ceph/src/boost/libs/interprocess/include/boost/interprocess/sync/spin/mutex.hpp

   1 //////////////////////////////////////////////////////////////////////////////
   2 //
   3 // (C) Copyright Ion Gaztanaga 2005-2012. Distributed under the Boost
   4 // Software License, Version 1.0. (See accompanying file
   5 // LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
   6 //
   7 // See http://www.boost.org/libs/interprocess for documentation.
   8 //
   9 //////////////////////////////////////////////////////////////////////////////
  10
  11 #ifndef BOOST_INTERPROCESS_DETAIL_SPIN_MUTEX_HPP
  12 #define BOOST_INTERPROCESS_DETAIL_SPIN_MUTEX_HPP
  13
  14 #ifndef BOOST_CONFIG_HPP
  15 #  include <boost/config.hpp>
  16 #endif
  17 #
  18 #if defined(BOOST_HAS_PRAGMA_ONCE)
  19 #  pragma once
  20 #endif
  21
  22 #include <boost/interprocess/detail/config_begin.hpp>
  23 #include <boost/interprocess/detail/workaround.hpp>
  24 #include <boost/interprocess/detail/posix_time_types_wrk.hpp>
  25 #include <boost/assert.hpp>
  26 #include <boost/interprocess/detail/atomic.hpp>
  27 #include <boost/cstdint.hpp>
  28 #include <boost/interprocess/detail/os_thread_functions.hpp>
  29 #include <boost/interprocess/sync/detail/common_algorithms.hpp>
  30
  31 namespace boost {
  32 namespace interprocess {
  33 namespace ipcdetail {
  34
  35 class spin_mutex
  36 {
  37    spin_mutex(const spin_mutex &);
  38    spin_mutex &operator=(const spin_mutex &);
  39    public:
  40
  41    spin_mutex();
  42    ~spin_mutex();
  43
  44    void lock();
  45    bool try_lock();
  46    bool timed_lock(const boost::posix_time::ptime &abs_time);
  47    void unlock();
  48    void take_ownership(){};
  49    private:
  50    volatile boost::uint32_t m_s;
  51 };
  52
  53 inline spin_mutex::spin_mutex()
  54    : m_s(0)
  55 {
  56    //Note that this class is initialized to zero.
  57    //So zeroed memory can be interpreted as an
  58    //initialized mutex
  59 }
  60
  61 inline spin_mutex::~spin_mutex()
  62 {
  63    //Trivial destructor
  64 }
  65
  66 inline void spin_mutex::lock(void)
  67 {  return ipcdetail::try_based_lock(*this); }
  68
  69 inline bool spin_mutex::try_lock(void)
  70 {
  71    boost::uint32_t prev_s = ipcdetail::atomic_cas32(const_cast<boost::uint32_t*>(&m_s), 1, 0);
  72    return m_s == 1 && prev_s == 0;
  73 }
  74
  75 inline bool spin_mutex::timed_lock(const boost::posix_time::ptime &abs_time)
  76 {  return ipcdetail::try_based_timed_lock(*this, abs_time); }
  77
  78 inline void spin_mutex::unlock(void)
  79 {  ipcdetail::atomic_cas32(const_cast<boost::uint32_t*>(&m_s), 0, 1);   }
  80
  81 }  //namespace ipcdetail {
  82 }  //namespace interprocess {
  83 }  //namespace boost {
  84
  85 #include <boost/interprocess/detail/config_end.hpp>
  86
  87 #endif   //BOOST_INTERPROCESS_DETAIL_SPIN_MUTEX_HPP