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