sync/spin/mutex.hpp

0001 //////////////////////////////////////////////////////////////////////////////
0002 //
0003 // (C) Copyright Ion Gaztanaga 2005-2012. Distributed under the Boost
0004 // Software License, Version 1.0. (See accompanying file
0005 // LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
0006 //
0007 // See http://www.boost.org/libs/interprocess for documentation.
0008 //
0009 //////////////////////////////////////////////////////////////////////////////
0010
0011 #ifndef BOOST_INTERPROCESS_DETAIL_SPIN_MUTEX_HPP
0012 #define BOOST_INTERPROCESS_DETAIL_SPIN_MUTEX_HPP
0013
0014 #ifndef BOOST_CONFIG_HPP
0015 #  include <boost/config.hpp>
0016 #endif
0017 #
0018 #if defined(BOOST_HAS_PRAGMA_ONCE)
0019 #  pragma once
0020 #endif
0021
0022 #include <boost/interprocess/detail/config_begin.hpp>
0023 #include <boost/interprocess/detail/workaround.hpp>
0024 #include <boost/assert.hpp>
0025 #include <boost/interprocess/detail/atomic.hpp>
0026 #include <boost/cstdint.hpp>
0027 #include <boost/interprocess/detail/os_thread_functions.hpp>
0028 #include <boost/interprocess/sync/detail/common_algorithms.hpp>
0029 #include <boost/interprocess/timed_utils.hpp>
0030
0031 namespace boost {
0032 namespace interprocess {
0033 namespace ipcdetail {
0034
0035 class spin_mutex
0036 {
0037    spin_mutex(const spin_mutex &);
0038    spin_mutex &operator=(const spin_mutex &);
0039    public:
0040
0041    spin_mutex();
0042    ~spin_mutex();
0043
0044    void lock();
0045    bool try_lock();
0046    template<class TimePoint>
0047    bool timed_lock(const TimePoint &abs_time);
0048
0049    template<class TimePoint> bool try_lock_until(const TimePoint &abs_time)
0050    {  return this->timed_lock(abs_time);  }
0051
0052    template<class Duration>  bool try_lock_for(const Duration &dur)
0053    {  return this->timed_lock(duration_to_ustime(dur)); }
0054
0055    void unlock();
0056    void take_ownership(){}
0057    private:
0058    volatile boost::uint32_t m_s;
0059
0060    struct common_lock_wrapper
0061    {
0062       common_lock_wrapper(spin_mutex &sp)
0063          : m_sp(sp)
0064       {}
0065
0066       void lock()
0067       {
0068          ipcdetail::try_based_lock(m_sp);
0069       }
0070
0071       template<class TimePoint>
0072       bool timed_lock(const TimePoint &abs_time)
0073       {  return m_sp.timed_lock(abs_time);   }
0074
0075       spin_mutex &m_sp;
0076    };
0077 };
0078
0079 inline spin_mutex::spin_mutex()
0080    : m_s(0)
0081 {
0082    //Note that this class is initialized to zero.
0083    //So zeroed memory can be interpreted as an
0084    //initialized mutex
0085 }
0086
0087 inline spin_mutex::~spin_mutex()
0088 {
0089    //Trivial destructor
0090 }
0091
0092 inline void spin_mutex::lock(void)
0093 {
0094    common_lock_wrapper clw(*this);
0095    ipcdetail::timeout_when_locking_aware_lock(clw);
0096 }
0097
0098 inline bool spin_mutex::try_lock(void)
0099 {
0100    boost::uint32_t prev_s = ipcdetail::atomic_cas32(const_cast<boost::uint32_t*>(&m_s), 1, 0);
0101    return m_s == 1 && prev_s == 0;
0102 }
0103
0104 template<class TimePoint>
0105 inline bool spin_mutex::timed_lock(const TimePoint &abs_time)
0106 {  return ipcdetail::try_based_timed_lock(*this, abs_time); }
0107
0108 inline void spin_mutex::unlock(void)
0109 {  ipcdetail::atomic_cas32(const_cast<boost::uint32_t*>(&m_s), 0, 1);   }
0110
0111 }  //namespace ipcdetail {
0112 }  //namespace interprocess {
0113 }  //namespace boost {
0114
0115 #include <boost/interprocess/detail/config_end.hpp>
0116
0117 #endif   //BOOST_INTERPROCESS_DETAIL_SPIN_MUTEX_HPP