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 //////////////////////////////////////////////////////////////////////////////
 //
 // (C) Copyright Ion Gaztanaga 2005-2012. 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_FILE_LOCK_HPP
 #define BOOST_INTERPROCESS_FILE_LOCK_HPP
 
 #ifndef BOOST_CONFIG_HPP
 #  include <boost/config.hpp>
 #endif
 #
 #if defined(BOOST_HAS_PRAGMA_ONCE)
 #  pragma once
 #endif
 
 #include <boost/interprocess/detail/config_begin.hpp>
 #include <boost/interprocess/detail/workaround.hpp>
 #include <boost/interprocess/exceptions.hpp>
 #include <boost/interprocess/timed_utils.hpp>
 #include <boost/interprocess/detail/os_file_functions.hpp>
 #include <boost/interprocess/detail/os_thread_functions.hpp>
 #include <boost/interprocess/sync/detail/common_algorithms.hpp>
 #include <boost/interprocess/sync/detail/locks.hpp>
 #include <boost/move/utility_core.hpp>
 
 //!\file
 //!Describes a class that wraps file locking capabilities.
 
 namespace boost {
 namespace interprocess {
 
 
 //!A file lock, is a mutual exclusion utility similar to a mutex using a
 //!file. A file lock has sharable and exclusive locking capabilities and
 //!can be used with scoped_lock and sharable_lock classes.
 //!A file lock can't guarantee synchronization between threads of the same
 //!process so just use file locks to synchronize threads from different processes.
 class file_lock
 {
    #if !defined(BOOST_INTERPROCESS_DOXYGEN_INVOKED)
    //Non-copyable
    BOOST_MOVABLE_BUT_NOT_COPYABLE(file_lock)
    #endif   //#ifndef BOOST_INTERPROCESS_DOXYGEN_INVOKED
 
    public:
    //!Constructs an empty file mapping.
    //!Does not throw
    file_lock() BOOST_NOEXCEPT
       :  m_file_hnd(file_handle_t(ipcdetail::invalid_file()))
    {}
 
    //!Opens a file lock. Throws interprocess_exception if the file does not
    //!exist or there are no operating system resources.
    file_lock(const char *name);
 
    #if defined(BOOST_INTERPROCESS_WCHAR_NAMED_RESOURCES) || defined(BOOST_INTERPROCESS_DOXYGEN_INVOKED)
    //!Opens a file lock. Throws interprocess_exception if the file does not
    //!exist or there are no operating system resources.
    //! 
    //!Note: This function is only available on operating systems with
    //!      native wchar_t APIs (e.g. Windows).
    file_lock(const wchar_t *name);
    #endif
 
    //!Moves the ownership of "moved"'s file mapping object to *this.
    //!After the call, "moved" does not represent any file mapping object.
    //!Does not throw
    file_lock(BOOST_RV_REF(file_lock) moved) BOOST_NOEXCEPT
       :  m_file_hnd(file_handle_t(ipcdetail::invalid_file()))
    {  this->swap(moved);   }
 
    //!Moves the ownership of "moved"'s file mapping to *this.
    //!After the call, "moved" does not represent any file mapping.
    //!Does not throw
    file_lock &operator=(BOOST_RV_REF(file_lock) moved) BOOST_NOEXCEPT
    {
       file_lock tmp(boost::move(moved));
       this->swap(tmp);
       return *this;
    }
 
    //!Closes a file lock. Does not throw.
    ~file_lock();
 
    //!Swaps two file_locks.
    //!Does not throw.
    void swap(file_lock &other) BOOST_NOEXCEPT
    {
       file_handle_t tmp = m_file_hnd;
       m_file_hnd = other.m_file_hnd;
       other.m_file_hnd = tmp;
    }
 
    //Exclusive locking
 
    //!Requires: The calling thread does not own the mutex.
    //!
    //!Effects: The calling thread tries to obtain exclusive ownership of the mutex,
    //!   and if another thread has exclusive, or sharable ownership of
    //!   the mutex, it waits until it can obtain the ownership.
    //!Throws: interprocess_exception on error.
    //!
    //!Note: A program may deadlock if the thread that has ownership calls 
    //!   this function. If the implementation can detect the deadlock,
    //!   an exception could be thrown.
    void lock();
 
