libMesh::StoredRange< iterator_type, object_type > Class Template Reference

Utility class for defining generic ranges for threading. More...

#include <stored_range.h>

Public Types
typedef std::vector< object_type >::const_iterator	const_iterator

Public Member Functions
	StoredRange (const unsigned int new_grainsize=1000)
	StoredRange (const iterator_type &first, const iterator_type &last, const unsigned int new_grainsize=1000)
	StoredRange (std::vector< object_type > *objs, const unsigned int new_grainsize=1000)
	StoredRange (const StoredRange< iterator_type, object_type > &er)
	StoredRange (const StoredRange< iterator_type, object_type > &er, const const_iterator &begin_range, const const_iterator &end_range)
	StoredRange (StoredRange< iterator_type, object_type > &r, Threads::split)
	~StoredRange ()
StoredRange< iterator_type, object_type > &	reset (const iterator_type &first, const iterator_type &last)
StoredRange< iterator_type, object_type > &	reset ()
const_iterator	begin () const
const_iterator	end () const
std::size_t	first_idx () const
std::size_t	last_idx () const
std::size_t	grainsize () const
void	grainsize (const unsigned int &gs)
std::size_t	size () const
bool	empty () const
bool	is_divisible () const

Private Attributes
const_iterator	_end
const_iterator	_begin
std::size_t	_last
std::size_t	_first
std::size_t	_grainsize
std::vector< object_type > *	_objs
bool	_should_release

Detailed Description

template<typename iterator_type, typename object_type>
class libMesh::StoredRange< iterator_type, object_type >

Utility class for defining generic ranges for threading.

The StoredRange class defines a contiguous, divisible set of objects. This class is used primarily as the argument to function objects. The range can then be subdivided into a number of "tasks" which can be executed in parallel. This concept is central to the Threading Building Blocks template library which can optionally be used by libMesh to implement shared-memory parallelism.

The implementation takes a user-provided object range and packs it into a contiguous vector which can then be subdivided efficiently. A first-cut implementation using raw element iterators incurred simply too much overhead by using the predicated iterators, specifically operations such as advancing such iterators has a cost proportional to the amount the iterator is advanced. Hence in this implementation the user-provided range is packed into a vector.

Author

Benjamin S. Kirk

Date

2008

Definition at line 52 of file stored_range.h.

Member Typedef Documentation

const_iterator

template<typename iterator_type, typename object_type>

typedef std::vector<object_type>::const_iterator libMesh::StoredRange< iterator_type, object_type >::const_iterator

Allows an StoredRange to behave like an STL container.

Definition at line 58 of file stored_range.h.

Constructor & Destructor Documentation

StoredRange() [1/6]

template<typename iterator_type, typename object_type>

libMesh::StoredRange< iterator_type, object_type >::StoredRange ( const unsigned int  new_grainsize = 1000 )

inline

Constructor. Optionally takes the grainsize parameter, which is the smallest chunk the range may be broken into for parallel execution.

Definition at line 65 of file stored_range.h.

                                                        :
    _end(),
    _begin(),
    _last(),
    _first(),
    _grainsize(new_grainsize),
    _objs(new std::vector<object_type>()),
    _should_release(true)
  {}

StoredRange() [2/6]

template<typename iterator_type, typename object_type>

libMesh::StoredRange< iterator_type, object_type >::StoredRange ( const iterator_type &  first, const iterator_type &  last, const unsigned int  new_grainsize = 1000  )

inline

Constructor. Takes the beginning and end of the range. Optionally takes the grainsize parameter, which is the smallest chunk the range may be broken into for parallel execution.

Definition at line 81 of file stored_range.h.

References libMesh::StoredRange< iterator_type, object_type >::reset().

                                                        :
    _end(),
    _begin(),
    _last(),
    _first(),
    _grainsize(new_grainsize),
    _objs(new std::vector<object_type>()),
    _should_release(true)
  {
    this->reset(first, last);
  }

StoredRange() [3/6]

template<typename iterator_type, typename object_type>

libMesh::StoredRange< iterator_type, object_type >::StoredRange ( std::vector< object_type > *  objs, const unsigned int  new_grainsize = 1000  )

inline

Constructor. Takes a std::vector of objects. Optionally takes the grainsize parameter, which is the smallest chunk the range may be broken into for parallel execution.

Note

The std::vector passed in here MUST live for the lifetime of this StoredRange!

