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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.
 //
 //////////////////////////////////////////////////////////////////////////////
 //
 // This interface is inspired by Howard Hinnant's lock proposal.
 // http://home.twcny.rr.com/hinnant/cpp_extensions/threads_move.html
 //
 //////////////////////////////////////////////////////////////////////////////
 
 #ifndef BOOST_INTERPROCESS_SCOPED_LOCK_HPP
 #define BOOST_INTERPROCESS_SCOPED_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/interprocess_fwd.hpp>
 #include <boost/interprocess/sync/lock_options.hpp>
 #include <boost/interprocess/exceptions.hpp>
 #include <boost/interprocess/detail/mpl.hpp>
 #include <boost/interprocess/detail/type_traits.hpp>
 #include <boost/move/utility_core.hpp>
 #include <boost/interprocess/detail/simple_swap.hpp>
 
 //!\file
 //!Describes the scoped_lock class.
 
 namespace boost {
 namespace interprocess {
 
 
 //!scoped_lock is meant to carry out the tasks for locking, unlocking, try-locking
 //!and timed-locking (recursive or not) for the Mutex. The Mutex need not supply all
 //!of this functionality. If the client of scoped_lock<Mutex> does not use
 //!functionality which the Mutex does not supply, no harm is done. Mutex ownership
 //!transfer is supported through the syntax of move semantics. Ownership transfer
 //!is allowed both by construction and assignment. The scoped_lock does not support
 //!copy semantics. A compile time error results if copy construction or copy
 //!assignment is attempted. Mutex ownership can also be moved from an
 //!upgradable_lock and sharable_lock via constructor. In this role, scoped_lock
 //!shares the same functionality as a write_lock.
 template <class Mutex>
 class scoped_lock
 {
    #if !defined(BOOST_INTERPROCESS_DOXYGEN_INVOKED)
    private:
    typedef scoped_lock<Mutex> this_type;
    BOOST_MOVABLE_BUT_NOT_COPYABLE(scoped_lock)
    typedef bool this_type::*unspecified_bool_type;
    #endif   //#ifndef BOOST_INTERPROCESS_DOXYGEN_INVOKED
    public:
 
    typedef Mutex mutex_type;
 
    //!Effects: Default constructs a scoped_lock.
    //!Postconditions: owns() == false and mutex() == 0.
    scoped_lock() BOOST_NOEXCEPT
       : mp_mutex(0), m_locked(false)
    {}
 
    //!Effects: m.lock().
    //!Postconditions: owns() == true and mutex() == &m.
    //!Notes: The constructor will take ownership of the mutex. If another thread
    //!   already owns the mutex, this thread will block until the mutex is released.
    //!   Whether or not this constructor handles recursive locking depends upon the mutex.
    explicit scoped_lock(mutex_type& m)
       : mp_mutex(&m), m_locked(false)
    {  mp_mutex->lock();   m_locked = true;  }
 
    //!Postconditions: owns() == false, and mutex() == &m.
    //!Notes: The constructor will not take ownership of the mutex. There is no effect
    //!   required on the referenced mutex.
    scoped_lock(mutex_type& m, defer_lock_type)
       : mp_mutex(&m), m_locked(false)
    {}
 
    //!Postconditions: owns() == true, and mutex() == &m.
    //!Notes: The constructor will suppose that the mutex is already locked. There
    //!   is no effect required on the referenced mutex.
    scoped_lock(mutex_type& m, accept_ownership_type)
       : mp_mutex(&m), m_locked(true)
    {}
 
    //!Effects: m.try_lock().
    //!Postconditions: mutex() == &m. owns() == the return value of the
    //!   m.try_lock() executed within the constructor.
    //!Notes: The constructor will take ownership of the mutex if it can do
    //!   so without waiting. Whether or not this constructor handles recursive
    //!   locking depends upon the mutex. If the mutex_type does not support try_lock,
    //!   this constructor will fail at compile time if instantiated, but otherwise
    //!   have no effect.
    scoped_lock(mutex_type& m, try_to_lock_type)
       : mp_mutex(&m), m_locked(mp_mutex->try_lock())
    {}
 
    //!Effects: m.timed_lock(abs_time).
    //!Postconditions: mutex() == &m. owns() == the return value of the
    //!   m.timed_lock(abs_time) executed within the constructor.
    //!Notes: The constructor will take ownership of the mutex if it can do
    //!   it until abs_time is reached. Whether or not this constructor
    //!   handles recursive locking depends upon the mutex. If the mutex_type
    //!   does not support try_lock, this constructor will fail at compile
    //!   time if instantiated, but otherwise have no effect.
    template<class TimePoint>
    scoped_lock(mutex_type& m, const TimePoint& abs_time)
       : mp_mutex(&m), m_locked(mp_mutex->timed_lock(abs_time))
    {}
 
