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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.
+//
+//////////////////////////////////////////////////////////////////////////////
+//
+// This interface is inspired by Howard Hinnant's lock proposal.
+// http://home.twcny.rr.com/hinnant/cpp_extensions/threads_move.html
+//
+//////////////////////////////////////////////////////////////////////////////
+
+#ifndef BOOST_INTERPROCESS_SHARABLE_LOCK_HPP
+#define BOOST_INTERPROCESS_SHARABLE_LOCK_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/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/move.hpp>
+#include <boost/interprocess/detail/posix_time_types_wrk.hpp>
+
+//!\file
+//!Describes the upgradable_lock class that serves to acquire the upgradable
+//!lock of a mutex.
+
+namespace boost {
+namespace interprocess {
+
+
+//!sharable_lock is meant to carry out the tasks for sharable-locking
+//!(such as read-locking), unlocking, try-sharable-locking and timed-sharable-locking
+//!(recursive or not) for the Mutex. The Mutex need not supply all of this
+//!functionality. If the client of sharable_lock<Mutex> does not use functionality which
+//!the Mutex does not supply, no harm is done. Mutex ownership can be shared among
+//!sharable_locks, and a single upgradable_lock. sharable_lock does not support
+//!copy semantics. But sharable_lock supports ownership transfer from an sharable_lock,
+//!upgradable_lock and scoped_lock via transfer_lock syntax.*/
+template <class SharableMutex>
+class sharable_lock
+{
+ public:
+ typedef SharableMutex mutex_type;
+ /// @cond
+ private:
+ typedef sharable_lock<SharableMutex> this_type;
+ explicit sharable_lock(scoped_lock<mutex_type>&);
+ typedef bool this_type::*unspecified_bool_type;
+ BOOST_MOVABLE_BUT_NOT_COPYABLE(sharable_lock)
+ /// @endcond
+ public:
+
+ //!Effects: Default constructs a sharable_lock.
+ //!Postconditions: owns() == false and mutex() == 0.
+ sharable_lock()
+ : mp_mutex(0), m_locked(false)
+ {}
+
+ //!Effects: m.lock_sharable().
+ //!Postconditions: owns() == true and mutex() == &m.
+ //!Notes: The constructor will take sharable-ownership of the mutex. If
+ //! another thread already owns the mutex with exclusive ownership
+ //! (scoped_lock), this thread will block until the mutex is released.
+ //! If another thread owns the mutex with sharable or upgradable ownership,
+ //! then no blocking will occur. Whether or not this constructor handles
+ //! recursive locking depends upon the mutex.
+ explicit sharable_lock(mutex_type& m)
+ : mp_mutex(&m), m_locked(false)
+ { mp_mutex->lock_sharable(); 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.
+ sharable_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 sharable
+ //! locked. There is no effect required on the referenced mutex.
+ sharable_lock(mutex_type& m, accept_ownership_type)
+ : mp_mutex(&m), m_locked(true)
+ {}
+
+ //!Effects: m.try_lock_sharable()
+ //!Postconditions: mutex() == &m. owns() == the return value of the
+ //! m.try_lock_sharable() executed within the constructor.
+ //!Notes: The constructor will take sharable-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_sharable, this constructor will fail at compile
+ //! time if instantiated, but otherwise have no effect.
+ sharable_lock(mutex_type& m, try_to_lock_type)
+ : mp_mutex(&m), m_locked(false)
+ { m_locked = mp_mutex->try_lock_sharable(); }
+
+ //!Effects: m.timed_lock_sharable(abs_time)
+ //!Postconditions: mutex() == &m. owns() == the return value of the
+ //! m.timed_lock_sharable() executed within the constructor.
+ //!Notes: The constructor will take sharable-ownership of the mutex if it
+ //! can do so within the time specified. Whether or not this constructor
+ //! handles recursive locking depends upon the mutex. If the mutex_type
+ //! does not support timed_lock_sharable, this constructor will fail at
+ //! compile time if instantiated, but otherwise have no effect.
+ sharable_lock(mutex_type& m, const boost::posix_time::ptime& abs_time)
+ : mp_mutex(&m), m_locked(false)
+ { m_locked = mp_mutex->timed_lock_sharable(abs_time); }
+
+ //!Postconditions: mutex() == upgr.mutex(). owns() == the value of upgr.owns()
+ //! before the construction. upgr.owns() == false after the construction.
+ //!Notes: If the upgr sharable_lock owns the mutex, ownership is moved to this
+ //! sharable_lock with no blocking. If the upgr sharable_lock does not own the mutex, then
+ //! neither will this sharable_lock. Only a moved sharable_lock's will match this
+ //! signature. An non-moved sharable_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.
+ sharable_lock(BOOST_RV_REF(sharable_lock<mutex_type>) upgr)
+ : mp_mutex(0), m_locked(upgr.owns())
+ { mp_mutex = upgr.release(); }
+
+ //!Effects: If upgr.owns() then calls unlock_upgradable_and_lock_sharable() on the
+ //! referenced mutex.
+ //!Postconditions: mutex() == the value upgr.mutex() had before the construction.
+ //! upgr.mutex() == 0 owns() == the value of upgr.owns() before construction.
+ //! upgr.owns() == false after the construction.