Todo:

This should be a std::shared_ptr in the future!

Definition at line 106 of file stored_range.h.

                                                        :
    _end(objs->end()),
    _begin(objs->begin()),
    _last(objs->size()),
    _first(0),
    _grainsize(new_grainsize),
    _objs(objs),
    _should_release(false)
  {
  }

StoredRange() [4/6]

template<typename iterator_type, typename object_type>

libMesh::StoredRange< iterator_type, object_type >::StoredRange ( const StoredRange< iterator_type, object_type > &  er )

inline

Copy constructor. The StoredRange can be copied into subranges for parallel execution. In this way the initial StoredRange can be thought of as the root of a binary tree. The root element is the only element which interacts with the user. It takes a specified range of objects and packs it into a contiguous vector which can be split efficiently. However, there is no need for the child ranges to contain this vector, so long as the parent outlives the children. So we implement the copy constructor to specifically omit the _objs vector.

Definition at line 131 of file stored_range.h.

                                                                 :
    _end(er._end),
    _begin(er._begin),
    _last(er._last),
    _first(er._first),
    _grainsize(er._grainsize),
    _objs(nullptr),
    _should_release(false)
  {
    // specifically, do *not* copy the vector
  }

StoredRange() [5/6]

template<typename iterator_type, typename object_type>

libMesh::StoredRange< iterator_type, object_type >::StoredRange ( const StoredRange< iterator_type, object_type > &  er, const const_iterator &  begin_range, const const_iterator &  end_range  )

inline

NOTE: When using pthreads this constructor is MANDATORY!!!

Copy constructor. The StoredRange can be copied into subranges for parallel execution. In this way the initial StoredRange can be thought of as the root of a binary tree. The root element is the only element which interacts with the user. It takes a specified range of objects and packs it into a contiguous vector which can be split efficiently. However, there is no need for the child ranges to contain this vector, so long as the parent outlives the children. So we implement the copy constructor to specifically omit the _objs vector. This version allows you to set the beginning and ending of this new range to be different from that of the one we're copying.

Definition at line 160 of file stored_range.h.

References libMesh::StoredRange< iterator_type, object_type >::_begin, libMesh::StoredRange< iterator_type, object_type >::_end, libMesh::StoredRange< iterator_type, object_type >::_first, and libMesh::StoredRange< iterator_type, object_type >::_last.

                                                :
    _end(end_range),
    _begin(begin_range),
    _last(0), // Initialize these in a moment
    _first(0),
    _grainsize(er._grainsize),
    _objs(nullptr),
    _should_release(false)
  {
    // specifically, do *not* copy the vector

    _first = std::distance(er._begin, _begin);
    _last = _first + std::distance(_begin, _end);
  }

StoredRange() [6/6]

template<typename iterator_type, typename object_type>

libMesh::StoredRange< iterator_type, object_type >::StoredRange ( StoredRange< iterator_type, object_type > &  r, Threads::split    )

inline

Splits the range r. The first half of the range is left in place, the second half of the range is placed in *this.

Definition at line 182 of file stored_range.h.

References libMesh::StoredRange< iterator_type, object_type >::_begin, libMesh::StoredRange< iterator_type, object_type >::_end, libMesh::StoredRange< iterator_type, object_type >::_first, and libMesh::StoredRange< iterator_type, object_type >::_last.

                                                                          :
    _end(r._end),
    _begin(r._begin),
    _last(r._last),
    _first(r._first),
    _grainsize(r._grainsize),
    _objs(nullptr),
    _should_release(false)
  {
    const_iterator
      beginning = r._begin,
      ending    = r._end,
      middle    = beginning + std::distance(beginning, ending)/2u;

    r._end = _begin = middle;

    std::size_t
      first = r._first,
      last  = r._last,
      half  = first + (last-first)/2u;

    r._last = _first = half;
  }

~StoredRange()

template<typename iterator_type, typename object_type>

libMesh::StoredRange< iterator_type, object_type >::~StoredRange ( )

inline

Destructor. Releases the object array if we created it.

Definition at line 209 of file stored_range.h.

References libMesh::StoredRange< iterator_type, object_type >::_objs, and libMesh::StoredRange< iterator_type, object_type >::_should_release.

  {
    if (_should_release)
      delete _objs;
  }

Member Function Documentation

begin()

template<typename iterator_type, typename object_type>

const_iterator libMesh::StoredRange< iterator_type, object_type >::begin ( ) const

inline

Beginning of the range.

