CSRPattern.h

#ifndef DASH__CSR_PATTERN_1D_H_
#define DASH__CSR_PATTERN_1D_H_

#include <dash/Types.h>
#include <dash/Distribution.h>
#include <dash/Exception.h>
#include <dash/Dimensional.h>
#include <dash/Cartesian.h>
#include <dash/Team.h>

#include <dash/pattern/PatternProperties.h>
#include <dash/pattern/internal/PatternArguments.h>

#include <dash/internal/Math.h>
#include <dash/internal/Logging.h>

#include <functional>
#include <array>
#include <utility>
#include <vector>
#include <type_traits>


namespace dash {

#ifndef DOXYGEN

template <
  dim_t      NumDimensions,
  MemArrange Arrangement  = dash::ROW_MAJOR,
  typename   IndexType    = dash::default_index_t
>
class CSRPattern;

#endif // DOXYGEN

template<
  MemArrange Arrangement,
  typename   IndexType
>
class CSRPattern<1, Arrangement, IndexType>
{
private:
  static const dim_t NumDimensions = 1;

public:
  static constexpr char const * PatternName = "CSRPattern1D";

public:
  typedef pattern_partitioning_properties<
              // Minimal number of blocks in every dimension, i.e. one block
              // per unit.
              pattern_partitioning_tag::minimal,
              // Block extents are constant for every dimension.
              pattern_partitioning_tag::rectangular,
              // Identical number of elements in every block.
              pattern_partitioning_tag::balanced,
              // Size of blocks may differ.
              pattern_partitioning_tag::unbalanced
          > partitioning_properties;
  typedef pattern_mapping_properties<
              // Number of blocks assigned to a unit may differ.
              pattern_mapping_tag::unbalanced
          > mapping_properties;
  typedef pattern_layout_properties<
              // Elements are contiguous in local memory within single block.
              pattern_layout_tag::blocked,
              // Local element order corresponds to a logical linearization
              // within single blocks.
              pattern_layout_tag::linear
          > layout_properties;

private:
  typedef CSRPattern<NumDimensions, Arrangement, IndexType>
    self_t;
  typedef typename std::make_unsigned<IndexType>::type
    SizeType;
  typedef CartesianIndexSpace<NumDimensions, Arrangement, IndexType>
    MemoryLayout_t;
  typedef CartesianIndexSpace<NumDimensions, Arrangement, IndexType>
    LocalMemoryLayout_t;
  typedef CartesianSpace<NumDimensions, SizeType>
    BlockSpec_t;
  typedef DistributionSpec<NumDimensions>
    DistributionSpec_t;
  typedef TeamSpec<NumDimensions, IndexType>
    TeamSpec_t;
  typedef SizeSpec<NumDimensions, SizeType>
    SizeSpec_t;
  typedef ViewSpec<NumDimensions, IndexType>
    ViewSpec_t;
  typedef internal::PatternArguments<NumDimensions, IndexType>
    PatternArguments_t;

public:
  typedef IndexType   index_type;
  typedef SizeType    size_type;
  typedef ViewSpec_t  viewspec_type;
  typedef struct {
    team_unit_t                            unit;
    IndexType                             index{};
  } local_index_t;
  typedef struct {
    team_unit_t                            unit;
    std::array<index_type, NumDimensions> coords;
  } local_coords_t;

private:
  SizeType                    _size            = 0;
  std::vector<size_type>      _local_sizes;
  std::vector<size_type>      _block_offsets;
  MemoryLayout_t              _memory_layout;
  BlockSpec_t                 _blockspec;
  DistributionSpec_t          _distspec;
  dash::Team *                _team            = nullptr;
  TeamSpec_t                  _teamspec;
  SizeType                    _nunits          = 0;
  SizeType                    _local_size      = 0;
  LocalMemoryLayout_t         _local_memory_layout;
  SizeType                    _local_capacity  = 0;
  IndexType                   _lbegin          = 0;
  IndexType                   _lend            = 0;

public:
  template<typename ... Args>
  CSRPattern(
    SizeType arg,
    Args && ... args)
  : CSRPattern(PatternArguments_t(arg, args...))
  {
    DASH_LOG_TRACE("CSRPattern()", "Constructor with argument list");
    DASH_ASSERT_EQ(
      _local_sizes.size(), _nunits,
      "Number of given local sizes "   << _local_sizes.size() << " " <<
      "does not match number of units" << _nunits);
    initialize_local_range();
    DASH_LOG_TRACE("CSRPattern()", "CSRPattern initialized");
  }

