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_TIMED_BACKOFF_POLICY_H
11#define _LIBCPP___THREAD_TIMED_BACKOFF_POLICY_H
12
13#include <__config>
14
15#if _LIBCPP_HAS_THREADS
16
17# include <__chrono/duration.h>
18# include <__thread/support.h>
19
20# if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
21# pragma GCC system_header
22# endif
23
24_LIBCPP_BEGIN_NAMESPACE_STD
25
26struct __libcpp_timed_backoff_policy {
27 _LIBCPP_HIDE_FROM_ABI bool operator()(chrono::nanoseconds __elapsed) const {
28 if (__elapsed > chrono::milliseconds(128))
29 __libcpp_thread_sleep_for(ns: chrono::milliseconds(8));
30 else if (__elapsed > chrono::microseconds(64))
31 __libcpp_thread_sleep_for(ns: __elapsed / 2);
32 else if (__elapsed > chrono::microseconds(4))
33 __libcpp_thread_yield();
34 else {
35 } // poll
36 return false;
37 }
38};
39
40_LIBCPP_END_NAMESPACE_STD
41
42#endif // _LIBCPP_HAS_THREADS
43
44#endif // _LIBCPP___THREAD_TIMED_BACKOFF_POLICY_H
45