Definition at line 261 of file stored_range.h.

References libMesh::StoredRange< iterator_type, object_type >::_begin.

{ return _begin; }

empty()

template<typename iterator_type, typename object_type>

bool libMesh::StoredRange< iterator_type, object_type >::empty ( ) const

inline

Returns

true if the range is empty.

Definition at line 301 of file stored_range.h.

References libMesh::StoredRange< iterator_type, object_type >::_begin, and libMesh::StoredRange< iterator_type, object_type >::_end.

Referenced by libMesh::DofMap::create_dof_constraints().

{ return (_begin == _end); }

end()

template<typename iterator_type, typename object_type>

const_iterator libMesh::StoredRange< iterator_type, object_type >::end ( ) const

inline

End of the range.

Definition at line 266 of file stored_range.h.

References libMesh::StoredRange< iterator_type, object_type >::_end.

{ return _end; }

first_idx()

template<typename iterator_type, typename object_type>

std::size_t libMesh::StoredRange< iterator_type, object_type >::first_idx ( ) const

inline

Index in the stored vector of the first object.

Definition at line 271 of file stored_range.h.

References libMesh::StoredRange< iterator_type, object_type >::_first.

{ return _first; }

grainsize() [1/2]

template<typename iterator_type, typename object_type>

std::size_t libMesh::StoredRange< iterator_type, object_type >::grainsize ( ) const

inline

The grain size for the range. The range will be subdivided into subranges not to exceed the grain size.

Definition at line 282 of file stored_range.h.

References libMesh::StoredRange< iterator_type, object_type >::_grainsize.

Referenced by libMesh::StoredRange< iterator_type, object_type >::is_divisible().

{return _grainsize;}

grainsize() [2/2]

template<typename iterator_type, typename object_type>

void libMesh::StoredRange< iterator_type, object_type >::grainsize ( const unsigned int &  gs )

inline

Set the grain size.

Definition at line 287 of file stored_range.h.

References libMesh::StoredRange< iterator_type, object_type >::_grainsize.

{_grainsize = gs;}

is_divisible()

template<typename iterator_type, typename object_type>

bool libMesh::StoredRange< iterator_type, object_type >::is_divisible ( ) const

inline

Returns

true if the range can be subdivided.

Definition at line 306 of file stored_range.h.

References libMesh::StoredRange< iterator_type, object_type >::_begin, libMesh::StoredRange< iterator_type, object_type >::_end, and libMesh::StoredRange< iterator_type, object_type >::grainsize().

{ return this->grainsize() < static_cast<unsigned int>(std::distance(_begin, _end)); }

last_idx()

template<typename iterator_type, typename object_type>

std::size_t libMesh::StoredRange< iterator_type, object_type >::last_idx ( ) const

inline

Index in the stored vector of the last object.

Definition at line 276 of file stored_range.h.

References libMesh::StoredRange< iterator_type, object_type >::_last.

{ return _last; }

reset() [1/2]

template<typename iterator_type, typename object_type>

StoredRange<iterator_type, object_type>& libMesh::StoredRange< iterator_type, object_type >::reset ( const iterator_type &  first, const iterator_type &  last  )

inline

Resets the StoredRange to contain [first,last).

Returns

A reference to itself for convenience, so functions expecting a StoredRange<> can be passed e.g. foo.reset(begin,end).

Definition at line 222 of file stored_range.h.

References libMesh::StoredRange< iterator_type, object_type >::_begin, libMesh::StoredRange< iterator_type, object_type >::_end, libMesh::StoredRange< iterator_type, object_type >::_first, libMesh::StoredRange< iterator_type, object_type >::_last, and libMesh::StoredRange< iterator_type, object_type >::_objs.

Referenced by libMesh::FEMSystem::assemble_qoi(), libMesh::FEMSystem::assemble_qoi_derivative(), libMesh::FEMSystem::assembly(), libMesh::DofMap::create_dof_constraints(), and libMesh::FEMSystem::postprocess().

  {
    _objs->clear();

    for (iterator_type it=first; it!=last; ++it)
      _objs->push_back(*it);

    _begin = _objs->begin();
    _end   = _objs->end();

    _first = 0;
    _last  = _objs->size();

    return *this;
  }

reset() [2/2]

template<typename iterator_type, typename object_type>

StoredRange<iterator_type, object_type>& libMesh::StoredRange< iterator_type, object_type >::reset ( )

inline

Resets the range to the last specified range. This method only exists for efficiency – it is more efficient to set the range to its previous value without rebuilding the underlying vector.

