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2dda038306
Instead of using atomic<> to access global function pointers, use raw pointers and atomic_ref to access them safely in multi-threaded builds. This allows to ensure constant initialization of the function pointers, even in C++03. This also solves the problem of undefined dynamic initialization order that we previously tried to solve with the init_priority attribute. The attribute turns out to not work if the pointers were raw pointers (in single-threaded builds). It is also not supported by Intel Compiler and possibly other, which required us to avoid using the function pointer for fill_random. The resulting code should be simpler and more portable. In order to check for C++20 std::atomic_ref availability, the older check for <atomic> header was replaced with a check for std::atomic_ref. If not available, we're using Boost.Atomic, as before.
70 lines
1.6 KiB
C++
70 lines
1.6 KiB
C++
// atomic_tools.hpp ------------------------------------------------------------------//
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// Copyright 2021 Andrey Semashev
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// Distributed under the Boost Software License, Version 1.0.
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// See http://www.boost.org/LICENSE_1_0.txt
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// See library home page at http://www.boost.org/libs/filesystem
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//--------------------------------------------------------------------------------------//
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#ifndef BOOST_FILESYSTEM_SRC_ATOMIC_TOOLS_HPP_
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#define BOOST_FILESYSTEM_SRC_ATOMIC_TOOLS_HPP_
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#include <boost/filesystem/config.hpp>
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#if !defined(BOOST_FILESYSTEM_SINGLE_THREADED)
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#include "atomic_ref.hpp"
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namespace boost {
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namespace filesystem {
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namespace detail {
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//! Atomically loads the value
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template< typename T >
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BOOST_FORCEINLINE T atomic_load_relaxed(T& a)
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{
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return atomic_ns::atomic_ref< T >(a).load(atomic_ns::memory_order_relaxed);
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}
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//! Atomically stores the value
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template< typename T >
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BOOST_FORCEINLINE void atomic_store_relaxed(T& a, T val)
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{
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atomic_ns::atomic_ref< T >(a).store(val, atomic_ns::memory_order_relaxed);
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}
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} // namespace detail
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} // namespace filesystem
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} // namespace boost
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#else // !defined(BOOST_FILESYSTEM_SINGLE_THREADED)
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namespace boost {
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namespace filesystem {
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namespace detail {
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//! Atomically loads the value
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template< typename T >
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BOOST_FORCEINLINE T atomic_load_relaxed(T const& a)
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{
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return a;
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}
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//! Atomically stores the value
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template< typename T >
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BOOST_FORCEINLINE void atomic_store_relaxed(T& a, T val)
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{
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a = val;
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}
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} // namespace detail
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} // namespace filesystem
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} // namespace boost
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#endif // !defined(BOOST_FILESYSTEM_SINGLE_THREADED)
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#endif // BOOST_FILESYSTEM_SRC_ATOMIC_TOOLS_HPP_
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