zig/lib/libcxx/include/__thread/timed_backoff_policy.h
Alex Rønne Petersen 156ab87500
libcxx: Update to Clang 20.
See:

* https://discourse.llvm.org/t/rfc-freezing-c-03-headers-in-libc/77319
* https://discourse.llvm.org/t/rfc-project-hand-in-hand-llvm-libc-libc-code-sharing/77701

We're dropping support for C++03 for Zig due to the first change; it would be
insane to ship 1018 duplicate header files just for this outdated use case.

As a result of the second change, I had to bring in a subset of the headers from
llvm-libc since libc++ now depends on these. Hopefully we can continue to get
away with not copying the entirety of llvm-libc.
2025-04-04 06:08:09 +02:00

44 lines
1.2 KiB
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// -*- C++ -*-
//===----------------------------------------------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
#ifndef _LIBCPP___THREAD_TIMED_BACKOFF_POLICY_H
#define _LIBCPP___THREAD_TIMED_BACKOFF_POLICY_H
#include <__config>
#if _LIBCPP_HAS_THREADS
# include <__chrono/duration.h>
# include <__thread/support.h>
# if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
# pragma GCC system_header
# endif
_LIBCPP_BEGIN_NAMESPACE_STD
struct __libcpp_timed_backoff_policy {
_LIBCPP_HIDE_FROM_ABI bool operator()(chrono::nanoseconds __elapsed) const {
if (__elapsed > chrono::milliseconds(128))
__libcpp_thread_sleep_for(chrono::milliseconds(8));
else if (__elapsed > chrono::microseconds(64))
__libcpp_thread_sleep_for(__elapsed / 2);
else if (__elapsed > chrono::microseconds(4))
__libcpp_thread_yield();
else {
} // poll
return false;
}
};
_LIBCPP_END_NAMESPACE_STD
#endif // _LIBCPP_HAS_THREADS
#endif // _LIBCPP___THREAD_TIMED_BACKOFF_POLICY_H