blocked_pmap.h

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/*
 *  This file is a part of TiledArray.
 *  Copyright (C) 2013  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
 *
 *  add.h
 *  April 24, 2012
 *
 */

#ifndef TILEDARRAY_PMAP_BLOCKED_PMAP_H__INCLUDED
#define TILEDARRAY_PMAP_BLOCKED_PMAP_H__INCLUDED

#include <TiledArray/pmap/pmap.h>

namespace TiledArray {
  namespace detail {


    class BlockedPmap : public Pmap {
    protected:

      // Import Pmap protected variables
      using Pmap::rank_; 
      using Pmap::procs_; 
      using Pmap::size_; 
      using Pmap::local_; 

    private:

      const size_type block_size_; 
      const size_type remainder_; 
      const size_type block_size_plus_1_; 
      const size_type block_size_plus_1_times_remainder_; 
      const size_type local_first_; 
      const size_type local_last_; 

    public:
      typedef Pmap::size_type size_type; 


      BlockedPmap(World& world, size_type size) :
          Pmap(world, size),
          block_size_(size_ / procs_),
          remainder_(size_ % procs_),
          block_size_plus_1_(block_size_ + 1),
          block_size_plus_1_times_remainder_(remainder_ * block_size_plus_1_),
          local_first_(rank_ * block_size_ + std::min<size_type>(rank_, remainder_)),
          local_last_((rank_ + 1) * block_size_ + std::min<size_type>((rank_ + 1), remainder_))
      {
        local_.reserve(local_last_ - local_first_);


        // Construct a map of all local processes
        for(size_type first = local_first_; first < local_last_; ++first) {
          TA_ASSERT(BlockedPmap::owner(first) == rank_);
          local_.push_back(first);
        }
      }

      virtual ~BlockedPmap() { }


      virtual size_type owner(const size_type tile) const {
        TA_ASSERT(tile < size_);
        return (tile < block_size_plus_1_times_remainder_ ?
            tile / block_size_plus_1_ :
            ((tile - block_size_plus_1_times_remainder_) / block_size_) + remainder_);
      }



      virtual bool is_local(const size_type tile) const {
        return ((tile >= local_first_) && (tile < local_last_));
      }
    }; // class BlockedPmap

  }  // namespace detail
}  // namespace TiledArray


#endif // TILEDARRAY_PMAP_BLOCKED_PMAP_H__INCLUDED