+ //!Notes: If upgr is locked, this constructor will lock this sharable_lock while
+ //! unlocking upgr. Only a moved sharable_lock's will match this
+ //! signature. An non-moved upgradable_lock can be moved with the expression:
+ //! "boost::move(lock);".*/
+ template<class T>
+ sharable_lock(BOOST_RV_REF(upgradable_lock<T>) upgr
+ , typename ipcdetail::enable_if< ipcdetail::is_same<T, SharableMutex> >::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_sharable();
+ m_locked = true;
+ }
+ mp_mutex = u_lock.release();
+ }
+
+ //!Effects: If scop.owns() then calls unlock_and_lock_sharable() on the
+ //! referenced mutex.
+ //!Postconditions: mutex() == the value scop.mutex() had before the construction.
+ //! scop.mutex() == 0 owns() == scop.owns() before the constructor. After the
+ //! construction, scop.owns() == false.
+ //!Notes: If scop is locked, this constructor will transfer the exclusive ownership
+ //! to a sharable-ownership of this sharable_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);".
+ template<class T>
+ sharable_lock(BOOST_RV_REF(scoped_lock<T>) scop
+ , typename ipcdetail::enable_if< ipcdetail::is_same<T, SharableMutex> >::type * = 0)
+ : mp_mutex(0), m_locked(false)
+ {
+ scoped_lock<mutex_type> &e_lock = scop;
+ if(e_lock.owns()){
+ e_lock.mutex()->unlock_and_lock_sharable();
+ m_locked = true;
+ }
+ mp_mutex = e_lock.release();
+ }
+
+ //!Effects: if (owns()) mp_mutex->unlock_sharable().
+ //!Notes: The destructor behavior ensures that the mutex lock is not leaked.
+ ~sharable_lock()
+ {
+ try{
+ if(m_locked && mp_mutex) mp_mutex->unlock_sharable();
+ }
+ catch(...){}
+ }
+
+ //!Effects: If owns() before the call, then unlock_sharable() is called on mutex().
+ //! *this gets the state of upgr and upgr gets set to a default constructed state.
+ //!Notes: With a recursive mutex it is possible that both this and upgr own the mutex
+ //! before the assignment. In this case, this will own the mutex after the assignment
+ //! (and upgr will not), but the mutex's lock count will be decremented by one.
+ sharable_lock &operator=(BOOST_RV_REF(sharable_lock<mutex_type>) upgr)
+ {
+ if(this->owns())
+ this->unlock();
+ m_locked = upgr.owns();
+ mp_mutex = upgr.release();
+ return *this;
+ }
+
+ //!Effects: If mutex() == 0 or already locked, throws a lock_exception()
+ //! exception. Calls lock_sharable() on the referenced mutex.
+ //!Postconditions: owns() == true.
+ //!Notes: The sharable_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_sharable();
+ m_locked = true;
+ }
+
+ //!Effects: If mutex() == 0 or already locked, throws a lock_exception()
+ //! exception. Calls try_lock_sharable() on the referenced mutex.
+ //!Postconditions: owns() == the value returned from
+ //! mutex()->try_lock_sharable().
+ //!Notes: The sharable_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_sharable(), 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_sharable();
+ return m_locked;
+ }
+
+ //!Effects: If mutex() == 0 or already locked, throws a lock_exception()
+ //! exception. Calls timed_lock_sharable(abs_time) on the referenced mutex.
+ //!Postconditions: owns() == the value returned from
+ //! mutex()->timed_lock_sharable(elps_time).
+ //!Notes: The sharable_lock changes from a state of not owning the mutex,
+ //! to owning the mutex, but only if it can obtain ownership within the
+ //! specified time interval. If the mutex_type does not support
+ //! timed_lock_sharable(), this function will fail at compile time if
+ //! instantiated, but otherwise have no effect.
+ bool timed_lock(const boost::posix_time::ptime& abs_time)
+ {
+ if(!mp_mutex || m_locked)
+ throw lock_exception();
+ m_locked = mp_mutex->timed_lock_sharable(abs_time);
+ return m_locked;
+ }
+
+ //!Effects: If mutex() == 0 or not locked, throws a lock_exception() exception.
+ //! Calls unlock_sharable() on the referenced mutex.
+ //!Postconditions: owns() == false.
+ //!Notes: The sharable_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_sharable();
+ m_locked = false;
+ }
+
+ //!Effects: Returns true if this scoped_lock has
+ //!acquired the referenced mutex.
+ bool owns() const
+ { return m_locked && mp_mutex; }
+
+ //!Conversion to bool.
+ //!Returns owns().
+ operator unspecified_bool_type() const
+ { 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
+ { 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()
+ {
+ mutex_type *mut = mp_mutex;
+ mp_mutex = 0;
+ m_locked = false;
+ return mut;
+ }
+
+ //!Effects: Swaps state with moved lock.
+ //!Throws: Nothing.
+ void swap(sharable_lock<mutex_type> &other)
+ {
+ std::swap(mp_mutex, other.mp_mutex);
+ std::swap(m_locked, other.m_locked);
+ }
+
+ /// @cond
+ private:
+ mutex_type *mp_mutex;
+ bool m_locked;
+ /// @endcond
+};
+
+} // namespace interprocess
+} // namespace boost
+
+#include <boost/interprocess/detail/config_end.hpp>
+
+#endif // BOOST_INTERPROCESS_SHARABLE_LOCK_HPP