On 19/04/21 12:23 -0700, Thomas Rodgers wrote:
+ struct __timed_backoff_spin_policy
+ {
+ __wait_clock_t::time_point _M_deadline;
+ __wait_clock_t::time_point _M_t0;
+
+ template<typename _Clock, typename _Dur>
+ __timed_backoff_spin_policy(chrono::time_point<_Clock, _Dur>
+ __deadline = _Clock::time_point::max(),
+ chrono::time_point<_Clock, _Dur>
+ __t0 = _Clock::now()) noexcept
+ : _M_deadline(__to_wait_clock(__deadline))
+ , _M_t0(__to_wait_clock(__t0))
+ { }
+
+ bool
+ operator()() const noexcept
{
- static_assert(sizeof(__timed_waiters) == sizeof(__waiters));
- return static_cast<__timed_waiters&>(__waiters::_S_for(__t));
+ using namespace literals::chrono_literals;
+ auto __now = __wait_clock_t::now();
+ if (_M_deadline <= __now)
+ return false;
+
+ auto __elapsed = __now - _M_t0;
+ if (__elapsed > 128ms)
+ {
+ this_thread::sleep_for(64ms);
+ }
+ else if (__elapsed > 64us)
+ {
+ this_thread::sleep_for(__elapsed / 2);
+ }
+ else if (__elapsed > 4us)
+ {
+ __thread_yield();
+ }
+ else
+ return false;
Ah, the reason for some of the time outs I'm seeing is that this
function doesn't return anything!
/home/jwakely/gcc/12/include/c++/12.0.0/bits/atomic_timed_wait.h: In member
function 'bool std::__detail::__timed_backoff_spin_policy::operator()() const':
/home/jwakely/gcc/12/include/c++/12.0.0/bits/atomic_timed_wait.h:259:7:
warning: control reaches end of non-void function [-Wreturn-type]
259 | }
| ^
Should it return true if it waited?
