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//////////////////////////////////////////////////////////////////////////////
//
// (C) Copyright Ion Gaztanaga 2005-2011. 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/named_semaphore.hpp>
#else
#include <boost/interprocess/sync/shm/named_semaphore.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 ipcdetail::interprocess_tester;
void dont_close_on_destruction();
#if defined(BOOST_INTERPROCESS_NAMED_SEMAPHORE_USES_POSIX_SEMAPHORES)
typedef ipcdetail::posix_named_semaphore impl_t;
#else
typedef ipcdetail::shm_named_semaphore impl_t;
#endif
impl_t m_sem;
/// @endcond
};
/// @cond
inline named_semaphore::named_semaphore
(create_only_t, const char *name, unsigned int initialCount, const permissions &perm)
: m_sem(create_only, name, initialCount, perm)
{}
inline named_semaphore::named_semaphore
(open_or_create_t, const char *name, unsigned int initialCount, const permissions &perm)
: m_sem(open_or_create, name, initialCount, perm)
{}
inline named_semaphore::named_semaphore(open_only_t, const char *name)
: m_sem(open_only, name)
{}
inline named_semaphore::~named_semaphore()
{}
inline void named_semaphore::dont_close_on_destruction()
{ ipcdetail::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 impl_t::remove(name); }
/// @endcond
} //namespace interprocess {
} //namespace boost {
#include <boost/interprocess/detail/config_end.hpp>
#endif //BOOST_INTERPROCESS_NAMED_SEMAPHORE_HPP
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