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116 lines
3.0 KiB
116 lines
3.0 KiB
////////////////////////////////////////////////////////////////////////////// |
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// |
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// (C) Copyright Ion Gaztanaga 2005-2009. Distributed under the Boost |
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// Software License, Version 1.0. (See accompanying file |
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// LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt) |
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// |
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// See http://www.boost.org/libs/interprocess for documentation. |
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// |
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////////////////////////////////////////////////////////////////////////////// |
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#ifndef BOOST_INTERPROCESS_DETAIL_EMULATION_MUTEX_HPP |
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#define BOOST_INTERPROCESS_DETAIL_EMULATION_MUTEX_HPP |
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#if (defined _MSC_VER) && (_MSC_VER >= 1200) |
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# pragma once |
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#endif |
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#include <boost/interprocess/detail/config_begin.hpp> |
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#include <boost/interprocess/detail/workaround.hpp> |
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#include <boost/interprocess/detail/posix_time_types_wrk.hpp> |
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#include <boost/assert.hpp> |
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#include <boost/interprocess/detail/atomic.hpp> |
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#include <boost/cstdint.hpp> |
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#include <boost/interprocess/detail/os_thread_functions.hpp> |
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namespace boost { |
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namespace interprocess { |
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namespace ipcdetail { |
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class emulation_mutex |
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{ |
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emulation_mutex(const emulation_mutex &); |
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emulation_mutex &operator=(const emulation_mutex &); |
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public: |
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emulation_mutex(); |
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~emulation_mutex(); |
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void lock(); |
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bool try_lock(); |
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bool timed_lock(const boost::posix_time::ptime &abs_time); |
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void unlock(); |
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void take_ownership(){}; |
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private: |
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volatile boost::uint32_t m_s; |
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}; |
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inline emulation_mutex::emulation_mutex() |
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: m_s(0) |
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{ |
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//Note that this class is initialized to zero. |
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//So zeroed memory can be interpreted as an |
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//initialized mutex |
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} |
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inline emulation_mutex::~emulation_mutex() |
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{ |
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//Trivial destructor |
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} |
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inline void emulation_mutex::lock(void) |
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{ |
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do{ |
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boost::uint32_t prev_s = ipcdetail::atomic_cas32(const_cast<boost::uint32_t*>(&m_s), 1, 0); |
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if (m_s == 1 && prev_s == 0){ |
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break; |
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} |
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// relinquish current timeslice |
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ipcdetail::thread_yield(); |
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}while (true); |
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} |
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inline bool emulation_mutex::try_lock(void) |
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{ |
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boost::uint32_t prev_s = ipcdetail::atomic_cas32(const_cast<boost::uint32_t*>(&m_s), 1, 0); |
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return m_s == 1 && prev_s == 0; |
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} |
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inline bool emulation_mutex::timed_lock(const boost::posix_time::ptime &abs_time) |
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{ |
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if(abs_time == boost::posix_time::pos_infin){ |
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this->lock(); |
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return true; |
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} |
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//Obtain current count and target time |
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boost::posix_time::ptime now = microsec_clock::universal_time(); |
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if(now >= abs_time) return false; |
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do{ |
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if(this->try_lock()){ |
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break; |
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} |
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now = microsec_clock::universal_time(); |
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if(now >= abs_time){ |
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return false; |
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} |
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// relinquish current time slice |
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ipcdetail::thread_yield(); |
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}while (true); |
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return true; |
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} |
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inline void emulation_mutex::unlock(void) |
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{ ipcdetail::atomic_cas32(const_cast<boost::uint32_t*>(&m_s), 0, 1); } |
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} //namespace ipcdetail { |
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} //namespace interprocess { |
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} //namespace boost { |
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#include <boost/interprocess/detail/config_end.hpp> |
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#endif //BOOST_INTERPROCESS_DETAIL_EMULATION_MUTEX_HPP
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