  CSRPattern(
    const SizeSpec_t         & sizespec,
    const DistributionSpec_t & distspec,
    const TeamSpec_t         & teamspec,
    Team                     & team = dash::Team::All())
  : _size(sizespec.size()),
    _local_sizes(initialize_local_sizes(
        _size,
        distspec,
        team)),
    _block_offsets(initialize_block_offsets(
        _local_sizes)),
    _memory_layout(std::array<SizeType, 1> {{ _size }}),
    _blockspec(initialize_blockspec(
        _local_sizes)),
    _distspec(DistributionSpec_t()),
    _team(&team),
    _teamspec(
      teamspec,
      _distspec,
      *_team),
    _nunits(_team->size()),
    _local_size(
        initialize_local_extent(
          _team->myid(),
          _local_sizes)),
    _local_memory_layout(std::array<SizeType, 1> {{ _local_size }}),
    _local_capacity(initialize_local_capacity(_local_sizes))
  {
    DASH_LOG_TRACE("CSRPattern()", "(sizespec, dist, team)");
    DASH_ASSERT_EQ(
      _local_sizes.size(), _nunits,
      "Number of given local sizes "   << _local_sizes.size() << " " <<
      "does not match number of units" << _nunits);
    initialize_local_range();
    DASH_LOG_TRACE("CSRPattern()", "CSRPattern initialized");
  }

  CSRPattern(
    const SizeSpec_t         & sizespec,
    const DistributionSpec_t & distspec,
    Team                     & team = dash::Team::All())
  : _size(sizespec.size()),
    _local_sizes(initialize_local_sizes(
        _size,
        distspec,
        team)),
    _block_offsets(initialize_block_offsets(
        _local_sizes)),
    _memory_layout(std::array<SizeType, 1> {{ _size }}),
    _blockspec(initialize_blockspec(
        _local_sizes)),
    _distspec(DistributionSpec_t()),
    _team(&team),
    _teamspec(_distspec, *_team),
    _nunits(_team->size()),
    _local_size(
        initialize_local_extent(
          _team->myid(),
          _local_sizes)),
    _local_memory_layout(std::array<SizeType, 1> {{ _local_size }}),
    _local_capacity(initialize_local_capacity(_local_sizes))
  {
    DASH_LOG_TRACE("CSRPattern()", "(sizespec, dist, team)");
    DASH_ASSERT_EQ(
      _local_sizes.size(), _nunits,
      "Number of given local sizes "   << _local_sizes.size() << " " <<
      "does not match number of units" << _nunits);
    initialize_local_range();
    DASH_LOG_TRACE("CSRPattern()", "CSRPattern initialized");
  }

  template<typename ... Args>
  CSRPattern(
    const std::vector<size_type> & local_sizes,
    SizeType arg,
    Args && ... args)
  : CSRPattern(local_sizes, PatternArguments_t(arg, args...))
  {
    DASH_LOG_TRACE("CSRPattern()", "Constructor with argument list");
    DASH_ASSERT_EQ(
      _local_sizes.size(), _nunits,
      "Number of given local sizes "   << _local_sizes.size() << " " <<
      "does not match number of units" << _nunits);
    initialize_local_range();
    DASH_LOG_TRACE("CSRPattern()", "CSRPattern initialized");
  }

