ceph/src/boost/boost/interprocess/sync/interprocess_semaphore.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_SEMAPHORE_HPP
  12 #define BOOST_INTERPROCESS_SEMAPHORE_HPP
  13
  14 #if !defined(BOOST_INTERPROCESS_DOXYGEN_INVOKED)
  15
  16 #ifndef BOOST_CONFIG_HPP
  17 #  include <boost/config.hpp>
  18 #endif
  19 #
  20 #if defined(BOOST_HAS_PRAGMA_ONCE)
  21 #  pragma once
  22 #endif
  23
  24 #include <boost/interprocess/detail/config_begin.hpp>
  25 #include <boost/interprocess/detail/workaround.hpp>
  26
  27 #include <boost/interprocess/creation_tags.hpp>
  28 #include <boost/interprocess/exceptions.hpp>
  29 #include <boost/interprocess/sync/detail/locks.hpp>
  30 #include <boost/interprocess/sync/detail/common_algorithms.hpp>
  31
  32 #if   !defined(BOOST_INTERPROCESS_FORCE_GENERIC_EMULATION) && \
  33        defined(BOOST_INTERPROCESS_POSIX_PROCESS_SHARED)    && \
  34        defined(BOOST_INTERPROCESS_POSIX_UNNAMED_SEMAPHORES)
  35    #include <boost/interprocess/sync/posix/semaphore.hpp>
  36    #define BOOST_INTERPROCESS_SEMAPHORE_USE_POSIX
  37 #elif !defined(BOOST_INTERPROCESS_FORCE_GENERIC_EMULATION) && defined (BOOST_INTERPROCESS_WINDOWS)
  38    //Experimental...
  39    #include <boost/interprocess/sync/windows/semaphore.hpp>
  40    #define BOOST_INTERPROCESS_SEMAPHORE_USE_WINAPI
  41 #else
  42    //spin_semaphore is used
  43    #include <boost/interprocess/sync/spin/semaphore.hpp>
  44 #endif
  45
  46 #endif   //#ifndef BOOST_INTERPROCESS_DOXYGEN_INVOKED
  47
  48 //!\file
  49 //!Describes a interprocess_semaphore class for inter-process synchronization
  50
  51 namespace boost {
  52 namespace interprocess {
  53
  54 //!Wraps a interprocess_semaphore that can be placed in shared memory and can be
  55 //!shared between processes. Allows timed lock tries
  56 class interprocess_semaphore
  57 {
  58    #if !defined(BOOST_INTERPROCESS_DOXYGEN_INVOKED)
  59    //Non-copyable
  60    interprocess_semaphore(const interprocess_semaphore &);
  61    interprocess_semaphore &operator=(const interprocess_semaphore &);
  62    #endif   //#ifndef BOOST_INTERPROCESS_DOXYGEN_INVOKED
  63    public:
  64    //!Creates a interprocess_semaphore with the given initial count.
  65    //!interprocess_exception if there is an error.*/
  66    interprocess_semaphore(unsigned int initialCount);
  67
  68    //!Destroys the interprocess_semaphore.
  69    //!Does not throw
  70    ~interprocess_semaphore();
  71
  72    //!Increments the interprocess_semaphore count. If there are processes/threads blocked waiting
  73    //!for the interprocess_semaphore, then one of these processes will return successfully from
  74    //!its wait function. If there is an error an interprocess_exception exception is thrown.
  75    void post();
  76
  77    //!Decrements the interprocess_semaphore. If the interprocess_semaphore value is not greater than zero,
  78    //!then the calling process/thread blocks until it can decrement the counter.
  79    //!If there is an error an interprocess_exception exception is thrown.
  80    void wait();
  81
  82    //!Decrements the interprocess_semaphore if the interprocess_semaphore's value is greater than zero
  83    //!and returns true. If the value is not greater than zero returns false.
  84    //!If there is an error an interprocess_exception exception is thrown.
  85    bool try_wait();
  86
  87    //!Decrements the interprocess_semaphore if the interprocess_semaphore's value is greater
  88    //!than zero and returns true. Otherwise, waits for the interprocess_semaphore
  89    //!to the posted or the timeout expires. If the timeout expires, the
  90    //!function returns false. If the interprocess_semaphore is posted the function
  91    //!returns true. If there is an error throws sem_exception
  92    template<class TimePoint>
  93    bool timed_wait(const TimePoint &abs_time);
  94
  95    //!Returns the interprocess_semaphore count
  96 //   int get_count() const;
  97    #if !defined(BOOST_INTERPROCESS_DOXYGEN_INVOKED)
  98    private:
  99    #if defined(BOOST_INTERPROCESS_SEMAPHORE_USE_POSIX)
 100       typedef ipcdetail::posix_semaphore internal_sem_t;
 101    #elif defined(BOOST_INTERPROCESS_SEMAPHORE_USE_WINAPI)
 102       typedef ipcdetail::winapi_semaphore internal_sem_t;
 103    #else
 104       typedef ipcdetail::spin_semaphore internal_sem_t;
 105    #endif   //#if defined(BOOST_INTERPROCESS_FORCE_GENERIC_EMULATION)
 106    internal_sem_t m_sem;
 107    #endif   //#ifndef BOOST_INTERPROCESS_DOXYGEN_INVOKED
 108 };
 109
 110 }  //namespace interprocess {
 111 }  //namespace boost {
 112
 113 namespace boost {
 114 namespace interprocess {
 115
 116 inline interprocess_semaphore::interprocess_semaphore(unsigned int initialCount)
 117    : m_sem(initialCount)
 118 {}
 119
 120 inline interprocess_semaphore::~interprocess_semaphore(){}
 121
 122 inline void interprocess_semaphore::wait()
 123 {
 124    ipcdetail::lock_to_wait<internal_sem_t> ltw(m_sem);
 125    timeout_when_locking_aware_lock(ltw);
 126 }
 127
 128 inline bool interprocess_semaphore::try_wait()
 129 { return m_sem.try_wait(); }
 130
 131 template<class TimePoint>
 132 inline bool interprocess_semaphore::timed_wait(const TimePoint &abs_time)
 133 { return m_sem.timed_wait(abs_time); }
 134
 135 inline void interprocess_semaphore::post()
 136 { m_sem.post(); }
 137
 138 }  //namespace interprocess {
 139 }  //namespace boost {
 140
 141 #include <boost/interprocess/detail/config_end.hpp>
 142
 143 #endif   //BOOST_INTERPROCESS_SEMAPHORE_HPP