io/gen_file.cpp

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/***************************************************************************
 *  algo/gen_file.cpp
 *
 *  Part of the STXXL. See http://stxxl.sourceforge.net
 *
 *  Copyright (C) 2002-2003 Roman Dementiev <dementiev@mpi-sb.mpg.de>
 *  Copyright (C) 2009 Andreas Beckmann <beckmann@cs.uni-frankfurt.de>
 *
 *  Distributed under the Boost Software License, Version 1.0.
 *  (See accompanying file LICENSE_1_0.txt or copy at
 *  http://www.boost.org/LICENSE_1_0.txt)
 **************************************************************************/

#include <limits>
#include <stxxl/io>
#include <stxxl/aligned_alloc>


struct my_type
{
    typedef unsigned key_type;

    key_type _key;
    char _data[128 - sizeof(key_type)];
    key_type key() const
    {
        return _key;
    }

    my_type() { }
    my_type(key_type __key) : _key(__key) { }

    static my_type min_value()
    {
        return my_type((std::numeric_limits<key_type>::min)());
    }
    static my_type max_value()
    {
        return my_type((std::numeric_limits<key_type>::max)());
    }
};

bool operator < (const my_type & a, const my_type & b)
{
    return a.key() < b.key();
}


int main(int argc, char ** argv)
{
    if (argc < 2)
    {
        std::cout << "Usage: " << argv[0] << " output_file" << std::endl;
        return -1;
    }

    const my_type::key_type max_key = 1 * 1024 * 1024;
    const unsigned int block_size = 1 * 1024 * 1024;
    const unsigned int records_in_block = block_size / sizeof(my_type);
    my_type * array = (my_type *)stxxl::aligned_alloc<BLOCK_ALIGN>(block_size);
    memset(array, 0, block_size);
    stxxl::syscall_file f(argv[1], stxxl::file::CREAT | stxxl::file::RDWR);
    stxxl::request_ptr req;

    my_type::key_type cur_key = max_key;
    for (unsigned i = 0; i < max_key / records_in_block; i++)
    {
        for (unsigned j = 0; j < records_in_block; j++)
            array[j]._key = cur_key--;

        req = f.awrite((void *)array, stxxl::int64(i) * block_size, block_size, stxxl::default_completion_handler());
        req->wait();
    }

    stxxl::aligned_dealloc<BLOCK_ALIGN>(array);

    return 0;
}