/usr/include/boost/atomic/detail
Edit: /usr/include/boost/atomic/detail/futex.hpp (5388B)
/*
* 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 atomic/detail/futex.hpp
*
* This header defines wrappers around futex syscall.
*
* http://man7.org/linux/man-pages/man2/futex.2.html
* https://man.openbsd.org/futex
*/
#ifndef BOOST_ATOMIC_DETAIL_FUTEX_HPP_INCLUDED_
#define BOOST_ATOMIC_DETAIL_FUTEX_HPP_INCLUDED_
#include
#ifdef BOOST_HAS_PRAGMA_ONCE
#pragma once
#endif
#if defined(__linux__) || defined(__OpenBSD__) || defined(__NETBSD__) || defined(__NetBSD__)
#include
// Some Android NDKs (Google NDK and older Crystax.NET NDK versions) don't define SYS_futex.
#if defined(SYS_futex)
#define BOOST_ATOMIC_DETAIL_SYS_FUTEX SYS_futex
#elif defined(__NR_futex)
#define BOOST_ATOMIC_DETAIL_SYS_FUTEX __NR_futex
#elif defined(SYS___futex)
// NetBSD defines SYS___futex, which has slightly different parameters. Basically, it has decoupled timeout and val2 parameters:
// int __futex(int *addr1, int op, int val1, const struct timespec *timeout, int *addr2, int val2, int val3);
// https://ftp.netbsd.org/pub/NetBSD/NetBSD-current/src/sys/sys/syscall.h
// http://bxr.su/NetBSD/sys/kern/sys_futex.c
#define BOOST_ATOMIC_DETAIL_SYS_FUTEX SYS___futex
#define BOOST_ATOMIC_DETAIL_NETBSD_FUTEX
#endif
#if defined(BOOST_ATOMIC_DETAIL_SYS_FUTEX)
#include
#if defined(__linux__)
#include
#else
#include
#endif
#include
#include
#define BOOST_ATOMIC_DETAIL_HAS_FUTEX
#if defined(FUTEX_PRIVATE_FLAG)
#define BOOST_ATOMIC_DETAIL_FUTEX_PRIVATE_FLAG FUTEX_PRIVATE_FLAG
#else
#define BOOST_ATOMIC_DETAIL_FUTEX_PRIVATE_FLAG 0
#endif
namespace boost {
namespace atomics {
namespace detail {
//! Invokes an operation on the futex
BOOST_FORCEINLINE int futex_invoke(void* addr1, int op, unsigned int val1, const void* timeout = NULL, void* addr2 = NULL, unsigned int val3 = 0) BOOST_NOEXCEPT
{
#if !defined(BOOST_ATOMIC_DETAIL_NETBSD_FUTEX)
return ::syscall(BOOST_ATOMIC_DETAIL_SYS_FUTEX, addr1, op, val1, timeout, addr2, val3);
#else
// Pass 0 in val2.
return ::syscall(BOOST_ATOMIC_DETAIL_SYS_FUTEX, addr1, op, val1, timeout, addr2, 0u, val3);
#endif
}
//! Invokes an operation on the futex
BOOST_FORCEINLINE int futex_invoke(void* addr1, int op, unsigned int val1, unsigned int val2, void* addr2 = NULL, unsigned int val3 = 0) BOOST_NOEXCEPT
{
#if !defined(BOOST_ATOMIC_DETAIL_NETBSD_FUTEX)
return ::syscall(BOOST_ATOMIC_DETAIL_SYS_FUTEX, addr1, op, val1, static_cast< atomics::detail::uintptr_t >(val2), addr2, val3);
#else
// Pass NULL in timeout.
return ::syscall(BOOST_ATOMIC_DETAIL_SYS_FUTEX, addr1, op, val1, static_cast< void* >(NULL), addr2, val2, val3);
#endif
}
//! Checks that the value \c pval is \c expected and blocks
BOOST_FORCEINLINE int futex_wait(void* pval, unsigned int expected) BOOST_NOEXCEPT
{
return futex_invoke(pval, FUTEX_WAIT, expected);
}
//! Checks that the value \c pval is \c expected and blocks
BOOST_FORCEINLINE int futex_wait_private(void* pval, unsigned int expected) BOOST_NOEXCEPT
{
return futex_invoke(pval, FUTEX_WAIT | BOOST_ATOMIC_DETAIL_FUTEX_PRIVATE_FLAG, expected);
}
//! Wakes the specified number of threads waiting on the futex
BOOST_FORCEINLINE int futex_signal(void* pval, unsigned int count = 1u) BOOST_NOEXCEPT
{
return futex_invoke(pval, FUTEX_WAKE, count);
}
//! Wakes the specified number of threads waiting on the futex
BOOST_FORCEINLINE int futex_signal_private(void* pval, unsigned int count = 1u) BOOST_NOEXCEPT
{
return futex_invoke(pval, FUTEX_WAKE | BOOST_ATOMIC_DETAIL_FUTEX_PRIVATE_FLAG, count);
}
//! Wakes all threads waiting on the futex
BOOST_FORCEINLINE int futex_broadcast(void* pval) BOOST_NOEXCEPT
{
return futex_signal(pval, (~static_cast< unsigned int >(0u)) >> 1);
}
//! Wakes all threads waiting on the futex
BOOST_FORCEINLINE int futex_broadcast_private(void* pval) BOOST_NOEXCEPT
{
return futex_signal_private(pval, (~static_cast< unsigned int >(0u)) >> 1);
}
//! Wakes the wake_count threads waiting on the futex pval1 and requeues up to requeue_count of the blocked threads onto another futex pval2
BOOST_FORCEINLINE int futex_requeue(void* pval1, void* pval2, unsigned int wake_count = 1u, unsigned int requeue_count = (~static_cast< unsigned int >(0u)) >> 1) BOOST_NOEXCEPT
{
return futex_invoke(pval1, FUTEX_REQUEUE, wake_count, requeue_count, pval2);
}
//! Wakes the wake_count threads waiting on the futex pval1 and requeues up to requeue_count of the blocked threads onto another futex pval2
BOOST_FORCEINLINE int futex_requeue_private(void* pval1, void* pval2, unsigned int wake_count = 1u, unsigned int requeue_count = (~static_cast< unsigned int >(0u)) >> 1) BOOST_NOEXCEPT
{
return futex_invoke(pval1, FUTEX_REQUEUE | BOOST_ATOMIC_DETAIL_FUTEX_PRIVATE_FLAG, wake_count, requeue_count, pval2);
}
} // namespace detail
} // namespace atomics
} // namespace boost
#include
#endif // defined(BOOST_ATOMIC_DETAIL_SYS_FUTEX)
#endif // defined(__linux__) || defined(__OpenBSD__) || defined(__NETBSD__) || defined(__NetBSD__)
#endif // BOOST_ATOMIC_DETAIL_FUTEX_HPP_INCLUDED_