atomic.hpp

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//
// Copyright 2012 Ettus Research LLC
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program.  If not, see <http://www.gnu.org/licenses/>.
//

#ifndef INCLUDED_UHD_UTILS_ATOMIC_HPP
#define INCLUDED_UHD_UTILS_ATOMIC_HPP

#include <uhd/config.hpp>
#include <uhd/types/time_spec.hpp>
#include <boost/thread/thread.hpp>
#include <boost/interprocess/detail/atomic.hpp>

#include <boost/version.hpp>
#if BOOST_VERSION >= 104800
#  define BOOST_IPC_DETAIL boost::interprocess::ipcdetail
#else
#  define BOOST_IPC_DETAIL boost::interprocess::detail
#endif

namespace uhd{

    class UHD_API atomic_uint32_t{
    public:

        UHD_INLINE atomic_uint32_t(void){
            this->write(0);
        }

        UHD_INLINE boost::uint32_t cas(boost::uint32_t newval, boost::uint32_t cmp){
            return BOOST_IPC_DETAIL::atomic_cas32(&_num, newval, cmp);
        }

        UHD_INLINE void write(const boost::uint32_t newval){
            BOOST_IPC_DETAIL::atomic_write32(&_num, newval);
        }

        UHD_INLINE boost::uint32_t read(void){
            return BOOST_IPC_DETAIL::atomic_read32(&_num);
        }

        UHD_INLINE boost::uint32_t inc(void){
            return BOOST_IPC_DETAIL::atomic_inc32(&_num);
        }

        UHD_INLINE boost::uint32_t dec(void){
            return BOOST_IPC_DETAIL::atomic_dec32(&_num);
        }

    private: volatile boost::uint32_t _num;
    };

    class UHD_API reusable_barrier{
    public:

        void resize(const size_t size){
            _size = size;
            _count.write(size);
        }

        void interrupt(void)
        {
            _count.write(boost::uint32_t(~0));
        }

        UHD_INLINE void wait(void){
            _count.dec();
            _count.cas(_size, 0);
            while (_count.read() != _size){
                boost::this_thread::interruption_point();
                if (_count.read() == boost::uint32_t(~0))
                    throw boost::thread_interrupted();
                boost::this_thread::yield();
            }
        }

    private:
        size_t _size;
        atomic_uint32_t _count;
    };

    UHD_INLINE bool spin_wait_with_timeout(
        atomic_uint32_t &cond,
        boost::uint32_t value,
        const double timeout
    ){
        if (cond.read() == value) return true;
        const time_spec_t exit_time = time_spec_t::get_system_time() + time_spec_t(timeout);
        while (cond.read() != value){
            if (time_spec_t::get_system_time() > exit_time) return false;
            boost::this_thread::interruption_point();
            boost::this_thread::yield();
        }
        return true;
    }

    class simple_claimer{
    public:
        simple_claimer(void){
            this->release();
        }

        UHD_INLINE void release(void){
            _locked.write(0);
        }

        UHD_INLINE bool claim_with_wait(const double timeout){
            if (spin_wait_with_timeout(_locked, 0, timeout)){
                _locked.write(1);
                return true;
            }
            return false;
        }

    private:
        atomic_uint32_t _locked;
    };

} //namespace uhd

#endif /* INCLUDED_UHD_UTILS_ATOMIC_HPP */