  CSRPattern(
    const std::vector<size_type>          & local_sizes,
    const TeamSpec_t                      & teamspec,
    dash::Team                            & team     = dash::Team::All())
  : _size(initialize_size(
        local_sizes)),
    _local_sizes(local_sizes),
    _block_offsets(initialize_block_offsets(
        _local_sizes)),
    _memory_layout(std::array<SizeType, 1> {{ _size }}),
    _blockspec(initialize_blockspec(
        _local_sizes)),
    _distspec(DistributionSpec_t()),
    _team(&team),
    _teamspec(
        teamspec,
        _distspec,
        *_team),
    _nunits(_team->size()),
    _local_size(
        initialize_local_extent(
          _team->myid(),
          _local_sizes)),
    _local_memory_layout(std::array<SizeType, 1> {{ _local_size }}),
    _local_capacity(initialize_local_capacity(_local_sizes))
  {
    DASH_LOG_TRACE("CSRPattern()", "(sizespec, dist, teamspec, team)");
    DASH_ASSERT_EQ(
      _local_sizes.size(), _nunits,
      "Number of given local sizes "   << _local_sizes.size() << " " <<
      "does not match number of units" << _nunits);
    initialize_local_range();
    DASH_LOG_TRACE("CSRPattern()", "CSRPattern initialized");
  }

  CSRPattern(
    const std::vector<size_type>  & local_sizes,
    Team                          & team = dash::Team::All())
  : _size(
      initialize_size(
        local_sizes)),
    _local_sizes(local_sizes),
    _block_offsets(
      initialize_block_offsets(
        _local_sizes)),
    _memory_layout(std::array<SizeType, 1> {{ _size }}),
    _blockspec(
      initialize_blockspec(
        _local_sizes)),
    _distspec(DistributionSpec_t()),
    _team(&team),
    _teamspec(_distspec, *_team),
    _nunits(_team->size()),
    _local_size(
        initialize_local_extent(
          _team->myid(),
          _local_sizes)),
    _local_memory_layout(
      std::array<SizeType, 1> {{ _local_size }}),
    _local_capacity(
      initialize_local_capacity(_local_sizes))
  {
    DASH_LOG_TRACE("CSRPattern()", "(sizespec, dist, team)");
    DASH_ASSERT_EQ(
      _local_sizes.size(), _nunits,
      "Number of given local sizes "   << _local_sizes.size() << " " <<
      "does not match number of units" << _nunits);
    initialize_local_range();
    DASH_LOG_TRACE("CSRPattern()", "CSRPattern initialized");
  }

  CSRPattern(const self_t & other) = default;

  CSRPattern(self_t && other)      = default;

  CSRPattern(self_t & other)
  : CSRPattern(static_cast<const self_t &>(other))
  { }

  self_t & operator=(const self_t & other) = default;

  self_t & operator=(self_t && other)      = default;

  constexpr bool operator==(
    const self_t & other) const noexcept
  {
    return (this == &other) ||
           ( // no need to compare all members as most are derived from
             // constructor arguments.
             _size        == other._size &&
             _local_sizes == other._local_sizes &&
             _distspec    == other._distspec &&
             _teamspec    == other._teamspec &&
             _nunits      == other._nunits
           );
  }

  constexpr bool operator!=(
    const self_t & other) const noexcept
  {
    return !(*this == other);
  }

  constexpr IndexType lbegin() const noexcept
  {
    return _lbegin;
  }

  constexpr IndexType lend() const noexcept
  {
    return _lend;
  }


  constexpr team_unit_t unit_at(
    const std::array<IndexType, NumDimensions> & coords,
    const ViewSpec_t                           & viewspec) const
  {
    return unit_at(coords[0] + viewspec.offset(0));
  }

  constexpr team_unit_t unit_at(
    const std::array<IndexType, NumDimensions> & g_coords) const
  {
    return unit_at(g_coords[0]);
  }

  constexpr team_unit_t unit_at(
    IndexType          global_pos,
    const ViewSpec_t & viewspec) const
  {
    return unit_at(global_pos + viewspec.offset(0));
  }

  team_unit_t unit_at(
    IndexType g_index) const
  {
    DASH_LOG_TRACE_VAR("CSRPattern.unit_at()", g_index);

    for (team_unit_t unit_idx{0}; unit_idx < _nunits; ++unit_idx) {
      if (g_index < _local_sizes[unit_idx]) {
        DASH_LOG_TRACE_VAR("CSRPattern.unit_at >", unit_idx);
        return unit_idx;
      }
      g_index -= _local_sizes[unit_idx];
    }
    DASH_THROW(
      dash::exception::InvalidArgument,
      "CSRPattern.unit_at: " <<
      "global index " << g_index << " is out of bounds");
  }


