file_stream_base.h

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// -*- mode: c++; tab-width: 4; indent-tabs-mode: t; eval: (progn (c-set-style "stroustrup") (c-set-offset 'innamespace 0)); -*-
// vi:set ts=4 sts=4 sw=4 noet :
// Copyright 2012 The TPIE development team
// 
// This file is part of TPIE.
// 
// TPIE is free software: you can redistribute it and/or modify it under
// the terms of the GNU Lesser General Public License as published by the
// Free Software Foundation, either version 3 of the License, or (at your
// option) any later version.
// 
// TPIE 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 Lesser General Public
// License for more details.
// 
// You should have received a copy of the GNU Lesser General Public License
// along with TPIE.  If not, see <http://www.gnu.org/licenses/>


#ifndef __TPIE_FILE_STREAM_BASE_H__
#define __TPIE_FILE_STREAM_BASE_H__

#include <tpie/file_base_crtp.h>
#include <tpie/stream_crtp.h>
#include <algorithm>
namespace tpie {

class file_stream_base: public file_base_crtp<file_stream_base>, public stream_crtp<file_stream_base> {
public:
    typedef file_base_crtp<file_stream_base> p_t;
    typedef stream_crtp<file_stream_base> s_t;

    friend class file_base_crtp<file_stream_base>;

    struct block_t {
        memory_size_type size;
        stream_size_type number;
        bool dirty;
        char * data;
    };

    inline void close() throw(stream_exception) {
        if (m_open) flush_block();
        tpie_delete_array(m_block.data, m_itemSize * m_blockItems);
        m_block.data = 0;
        p_t::close();
    }


    inline void truncate(stream_size_type size) {
        stream_size_type o=offset();
        flush_block();
        m_block.number = std::numeric_limits<stream_size_type>::max();
        m_nextBlock = std::numeric_limits<stream_size_type>::max();
        m_nextIndex = std::numeric_limits<memory_size_type>::max();
        m_index = std::numeric_limits<memory_size_type>::max();
        m_size = size;
        m_fileAccessor->truncate(size);
        if (m_tempFile)
            m_tempFile->update_recorded_size(m_fileAccessor->byte_size());
        seek(std::min(o, size));
    }

protected:
    file_stream_base(memory_size_type itemSize,
                     double blockFactor,
                     file_accessor::file_accessor * fileAccessor);

    inline ~file_stream_base() {
        close();
    }

    void swap(file_stream_base & other) {
        using std::swap;
        swap(m_index,           other.m_index);
        swap(m_nextBlock,       other.m_nextBlock);
        swap(m_nextIndex,       other.m_nextIndex);
        swap(m_blockStartIndex, other.m_blockStartIndex);
        swap(m_blockItems,      other.m_blockItems);
        swap(m_blockSize,       other.m_blockSize);
        swap(m_size,            other.m_size);
        swap(m_canRead,         other.m_canRead);
        swap(m_canWrite,        other.m_canWrite);
        swap(m_itemSize,        other.m_itemSize);
        swap(m_open,            other.m_open);
        swap(m_fileAccessor,    other.m_fileAccessor);
        swap(m_block.size,      other.m_block.size);
        swap(m_block.number,    other.m_block.number);
        swap(m_block.dirty,     other.m_block.dirty);
        swap(m_block.data,      other.m_block.data);
        swap(m_ownedTempFile,   other.m_ownedTempFile);
        swap(m_tempFile,        other.m_tempFile);
    }

    inline void open_inner(const std::string & path,
                           access_type accessType,
                           memory_size_type userDataSize,
                           cache_hint cacheHint) throw (stream_exception) {
        p_t::open_inner(path, accessType, userDataSize, cacheHint);

        m_blockStartIndex = 0;
        m_nextBlock = std::numeric_limits<stream_size_type>::max();
        m_nextIndex = std::numeric_limits<memory_size_type>::max();
        m_index = std::numeric_limits<memory_size_type>::max();

        m_block.size = 0;
        m_block.number = std::numeric_limits<stream_size_type>::max();
        m_block.dirty = false;
        m_block.data = tpie_new_array<char>(m_blockItems * m_itemSize);

        initialize();
        seek(0);
    }

    void get_block(stream_size_type block);

    inline void flush_block() {
        if (m_block.dirty) {
            assert(m_canWrite);
            update_vars();
            m_fileAccessor->write_block(m_block.data, m_block.number, m_block.size);
            if (m_tempFile)
                m_tempFile->update_recorded_size(m_fileAccessor->byte_size());
        }
        m_block.dirty = false;
    }

    inline void update_vars() {
        if (m_block.dirty && m_index != std::numeric_limits<memory_size_type>::max()) {
            assert(m_index <= m_blockItems);
            m_block.size = std::max(m_block.size, m_index);
            m_size = std::max(m_size, static_cast<stream_size_type>(m_index)+m_blockStartIndex);
        }
    }

    inline void initialize() {
        flush_block();
        s_t::initialize();
    }

    inline void write_update() {
        m_block.dirty = true;
    }


    block_t m_block;

private:
    friend class stream_crtp<file_stream_base>;
    file_stream_base & get_file() {return *this;}
    const file_stream_base & get_file() const {return *this;}
    block_t & get_block() {return m_block;}
    const block_t & get_block() const {return m_block;}
    void update_block_core();
};

} // namespace tpie

#endif // __TPIE_FILE_STREAM_BASE_H__