/***************************************************************************
 *  tests/containers/test_ext_merger2.cpp
 *
 *  Part of the STXXL. See http://stxxl.sourceforge.net
 *
 *  Copyright (C) 2008, 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 <iterator>
#include <stxxl/priority_queue>

typedef int my_type;
typedef stxxl::typed_block<4096, my_type> block_type;

struct dummy_merger
{
    int current, delta;
    dummy_merger() : current(0), delta(1) { }
    void operator () (int current_, int delta_)
    {
        current = current_;
        delta = delta_;
    }
    template <class OutputIterator>
    void multi_merge(OutputIterator b, OutputIterator e)
    {
        while (b != e)
        {
            * b = current;
            ++b;
            current += delta;
        }
    }
};

struct my_cmp : public std::greater<my_type>
{
    my_type min_value() const
    {
        return std::numeric_limits<my_type>::max();
    }
};

my_type * make_sequence(dummy_merger& dummy, int l)
{
    my_type* seq = new my_type[l + 1];  // + sentinel
    dummy.multi_merge(seq, seq + l);
    seq[l] = my_cmp().min_value();      // sentinel
    return seq;
}

// forced instantiation
const unsigned volume = 3 * 1024 * 1024; // in KiB
const unsigned mem_for_queue = 256 * 1024 * 1024;
template class stxxl::PRIORITY_QUEUE_GENERATOR<my_type, my_cmp, mem_for_queue, volume / sizeof(my_type)>;
template class stxxl::priority_queue_local::ext_merger<block_type, my_cmp, 5>;

int main()
{
    stxxl::config::get_instance();
    const int B = block_type::size;
    dummy_merger dummy;

    if (1) {
        const unsigned volume = 3 * 1024 * 1024; // in KiB
        const unsigned mem_for_queue = 256 * 1024 * 1024;
        typedef stxxl::PRIORITY_QUEUE_GENERATOR<my_type, my_cmp, mem_for_queue, volume / sizeof(my_type)>::result pq_type;
        pq_type pq(mem_for_queue, mem_for_queue);
        pq.push(42);
        STXXL_CHECK(pq.top() == 42);
        pq.pop();
        pq.push(2);
        pq.push(0);
        pq.push(3);
        pq.push(1);
        my_type x0, x1, x2, x3;
        x0 = pq.top();
        pq.pop();
        x1 = pq.top();
        pq.pop();
        x2 = pq.top();
        pq.pop();
        x3 = pq.top();
        pq.pop();
        STXXL_MSG("Order: " << x0 << " " << x1 << " " << x2 << " " << x3);
        STXXL_CHECK(x0 <= x1);
        STXXL_CHECK(x1 <= x2);
        STXXL_CHECK(x2 <= x3);
        STXXL_CHECK(pq.empty());
    }

    if (1) { // ext_merger test
        stxxl::read_write_pool<block_type> pool(1, 2);
        stxxl::priority_queue_local::ext_merger<block_type, my_cmp, 5> merger;
        merger.set_pool(&pool);
        dummy(1, 0);
        merger.append_merger(dummy, B * 2);
        dummy(2, 0);
        merger.append_merger(dummy, B * 2);
        dummy(B, 1);
        merger.append_merger(dummy, B * 4);
        dummy(B, 2);
        merger.append_merger(dummy, B * 4);
        dummy(B, 4);
        merger.append_merger(dummy, B * 4);

        std::vector<my_type> output(B * 3);

        // zero length merge
        merger.multi_merge(output.begin(), output.begin());
        merger.multi_merge(output.begin(), output.begin());
        merger.multi_merge(output.begin(), output.begin());

        while (merger.size() > 0) {
            stxxl::unsigned_type l =
                std::min<stxxl::unsigned_type>(
                    (stxxl::unsigned_type)merger.size(), output.size()
                    );

            merger.multi_merge(output.begin(), output.begin() + l);
            STXXL_CHECK(stxxl::is_sorted(output.begin(), output.begin() + l));
            STXXL_MSG("merged " << l << " elements: (" << *output.begin() << ", ..., " << *(output.begin() + l - 1) << ")");
        }

        // zero length merge on empty data structure
        merger.multi_merge(output.begin(), output.begin());
        merger.multi_merge(output.begin(), output.begin());
        merger.multi_merge(output.begin(), output.begin());
    } // ext_merger test

    if (1) { // int_merger test
        stxxl::priority_queue_local::int_merger<my_type, my_cmp, 8> merger;
        dummy(1, 0);
        my_type* seq0 = make_sequence(dummy, 2 * B);
        dummy(2, 0);
        my_type* seq1 = make_sequence(dummy, 2 * B);
        dummy(B, 1);
        my_type* seq2 = make_sequence(dummy, 4 * B);
        dummy(B, 2);
        my_type* seq3 = make_sequence(dummy, 4 * B);
        dummy(2 * B, 1);
        my_type* seq4 = make_sequence(dummy, 4 * B);
        dummy(B, 4);
        my_type* seq5 = make_sequence(dummy, 4 * B);
        dummy(B, 8);
        my_type* seq6 = make_sequence(dummy, 4 * B);
        dummy(2 * B, 2);
        my_type* seq7 = make_sequence(dummy, 4 * B);

        merger.append_array(seq0, 2 * B);
        merger.append_array(seq1, 2 * B);
        merger.append_array(seq2, 4 * B);
        merger.append_array(seq3, 4 * B);
        merger.append_array(seq4, 4 * B);
        if (0) {
            merger.append_array(seq5, 4 * B);
            merger.append_array(seq6, 4 * B);
            merger.append_array(seq7, 4 * B);
        }
        else {
            delete[] seq5;
            delete[] seq6;
            delete[] seq7;
        }

        my_type* out = new my_type[2 * B];

        // zero length merge
        merger.multi_merge(out, out);
        merger.multi_merge(out, out);
        merger.multi_merge(out, out);

        while (merger.size() > 0) {
            stxxl::uint64 l = std::min<stxxl::uint64>(merger.size(), B + B / 2 + 1);
            merger.multi_merge(out, out + l);
            STXXL_CHECK(stxxl::is_sorted(out, out + l));
            STXXL_MSG("merged " << l << " elements: (" << out[0] << ", ..., " << out[l - 1] << ")");
        }

        // zero length merge on empty data structure
        merger.multi_merge(out, out);
        merger.multi_merge(out, out);
        merger.multi_merge(out, out);

        delete[] out;
    } // int_merger test
}

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