonathan Wakely <jwakely at redhat dot com>]

On 06/07/15 13:55 +0100, Mike Crowe wrote:
> If __gthread_cond_timedwaitonclock is available it can be used it to fix
> part of https://gcc.gnu.org/bugzilla/show_bug.cgi?id=41861 by supporting
> std::chrono::steady_clock properly with std::condition_variable.
>
> This means that code using std::condition_variable::wait_for or
> std::condition_variable::wait_until with std::chrono::steady_clock is no
> longer subject to timing out early or potentially waiting for much
> longer if the system clock is changed at an inopportune moment.
>
> If __gthread_cond_timedwaitonclock is available then
> std::chrono::steady_clock is deemed to be the "best" clock available
> which means that it is used for the relative wait_for calls and absolute
> wait_until calls that aren't choosing to use std::chrono::system_clock.
> Calls explicitly using std::chrono::system_clock continue to use
> CLOCK_REALTIME.
>
> If __gthread_cond_timedwaitonclock is not available then
> std::chrono::system_clock is deemed to be the "best" clock available
> which means that the previous suboptimal behaviour remains.

> From a quick glance this looks like a good change. As I said in my
other mail about the gthr-posix.h changes, it might be better to keep
this change to libstdc++ rather than splitting it across libstdc++ and
libgcc's gthr-posix.h

Do you have a copyright assignment in place for GCC contributions?