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
0030 namespace boost {
0031 namespace interprocess {
0032 namespace ipcdetail {
0033
0034 class spin_mutex
0035 {
0036    spin_mutex(const spin_mutex &);
0037    spin_mutex &operator=(const spin_mutex &);
0038    public:
0039
0040    spin_mutex();
0041    ~spin_mutex();
0042
0043    void lock();
0044    bool try_lock();
0045    template<class TimePoint>
0046    bool timed_lock(const TimePoint &abs_time);
0047
0048    template<class TimePoint> bool try_lock_until(const TimePoint &abs_time)
0049    {  return this->timed_lock(abs_time);  }
0050
0051    template<class Duration>  bool try_lock_for(const Duration &dur)
0052    {  return this->timed_lock(duration_to_ustime(dur)); }
0053
0054    void unlock();
0055    void take_ownership(){}
0056    private:
0057    volatile boost::uint32_t m_s;
0058
0059    struct common_lock_wrapper
0060    {
0061       common_lock_wrapper(spin_mutex &sp)
0062          : m_sp(sp)
0063       {}
0064
0065       void lock()
0066       {
0067          ipcdetail::try_based_lock(m_sp);
0068       }
0069
0070       template<class TimePoint>
0071       bool timed_lock(const TimePoint &abs_time)
0072       {  return m_sp.timed_lock(abs_time);   }
0073
0074       spin_mutex &m_sp;
0075    };
0076 };
0077
0078 inline spin_mutex::spin_mutex()
0079    : m_s(0)
0080 {
0081    //Note that this class is initialized to zero.
0082    //So zeroed memory can be interpreted as an
0083    //initialized mutex
0084 }
0085
0086 inline spin_mutex::~spin_mutex()
0087 {
0088    //Trivial destructor
0089 }
0090
0091 inline void spin_mutex::lock(void)
0092 {
0093    common_lock_wrapper clw(*this);
0094    ipcdetail::timeout_when_locking_aware_lock(clw);
0095 }
0096
0097 inline bool spin_mutex::try_lock(void)
0098 {
0099    boost::uint32_t prev_s = ipcdetail::atomic_cas32(const_cast<boost::uint32_t*>(&m_s), 1, 0);
0100    return m_s == 1 && prev_s == 0;
0101 }
0102
0103 template<class TimePoint>
0104 inline bool spin_mutex::timed_lock(const TimePoint &abs_time)
0105 {  return ipcdetail::try_based_timed_lock(*this, abs_time); }
0106
0107 inline void spin_mutex::unlock(void)
0108 {  ipcdetail::atomic_cas32(const_cast<boost::uint32_t*>(&m_s), 0, 1);   }
0109
0110 }  //namespace ipcdetail {
0111 }  //namespace interprocess {
0112 }  //namespace boost {
0113
0114 #include <boost/interprocess/detail/config_end.hpp>
0115
0116 #endif   //BOOST_INTERPROCESS_DETAIL_SPIN_MUTEX_HPP