1// -*- C++ -*-
 2//===----------------------------------------------------------------------===//
 3//
 4// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 5// See https://llvm.org/LICENSE.txt for license information.
 6// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 7//
 8//===----------------------------------------------------------------------===//
 9
10#ifndef _LIBCPP___THREAD_THIS_THREAD_H
11#define _LIBCPP___THREAD_THIS_THREAD_H
12
13#include <__chrono/duration.h>
14#include <__chrono/steady_clock.h>
15#include <__chrono/time_point.h>
16#include <__condition_variable/condition_variable.h>
17#include <__config>
18#include <__mutex/mutex.h>
19#include <__mutex/unique_lock.h>
20#include <__thread/support.h>
21
22#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
23#  pragma GCC system_header
24#endif
25
26_LIBCPP_PUSH_MACROS
27#include <__undef_macros>
28
29_LIBCPP_BEGIN_NAMESPACE_STD
30
31namespace this_thread {
32
33#if _LIBCPP_HAS_THREADS
34
35_LIBCPP_EXPORTED_FROM_ABI void sleep_for(const chrono::nanoseconds& __ns);
36
37template <class _Rep, class _Period>
38_LIBCPP_HIDE_FROM_ABI void sleep_for(const chrono::duration<_Rep, _Period>& __d) {
39  if (__d > chrono::duration<_Rep, _Period>::zero()) {
40    // The standard guarantees a 64bit signed integer resolution for nanoseconds,
41    // so use INT64_MAX / 1e9 as cut-off point. Use a constant to avoid <climits>
42    // and issues with long double folding on PowerPC with GCC.
43    _LIBCPP_CONSTEXPR chrono::duration<long double> __max = chrono::duration<long double>(9223372036.0L);
44    chrono::nanoseconds __ns;
45    if (__d < __max) {
46      __ns = chrono::duration_cast<chrono::nanoseconds>(__d);
47      if (__ns < __d)
48        ++__ns;
49    } else
50      __ns = chrono::nanoseconds::max();
51    this_thread::sleep_for(__ns);
52  }
53}
54
55template <class _Clock, class _Duration>
56_LIBCPP_HIDE_FROM_ABI void sleep_until(const chrono::time_point<_Clock, _Duration>& __t) {
57  mutex __mut;
58  condition_variable __cv;
59  unique_lock<mutex> __lk(__mut);
60  while (_Clock::now() < __t)
61    __cv.wait_until(__lk, __t);
62}
63
64template <class _Duration>
65inline _LIBCPP_HIDE_FROM_ABI void sleep_until(const chrono::time_point<chrono::steady_clock, _Duration>& __t) {
66  this_thread::sleep_for(__t - chrono::steady_clock::now());
67}
68
69inline _LIBCPP_HIDE_FROM_ABI void yield() _NOEXCEPT { __libcpp_thread_yield(); }
70
71#endif // _LIBCPP_HAS_THREADS
72
73} // namespace this_thread
74
75_LIBCPP_END_NAMESPACE_STD
76
77_LIBCPP_POP_MACROS
78
79#endif // _LIBCPP___THREAD_THIS_THREAD_H