    //!Requires: The calling thread does not own the mutex.
    //!
    //!Effects: The calling thread tries to acquire exclusive ownership of the mutex
    //!   without waiting. If no other thread has exclusive, or sharable
    //!   ownership of the mutex this succeeds.
    //!Returns: If it can acquire exclusive ownership immediately returns true.
    //!   If it has to wait, returns false.
    //!Throws: interprocess_exception on error.
    //! 
    //!Note: A program may deadlock if the thread that has ownership calls 
    //!   this function. If the implementation can detect the deadlock,
    //!   an exception could be thrown.
    bool try_lock();
 
    //!Requires: The calling thread does not own the mutex.
    //!
    //!Effects: The calling thread tries to acquire exclusive ownership of the mutex
    //!   waiting if necessary until no other thread has exclusive, or sharable
    //!   ownership of the mutex or abs_time is reached.
    //!Returns: If acquires exclusive ownership, returns true. Otherwise returns false.
    //!Throws: interprocess_exception on error.
    //! 
    //!Note: A program may deadlock if the thread that has ownership calls 
    //!   this function. If the implementation can detect the deadlock,
    //!   an exception could be thrown.
    template<class TimePoint>
    bool timed_lock(const TimePoint &abs_time);
 
    //!Same as `timed_lock`, but this function is modeled after the
    //!standard library interface.
    template<class TimePoint> bool try_lock_until(const TimePoint &abs_time)
    {  return this->timed_lock(abs_time);  }
 
    //!Same as `timed_lock`, but this function is modeled after the
    //!standard library interface.
    template<class Duration>  bool try_lock_for(const Duration &dur)
    {  return this->timed_lock(ipcdetail::duration_to_ustime(dur)); }
 
    //!Precondition: The thread must have exclusive ownership of the mutex.
    //!Effects: The calling thread releases the exclusive ownership of the mutex.
    //!Throws: An exception derived from interprocess_exception on error.
    void unlock();
 
    //Sharable locking
 
    //!Requires: The calling thread does not own the mutex.
    //!
    //!Effects: The calling thread tries to obtain sharable ownership of the mutex,
    //!   and if another thread has exclusive ownership of the mutex, waits until
    //!   it can obtain the ownership.
    //!Throws: interprocess_exception on error.
    //!
    //!Note: A program may deadlock if the thread that owns a mutex object calls 
    //!   this function. If the implementation can detect the deadlock,
    //!   an exception could be thrown.
    void lock_sharable();
 
    //!Same as `lock_sharable` but with a std-compatible interface
    //! 
    void lock_shared()
    {  this->lock_sharable();  }
 
    //!Effects: The calling thread tries to acquire sharable ownership of the mutex
    //!   without waiting. If no other thread has exclusive ownership of the
    //!   mutex this succeeds.
    //!Returns: If it can acquire sharable ownership immediately returns true. If it
    //!   has to wait, returns false.
    //!Throws: interprocess_exception on error.
    bool try_lock_sharable();
 
    //!Same as `try_lock_sharable` but with a std-compatible interface
    //! 
    bool try_lock_shared()
    {  return this->try_lock_sharable();  }
 
    //!Effects: The calling thread tries to acquire sharable ownership of the mutex
    //!   waiting if necessary until no other thread has exclusive ownership of
    //!   the mutex or abs_time is reached.
    //!Returns: If acquires sharable ownership, returns true. Otherwise returns false.
    //!Throws: interprocess_exception on error.
    template<class TimePoint>
    bool timed_lock_sharable(const TimePoint &abs_time);
 
    //!Same as `timed_lock_sharable`, but this function is modeled after the
    //!standard library interface.
    template<class TimePoint> bool try_lock_shared_until(const TimePoint &abs_time)
    {  return this->timed_lock_sharable(abs_time);  }
 
