boost/interprocess/sync/named_semaphore.hpp
////////////////////////////////////////////////////////////////////////////// // // (C) Copyright Ion Gaztanaga 2005-2009. Distributed under the Boost // Software License, Version 1.0. (See accompanying file // LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt) // // See http://www.boost.org/libs/interprocess for documentation. // ////////////////////////////////////////////////////////////////////////////// #ifndef BOOST_INTERPROCESS_NAMED_SEMAPHORE_HPP #define BOOST_INTERPROCESS_NAMED_SEMAPHORE_HPP #if (defined _MSC_VER) && (_MSC_VER >= 1200) # pragma once #endif #include <boost/interprocess/detail/config_begin.hpp> #include <boost/interprocess/detail/workaround.hpp> #include <boost/interprocess/creation_tags.hpp> #include <boost/interprocess/exceptions.hpp> #include <boost/interprocess/permissions.hpp> #include <boost/interprocess/detail/interprocess_tester.hpp> #include <boost/interprocess/detail/posix_time_types_wrk.hpp> #if defined(BOOST_INTERPROCESS_NAMED_SEMAPHORE_USES_POSIX_SEMAPHORES) #include <boost/interprocess/sync/posix/semaphore_wrapper.hpp> #else #include <boost/interprocess/shared_memory_object.hpp> #include <boost/interprocess/detail/managed_open_or_create_impl.hpp> #include <boost/interprocess/sync/interprocess_semaphore.hpp> #include <boost/interprocess/sync/emulation/named_creation_functor.hpp> #endif //!\file //!Describes a named semaphore class for inter-process synchronization namespace boost { namespace interprocess { //!A semaphore with a global name, so it can be found from different //!processes. Allows several resource sharing patterns and efficient //!acknowledgment mechanisms. class named_semaphore { /// @cond //Non-copyable named_semaphore(); named_semaphore(const named_semaphore &); named_semaphore &operator=(const named_semaphore &); /// @endcond public: //!Creates a global semaphore with a name, and an initial count. //!If the semaphore can't be created throws interprocess_exception named_semaphore(create_only_t, const char *name, unsigned int initialCount, const permissions &perm = permissions()); //!Opens or creates a global semaphore with a name, and an initial count. //!If the semaphore is created, this call is equivalent to //!named_semaphore(create_only_t, ...) //!If the semaphore is already created, this call is equivalent to //!named_semaphore(open_only_t, ... ) //!and initialCount is ignored. named_semaphore(open_or_create_t, const char *name, unsigned int initialCount, const permissions &perm = permissions()); //!Opens a global semaphore with a name if that semaphore is previously. //!created. If it is not previously created this function throws //!interprocess_exception. named_semaphore(open_only_t, const char *name); //!Destroys *this and indicates that the calling process is finished using //!the resource. The destructor function will deallocate //!any system resources allocated by the system for use by this process for //!this resource. The resource can still be opened again calling //!the open constructor overload. To erase the resource from the system //!use remove(). ~named_semaphore(); //!Increments the semaphore count. If there are processes/threads blocked waiting //!for the semaphore, then one of these processes will return successfully from //!its wait function. If there is an error an interprocess_exception exception is thrown. void post(); //!Decrements the semaphore. If the semaphore value is not greater than zero, //!then the calling process/thread blocks until it can decrement the counter. //!If there is an error an interprocess_exception exception is thrown. void wait(); //!Decrements the semaphore if the semaphore's value is greater than zero //!and returns true. If the value is not greater than zero returns false. //!If there is an error an interprocess_exception exception is thrown. bool try_wait(); //!Decrements the semaphore if the