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/*
* Distributed under the Boost Software License, Version 1.0.
* (See accompanying file LICENSE_1_0.txt or copy at
* http://www.boost.org/LICENSE_1_0.txt)
*
* Copyright (c) 2020 Andrey Semashev
*/
/*!
* \file wait_on_address.cpp
*
* This file contains implementation of runtime detection of \c WaitOnAddress and related APIs on Windows.
*
* https://docs.microsoft.com/en-us/windows/win32/api/synchapi/nf-synchapi-waitonaddress
* https://docs.microsoft.com/en-us/windows/win32/api/synchapi/nf-synchapi-wakebyaddresssingle
* https://docs.microsoft.com/en-us/windows/win32/api/synchapi/nf-synchapi-wakebyaddressall
*/
// Include boost/winapi/config.hpp first to make sure target Windows version is selected by Boost.WinAPI
#include <boost/winapi/config.hpp>
#include <boost/winapi/basic_types.hpp>
#include <boost/atomic/detail/config.hpp>
#include <boost/atomic/detail/link.hpp>
#include <boost/atomic/detail/once_flag.hpp>
#include <boost/atomic/detail/wait_on_address.hpp>
#if BOOST_WINAPI_PARTITION_DESKTOP || BOOST_WINAPI_PARTITION_SYSTEM
#include <boost/memory_order.hpp>
#include <boost/winapi/thread.hpp>
#include <boost/winapi/get_proc_address.hpp>
#include <boost/winapi/dll.hpp>
#include <boost/atomic/detail/core_operations.hpp>
#endif // BOOST_WINAPI_PARTITION_DESKTOP || BOOST_WINAPI_PARTITION_SYSTEM
#include <boost/atomic/detail/header.hpp>
namespace boost {
namespace atomics {
namespace detail {
BOOST_ATOMIC_DECL wait_on_address_t* wait_on_address = NULL;
BOOST_ATOMIC_DECL wake_by_address_t* wake_by_address_single = NULL;
BOOST_ATOMIC_DECL wake_by_address_t* wake_by_address_all = NULL;
#if BOOST_WINAPI_PARTITION_DESKTOP || BOOST_WINAPI_PARTITION_SYSTEM
BOOST_ATOMIC_DECL once_flag wait_functions_once_flag = { 2u };
BOOST_ATOMIC_DECL void initialize_wait_functions() BOOST_NOEXCEPT
{
static_assert(once_flag_operations::is_always_lock_free, "Boost.Atomic unsupported target platform: native atomic operations not implemented for bytes");
once_flag_operations::storage_type old_val = once_flag_operations::load(wait_functions_once_flag.m_flag, boost::memory_order_acquire);
while (true)
{
if (old_val == 2u)
{
if (BOOST_UNLIKELY(!once_flag_operations::compare_exchange_strong(wait_functions_once_flag.m_flag, old_val, 1u, boost::memory_order_relaxed, boost::memory_order_relaxed)))
continue;
boost::winapi::HMODULE_ kernel_base = boost::winapi::get_module_handle(L"api-ms-win-core-synch-l1-2-0.dll");
if (BOOST_LIKELY(kernel_base != NULL))
{
wait_on_address_t* woa = (wait_on_address_t*)boost::winapi::get_proc_address(kernel_base, "WaitOnAddress");
if (BOOST_LIKELY(woa != NULL))
{
wake_by_address_t* wbas = (wake_by_address_t*)boost::winapi::get_proc_address(kernel_base, "WakeByAddressSingle");
wake_by_address_t* wbaa = (wake_by_address_t*)boost::winapi::get_proc_address(kernel_base, "WakeByAddressAll");
if (BOOST_LIKELY(wbas != NULL && wbaa != NULL))
{
wait_on_address = woa;
wake_by_address_single = wbas;
wake_by_address_all = wbaa;
}
}
}
once_flag_operations::store(wait_functions_once_flag.m_flag, 0u, boost::memory_order_release);
break;
}
else if (old_val == 1u)
{
boost::winapi::SwitchToThread();
old_val = once_flag_operations::load(wait_functions_once_flag.m_flag, boost::memory_order_acquire);
}
else
{
break;
}
}
}
#else // BOOST_WINAPI_PARTITION_DESKTOP || BOOST_WINAPI_PARTITION_SYSTEM
BOOST_ATOMIC_DECL once_flag wait_functions_once_flag = { 0u };
BOOST_ATOMIC_DECL void initialize_wait_functions() BOOST_NOEXCEPT
{
}
#endif // BOOST_WINAPI_PARTITION_DESKTOP || BOOST_WINAPI_PARTITION_SYSTEM
} // namespace detail
} // namespace atomics
} // namespace boost
#include <boost/atomic/detail/footer.hpp>
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