    //!Postconditions: mutex() == the value scop.mutex() had before the
    //!   constructor executes. s1.mutex() == 0. owns() == the value of
    //!   scop.owns() before the constructor executes. scop.owns().
    //!Notes: If the scop scoped_lock owns the mutex, ownership is moved
    //!   to thisscoped_lock with no blocking. If the scop scoped_lock does not
    //!   own the mutex, then neither will this scoped_lock. Only a moved
    //!   scoped_lock's will match this signature. An non-moved scoped_lock
    //!   can be moved with the expression: "boost::move(lock);". This
    //!   constructor does not alter the state of the mutex, only potentially
    //!   who owns it.
    scoped_lock(BOOST_RV_REF(scoped_lock) scop) BOOST_NOEXCEPT
       : mp_mutex(0), m_locked(scop.owns())
    {  mp_mutex = scop.release(); }
 
    //!Effects: If upgr.owns() then calls unlock_upgradable_and_lock() on the
    //!   referenced mutex. upgr.release() is called.
    //!Postconditions: mutex() == the value upgr.mutex() had before the construction.
    //!   upgr.mutex() == 0. owns() == upgr.owns() before the construction.
    //!   upgr.owns() == false after the construction.
    //!Notes: If upgr is locked, this constructor will lock this scoped_lock while
    //!   unlocking upgr. If upgr is unlocked, then this scoped_lock will be
    //!   unlocked as well. Only a moved upgradable_lock's will match this
    //!   signature. An non-moved upgradable_lock can be moved with
    //!   the expression: "boost::move(lock);" This constructor may block if
    //!   other threads hold a sharable_lock on this mutex (sharable_lock's can
    //!   share ownership with an upgradable_lock).
    template<class T>
    explicit scoped_lock(BOOST_RV_REF(upgradable_lock<T>) upgr
       , typename ipcdetail::enable_if< ipcdetail::is_same<T, Mutex> >::type * = 0)
       : mp_mutex(0), m_locked(false)
    {
       upgradable_lock<mutex_type> &u_lock = upgr;
       if(u_lock.owns()){
          u_lock.mutex()->unlock_upgradable_and_lock();
          m_locked = true;
       }
       mp_mutex = u_lock.release();
    }
 
    //!Effects: If upgr.owns() then calls try_unlock_upgradable_and_lock() on the
    //!referenced mutex:
    //!   a)if try_unlock_upgradable_and_lock() returns true then mutex() obtains
    //!      the value from upgr.release() and owns() is set to true.
    //!   b)if try_unlock_upgradable_and_lock() returns false then upgr is
    //!      unaffected and this scoped_lock construction as the same effects as
    //!      a default construction.
    //!   c)Else upgr.owns() is false. mutex() obtains the value from upgr.release()
    //!      and owns() is set to false
    //!Notes: This construction will not block. It will try to obtain mutex
    //!   ownership from upgr immediately, while changing the lock type from a
    //!   "read lock" to a "write lock". If the "read lock" isn't held in the
    //!   first place, the mutex merely changes type to an unlocked "write lock".
    //!   If the "read lock" is held, then mutex transfer occurs only if it can
    //!   do so in a non-blocking manner.
    template<class T>
    scoped_lock(BOOST_RV_REF(upgradable_lock<T>) upgr, try_to_lock_type
          , typename ipcdetail::enable_if< ipcdetail::is_same<T, Mutex> >::type * = 0)
       : mp_mutex(0), m_locked(false)
    {
       upgradable_lock<mutex_type> &u_lock = upgr;
       if(u_lock.owns()){
          if((m_locked = u_lock.mutex()->try_unlock_upgradable_and_lock()) == true){
             mp_mutex = u_lock.release();
          }
       }
       else{
          u_lock.release();
       }
    }
 