  inline IndexType extent(dim_t dim) const
  {
    DASH_ASSERT_EQ(
      0, dim,
      "Wrong dimension for Pattern::local_extent. " <<
      "Expected dimension = 0, got " << dim);
    return _size;
  }

  inline IndexType local_extent(dim_t dim) const
  {
    DASH_ASSERT_EQ(
      0, dim,
      "Wrong dimension for Pattern::local_extent. " <<
      "Expected dimension = 0, got " << dim);
    return _local_size;
  }

  constexpr std::array<SizeType, NumDimensions>
  local_extents() const noexcept
  {
    return std::array<SizeType, 1> {{ _local_sizes[_team->myid()] }};
  }
  constexpr std::array<SizeType, NumDimensions> local_extents(
      team_unit_t unit) const noexcept
  {
    return std::array<SizeType, 1> {{ _local_sizes[unit] }};
  }


  constexpr IndexType local_at(
    const std::array<IndexType, NumDimensions> & local_coords,
    const ViewSpec_t & viewspec) const noexcept
  {
    return local_coords[0] + viewspec.offset(0);
  }

  constexpr IndexType local_at(
    const std::array<IndexType, NumDimensions> & local_coords) const
  {
    return local_coords[0];
  }

  inline local_coords_t local(
    const std::array<IndexType, NumDimensions> & g_coords) const
  {
    local_index_t  l_index =  local(g_coords[0]);
    local_coords_t l_coords;
    l_coords.unit      = l_index.unit;
    l_coords.coords[0] = l_index.index;
    return l_coords;
  }

  inline local_index_t local(
    IndexType g_index) const
  {
    DASH_LOG_TRACE_VAR("CSRPattern.local()", g_index);
    local_index_t l_index;

    for (team_unit_t unit_idx{0}; unit_idx < _nunits; ++unit_idx) {
      if (g_index < _local_sizes[unit_idx]) {
        l_index.unit  = unit_idx;
        l_index.index = g_index;
        DASH_LOG_TRACE("CSRPattern.local >",
                       "unit:",  l_index.unit,
                       "index:", l_index.index);
        return l_index;
      }
      g_index -= _local_sizes[unit_idx];
    }
    DASH_THROW(
      dash::exception::InvalidArgument,
      "CSRPattern.local: " <<
      "global index " << g_index << " is out of bounds");
  }

  constexpr std::array<IndexType, NumDimensions> local_coords(
    const std::array<IndexType, NumDimensions> & g_coords) const
  {
    return std::array<IndexType, 1> {{ local(g_coords[0]).index }};
  }

  constexpr local_index_t local_index(
    const std::array<IndexType, NumDimensions> & g_coords) const
  {
    return local(g_coords[0]);
  }


  inline std::array<IndexType, NumDimensions> global(
      team_unit_t unit,
    const std::array<IndexType, NumDimensions> & local_coords) const
  {
    DASH_LOG_DEBUG_VAR("CSRPattern.global()", unit);
    DASH_LOG_DEBUG_VAR("CSRPattern.global()", local_coords);
    DASH_LOG_TRACE_VAR("CSRPattern.global", _nunits);
    if (_nunits < 2) {
      return local_coords;
    }
    // Initialize global index with element phase (= local coords):
    index_type glob_index = _block_offsets[unit] + local_coords[0];
    DASH_LOG_TRACE_VAR("CSRPattern.global >", glob_index);
    return std::array<IndexType, 1> {{ glob_index }};
  }

  constexpr std::array<IndexType, NumDimensions> global(
    const std::array<IndexType, NumDimensions> & l_coords) const
  {
    return global(_team->myid(), l_coords);
  }

  constexpr IndexType global(
    team_unit_t unit,
    IndexType l_index) const
  {
    return global(unit, std::array<IndexType, 1> {{ l_index }})[0];
  }

