PointerPool.h

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/******************************************************************************
 * Project:  libspatialindex - A C++ library for spatial indexing
 * Author:   Marios Hadjieleftheriou, mhadji@gmail.com
 ******************************************************************************
 * Copyright (c) 2004, Marios Hadjieleftheriou
 *
 * All rights reserved.
 * 
 * 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.
******************************************************************************/

#pragma once

#include "PoolPointer.h"

namespace Tools
{
    template <class X> class PointerPool
    {
    public:
        explicit PointerPool(uint32_t capacity) : m_capacity(capacity)
        {
            #ifndef NDEBUG
            m_hits = 0;
            m_misses = 0;
            m_pointerCount = 0;
            #endif
        }

        ~PointerPool()
        {
            assert(m_pool.size() <= m_capacity);

            while (! m_pool.empty())
            {
                X* x = m_pool.top(); m_pool.pop();
                #ifndef NDEBUG
                --m_pointerCount;
                #endif
                delete x;
            }

            #ifndef NDEBUG
            std::cerr << "Lost pointers: " << m_pointerCount << std::endl;
            #endif
        }

        PoolPointer<X> acquire()
        {
            X* p = nullptr;

            if (! m_pool.empty())
            {
                p = m_pool.top(); m_pool.pop();
                #ifndef NDEBUG
                m_hits++;
                #endif
            }
            else
            {
                p = new X();
                #ifndef NDEBUG
                m_pointerCount++;
                m_misses++;
                #endif
            }

            return PoolPointer<X>(p, this);
        }

        void release(X* p)
        {
            if (m_pool.size() < m_capacity)
            {
                m_pool.push(p);
            }
            else
            {
                #ifndef NDEBUG
                --m_pointerCount;
                #endif
                delete p;
            }

            assert(m_pool.size() <= m_capacity);
        }

        uint32_t getCapacity() const { return m_capacity; }
        void setCapacity(uint32_t c)
        {
            assert (c >= 0);
            m_capacity = c;
        }

    private:
        uint32_t m_capacity;
        std::stack<X*> m_pool;

    #ifndef NDEBUG
    public:
        uint64_t m_hits;
        uint64_t m_misses;
        uint64_t m_pointerCount;
    #endif
    };
}