7162fd750e
The <__threading_support> header is a huge beast and it's really difficult to navigate. I find myself struggling to find what I want every time I have to open it, and I've been considering splitting it up for years for that reason. This patch aims not to contain any functional change. The various implementations of the threading base are simply moved to separate headers and then the individual headers are simplified in mechanical ways. For example, we used to have redundant declarations of all the functions at the top of `__threading_support`, and those are removed since they are not needed anymore. The various #ifdefs are also simplified and removed when they become unnecessary. Finally, this patch adds documentation for the API we expect from any threading implementation.
45 lines
1.3 KiB
C++
45 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 <__thread/support.h>
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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_HIDE_FROM_ABI bool operator()(chrono::nanoseconds __elapsed) const {
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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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