inmemsort.h

Go to the documentation of this file.

/***************************************************************************
 * include/stxxl/bits/algo/inmemsort.h
 *
 * Part of the STXXL. See http://stxxl.sourceforge.net
 *
 * Copyright (C) 2003 Roman Dementiev <[email protected]>
 * Copyright (C) 2010 Andreas Beckmann <[email protected]>
 *
 * 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)
 **************************************************************************/

#ifndef STXXL_ALGO_INMEMSORT_HEADER
#define STXXL_ALGO_INMEMSORT_HEADER

#include <stxxl/bits/namespace.h>
#include <stxxl/bits/common/simple_vector.h>
#include <stxxl/bits/io/request_operations.h>
#include <stxxl/bits/algo/adaptor.h>
#include <stxxl/bits/mng/adaptor.h>
#include <stxxl/bits/parallel.h>

#include <algorithm>

STXXL_BEGIN_NAMESPACE

template <typename ExtIterator, typename StrictWeakOrdering>
void stl_in_memory_sort(ExtIterator first, ExtIterator last, StrictWeakOrdering cmp)
{
 typedef typename ExtIterator::block_type block_type;

 STXXL_VERBOSE("stl_in_memory_sort, range: " << (last - first));
 first.flush();
 unsigned_type nblocks = last.bid() - first.bid() + (last.block_offset() ? 1 : 0);
 simple_vector<block_type> blocks(nblocks);
 simple_vector<request_ptr> reqs(nblocks);
 unsigned_type i;

 for (i = 0; i < nblocks; ++i)
 reqs[i] = blocks[i].read(*(first.bid() + i));

 wait_all(reqs.begin(), nblocks);

 unsigned_type last_block_correction = last.block_offset() ? (block_type::size - last.block_offset()) : 0;
 check_sort_settings();
 potentially_parallel::
 sort(make_element_iterator(blocks.begin(), first.block_offset()),
 make_element_iterator(blocks.begin(), nblocks * block_type::size - last_block_correction),
 cmp);

 for (i = 0; i < nblocks; ++i)
 reqs[i] = blocks[i].write(*(first.bid() + i));

 wait_all(reqs.begin(), nblocks);
}

STXXL_END_NAMESPACE

#endif // !STXXL_ALGO_INMEMSORT_HEADER