MemoryPool.hpp

/*-
 * Copyright (c) 2013 Cosku Acay, http://www.coskuacay.com
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
 * IN THE SOFTWARE.
 */

#ifndef MEMORY_POOL_H
#define MEMORY_POOL_H

#include <climits>
#include <cstddef>

template <typename T, size_t BlockSize = 4096>
class MemoryPool
{
    public:
        /* Member types */
        typedef T value_type;
        typedef T* pointer_t;
        typedef T& reference;
        typedef const T* const_pointer;
        typedef const T& const_reference;
        typedef size_t size_type;
        typedef ptrdiff_t difference_type;
        typedef std::false_type propagate_on_container_copy_assignment;
        typedef std::true_type propagate_on_container_move_assignment;
        typedef std::true_type propagate_on_container_swap;

        template <typename U> struct rebind {
            typedef MemoryPool<U> other;
        };

        /* Member functions */
        MemoryPool( string &basedir ) noexcept;
        MemoryPool(const MemoryPool& memoryPool) noexcept;
        MemoryPool(MemoryPool&& memoryPool) noexcept;
        template <class U> MemoryPool(const MemoryPool<U>& memoryPool) noexcept;

        ~MemoryPool() noexcept;

        MemoryPool& operator=( const MemoryPool& memoryPool ) = delete;
        MemoryPool& operator=( MemoryPool&& memoryPool ) noexcept;

        pointer_t address( reference x) const noexcept;
        const_pointer address( const_reference x ) const noexcept;

        // Can only allocate one object at a time. n and hint are ignored
        pointer_t allocate( size_type n = 1, const_pointer hint = 0 );
        void deallocate(pointer_t p, size_type n = 1);

        size_type max_size() const noexcept;

        template <class U, class... Args> void construct(U* p, Args&&... args);
        template <class U> void destroy(U* p);

        template <class... Args> pointer_t newElement(Args&&... args);
        void deleteElement( pointer_t p );

    private:
        union Slot_ {
            value_type element;
            Slot_* next;
        };

        typedef char *data_pointer_t;
        typedef Slot_ slot_type_t;
        typedef Slot_ *slot_pointer_t;

        slot_pointer_t currentBlock_;
        slot_pointer_t currentSlot_;
        slot_pointer_t lastSlot_;
        slot_pointer_t freeSlots_;

        string basedir_;

        size_type padPointer( data_pointer_t p, size_type align ) const noexcept;
        void allocateBlock();
        void allocateBlock_mmap();

        static_assert( BlockSize >= 2 * sizeof(slot_type_t),
                       "BlockSize too small." );
};

#include "MemoryPool.inl"

#endif // MEMORY_POOL_H