1*4bdff4beSrobert // -*- C++ -*- 2*4bdff4beSrobert //===----------------------------------------------------------------------===// 3*4bdff4beSrobert // 4*4bdff4beSrobert // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 5*4bdff4beSrobert // See https://llvm.org/LICENSE.txt for license information. 6*4bdff4beSrobert // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 7*4bdff4beSrobert // 8*4bdff4beSrobert //===----------------------------------------------------------------------===// 9*4bdff4beSrobert 10*4bdff4beSrobert #ifndef _LIBCPP___THREAD_TIMED_BACKOFF_POLICY_H 11*4bdff4beSrobert #define _LIBCPP___THREAD_TIMED_BACKOFF_POLICY_H 12*4bdff4beSrobert 13*4bdff4beSrobert #include <__config> 14*4bdff4beSrobert 15*4bdff4beSrobert #ifndef _LIBCPP_HAS_NO_THREADS 16*4bdff4beSrobert 17*4bdff4beSrobert # include <__chrono/duration.h> 18*4bdff4beSrobert # include <__threading_support> 19*4bdff4beSrobert 20*4bdff4beSrobert #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER) 21*4bdff4beSrobert # pragma GCC system_header 22*4bdff4beSrobert #endif 23*4bdff4beSrobert 24*4bdff4beSrobert _LIBCPP_BEGIN_NAMESPACE_STD 25*4bdff4beSrobert 26*4bdff4beSrobert struct __libcpp_timed_backoff_policy { 27*4bdff4beSrobert _LIBCPP_INLINE_VISIBILITY operator__libcpp_timed_backoff_policy28*4bdff4beSrobert bool operator()(chrono::nanoseconds __elapsed) const 29*4bdff4beSrobert { 30*4bdff4beSrobert if(__elapsed > chrono::milliseconds(128)) 31*4bdff4beSrobert __libcpp_thread_sleep_for(chrono::milliseconds(8)); 32*4bdff4beSrobert else if(__elapsed > chrono::microseconds(64)) 33*4bdff4beSrobert __libcpp_thread_sleep_for(__elapsed / 2); 34*4bdff4beSrobert else if(__elapsed > chrono::microseconds(4)) 35*4bdff4beSrobert __libcpp_thread_yield(); 36*4bdff4beSrobert else 37*4bdff4beSrobert {} // poll 38*4bdff4beSrobert return false; 39*4bdff4beSrobert } 40*4bdff4beSrobert }; 41*4bdff4beSrobert 42*4bdff4beSrobert _LIBCPP_END_NAMESPACE_STD 43*4bdff4beSrobert 44*4bdff4beSrobert #endif // _LIBCPP_HAS_NO_THREADS 45*4bdff4beSrobert 46*4bdff4beSrobert #endif // _LIBCPP___THREAD_TIMED_BACKOFF_POLICY_H 47