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
  31 #if !defined(BOOST_INTERPROCESS_FORCE_GENERIC_EMULATION) && \
  32    (defined(BOOST_INTERPROCESS_POSIX_PROCESS_SHARED) && defined(BOOST_INTERPROCESS_POSIX_UNNAMED_SEMAPHORES))
  33    #include <boost/interprocess/sync/posix/semaphore.hpp>
  34    #define BOOST_INTERPROCESS_USE_POSIX
  35 //Experimental...
  36 #elif !defined(BOOST_INTERPROCESS_FORCE_GENERIC_EMULATION) && defined (BOOST_INTERPROCESS_WINDOWS)
  37    #include <boost/interprocess/sync/windows/semaphore.hpp>
  38    #define BOOST_INTERPROCESS_USE_WINDOWS
  39 #elif !defined(BOOST_INTERPROCESS_DOXYGEN_INVOKED)
  40    #include <boost/interprocess/sync/spin/semaphore.hpp>
  41    #define BOOST_INTERPROCESS_USE_GENERIC_EMULATION
  42 #endif
  43
  44 #endif   //#ifndef BOOST_INTERPROCESS_DOXYGEN_INVOKED
  45
  46 //!\file
  47 //!Describes a interprocess_semaphore class for inter-process synchronization
  48
  49 namespace boost {
  50 namespace interprocess {
  51
  52 //!Wraps a interprocess_semaphore that can be placed in shared memory and can be
  53 //!shared between processes. Allows timed lock tries
  54 class interprocess_semaphore
  55 {
  56    #if !defined(BOOST_INTERPROCESS_DOXYGEN_INVOKED)
  57    //Non-copyable
  58    interprocess_semaphore(const interprocess_semaphore &);
  59    interprocess_semaphore &operator=(const interprocess_semaphore &);
  60    #endif   //#ifndef BOOST_INTERPROCESS_DOXYGEN_INVOKED
  61    public:
  62    //!Creates a interprocess_semaphore with the given initial count.
  63    //!interprocess_exception if there is an error.*/
  64    interprocess_semaphore(unsigned int initialCount);
  65
  66    //!Destroys the interprocess_semaphore.
  67    //!Does not throw
  68    ~interprocess_semaphore();
  69
  70    //!Increments the interprocess_semaphore count. If there are processes/threads blocked waiting
  71    //!for the interprocess_semaphore, then one of these processes will return successfully from
  72    //!its wait function. If there is an error an interprocess_exception exception is thrown.
  73    void post();
  74
  75    //!Decrements the interprocess_semaphore. If the interprocess_semaphore value is not greater than zero,
  76    //!then the calling process/thread blocks until it can decrement the counter.
  77    //!If there is an error an interprocess_exception exception is thrown.
  78    void wait();
  79
  80    //!Decrements the interprocess_semaphore if the interprocess_semaphore's value is greater than zero
  81    //!and returns true. If the value is not greater than zero returns false.
  82    //!If there is an error an interprocess_exception exception is thrown.
  83    bool try_wait();
  84
  85    //!Decrements the interprocess_semaphore if the interprocess_semaphore's value is greater
  86    //!than zero and returns true. Otherwise, waits for the interprocess_semaphore
  87    //!to the posted or the timeout expires. If the timeout expires, the
  88    //!function returns false. If the interprocess_semaphore is posted the function
  89    //!returns true. If there is an error throws sem_exception
  90    bool timed_wait(const boost::posix_time::ptime &abs_time);
  91
  92    //!Returns the interprocess_semaphore count
  93 //   int get_count() const;
  94    #if !defined(BOOST_INTERPROCESS_DOXYGEN_INVOKED)
  95    private:
  96    #if defined(BOOST_INTERPROCESS_USE_GENERIC_EMULATION)
  97       #undef BOOST_INTERPROCESS_USE_GENERIC_EMULATION
  98       ipcdetail::spin_semaphore m_sem;
  99    #elif defined(BOOST_INTERPROCESS_USE_WINDOWS)
 100       #undef BOOST_INTERPROCESS_USE_WINDOWS
 101       ipcdetail::windows_semaphore m_sem;
 102    #else
 103       #undef BOOST_INTERPROCESS_USE_POSIX
 104       ipcdetail::posix_semaphore m_sem;
 105    #endif   //#if defined(BOOST_INTERPROCESS_USE_GENERIC_EMULATION)
 106    #endif   //#ifndef BOOST_INTERPROCESS_DOXYGEN_INVOKED
 107 };
 108
 109 }  //namespace interprocess {
 110 }  //namespace boost {
 111
 112 namespace boost {
 113 namespace interprocess {
 114
 115 inline interprocess_semaphore::interprocess_semaphore(unsigned int initialCount)
 116    : m_sem(initialCount)
 117 {}
 118
 119 inline interprocess_semaphore::~interprocess_semaphore(){}
 120
 121 inline void interprocess_semaphore::wait()
 122 {
 123    #ifdef BOOST_INTERPROCESS_ENABLE_TIMEOUT_WHEN_LOCKING
 124       boost::posix_time::ptime wait_time
 125          = microsec_clock::universal_time()
 126          + boost::posix_time::milliseconds(BOOST_INTERPROCESS_TIMEOUT_WHEN_LOCKING_DURATION_MS);
 127       if (!m_sem.timed_wait(wait_time))
 128       {
 129          throw interprocess_exception(timeout_when_waiting_error, "Interprocess semaphore timeout when waiting. Possible deadlock: owner died without posting?");
 130       }
 131    #else
 132       m_sem.wait();
 133    #endif
 134 }
 135 inline bool interprocess_semaphore::try_wait()
 136 { return m_sem.try_wait(); }
 137
 138 inline bool interprocess_semaphore::timed_wait(const boost::posix_time::ptime &abs_time)
 139 { return m_sem.timed_wait(abs_time); }
 140
 141 inline void interprocess_semaphore::post()
 142 { m_sem.post(); }
 143
 144 }  //namespace interprocess {
 145 }  //namespace boost {
 146
 147 #include <boost/interprocess/detail/config_end.hpp>
 148
 149 #endif   //BOOST_INTERPROCESS_SEMAPHORE_HPP