deferred_cleanup.h

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/*
  This file is part of MADNESS.
 
  Copyright (C) 2007,2010 Oak Ridge National Laboratory
 
  This program is free software; you can redistribute it and/or modify
  it under the terms of the GNU General Public License as published by
  the Free Software Foundation; either version 2 of the License, or
  (at your option) any later version.
 
  This program is distributed in the hope that it will be useful,
  but WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  GNU General Public License for more details.
 
  You should have received a copy of the GNU General Public License
  along with this program; if not, write to the Free Software
  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 
  For more information please contact:
 
  Robert J. Harrison
  Oak Ridge National Laboratory
  One Bethel Valley Road
  P.O. Box 2008, MS-6367
 
  email: harrisonrj@ornl.gov
  tel:   865-241-3937
  fax:   865-572-0680
 
 
  $Id$
*/
 
#ifndef MADNESS_WORLD_DEFERRED_CLEANUP_H__INCLUDED
#define MADNESS_WORLD_DEFERRED_CLEANUP_H__INCLUDED
 
#include <madness/world/worldmutex.h>  // For Mutex
#include <list>
#include <memory>
 
namespace madness {
 
    // Forward declarations
    template <typename, typename>
    class DeferredDeleter;
    class World;
 
    namespace detail {
 
        template <typename objT>
        inline void deferred_cleanup(World& world, const std::shared_ptr<objT>& p, bool assume_p_is_unique = false);
 
        /// Deferred cleanup of shared_ptr's
 
        /// Holds dynamically allocated pointers until it is ready for cleanup.
        /// \note This object is considered an implementation detail and should
        /// not be used directly, instead use \c DeferredDeleter with a
        /// \c std::shared_ptr.
        class DeferredCleanup {
        public:
            typedef std::shared_ptr<void> void_ptr; ///< input pointer type
 
        private:
            typedef std::list<void_ptr> void_ptr_list;
 
            RecursiveMutex mutex_;      ///< Worldwide mutex
            void_ptr_list deferred_;    ///< List of pointers to cleanup
            bool destroy_;              ///< Object destroy mode
                                        ///< true = destroy immediate
                                        ///< false = destroy deferred (default)
 
            // not allowed
            DeferredCleanup(const DeferredCleanup&);
            DeferredCleanup& operator=(const DeferredCleanup&);
 
            template <typename objT>
            friend void deferred_cleanup(World&, const std::shared_ptr<objT>&, bool);
 
            /// Access deferred cleanup object of world
 
            /// \param w The \c World object that holds the \c DeferredCleanup object
            /// \return A shared pointer to the deferred cleanup object of world \c w.
            static std::shared_ptr<DeferredCleanup> get_deferred_cleanup(const World& w);
 
        public:
            /// Construct a deferred deleter object.
            DeferredCleanup() : mutex_(), deferred_(), destroy_(false) { }
 
            /// Set the destruction mode
 
            /// \param mode true for immediate destruction, false for deferred
            /// destruction.
            void destroy(bool mode);
 
            /// Get the current destruction mode mode
 
            /// \return true for immediate destruction and false for deferred
            /// destruction.
            bool destroy() const;
 
            /// Adds \c item to cleanup list
 
            /// If destroy mode is true then the pointer is destroyed immediately.
            /// Otherwise it is stored until \c do_cleanup() is called.
            /// \param obj Object that is ready for destruction
            void add(const void_ptr& obj);
 
            /// Adds \c item to cleanup list
 
            /// If destroy mode is true then the pointer is destroyed immediately.
            /// Otherwise it is stored until \c do_cleanup() is called.
            /// \tparam objT The object pointer type
            /// \param obj Object that is ready for destruction
            template <typename objT>
            void add(const std::shared_ptr<objT>& obj) {
                add(std::static_pointer_cast<void>(obj));
            }
 
 
 
            /// Deletes/frees any pointers that are in the list
            void do_cleanup();
        }; // class DeferredCleanup
 
 
        /// Defer the cleanup of a shared pointer to the end of the next fence
 
        /// Call this function before destroying a shared pointer. If the shared
        /// pointer is the last reference to the object,
        /// or \p assume_p_is_unique is true,
        /// it is placed in the deferred deletion list.
        /// Otherwise, nothing is done with the pointer.
        template <typename objT>
        inline void deferred_cleanup(World& world, const std::shared_ptr<objT>& p,
                                     bool assume_p_is_unique) {
            const auto p_is_unique = p.use_count() == 1;
            if(p_is_unique || assume_p_is_unique) {
                // This is the last local pointer so we will place it in the
                // deferred deleter list for later cleanup.
                DeferredCleanup::get_deferred_cleanup(world)->add(p);
            }
        }
 
    }  // namespace detail
}  // namespace madness
 
#endif // MADNESS_WORLD_DEFERRED_CLEANUP_H__INCLUDED