    //!Same as `timed_lock_sharable`, but this function is modeled after the
    //!standard library interface.
    template<class Duration>  bool try_lock_shared_for(const Duration &dur)
    {  return this->timed_lock_sharable(ipcdetail::duration_to_ustime(dur)); }
 
    //!Precondition: The thread must have sharable ownership of the mutex.
    //!Effects: The calling thread releases the sharable ownership of the mutex.
    //!Throws: An exception derived from interprocess_exception on error.
    void unlock_sharable();
 
    //!Same as `unlock_sharable` but with a std-compatible interface
    //! 
    void unlock_shared()
    {  this->unlock_sharable();  }
 
    #if !defined(BOOST_INTERPROCESS_DOXYGEN_INVOKED)
    private:
    file_handle_t m_file_hnd;
 
    #endif   //#ifndef BOOST_INTERPROCESS_DOXYGEN_INVOKED
 };
 
 inline file_lock::file_lock(const char *name)
 {
    m_file_hnd = ipcdetail::open_existing_file(name, read_write);
 
    if(m_file_hnd == ipcdetail::invalid_file()){
       error_info err(system_error_code());
       throw interprocess_exception(err);
    }
 }
 
 #if defined(BOOST_INTERPROCESS_WCHAR_NAMED_RESOURCES) || defined(BOOST_INTERPROCESS_DOXYGEN_INVOKED)
 
 inline file_lock::file_lock(const wchar_t *name)
 {
    m_file_hnd = ipcdetail::open_existing_file(name, read_write);
 
    if(m_file_hnd == ipcdetail::invalid_file()){
       error_info err(system_error_code());
       throw interprocess_exception(err);
    }
 }
 
 #endif //defined(BOOST_INTERPROCESS_WCHAR_NAMED_RESOURCES) || defined(BOOST_INTERPROCESS_DOXYGEN_INVOKED)
 
 inline file_lock::~file_lock()
 {
    if(m_file_hnd != ipcdetail::invalid_file()){
       ipcdetail::close_file(m_file_hnd);
       m_file_hnd = ipcdetail::invalid_file();
    }
 }
 
 inline void file_lock::lock()
 {
    if(!ipcdetail::acquire_file_lock(m_file_hnd)){
       error_info err(system_error_code());
       throw interprocess_exception(err);
    }
 }
 
 inline bool file_lock::try_lock()
 {
    bool result;
    if(!ipcdetail::try_acquire_file_lock(m_file_hnd, result)){
       error_info err(system_error_code());
       throw interprocess_exception(err);
    }
    return result;
 }
 
 template<class TimePoint>
 inline bool file_lock::timed_lock(const TimePoint &abs_time)
 {  return ipcdetail::try_based_timed_lock(*this, abs_time);   }
 
 inline void file_lock::unlock()
 {
    if(!ipcdetail::release_file_lock(m_file_hnd)){
       error_info err(system_error_code());
       throw interprocess_exception(err);
    }
 }
 
 inline void file_lock::lock_sharable()
 {
    if(!ipcdetail::acquire_file_lock_sharable(m_file_hnd)){
       error_info err(system_error_code());
       throw interprocess_exception(err);
    }
 }
 
 inline bool file_lock::try_lock_sharable()
 {
    bool result;
    if(!ipcdetail::try_acquire_file_lock_sharable(m_file_hnd, result)){
       error_info err(system_error_code());
       throw interprocess_exception(err);
    }
    return result;
 }
 
 template<class TimePoint>
 inline bool file_lock::timed_lock_sharable(const TimePoint &abs_time)
 {
    ipcdetail::lock_to_sharable<file_lock> lsh(*this);
    return ipcdetail::try_based_timed_lock(lsh, abs_time);
 }
 
 inline void file_lock::unlock_sharable()
 {
    if(!ipcdetail::release_file_lock_sharable(m_file_hnd)){
       error_info err(system_error_code());
       throw interprocess_exception(err);
    }
 }
 
 }  //namespace interprocess {
 }  //namespace boost {
 
 #include <boost/interprocess/detail/config_end.hpp>
 
 #endif   //BOOST_INTERPROCESS_FILE_LOCK_HPP

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