semaphore's value is greater //!than zero and returns true. Otherwise, waits for the semaphore //!to the posted or the timeout expires. If the timeout expires, the //!function returns false. If the semaphore is posted the function //!returns true. If there is an error throws sem_exception bool timed_wait(const boost::posix_time::ptime &abs_time); //!Erases a named semaphore from the system. //!Returns false on error. Never throws. static bool remove(const char *name); /// @cond private: friend class detail::interprocess_tester; void dont_close_on_destruction(); #if defined(BOOST_INTERPROCESS_NAMED_SEMAPHORE_USES_POSIX_SEMAPHORES) detail::named_semaphore_wrapper m_sem; #else interprocess_semaphore *semaphore() const { return static_cast<interprocess_semaphore*>(m_shmem.get_user_address()); } detail::managed_open_or_create_impl<shared_memory_object> m_shmem; typedef detail::named_creation_functor<interprocess_semaphore, int> construct_func_t; #endif /// @endcond }; /// @cond #if defined(BOOST_INTERPROCESS_NAMED_SEMAPHORE_USES_POSIX_SEMAPHORES) inline named_semaphore::named_semaphore (create_only_t, const char *name, unsigned int initialCount, const permissions &perm) : m_sem(detail::DoCreate, name, initialCount, perm) {} inline named_semaphore::named_semaphore (open_or_create_t, const char *name, unsigned int initialCount, const permissions &perm) : m_sem(detail::DoOpenOrCreate, name, initialCount, perm) {} inline named_semaphore::named_semaphore(open_only_t, const char *name) : m_sem(detail::DoOpen, name, 1, permissions()) {} inline named_semaphore::~named_semaphore() {} inline void named_semaphore::dont_close_on_destruction() { detail::interprocess_tester::dont_close_on_destruction(m_sem); } inline void named_semaphore::wait() { m_sem.wait(); } inline void named_semaphore::post() { m_sem.post(); } inline bool named_semaphore::try_wait() { return m_sem.try_wait(); } inline bool named_semaphore::timed_wait(const boost::posix_time::ptime &abs_time) { if(abs_time == boost::posix_time::pos_infin){ this->wait(); return true; } return m_sem.timed_wait(abs_time); } inline bool named_semaphore::remove(const char *name) { return detail::named_semaphore_wrapper::remove(name); } #else inline named_semaphore::~named_semaphore() {} inline void named_semaphore::dont_close_on_destruction() { detail::interprocess_tester::dont_close_on_destruction(m_shmem); } inline named_semaphore::named_semaphore (create_only_t, const char *name, unsigned int initialCount, const permissions &perm) : m_shmem (create_only ,name ,sizeof(interprocess_semaphore) + detail::managed_open_or_create_impl<shared_memory_object>:: ManagedOpenOrCreateUserOffset ,read_write ,0 ,construct_func_t(detail::DoCreate, initialCount) ,perm) {} inline named_semaphore::named_semaphore (open_or_create_t, const char *name, unsigned int initialCount, const permissions &perm) : m_shmem (open_or_create ,name ,sizeof(interprocess_semaphore) + detail::managed_open_or_create_impl<shared_memory_object>:: ManagedOpenOrCreateUserOffset ,read_write ,0 ,construct_func_t(detail::DoOpenOrCreate, initialCount) ,perm) {} inline named_semaphore::named_semaphore (open_only_t, const char *name) : m_shmem (open_only ,name ,read_write ,0 ,construct_func_t(detail::DoOpen, 0)) {} inline void named_semaphore::post() { semaphore()->post(); } inline void named_semaphore::wait() { semaphore()->wait(); } inline bool named_semaphore::try_wait() { return semaphore()->try_wait(); } inline bool named_semaphore::timed_wait(const boost::posix_time::ptime &abs_time) { if(abs_time == boost::posix_time::pos_infin){ this->wait(); return true; } return semaphore()->timed_wait(abs_time); } inline bool named_semaphore::remove(const char *name) { return shared_memory_object::remove(name); } #endif /// @endcond } //namespace interprocess { } //namespace boost { #include <boost/interprocess/detail/config_end.hpp> #endif //BOOST_INTERPROCESS_NAMED_SEMAPHORE_HPP