dg::MPI_Vector< container > Struct Template Reference

A simple wrapper around a container object and an MPI_Comm. More...

Public Types
using	container_type = container
	typedef to acces underlying container

Public Member Functions
	MPI_Vector ()
	no data is allocated, communicator is MPI_COMM_NULL
	MPI_Vector (container data, MPI_Comm comm)
	construct a vector
template<class OtherContainer >
	MPI_Vector (const MPI_Vector< OtherContainer > &src)
	Conversion operator.
const container &	data () const
	Get underlying data.
container &	data ()
	Set underlying data.
MPI_Comm	communicator () const
	Get the communicator to which this vector belongs.
void	set_communicator (MPI_Comm comm)
	Set the communicator.
unsigned	size () const
	Return the size of the data object.
void	swap (MPI_Vector &src)
	Swap data and communicator.

Friends
void	swap (MPI_Vector< container > &first, MPI_Vector< container > &second)

Detailed Description

template<class container>
struct dg::MPI_Vector< container >

A simple wrapper around a container object and an MPI_Comm.

This enables the tag dispatch system for e.g. blas1 and blas2 functions to choose the corresponding MPI implementation of a function over its shared memory analogon.

In the dg library MPI_Vectors are generated notably via the dg::evaluate function when called with a dg::RealMPIGrid

Note

The design choice to keep a communicator with the local data was made to allow to write global reductions like dg::blas1::dot in the same way as in shared memory code without an additional comm parameter.

Template Parameters

container

local container type. Must have a size() and a swap() member function and a specialization of the TensorTraits class.

See also

dg::x::HVec dg::MHVec dg::MDVec dg::x::DVec and others

Member Typedef Documentation

container_type

template<class container >

using dg::MPI_Vector< container >::container_type = container

typedef to acces underlying container

Constructor & Destructor Documentation

MPI_Vector() [1/3]

template<class container >

dg::MPI_Vector< container >::MPI_Vector ( )

inline

no data is allocated, communicator is MPI_COMM_NULL

MPI_Vector() [2/3]

template<class container >

dg::MPI_Vector< container >::MPI_Vector ( container data, MPI_Comm comm )

inline

construct a vector

Parameters

data	internal data copy
comm	MPI communicator (may not be MPI_COMM_NULL)

MPI_Vector() [3/3]

template<class container >

template<class OtherContainer >

dg::MPI_Vector< container >::MPI_Vector ( const MPI_Vector< OtherContainer > & src )

inline

Conversion operator.

uses conversion between compatible containers

Template Parameters

OtherContainer

another container class (container must be copy constructible from OtherContainer)

Parameters

src	the source

Member Function Documentation

communicator()

template<class container >

MPI_Comm dg::MPI_Vector< container >::communicator ( ) const

inline

Get the communicator to which this vector belongs.

Returns

read access to MPI communicator

data() [1/2]

template<class container >

container & dg::MPI_Vector< container >::data ( )

inline

Set underlying data.

Returns

write access to data

data() [2/2]

template<class container >

const container & dg::MPI_Vector< container >::data ( ) const

inline

Get underlying data.

Returns

read access to data

set_communicator()

template<class container >

void dg::MPI_Vector< container >::set_communicator ( MPI_Comm comm )

inline

Set the communicator.

Parameters

comm	new communicator to set

size()

template<class container >

unsigned dg::MPI_Vector< container >::size ( ) const

inline

Return the size of the data object.

Returns

data.size()

swap()

template<class container >

void dg::MPI_Vector< container >::swap ( MPI_Vector< container > & src )

inline

Swap data and communicator.

Parameters

src	communicator and data is swapped

Friends And Related Symbol Documentation

swap

template<class container >

void swap ( MPI_Vector< container > & first, MPI_Vector< container > & second )

friend

This follows the discussion in https://stackoverflow.com/questions/5695548/public-friend-swap-member-function

Note

the std library does call this function via unqualified calls in many algorithms, for example in std::iter_swap, it is just std::swap that will not call it directly. Most of the time this is not an issue because we have move assignments now, but if you do want to enable free swap functions like these use:

using std::swap;
swap(a,b);

Parameters

first	first instance
second	second instance

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

• backend/mpi_vector.h