368faacac7
This commit reverts 5aaefa51 (and also partly 7f285f48e77 and b6d75682f9, which were related to the original commit). As landed, 5aaefa51 had unintended consequences on some downstream bots and didn't have proper coverage upstream due to a few subtle things. Implementing this is something we should do in libc++, however we'll first need to address a few issues listed in https://reviews.llvm.org/D106124#3349710. Differential Revision: https://reviews.llvm.org/D120683
46 lines
1.3 KiB
C++
46 lines
1.3 KiB
C++
// -*- C++ -*-
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//===----------------------------------------------------------------------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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#ifndef _LIBCPP___THREAD_TIMED_BACKOFF_POLICY_H
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#define _LIBCPP___THREAD_TIMED_BACKOFF_POLICY_H
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#include <__config>
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#ifndef _LIBCPP_HAS_NO_THREADS
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# include <__chrono/duration.h>
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# include <__threading_support>
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#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
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# pragma GCC system_header
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#endif
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_LIBCPP_BEGIN_NAMESPACE_STD
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struct __libcpp_timed_backoff_policy {
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_LIBCPP_INLINE_VISIBILITY
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bool operator()(chrono::nanoseconds __elapsed) const
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{
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if(__elapsed > chrono::milliseconds(128))
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__libcpp_thread_sleep_for(chrono::milliseconds(8));
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else if(__elapsed > chrono::microseconds(64))
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__libcpp_thread_sleep_for(__elapsed / 2);
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else if(__elapsed > chrono::microseconds(4))
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__libcpp_thread_yield();
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else
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{} // poll
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return false;
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}
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};
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_LIBCPP_END_NAMESPACE_STD
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#endif // _LIBCPP_HAS_NO_THREADS
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#endif // _LIBCPP___THREAD_TIMED_BACKOFF_POLICY_H
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