    //!Effects: If upgr.owns() then calls timed_unlock_upgradable_and_lock(abs_time)
    //!   on the referenced mutex:
    //!   a)if timed_unlock_upgradable_and_lock(abs_time) returns true then mutex()
    //!      obtains the value from upgr.release() and owns() is set to true.
    //!   b)if timed_unlock_upgradable_and_lock(abs_time) returns false then upgr
    //!      is unaffected and this scoped_lock construction as the same effects
    //!      as a default construction.
    //!   c)Else upgr.owns() is false. mutex() obtains the value from upgr.release()
    //!      and owns() is set to false
    //!Notes: This construction will not block. It will try to obtain mutex ownership
    //!   from upgr immediately, while changing the lock type from a "read lock" to a
    //!   "write lock". If the "read lock" isn't held in the first place, the mutex
    //!   merely changes type to an unlocked "write lock". If the "read lock" is held,
    //!   then mutex transfer occurs only if it can do so in a non-blocking manner.
    template<class T, class TimePoint>
    scoped_lock(BOOST_RV_REF(upgradable_lock<T>) upgr, const TimePoint &abs_time
                , typename ipcdetail::enable_if< ipcdetail::is_same<T, Mutex> >::type * = 0)
       : mp_mutex(0), m_locked(false)
    {
       upgradable_lock<mutex_type> &u_lock = upgr;
       if(u_lock.owns()){
          if((m_locked = u_lock.mutex()->timed_unlock_upgradable_and_lock(abs_time)) == true){
             mp_mutex = u_lock.release();
          }
       }
       else{
          u_lock.release();
       }
    }
 
    //!Effects: If shar.owns() then calls try_unlock_sharable_and_lock() on the
    //!referenced mutex.
    //!   a)if try_unlock_sharable_and_lock() returns true then mutex() obtains
    //!      the value from shar.release() and owns() is set to true.
    //!   b)if try_unlock_sharable_and_lock() returns false then shar is
    //!      unaffected and this scoped_lock construction has the same
    //!      effects as a default construction.
    //!   c)Else shar.owns() is false. mutex() obtains the value from
    //!      shar.release() and owns() is set to false
    //!Notes: This construction will not block. It will try to obtain mutex
    //!   ownership from shar immediately, while changing the lock type from a
    //!   "read lock" to a "write lock". If the "read lock" isn't held in the
    //!   first place, the mutex merely changes type to an unlocked "write lock".
    //!   If the "read lock" is held, then mutex transfer occurs only if it can
    //!   do so in a non-blocking manner.
    template<class T>
    scoped_lock(BOOST_RV_REF(sharable_lock<T>) shar, try_to_lock_type
       , typename ipcdetail::enable_if< ipcdetail::is_same<T, Mutex> >::type * = 0)
       : mp_mutex(0), m_locked(false)
    {
       sharable_lock<mutex_type> &s_lock = shar;
       if(s_lock.owns()){
          if((m_locked = s_lock.mutex()->try_unlock_sharable_and_lock()) == true){
             mp_mutex = s_lock.release();
          }
       }
       else{
          s_lock.release();
       }
    }
 
    //!Effects: if (owns()) mp_mutex->unlock().
    //!Notes: The destructor behavior ensures that the mutex lock is not leaked.*/
    ~scoped_lock()
    {
       BOOST_TRY{  if(m_locked && mp_mutex)   mp_mutex->unlock();  }
       BOOST_CATCH(...){} BOOST_CATCH_END
    }
 
    //!Effects: If owns() before the call, then unlock() is called on mutex().
    //!   *this gets the state of scop and scop gets set to a default constructed state.
    //!Notes: With a recursive mutex it is possible that both this and scop own
    //!   the same mutex before the assignment. In this case, this will own the
    //!   mutex after the assignment (and scop will not), but the mutex's lock
    //!   count will be decremented by one.
    scoped_lock &operator=(BOOST_RV_REF(scoped_lock) scop)
    {
       if(this->owns())
          this->unlock();
       m_locked = scop.owns();
       mp_mutex = scop.release();
       return *this;
    }
 
    //!Effects: If mutex() == 0 or if already locked, throws a lock_exception()
    //!   exception. Calls lock() on the referenced mutex.
    //!Postconditions: owns() == true.
    //!Notes: The scoped_lock changes from a state of not owning the mutex, to
    //!   owning the mutex, blocking if necessary.
    void lock()
    {
       if(!mp_mutex || m_locked)
          throw lock_exception();
       mp_mutex->lock();
       m_locked = true;
    }
 
    //!Effects: If mutex() == 0 or if already locked, throws a lock_exception()
    //!   exception. Calls try_lock() on the referenced mutex.
    //!Postconditions: owns() == the value returned from mutex()->try_lock().
    //!Notes: The scoped_lock changes from a state of not owning the mutex, to
    //!   owning the mutex, but only if blocking was not required. If the
    //!   mutex_type does not support try_lock(), this function will fail at
    //!   compile time if instantiated, but otherwise have no effect.*/
    bool try_lock()
    {
       if(!mp_mutex || m_locked)
          throw lock_exception();
       m_locked = mp_mutex->try_lock();
       return m_locked;
    }
 
