Arena.h

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// -*- lsst-c++ -*-

/* 
 * LSST Data Management System
 * Copyright 2008, 2009, 2010 LSST Corporation.
 * 
 * This product includes software developed by the
 * LSST Project (http://www.lsst.org/).
 *
 * 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 3 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 LSST License Statement and 
 * the GNU General Public License along with this program.  If not, 
 * see <http://www.lsstcorp.org/LegalNotices/>.
 */

#ifndef LSST_AP_UTILS_ARENA_H
#define LSST_AP_UTILS_ARENA_H

#include <cassert>
#include <cstdlib>
#include <algorithm>
#include <stdexcept>
#include <vector>

#include "boost/static_assert.hpp"

#include "lsst/pex/exceptions.h"

// Forward declarations
namespace lsst { namespace ap { namespace utils {
    template <typename T> class Arena;
}}}

template <typename T> void * operator new(size_t, lsst::ap::utils::Arena<T> &);
template <typename T> void operator delete(void *, lsst::ap::utils::Arena<T> &);


namespace lsst { namespace ap { namespace utils {

template <typename T>
class Arena {
public:
    Arena(size_t blockCapacity=262144/sizeof(T));
    ~Arena();

    inline void destroy(T *ptr);

    inline size_t capacity() const;
    inline size_t getNumBytes() const;
    inline size_t getBlockCapacity() const;

private:
    // T might be or contain a vector type (e.g. an SSEx type).
    // These must be 16 byte aligned on some platforms.
    static const size_t ALIGN = 16;
    static const size_t SIZE = (sizeof(T) + ALIGN - 1) & ~(ALIGN - 1);

    BOOST_STATIC_ASSERT((ALIGN & (ALIGN - 1)) == 0);

    // disable copy construction/assignment
    Arena(Arena const &);
    Arena & operator=(Arena const &);

    inline void *_alloc();
    inline void _dealloc(void *ptr);
    void _grow();

    static inline unsigned char * _align(unsigned char *p);

    std::vector<unsigned char *> _blocks;   
    std::vector<std::vector<bool> > _masks; 
    size_t const _blockCapacity;            
    size_t _nFree;         
    unsigned char *_free;  

    friend void * (::operator new<>)(size_t, lsst::ap::utils::Arena<T> &);
    friend void (::operator delete<>)(void *, lsst::ap::utils::Arena<T> &);
};

}}} // namespace lsst::ap::utils

#include "Arena.cc"


template <typename T>
inline void * operator new(size_t, lsst::ap::utils::Arena<T> &arena) {
   return arena._alloc();
}

template <typename T>
inline void operator delete(void *ptr, lsst::ap::utils::Arena<T> &arena) {
   arena._dealloc(ptr);
}

#endif // LSST_AP_UTILS_ARENA_H