test/std/thread/thread.threads/thread.thread.this/sleep_until.pass.cpp

//===----------------------------------------------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// UNSUPPORTED: libcpp-has-no-threads
// FLAKY_TEST.

// <thread>

// template <class Clock, class Duration>
//   void sleep_until(const chrono::time_point<Clock, Duration>& abs_time);

#include <thread>
#include <cstdlib>
#include <cassert>

#include "test_macros.h"

int main(int, char**)
{
    typedef std::chrono::system_clock Clock;
    typedef Clock::time_point time_point;
    std::chrono::milliseconds ms(500);
    time_point t0 = Clock::now();
    std::this_thread::sleep_until(t0 + ms);
    time_point t1 = Clock::now();
    std::chrono::nanoseconds ns = (t1 - t0) - ms;
    std::chrono::nanoseconds err = 5 * ms / 100;
    // The time slept is within 5% of 500ms
    assert(std::abs(ns.count()) < err.count());

  return 0;
}