    //!Effects: If mutex() == 0 or if already locked, throws a lock_exception()
    //!   exception. Calls timed_lock(abs_time) on the referenced mutex.
    //!Postconditions: owns() == the value returned from mutex()-> timed_lock(abs_time).
    //!Notes: The scoped_lock changes from a state of not owning the mutex, to
    //!   owning the mutex, but only if it can obtain ownership by the specified
    //!   time. If the mutex_type does not support timed_lock (), this function
    //!   will fail at compile time if instantiated, but otherwise have no effect.*/
    template<class TimePoint>
    bool timed_lock(const TimePoint& abs_time)
    {
       if(!mp_mutex || m_locked)
          throw lock_exception();
       m_locked = mp_mutex->timed_lock(abs_time);
       return m_locked;
    }
 
    //!Effects: If mutex() == 0 or if already locked, throws a lock_exception()
    //!   exception. Calls try_lock_until(abs_time) on the referenced mutex.
    //!Postconditions: owns() == the value returned from mutex()-> timed_lock(abs_time).
    //!Notes: The scoped_lock changes from a state of not owning the mutex, to
    //!   owning the mutex, but only if it can obtain ownership by the specified
    //!   time. If the mutex_type does not support timed_lock (), this function
    //!   will fail at compile time if instantiated, but otherwise have no effect.*/
    template<class TimePoint>
    bool try_lock_until(const TimePoint& abs_time)
    {
       if(!mp_mutex || m_locked)
          throw lock_exception();
       m_locked = mp_mutex->try_lock_until(abs_time);
       return m_locked;
    }
 
    //!Effects: If mutex() == 0 or if already locked, throws a lock_exception()
    //!   exception. Calls try_lock_until(abs_time) on the referenced mutex.
    //!Postconditions: owns() == the value returned from mutex()-> timed_lock(abs_time).
    //!Notes: The scoped_lock changes from a state of not owning the mutex, to
    //!   owning the mutex, but only if it can obtain ownership by the specified
    //!   time. If the mutex_type does not support timed_lock (), this function
    //!   will fail at compile time if instantiated, but otherwise have no effect.*/
    template<class Duration>
    bool try_lock_for(const Duration& dur)
    {
       if(!mp_mutex || m_locked)
          throw lock_exception();
       m_locked = mp_mutex->try_lock_for(dur);
       return m_locked;
    }
 
    //!Effects: If mutex() == 0 or if not locked, throws a lock_exception()
    //!   exception. Calls unlock() on the referenced mutex.
    //!Postconditions: owns() == false.
    //!Notes: The scoped_lock changes from a state of owning the mutex, to not
    //!   owning the mutex.*/
    void unlock()
    {
       if(!mp_mutex || !m_locked)
          throw lock_exception();
       mp_mutex->unlock();
       m_locked = false;
    }
 
    //!Effects: Returns true if this scoped_lock has acquired
    //!the referenced mutex.
    bool owns() const BOOST_NOEXCEPT
    {  return m_locked && mp_mutex;  }
 
    //!Conversion to bool.
    //!Returns owns().
    operator unspecified_bool_type() const BOOST_NOEXCEPT
    {  return m_locked? &this_type::m_locked : 0;   }
 
    //!Effects: Returns a pointer to the referenced mutex, or 0 if
    //!there is no mutex to reference.
    mutex_type* mutex() const BOOST_NOEXCEPT
    {  return  mp_mutex;  }
 
    //!Effects: Returns a pointer to the referenced mutex, or 0 if there is no
    //!   mutex to reference.
    //!Postconditions: mutex() == 0 and owns() == false.
    mutex_type* release() BOOST_NOEXCEPT
    {
       mutex_type *mut = mp_mutex;
       mp_mutex = 0;
       m_locked = false;
       return mut;
    }
 
    //!Effects: Swaps state with moved lock.
    //!Throws: Nothing.
    void swap( scoped_lock<mutex_type> &other) BOOST_NOEXCEPT
    {
       (simple_swap)(mp_mutex, other.mp_mutex);
       (simple_swap)(m_locked, other.m_locked);
    }
 
    #if !defined(BOOST_INTERPROCESS_DOXYGEN_INVOKED)
    private:
    mutex_type *mp_mutex;
    bool        m_locked;
    #endif   //#ifndef BOOST_INTERPROCESS_DOXYGEN_INVOKED
 };
 
 } // namespace interprocess
 } // namespace boost
 
 #include <boost/interprocess/detail/config_end.hpp>
 
 #endif // BOOST_INTERPROCESS_SCOPED_LOCK_HPP

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