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(); take_ownership()48 void take_ownership(){} 49 private: 50 volatile boost::uint32_t m_s; 51 52 struct common_lock_wrapper 53 { common_lock_wrapperboost::interprocess::ipcdetail::spin_mutex::common_lock_wrapper54 common_lock_wrapper(spin_mutex &sp) 55 : m_sp(sp) 56 {} 57 lockboost::interprocess::ipcdetail::spin_mutex::common_lock_wrapper58 void lock() 59 { 60 ipcdetail::try_based_lock(m_sp); 61 } 62 timed_lockboost::interprocess::ipcdetail::spin_mutex::common_lock_wrapper63 bool timed_lock(const boost::posix_time::ptime &abs_time) 64 { return m_sp.timed_lock(abs_time); } 65 66 spin_mutex &m_sp; 67 }; 68 }; 69 spin_mutex()70inline spin_mutex::spin_mutex() 71 : m_s(0) 72 { 73 //Note that this class is initialized to zero. 74 //So zeroed memory can be interpreted as an 75 //initialized mutex 76 } 77 ~spin_mutex()78inline spin_mutex::~spin_mutex() 79 { 80 //Trivial destructor 81 } 82 lock(void)83inline void spin_mutex::lock(void) 84 { 85 common_lock_wrapper clw(*this); 86 ipcdetail::timeout_when_locking_aware_lock(clw); 87 } 88 try_lock(void)89inline bool spin_mutex::try_lock(void) 90 { 91 boost::uint32_t prev_s = ipcdetail::atomic_cas32(const_cast<boost::uint32_t*>(&m_s), 1, 0); 92 return m_s == 1 && prev_s == 0; 93 } 94 timed_lock(const boost::posix_time::ptime & abs_time)95inline bool spin_mutex::timed_lock(const boost::posix_time::ptime &abs_time) 96 { return ipcdetail::try_based_timed_lock(*this, abs_time); } 97 unlock(void)98inline void spin_mutex::unlock(void) 99 { ipcdetail::atomic_cas32(const_cast<boost::uint32_t*>(&m_s), 0, 1); } 100 101 } //namespace ipcdetail { 102 } //namespace interprocess { 103 } //namespace boost { 104 105 #include <boost/interprocess/detail/config_end.hpp> 106 107 #endif //BOOST_INTERPROCESS_DETAIL_SPIN_MUTEX_HPP 108