Returns

A reference to itself for convenience, so functions expecting a StoredRange<> can be passed e.g. foo.reset().

Definition at line 247 of file stored_range.h.

References libMesh::StoredRange< iterator_type, object_type >::_begin, libMesh::StoredRange< iterator_type, object_type >::_end, libMesh::StoredRange< iterator_type, object_type >::_first, libMesh::StoredRange< iterator_type, object_type >::_last, and libMesh::StoredRange< iterator_type, object_type >::_objs.

Referenced by libMesh::StoredRange< iterator_type, object_type >::StoredRange().

  {
    _begin = _objs->begin();
    _end   = _objs->end();

    _first = 0;
    _last  = _objs->size();

    return *this;
  }

size()

template<typename iterator_type, typename object_type>

std::size_t libMesh::StoredRange< iterator_type, object_type >::size ( ) const

inline

Returns

The size of the range.

Definition at line 292 of file stored_range.h.

References libMesh::StoredRange< iterator_type, object_type >::_begin, and libMesh::StoredRange< iterator_type, object_type >::_end.

{ return std::distance(_begin, _end); }

Member Data Documentation

_begin

template<typename iterator_type, typename object_type>

const_iterator libMesh::StoredRange< iterator_type, object_type >::_begin

private

Definition at line 311 of file stored_range.h.

Referenced by libMesh::StoredRange< iterator_type, object_type >::begin(), libMesh::StoredRange< iterator_type, object_type >::empty(), libMesh::StoredRange< iterator_type, object_type >::is_divisible(), libMesh::StoredRange< iterator_type, object_type >::reset(), libMesh::StoredRange< iterator_type, object_type >::size(), and libMesh::StoredRange< iterator_type, object_type >::StoredRange().

_end

template<typename iterator_type, typename object_type>

const_iterator libMesh::StoredRange< iterator_type, object_type >::_end

private

Definition at line 310 of file stored_range.h.

Referenced by libMesh::StoredRange< iterator_type, object_type >::empty(), libMesh::StoredRange< iterator_type, object_type >::end(), libMesh::StoredRange< iterator_type, object_type >::is_divisible(), libMesh::StoredRange< iterator_type, object_type >::reset(), libMesh::StoredRange< iterator_type, object_type >::size(), and libMesh::StoredRange< iterator_type, object_type >::StoredRange().

_first

template<typename iterator_type, typename object_type>

std::size_t libMesh::StoredRange< iterator_type, object_type >::_first

private

Definition at line 313 of file stored_range.h.

Referenced by libMesh::StoredRange< iterator_type, object_type >::first_idx(), libMesh::StoredRange< iterator_type, object_type >::reset(), and libMesh::StoredRange< iterator_type, object_type >::StoredRange().

_grainsize

template<typename iterator_type, typename object_type>

std::size_t libMesh::StoredRange< iterator_type, object_type >::_grainsize

private

Definition at line 314 of file stored_range.h.

Referenced by libMesh::StoredRange< iterator_type, object_type >::grainsize().

_last

template<typename iterator_type, typename object_type>

std::size_t libMesh::StoredRange< iterator_type, object_type >::_last

private

Definition at line 312 of file stored_range.h.

Referenced by libMesh::StoredRange< iterator_type, object_type >::last_idx(), libMesh::StoredRange< iterator_type, object_type >::reset(), and libMesh::StoredRange< iterator_type, object_type >::StoredRange().

_objs

template<typename iterator_type, typename object_type>

std::vector<object_type>* libMesh::StoredRange< iterator_type, object_type >::_objs

private

Definition at line 317 of file stored_range.h.

Referenced by libMesh::StoredRange< iterator_type, object_type >::reset(), and libMesh::StoredRange< iterator_type, object_type >::~StoredRange().

_should_release

template<typename iterator_type, typename object_type>

bool libMesh::StoredRange< iterator_type, object_type >::_should_release

private

Definition at line 318 of file stored_range.h.

Referenced by libMesh::StoredRange< iterator_type, object_type >::~StoredRange().

---

The documentation for this class was generated from the following file:

• stored_range.h