comparison DEPENDENCIES/generic/include/boost/interprocess/sync/sharable_lock.hpp @ 16:2665513ce2d3

Add boost headers

+//////////////////////////////////////////////////////////////////////////////
+//
+// (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_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