ceph/src/boost/libs/interprocess/include/boost/interprocess/sync/named_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_NAMED_SEMAPHORE_HPP
  12 #define BOOST_INTERPROCESS_NAMED_SEMAPHORE_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/creation_tags.hpp>
  25 #include <boost/interprocess/exceptions.hpp>
  26 #include <boost/interprocess/permissions.hpp>
  27 #include <boost/interprocess/detail/interprocess_tester.hpp>
  28 #include <boost/interprocess/detail/posix_time_types_wrk.hpp>
  29
  30 #if defined(BOOST_INTERPROCESS_NAMED_SEMAPHORE_USES_POSIX_SEMAPHORES)
  31 #include <boost/interprocess/sync/posix/named_semaphore.hpp>
  32 //Experimental...
  33 #elif !defined(BOOST_INTERPROCESS_FORCE_GENERIC_EMULATION) && defined (BOOST_INTERPROCESS_WINDOWS)
  34    #include <boost/interprocess/sync/windows/named_semaphore.hpp>
  35    #define BOOST_INTERPROCESS_USE_WINDOWS
  36 #else
  37 #include <boost/interprocess/sync/shm/named_semaphore.hpp>
  38 #endif
  39
  40 //!\file
  41 //!Describes a named semaphore class for inter-process synchronization
  42
  43 namespace boost {
  44 namespace interprocess {
  45
  46 //!A semaphore with a global name, so it can be found from different
  47 //!processes. Allows several resource sharing patterns and efficient
  48 //!acknowledgment mechanisms.
  49 class named_semaphore
  50 {
  51    #if !defined(BOOST_INTERPROCESS_DOXYGEN_INVOKED)
  52
  53    //Non-copyable
  54    named_semaphore();
  55    named_semaphore(const named_semaphore &);
  56    named_semaphore &operator=(const named_semaphore &);
  57    #endif   //#ifndef BOOST_INTERPROCESS_DOXYGEN_INVOKED
  58
  59    public:
  60    //!Creates a global semaphore with a name, and an initial count.
  61    //!If the semaphore can't be created throws interprocess_exception
  62    named_semaphore(create_only_t, const char *name, unsigned int initialCount, const permissions &perm = permissions());
  63
  64    //!Opens or creates a global semaphore with a name, and an initial count.
  65    //!If the semaphore is created, this call is equivalent to
  66    //!named_semaphore(create_only_t, ...)
  67    //!If the semaphore is already created, this call is equivalent to
  68    //!named_semaphore(open_only_t, ... )
  69    //!and initialCount is ignored.
  70    named_semaphore(open_or_create_t, const char *name, unsigned int initialCount, const permissions &perm = permissions());
  71
  72    //!Opens a global semaphore with a name if that semaphore is previously.
  73    //!created. If it is not previously created this function throws
  74    //!interprocess_exception.
  75    named_semaphore(open_only_t, const char *name);
  76
  77    //!Destroys *this and indicates that the calling process is finished using
  78    //!the resource. The destructor function will deallocate
  79    //!any system resources allocated by the system for use by this process for
  80    //!this resource. The resource can still be opened again calling
  81    //!the open constructor overload. To erase the resource from the system
  82    //!use remove().
  83    ~named_semaphore();
  84
  85    //!Increments the semaphore count. If there are processes/threads blocked waiting
  86    //!for the semaphore, then one of these processes will return successfully from
  87    //!its wait function. If there is an error an interprocess_exception exception is thrown.
  88    void post();
  89
  90    //!Decrements the semaphore. If the semaphore value is not greater than zero,
  91    //!then the calling process/thread blocks until it can decrement the counter.
  92    //!If there is an error an interprocess_exception exception is thrown.
  93    void wait();
  94
  95    //!Decrements the semaphore if the semaphore's value is greater than zero
  96    //!and returns true. If the value is not greater than zero returns false.
  97    //!If there is an error an interprocess_exception exception is thrown.
  98    bool try_wait();
  99
 100    //!Decrements the semaphore if the semaphore's value is greater
 101    //!than zero and returns true. Otherwise, waits for the semaphore
 102    //!to the posted or the timeout expires. If the timeout expires, the
 103    //!function returns false. If the semaphore is posted the function
 104    //!returns true. If there is an error throws sem_exception
 105    bool timed_wait(const boost::posix_time::ptime &abs_time);
 106
 107    //!Erases a named semaphore from the system.
 108    //!Returns false on error. Never throws.
 109    static bool remove(const char *name);
 110
 111    #if !defined(BOOST_INTERPROCESS_DOXYGEN_INVOKED)
 112    private:
 113    friend class ipcdetail::interprocess_tester;
 114    void dont_close_on_destruction();
 115
 116    #if defined(BOOST_INTERPROCESS_NAMED_SEMAPHORE_USES_POSIX_SEMAPHORES)
 117       typedef ipcdetail::posix_named_semaphore   impl_t;
 118    #elif defined(BOOST_INTERPROCESS_USE_WINDOWS)
 119       #undef BOOST_INTERPROCESS_USE_WINDOWS
 120       typedef ipcdetail::windows_named_semaphore impl_t;
 121    #else
 122       typedef ipcdetail::shm_named_semaphore     impl_t;
 123    #endif
 124    impl_t m_sem;
 125    #endif   //#ifndef BOOST_INTERPROCESS_DOXYGEN_INVOKED
 126 };
 127
 128 #if !defined(BOOST_INTERPROCESS_DOXYGEN_INVOKED)
 129
 130 inline named_semaphore::named_semaphore
 131    (create_only_t, const char *name, unsigned int initialCount, const permissions &perm)
 132    :  m_sem(create_only, name, initialCount, perm)
 133 {}
 134
 135 inline named_semaphore::named_semaphore
 136    (open_or_create_t, const char *name, unsigned int initialCount, const permissions &perm)
 137    :  m_sem(open_or_create, name, initialCount, perm)
 138 {}
 139
 140 inline named_semaphore::named_semaphore(open_only_t, const char *name)
 141    :  m_sem(open_only, name)
 142 {}
 143
 144 inline named_semaphore::~named_semaphore()
 145 {}
 146
 147 inline void named_semaphore::dont_close_on_destruction()
 148 {  ipcdetail::interprocess_tester::dont_close_on_destruction(m_sem);  }
 149
 150 inline void named_semaphore::wait()
 151 {  m_sem.wait();  }
 152
 153 inline void named_semaphore::post()
 154 {  m_sem.post();  }
 155
 156 inline bool named_semaphore::try_wait()
 157 {  return m_sem.try_wait();  }
 158
 159 inline bool named_semaphore::timed_wait(const boost::posix_time::ptime &abs_time)
 160 {  return m_sem.timed_wait(abs_time);  }
 161
 162 inline bool named_semaphore::remove(const char *name)
 163 {  return impl_t::remove(name);   }
 164
 165 #endif   //#ifndef BOOST_INTERPROCESS_DOXYGEN_INVOKED
 166
 167 }  //namespace interprocess {
 168 }  //namespace boost {
 169
 170
 171 #include <boost/interprocess/detail/config_end.hpp>
 172
 173 #endif   //BOOST_INTERPROCESS_NAMED_SEMAPHORE_HPP