  constexpr IndexType global(
    IndexType l_index) const
  {
    return global(_team->myid(), std::array<IndexType, 1> {{ l_index }})[0];
  }

  constexpr IndexType global_index(
    team_unit_t unit,
    const std::array<IndexType, NumDimensions> & l_coords) const
  {
    return global(unit, l_coords[0]);
  }


  constexpr IndexType at(
    const std::array<IndexType, NumDimensions> & g_coords) const
  {
    return local_coords(g_coords)[0];
  }

  inline IndexType at(
    const std::array<IndexType, NumDimensions> & g_coords,
    const ViewSpec_t & viewspec) const
  {
    auto vs_coords = g_coords;
    vs_coords[0] += viewspec.offset(0);
    return local_coords(vs_coords)[0];
  }

  template<typename ... Values>
  constexpr IndexType at(IndexType value, Values ... values) const
  {
    static_assert(
      sizeof...(values) == NumDimensions-1,
      "Wrong parameter number");
    return at(std::array<IndexType, NumDimensions> {{
             value, (IndexType)values...
           }});
  }


  constexpr bool is_local(
    IndexType index,
    team_unit_t unit) const noexcept
  {
    return (index >= _block_offsets[unit])
           && ( unit == _nunits-1
                || index <  _block_offsets[unit+1]
              );
  }

  inline bool is_local(
    IndexType index) const
  {
    auto unit = team().myid();
    bool is_loc = index >= _block_offsets[unit] &&
                  (unit == _nunits-1 ||
                   index <  _block_offsets[unit+1]);
    return is_loc;
  }


  constexpr const BlockSpec_t & blockspec() const noexcept
  {
    return _blockspec;
  }

  constexpr index_type block_at(
    const std::array<index_type, NumDimensions> & g_coords) const
  {
    return static_cast<index_type>(unit_at(g_coords[0]));
  }

  ViewSpec_t block(
    index_type g_block_index) const
  {
    DASH_LOG_DEBUG_VAR("CSRPattern<1>.block >", g_block_index);
    index_type offset = _block_offsets[g_block_index];
    auto block_size   = _local_sizes[g_block_index];
    std::array<index_type, NumDimensions> offsets = {{ offset }};
    std::array<size_type, NumDimensions>  extents = {{ block_size }};
    ViewSpec_t block_vs(offsets, extents);
    DASH_LOG_DEBUG_VAR("CSRPattern<1>.block >", block_vs);
    return block_vs;
  }

  ViewSpec_t local_block(
    index_type l_block_index) const
  {
    DASH_LOG_DEBUG_VAR("CSRPattern<1>.local_block()", l_block_index);
    DASH_ASSERT_EQ(
      0, l_block_index,
      "CSRPattern always assigns exactly 1 block to a single unit");
    index_type block_offset = _block_offsets[_team->myid()];
    size_type  block_size   = _local_sizes[_team->myid()];
    std::array<index_type, NumDimensions> offsets = {{ block_offset }};
    std::array<size_type, NumDimensions>  extents = {{ block_size }};
    ViewSpec_t block_vs(offsets, extents);
    DASH_LOG_DEBUG_VAR("CSRPattern<1>.local_block >", block_vs);
    return block_vs;
  }

  inline ViewSpec_t local_block_local(
    index_type l_block_index) const
  {
    DASH_LOG_DEBUG_VAR("CSRPattern<1>.local_block_local >", l_block_index);
    size_type block_size = _local_sizes[_team->myid()];
    std::array<index_type, NumDimensions> offsets = {{ 0 }};
    std::array<size_type, NumDimensions>  extents = {{ block_size }};
    ViewSpec_t block_vs(offsets, extents);
    DASH_LOG_DEBUG_VAR("CSRPattern<1>.local_block_local >", block_vs);
    return block_vs;
  }

  constexpr SizeType blocksize(
    dim_t dimension) const noexcept
  {
    return _local_capacity;
  }

  constexpr SizeType max_blocksize() const noexcept
  {
    return _local_capacity;
  }

  constexpr SizeType local_capacity() const noexcept
  {
    return _local_capacity;
  }

