make_array.h

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/*
 *  This file is a part of TiledArray.
 *  Copyright (C) 2015  Virginia Tech
 *
 *  This program is free software: you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation, either version 3 of the License, or
 *  (at your option) any later version.
 *
 *  This program 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 this program.  If not, see <http://www.gnu.org/licenses/>.
 *
 *  Justus Calvin
 *  Department of Chemistry, Virginia Tech
 *
 *  array_init.h
 *  Dec 15, 2015
 *
 */

#ifndef TILEDARRAY_CONVERSIONS_MAKE_ARRAY_H__INCLUDED
#define TILEDARRAY_CONVERSIONS_MAKE_ARRAY_H__INCLUDED

#include <TiledArray/madness.h>
#include <TiledArray/type_traits.h>

namespace Eigen {
  template <typename> class aligned_allocator;
} // namespace Eigen

namespace TiledArray {


  template <typename Array, typename Op,
      typename std::enable_if<is_dense<Array>::value>::type* = nullptr>
  inline Array
  make_array(World& world, const detail::trange_t<Array>& trange,
      const std::shared_ptr<detail::pmap_t<Array> >& pmap, Op&& op)
  {
    typedef typename Array::value_type value_type;
    typedef typename value_type::range_type range_type;

    // Make an empty result array
    Array result(world, trange);

    // Iterate over local tiles of arg
    for(const auto index : * result.pmap()) {

      // Spawn a task to evaluate the tile
      auto tile =
          world.taskq.add([=] (const range_type& range) -> value_type {
            value_type tile;
            op(tile, range);
            return tile;
          }, trange.make_tile_range(index));

      // Store result tile
      result.set(index, tile);
    }

    return result;
  }


  template <typename Array, typename Op,
      typename std::enable_if<! is_dense<Array>::value>::type* = nullptr>
  inline Array
  make_array(World& world, const detail::trange_t<Array>& trange,
      const std::shared_ptr<detail::pmap_t<Array> >& pmap, Op&& op)
  {
    typedef typename Array::value_type value_type;
    typedef typename Array::size_type size_type;
    typedef std::pair<size_type, Future<value_type> > datum_type;

    // Create a vector to hold local tiles
    std::vector<datum_type> tiles;
    tiles.reserve(pmap->size());

    // Construct a tensor to hold updated tile norms for the result shape.
    TiledArray::Tensor<typename detail::shape_t<Array>::value_type,
        Eigen::aligned_allocator<typename detail::shape_t<Array>::value_type> >
    tile_norms(trange.tiles_range(), 0);

    // Construct the task function used to construct the result tiles.
    madness::AtomicInt counter; counter = 0;
    int task_count = 0;
    auto task = [&](const size_type index) -> value_type {
      value_type tile;
      tile_norms[index] = op(tile, trange.make_tile_range(index));
      ++counter;
      return tile;
    };

    for(const auto index : *pmap) {
      auto result_tile = world.taskq.add(task, index);
      ++task_count;
      tiles.emplace_back(index, std::move(result_tile));
    }

    // Wait for tile norm data to be collected.
    if(task_count > 0)
      world.await([&counter,task_count] () -> bool { return counter == task_count; });

    // Construct the new array
    Array result(world, trange,
        typename Array::shape_type(world, tile_norms, trange), pmap);
    for(auto& it : tiles) {
      const size_type index = it.first;
      if(! result.is_zero(index))
        result.set(it.first, it.second);
    }

    return result;
  }



  template <typename Array, typename Op>
  inline Array
  make_array(World& world, const detail::trange_t<Array>& trange, Op&& op) {
    return make_array<Array>(world, trange,
        detail::policy_t<Array>::default_pmap(world,
        trange.tiles_range().volume()), op);
  }

} // namespace TiledArray

#endif // TILEDARRAY_CONVERSIONS_MAKE_ARRAY_H__INCLUDED