/* -*- mode: C++; c-basic-offset: 4; indent-tabs-mode: nil -*- */
#ident "$Id$"
/*======
This file is part of PerconaFT.


Copyright (c) 2006, 2015, Percona and/or its affiliates. All rights reserved.

    PerconaFT is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License, version 2,
    as published by the Free Software Foundation.

    PerconaFT 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 PerconaFT.  If not, see <http://www.gnu.org/licenses/>.

----------------------------------------

    PerconaFT is free software: you can redistribute it and/or modify
    it under the terms of the GNU Affero General Public License, version 3,
    as published by the Free Software Foundation.

    PerconaFT 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 Affero General Public License for more details.

    You should have received a copy of the GNU Affero General Public License
    along with PerconaFT.  If not, see <http://www.gnu.org/licenses/>.
======= */

#ident "Copyright (c) 2006, 2015, Percona and/or its affiliates. All rights reserved."

#include <algorithm>
#include <cassert>
#include <cstdlib>
#include <memory>

#include "buffer.hpp"

namespace ftcxx {

    const size_t Buffer::INITIAL_CAPACITY = 1<<10;
    const size_t Buffer::MAXIMUM_CAPACITY = 1<<18;
    const double Buffer::FULLNESS_RATIO = 0.9;

    Buffer::Buffer()
        : _cur(0),
          _end(0),
          _capacity(INITIAL_CAPACITY),
          _buf(nullptr, &std::free)
    {
        init();
    }

    Buffer::Buffer(size_t capacity)
        : _end(0),
          _capacity(capacity),
          _buf(nullptr, &std::free)
    {
        init();
    }

    char *Buffer::alloc(size_t sz) {
        grow(sz);
        char *p = raw(_end);
        _end += sz;
        return p;
    }

    bool Buffer::full() const {
        return _end > MAXIMUM_CAPACITY * FULLNESS_RATIO;
    }

    bool Buffer::more() const {
        return _cur < _end;
    }

    char *Buffer::current() const {
        return raw(_cur);
    }

    void Buffer::advance(size_t sz) {
        _cur += sz;
    }

    void Buffer::clear() {
        _cur = 0;
        _end = 0;
    }

    void Buffer::init() {
        _buf.reset(static_cast<char *>(std::malloc(_capacity)));
    }

    size_t Buffer::next_alloc_size(size_t sz) {
        return sz * 2;
    }

    void Buffer::grow(size_t sz) {
        size_t new_capacity = _capacity;
        while (new_capacity < _end + sz) {
            new_capacity = next_alloc_size(new_capacity);
        }
        assert(new_capacity >= _capacity);  // overflow?
        if (new_capacity > _capacity) {
            std::unique_ptr<char, void (*)(void *)> new_buf(static_cast<char *>(std::malloc(new_capacity)), &std::free);
            std::copy(raw(0), raw(_end), &new_buf.get()[0]);
            std::swap(_buf, new_buf);
            _capacity = new_capacity;
        }
    }

} // namespace ftcxx