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/detail/posix_time_types_wrk.hpp>
  30 #include <boost/interprocess/sync/detail/locks.hpp>
  31 #include <boost/interprocess/sync/detail/common_algorithms.hpp>
  32
  33 #if !defined(BOOST_INTERPROCESS_FORCE_GENERIC_EMULATION) && \
  34    (defined(BOOST_INTERPROCESS_POSIX_PROCESS_SHARED) && defined(BOOST_INTERPROCESS_POSIX_UNNAMED_SEMAPHORES))
  35    #include <boost/interprocess/sync/posix/semaphore.hpp>
  36    #define BOOST_INTERPROCESS_USE_POSIX
  37 //Experimental...
  38 #elif !defined(BOOST_INTERPROCESS_FORCE_GENERIC_EMULATION) && defined (BOOST_INTERPROCESS_WINDOWS)
  39    #include <boost/interprocess/sync/windows/semaphore.hpp>
  40    #define BOOST_INTERPROCESS_USE_WINDOWS
  41 #elif !defined(BOOST_INTERPROCESS_DOXYGEN_INVOKED)
  42    #include <boost/interprocess/sync/spin/semaphore.hpp>
  43    #define BOOST_INTERPROCESS_USE_GENERIC_EMULATION
  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    bool timed_wait(const boost::posix_time::ptime &abs_time);
  93
  94    //!Returns the interprocess_semaphore count
  95 //   int get_count() const;
  96    #if !defined(BOOST_INTERPROCESS_DOXYGEN_INVOKED)
  97    private:
  98    #if defined(BOOST_INTERPROCESS_USE_GENERIC_EMULATION)
  99       #undef BOOST_INTERPROCESS_USE_GENERIC_EMULATION
 100       typedef ipcdetail::spin_semaphore internal_sem_t;
 101    #elif defined(BOOST_INTERPROCESS_USE_WINDOWS)
 102       #undef BOOST_INTERPROCESS_USE_WINDOWS
 103       typedef ipcdetail::windows_semaphore internal_sem_t;
 104    #else
 105       #undef BOOST_INTERPROCESS_USE_POSIX
 106       typedef ipcdetail::posix_semaphore internal_sem_t;
 107    #endif   //#if defined(BOOST_INTERPROCESS_USE_GENERIC_EMULATION)
 108    internal_sem_t m_sem;
 109    #endif   //#ifndef BOOST_INTERPROCESS_DOXYGEN_INVOKED
 110 };
 111
 112 }  //namespace interprocess {
 113 }  //namespace boost {
 114
 115 namespace boost {
 116 namespace interprocess {
 117
 118 inline interprocess_semaphore::interprocess_semaphore(unsigned int initialCount)
 119    : m_sem(initialCount)
 120 {}
 121
 122 inline interprocess_semaphore::~interprocess_semaphore(){}
 123
 124 inline void interprocess_semaphore::wait()
 125 {
 126    ipcdetail::lock_to_wait<internal_sem_t> ltw(m_sem);
 127    timeout_when_locking_aware_lock(ltw);
 128 }
 129
 130 inline bool interprocess_semaphore::try_wait()
 131 { return m_sem.try_wait(); }
 132
 133 inline bool interprocess_semaphore::timed_wait(const boost::posix_time::ptime &abs_time)
 134 { return m_sem.timed_wait(abs_time); }
 135
 136 inline void interprocess_semaphore::post()
 137 { m_sem.post(); }
 138
 139 }  //namespace interprocess {
 140 }  //namespace boost {
 141
 142 #include <boost/interprocess/detail/config_end.hpp>
 143
 144 #endif   //BOOST_INTERPROCESS_SEMAPHORE_HPP