  constexpr SizeType local_size() const noexcept
  {
    return _local_size;
  }

  constexpr SizeType local_size(team_unit_t unit) const noexcept
  {
    return _local_sizes[unit.id];
  }

  constexpr IndexType num_units() const noexcept
  {
    return _nunits;
  }

  constexpr IndexType capacity() const noexcept
  {
    return _size;
  }

  constexpr IndexType size() const noexcept
  {
    return _size;
  }

  constexpr dash::Team & team() const noexcept
  {
    return *_team;
  }

  constexpr const DistributionSpec_t & distspec() const noexcept
  {
    return _distspec;
  }

  constexpr SizeSpec_t sizespec() const noexcept
  {
    return SizeSpec_t(std::array<SizeType, 1> {{ _size }});
  }

  constexpr const std::array<SizeType, NumDimensions>
    extents() const noexcept
  {
    return std::array<SizeType, 1> {{ _size }};
  }

  constexpr const TeamSpec_t & teamspec() const noexcept
  {
    return _teamspec;
  }

  constexpr std::array<IndexType, NumDimensions> coords(
    IndexType index) const noexcept
  {
    return std::array<IndexType, 1> {{ index }};
  }

  std::array<IndexType, NumDimensions> coords(
    IndexType          index,
    const ViewSpec_t & viewspec) const {
    return std::array<IndexType, 1> {{ index + viewspec.offset(0) }};
  }


  constexpr static MemArrange memory_order()
  {
    return Arrangement;
  }

  constexpr static dim_t ndim()
  {
    return 1;
  }

private:

  CSRPattern(
    const PatternArguments_t & arguments)
  : CSRPattern(
      initialize_local_sizes(
        arguments.sizespec().size(),
        arguments.distspec(),
        arguments.team()),
      arguments)
  {}

  CSRPattern(
      std::vector<size_type> local_sizes, const PatternArguments_t &arguments)
    : _size(arguments.sizespec().size())
    , _local_sizes(std::move(local_sizes))
    , _block_offsets(initialize_block_offsets(_local_sizes))
    , _memory_layout(std::array<SizeType, 1>{{_size}})
    , _blockspec(initialize_blockspec(_local_sizes))
    , _distspec(arguments.distspec())
    , _team(&arguments.team())
    , _teamspec(arguments.teamspec())
    , _nunits(_team->size())
    , _local_size(initialize_local_extent(_team->myid(), _local_sizes))
    , _local_memory_layout(std::array<SizeType, 1>{{_local_size}})
    , _local_capacity(initialize_local_capacity(_local_sizes))
  {}

  inline SizeType initialize_size(
    const std::vector<size_type> & local_sizes) const
  {
    DASH_LOG_TRACE_VAR("CSRPattern.init_size()", local_sizes);
    size_type size = 0;
    for (size_type unit_idx = 0; unit_idx < local_sizes.size(); ++
         unit_idx) {
      size += local_sizes[unit_idx];
    }
    DASH_LOG_TRACE_VAR("CSRPattern.init_size >", size);
    return size;
  }

  std::vector<size_type> initialize_local_sizes(
    size_type                  total_size,
    const DistributionSpec_t & distspec,
    const dash::Team         & team) const
  {
    DASH_LOG_TRACE_VAR("CSRPattern.init_local_sizes()", total_size);
    std::vector<size_type> l_sizes;
    auto nunits = team.size();
    DASH_LOG_TRACE_VAR("CSRPattern.init_local_sizes()", nunits);
    if (nunits == 1) {
      l_sizes.push_back(total_size);
    }
    if (nunits <= 1) {
      return l_sizes;
    }
    auto dist_type = distspec[0].type;
    DASH_LOG_TRACE_VAR("CSRPattern.init_local_sizes()", dist_type);
    // Tiled and blocked distribution:
    if (dist_type == dash::internal::DIST_BLOCKED ||
        dist_type == dash::internal::DIST_TILE) {
      auto blocksize = dash::math::div_ceil(total_size, nunits);
      for (size_type u = 0; u < nunits; ++u) {
        l_sizes.push_back(blocksize);
      }
    // Unspecified distribution (default-constructed pattern instance),
    // set all local sizes to 0:
    } else if (dist_type == dash::internal::DIST_UNDEFINED) {
      for (size_type u = 0; u < nunits; ++u) {
        l_sizes.push_back(0);
      }
    // No distribution, assign all indices to unit 0:
    } else if (dist_type == dash::internal::DIST_NONE) {
      l_sizes.push_back(total_size);
      for (size_type u = 0; u < nunits-1; ++u) {
        l_sizes.push_back(0);
      }
    // Incompatible distribution type:
    } else {
      DASH_THROW(
        dash::exception::InvalidArgument,
        "CSRPattern expects TILE (" << dash::internal::DIST_TILE << ") " <<
        "or BLOCKED (" << dash::internal::DIST_BLOCKED << ") " <<
        "distribution, got " << dist_type);
    }
    DASH_LOG_TRACE_VAR("CSRPattern.init_local_sizes >", l_sizes);
    return l_sizes;
  }

