Chris@16: // Copyright (C) 2005 Douglas Gregor.
Chris@16: 
Chris@16: // Use, modification and distribution is subject to the Boost Software
Chris@16: // License, Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
Chris@16: // http://www.boost.org/LICENSE_1_0.txt)
Chris@16: 
Chris@16: // Compute parents, children, levels, etc. to effect a parallel
Chris@16: // computation tree.
Chris@16: #ifndef BOOST_MPI_COMPUTATION_TREE_HPP
Chris@16: #define BOOST_MPI_COMPUTATION_TREE_HPP
Chris@16: 
Chris@16: namespace boost { namespace mpi { namespace detail {
Chris@16: 
Chris@16: /**
Chris@16:  * @brief Aids tree-based parallel collective algorithms.
Chris@16:  *
Chris@16:  * Objects of this type
Chris@16:  */
Chris@16: class computation_tree
Chris@16: {
Chris@16:  public:
Chris@16:   computation_tree(int rank, int size, int root, int branching_factor = -1);
Chris@16: 
Chris@16:   /// Returns the branching factor of the tree.
Chris@16:   int branching_factor() const { return branching_factor_; }
Chris@16: 
Chris@16:   /// Returns the level in the tree on which this process resides.
Chris@16:   int level() const { return level_; }
Chris@16: 
Chris@16:   /**
Chris@16:    * Returns the index corresponding to the n^th level of the tree.
Chris@16:    *
Chris@16:    * @param n The level in the tree whose index will be returned.
Chris@16:    */
Chris@16:   int level_index(int n) const;
Chris@16: 
Chris@16:   /**
Chris@16:    *  @brief Returns the parent of this process.
Chris@16:    *
Chris@16:    *  @returns If this process is the root, returns itself. Otherwise,
Chris@16:    *  returns the process number that is the parent in the computation
Chris@16:    *  tree.
Chris@16:    */
Chris@16:   int parent() const;
Chris@16: 
Chris@16:   /// Returns the index for the first child of this process.
Chris@16:   int child_begin() const;
Chris@16: 
Chris@16:   /**
Chris@16:    * @brief The default branching factor within the computation tree.
Chris@16:    *
Chris@16:    * This is the default branching factor for the computation tree, to
Chris@16:    * be used by any computation tree that does not fix the branching
Chris@16:    * factor itself. The default is initialized to 3, but may be
Chris@16:    * changed by the application so long as all processes have the same
Chris@16:    * branching factor.
Chris@16:    */
Chris@16:   static int default_branching_factor;
Chris@16: 
Chris@16:  protected:
Chris@16:   /// The rank of this process in the computation tree.
Chris@16:   int rank;
Chris@16: 
Chris@16:   /// The number of processes participating in the computation tree.
Chris@16:   int size;
Chris@16: 
Chris@16:   /// The process number that is acting as the root in the computation
Chris@16:   /// tree.
Chris@16:   int root;
Chris@16: 
Chris@16:   /**
Chris@16:    * @brief The branching factor within the computation tree.
Chris@16:    *
Chris@16:    * This is the default number of children that each node in a
Chris@16:    * computation tree will have. This value will be used for
Chris@16:    * collective operations that use tree-based algorithms.
Chris@16:    */
Chris@16:   int branching_factor_;
Chris@16: 
Chris@16:   /// The level in the tree at which this process resides.
Chris@16:   int level_;
Chris@16: };
Chris@16: 
Chris@16: } } } // end namespace boost::mpi::detail
Chris@16: 
Chris@16: #endif // BOOST_MPI_COMPUTATION_TREE_HPP