Perform general gather and its transpose (scatter) operation across processes on distributed vectors using mpi. More...

Inheritance diagram for dg::GeneralComm< Index, Vector >:

Public Member Functions
	GeneralComm ()=default
	no memory allocation; size 0 More...

	GeneralComm (unsigned local_size, const thrust::host_vector< int > &localIndexMap, const thrust::host_vector< int > &pidIndexMap, MPI_Comm comm)
	Construct from local indices and PIDs index map. More...

template<class ConversionPolicy >
	GeneralComm (const thrust::host_vector< int > &globalIndexMap, const ConversionPolicy &p)
	Construct from global indices index map. More...

template<class OtherIndex , class OtherVector >
	GeneralComm (const GeneralComm< OtherIndex, OtherVector > &src)
	reconstruct from another type; if src is empty, same as default constructor More...

const thrust::host_vector< int > &	getLocalIndexMap () const
	read access to the local index index map given in constructor More...

const thrust::host_vector< int > &	getPidIndexMap () const
	read access to the pid index map given in constructor More...

virtual GeneralComm *	clone () const override final
	Generic copy method. More...

Public Member Functions inherited from dg::aCommunicator< Vector >
Vector	allocate_buffer () const
	Allocate a buffer object of size `buffer_size()` More...

void	global_gather (const value_type *values, Vector &buffer) const
	\( w = G v\). Globally (across processes) gather data into a buffer More...

Vector	global_gather (const value_type *values) const
	\( w = G v\). Globally (across processes) gather data into a buffer (memory allocating version) More...

void	global_scatter_reduce (const Vector &toScatter, value_type *values) const
	\( v = G^\mathrm{T} w\). Globally (across processes) scatter data accross processes and reduce on multiple indices More...

unsigned	buffer_size () const
	The local size of the buffer vector w = local map size. More...

unsigned	local_size () const
	The local size of the source vector v = local size of the `dg::MPI_Vector` More...

bool	isCommunicating () const
	True if the gather/scatter operation involves actual MPI communication. More...

MPI_Comm	communicator () const
	The internal MPI communicator used. More...

virtual aCommunicator *	clone () const=0
	Generic copy method. More...

virtual	~aCommunicator ()
	vritual destructor More...

Additional Inherited Members
Public Types inherited from dg::aCommunicator< Vector >
using	value_type = get_value_type< Vector >
	reveal value type More...

using	container_type = Vector
	reveal local container type More...

Protected Member Functions inherited from dg::aCommunicator< Vector >
	aCommunicator (unsigned local_size=0)
	only derived classes can construct More...

	aCommunicator (const aCommunicator &src)
	only derived classes can copy More...

aCommunicator &	operator= (const aCommunicator &src)
	only derived classes can assign More...

void	set_local_size (unsigned new_size)
	Set the local size of the source vector v. More...

Detailed Description

template<class Index, class Vector>
struct dg::GeneralComm< Index, Vector >

Perform general gather and its transpose (scatter) operation across processes on distributed vectors using mpi.

This Communicator can perform general global gather and scatter operations. In general the index map idx[i] might or might not map an element of the source vector v. This means that the scatter matrix S can have one or more empty lines. (see aCommunicator for more details) Compared to SurjectiveComm the global_scatter_reduce function needs to perform an additional scatter as some elements of the source vector might be left empty

Template Parameters

Index	an integer thrust Vector (needs to be `int` due to MPI interface)
Vector	a thrust Vector

Constructor & Destructor Documentation

◆ GeneralComm() [1/4]

template<class Index , class Vector >

dg::GeneralComm< Index, Vector >::GeneralComm ( )

default

no memory allocation; size 0

◆ GeneralComm() [2/4]

template<class Index , class Vector >

dg::GeneralComm< Index, Vector >::GeneralComm	(	unsigned	local_size,
		const thrust::host_vector< int > &	localIndexMap,
		const thrust::host_vector< int > &	pidIndexMap,
		MPI_Comm	comm
	)

inline

Construct from local indices and PIDs index map.

The indices in the index map are written with respect to the buffer vector. Each location in the source vector is uniquely specified by a local vector index and the process rank.

Parameters

local_size	local size of a `dg::MPI_Vector` (same for all processes)
localIndexMap	Each element `localIndexMap[i]` represents a local vector index from (or to) where to take the value `buffer[i]`. There are `local_buffer_size = localIndexMap.size()` elements.
pidIndexMap	Each element `pidIndexMap[i]` represents the pid/rank to which the corresponding index `localIndexMap[i]` is local. Same size as `localIndexMap`. The pid/rank needs to be element of the given communicator.
comm	The MPI communicator participating in the scatter/gather operations

◆ GeneralComm() [3/4]

template<class Index , class Vector >

template<class ConversionPolicy >

dg::GeneralComm< Index, Vector >::GeneralComm	(	const thrust::host_vector< int > &	globalIndexMap,
		const ConversionPolicy &	p
	)

inline

Construct from global indices index map.

Uses the global2localIdx() member of MPITopology to generate localIndexMap and pidIndexMap

Parameters

globalIndexMap	Each element `globalIndexMap[i]` represents a global vector index from (or to) where to take the value `buffer[i]`. There are `local_buffer_size = globalIndexMap.size()` elements.
p	the conversion object

Template Parameters

ConversionPolicy

has to have the members:

bool global2localIdx(unsigned,unsigned&,unsigned&) const; where the first parameter is the global index and the other two are the output pair (localIdx, rank). return true if successful, false if global index is not part of the grid
MPI_Comm communicator() const; returns the communicator to use in the gather/scatter
local_size(); return the local vector size

See also: Topology base classes the MPI grids defined in Level 3 can all be used as a ConversionPolicy

◆ GeneralComm() [4/4]

template<class Index , class Vector >

template<class OtherIndex , class OtherVector >

dg::GeneralComm< Index, Vector >::GeneralComm ( const GeneralComm< OtherIndex, OtherVector > & src )

inline

reconstruct from another type; if src is empty, same as default constructor

Member Function Documentation

◆ clone()

template<class Index , class Vector >

virtual GeneralComm * dg::GeneralComm< Index, Vector >::clone ( ) const

inlinefinaloverridevirtual

Generic copy method.

Returns: pointer to allocated object

Implements dg::aCommunicator< Vector >.

◆ getLocalIndexMap()

template<class Index , class Vector >

const thrust::host_vector< int > & dg::GeneralComm< Index, Vector >::getLocalIndexMap ( ) const

inline

read access to the local index index map given in constructor

◆ getPidIndexMap()

template<class Index , class Vector >

const thrust::host_vector< int > & dg::GeneralComm< Index, Vector >::getPidIndexMap ( ) const

inline

read access to the pid index map given in constructor

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

backend/mpi_collective.h

Public Member Functions

Additional Inherited Members

Detailed Description

Constructor & Destructor Documentation

◆ GeneralComm() [1/4]

◆ GeneralComm() [2/4]

◆ GeneralComm() [3/4]

◆ GeneralComm() [4/4]

Member Function Documentation

◆ clone()

◆ getLocalIndexMap()

◆ getPidIndexMap()