/*
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* Distributed under the Boost Software License, Version 1.0.
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* (See accompanying file LICENSE_1_0.txt or copy at
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* http://www.boost.org/LICENSE_1_0.txt)
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*
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* Copyright (c) 2020 Andrey Semashev
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*/
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/*!
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* \file atomic/detail/wait_ops_generic.hpp
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*
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* This header contains generic (lock-based) implementation of the waiting/notifying atomic operations.
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*/
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#ifndef BOOST_ATOMIC_DETAIL_WAIT_OPS_GENERIC_HPP_INCLUDED_
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#define BOOST_ATOMIC_DETAIL_WAIT_OPS_GENERIC_HPP_INCLUDED_
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#include <cstddef>
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#include <boost/memory_order.hpp>
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#include <boost/atomic/detail/config.hpp>
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#include <boost/atomic/detail/pause.hpp>
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#include <boost/atomic/detail/lock_pool.hpp>
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#include <boost/atomic/detail/wait_operations_fwd.hpp>
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#include <boost/atomic/detail/header.hpp>
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#ifdef BOOST_HAS_PRAGMA_ONCE
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#pragma once
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#endif
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namespace boost {
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namespace atomics {
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namespace detail {
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//! Generic implementation of waiting/notifying operations
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template< typename Base, bool Interprocess >
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struct wait_operations_generic;
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template< typename Base >
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struct wait_operations_generic< Base, false > :
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public Base
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{
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typedef Base base_type;
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typedef typename base_type::storage_type storage_type;
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typedef lock_pool::scoped_lock< base_type::storage_alignment, true > scoped_lock;
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typedef lock_pool::scoped_wait_state< base_type::storage_alignment > scoped_wait_state;
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static BOOST_CONSTEXPR_OR_CONST bool always_has_native_wait_notify = false;
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static BOOST_FORCEINLINE bool has_native_wait_notify(storage_type const volatile&) BOOST_NOEXCEPT
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{
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return false;
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}
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static BOOST_FORCEINLINE storage_type wait(storage_type const volatile& storage, storage_type old_val, memory_order order) BOOST_NOEXCEPT
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{
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storage_type new_val = base_type::load(storage, order);
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if (new_val == old_val)
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{
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scoped_wait_state wait_state(&storage);
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new_val = base_type::load(storage, order);
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while (new_val == old_val)
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{
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wait_state.wait();
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new_val = base_type::load(storage, order);
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}
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}
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return new_val;
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}
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static BOOST_FORCEINLINE void notify_one(storage_type volatile& storage) BOOST_NOEXCEPT
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{
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scoped_lock lock(&storage);
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lock_pool::notify_one(lock.get_lock_state(), &storage);
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}
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static BOOST_FORCEINLINE void notify_all(storage_type volatile& storage) BOOST_NOEXCEPT
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{
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scoped_lock lock(&storage);
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lock_pool::notify_all(lock.get_lock_state(), &storage);
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}
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};
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template< typename Base >
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struct wait_operations_generic< Base, true > :
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public Base
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{
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typedef Base base_type;
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typedef typename base_type::storage_type storage_type;
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static BOOST_CONSTEXPR_OR_CONST bool always_has_native_wait_notify = false;
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static BOOST_FORCEINLINE bool has_native_wait_notify(storage_type const volatile&) BOOST_NOEXCEPT
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{
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return false;
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}
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static BOOST_FORCEINLINE storage_type wait(storage_type const volatile& storage, storage_type old_val, memory_order order) BOOST_NOEXCEPT
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{
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storage_type new_val = base_type::load(storage, order);
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if (new_val == old_val)
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{
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for (unsigned int i = 0u; i < 16u; ++i)
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{
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atomics::detail::pause();
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new_val = base_type::load(storage, order);
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if (new_val != old_val)
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goto finish;
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}
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do
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{
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atomics::detail::wait_some();
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new_val = base_type::load(storage, order);
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}
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while (new_val == old_val);
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}
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finish:
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return new_val;
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}
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static BOOST_FORCEINLINE void notify_one(storage_type volatile&) BOOST_NOEXCEPT
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{
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}
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static BOOST_FORCEINLINE void notify_all(storage_type volatile&) BOOST_NOEXCEPT
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{
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}
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};
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template< typename Base, std::size_t Size, bool Interprocess >
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struct wait_operations< Base, Size, true, Interprocess > :
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public wait_operations_generic< Base, Interprocess >
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{
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};
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} // namespace detail
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} // namespace atomics
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} // namespace boost
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#include <boost/atomic/detail/footer.hpp>
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#endif // BOOST_ATOMIC_DETAIL_WAIT_OPS_GENERIC_HPP_INCLUDED_
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