  BlockSpec_t initialize_blockspec(
    const std::vector<size_type> & local_sizes) const
  {
    DASH_LOG_TRACE_VAR("CSRPattern.init_blockspec", local_sizes);
    BlockSpec_t blockspec({
  static_cast<size_type>(local_sizes.size())
    });
    DASH_LOG_TRACE_VAR("CSRPattern.init_blockspec >", blockspec);
    return blockspec;
  }

  std::vector<size_type> initialize_block_offsets(
    const std::vector<size_type> & local_sizes) const
  {
    DASH_LOG_TRACE_VAR("CSRPattern.init_block_offsets", local_sizes);
    std::vector<size_type> block_offsets;
    if (local_sizes.size() > 0) {
      // NOTE: Assuming 1 block for every unit.
      block_offsets.push_back(0);
      for (size_type unit_idx = 0;
           unit_idx < local_sizes.size()-1;
           ++unit_idx)
      {
        auto block_offset = block_offsets[unit_idx] +
                            local_sizes[unit_idx];
        block_offsets.push_back(block_offset);
      }
    }
    DASH_LOG_TRACE_VAR("CSRPattern.init_block_offsets >", block_offsets);
    return block_offsets;
  }

  SizeType initialize_local_capacity(
    const std::vector<size_type> & local_sizes) const
  {
    SizeType l_capacity = 0;
    // Local capacity is maximum number of elements assigned to a single unit,
    // i.e. the maximum local size:
    auto max_local_size = std::max_element(local_sizes.begin(),
                                           local_sizes.end());
    if (max_local_size != local_sizes.end()) {
      l_capacity = *max_local_size;
    }
    DASH_LOG_DEBUG_VAR("CSRPattern.init_lcapacity >", l_capacity);
    return l_capacity;
  }

  void initialize_local_range()
  {
    auto l_size = _local_size;
    DASH_LOG_DEBUG_VAR("CSRPattern.init_local_range()", l_size);
    if (l_size == 0) {
      _lbegin = 0;
      _lend   = 0;
    } else {
      // First local index transformed to global index
      _lbegin = global(0);
      // Index past last local index transformed to global index.
      // global(l_size) would be out of range, so we use the global index
      // to the last element and increment by 1:
      _lend   = global(l_size - 1) + 1;
    }
    DASH_LOG_DEBUG_VAR("CSRPattern.init_local_range >", _lbegin);
    DASH_LOG_DEBUG_VAR("CSRPattern.init_local_range >", _lend);
  }

  SizeType initialize_local_extent(
    team_unit_t                    unit,
    const std::vector<size_type> & local_sizes) const
  {
    DASH_LOG_DEBUG_VAR("CSRPattern.init_local_extent()", unit);
    if (local_sizes.size() == 0) {
      return 0;
    }
    // Local size of given unit:
    SizeType l_extent = local_sizes[static_cast<int>(unit)];
    DASH_LOG_DEBUG_VAR("CSRPattern.init_local_extent >", l_extent);
    return l_extent;
  }

}; // class CSRPattern<1>

} // namespace dash

#endif // DASH__CSR_PATTERN_1D_H_