dolfinx::common::IndexMap Class Reference

This class represents the distribution index arrays across processes. An index array is a contiguous collection of N+1 indices [0, 1, . . ., N] that are distributed across M processes. On a given process, the IndexMap stores a portion of the index set using local indices [0, 1, . . . , n], and a map from the local indices to a unique global index. More...

#include <IndexMap.h>

Public Types
enum	Mode { insert, add }
	Mode for reverse scatter operation.
enum	Direction { reverse, forward, symmetric }
	Edge directions of neighborhood communicator.

Public Member Functions
	IndexMap (MPI_Comm comm, std::int32_t local_size)
	Create an non-overlapping index map with local_size owned on this process. More...
	IndexMap (MPI_Comm mpi_comm, std::int32_t local_size, const std::vector< int > &dest_ranks, const std::vector< std::int64_t > &ghosts, const std::vector< int > &src_ranks)
	Create an index map with local_size owned indiced on this process. More...
	IndexMap (const IndexMap &map)=delete
	IndexMap (IndexMap &&map)=default
	Move constructor.
	~IndexMap ()=default
	Destructor.
IndexMap &	operator= (IndexMap &&map)=default
	Move assignment.
IndexMap &	operator= (const IndexMap &map)=delete
std::array< std::int64_t, 2 >	local_range () const noexcept
	Range of indices (global) owned by this process.
std::int32_t	num_ghosts () const noexcept
	Number of ghost indices on this process.
std::int32_t	size_local () const noexcept
	Number of indices owned by on this process.
std::int64_t	size_global () const noexcept
	Number indices across communicator.
const std::vector< std::int64_t > &	ghosts () const noexcept
	Local-to-global map for ghosts (local indexing beyond end of local range)
MPI_Comm	comm (Direction dir=Direction::symmetric) const
	Return a MPI communicator with attached distributed graph topology information. More...
void	local_to_global (const xtl::span< const std::int32_t > &local, const xtl::span< std::int64_t > &global) const
	Compute global indices for array of local indices. More...
void	global_to_local (const xtl::span< const std::int64_t > &global, const xtl::span< std::int32_t > &local) const
	Compute local indices for array of global indices. More...
std::vector< std::int64_t >	global_indices () const
	Global indices. More...
const graph::AdjacencyList< std::int32_t > &	shared_indices () const noexcept
std::vector< int >	ghost_owner_rank () const
	Owner rank (on global communicator) of each ghost entry.
std::map< std::int32_t, std::set< int > >	compute_shared_indices () const
template<typename T >
void	scatter_fwd (xtl::span< const T > local_data, xtl::span< T > remote_data, int n) const
	Send n values for each index that is owned to processes that have the index as a ghost. The size of the input array local_data must be the same as n * size_local(). More...
template<typename T >
void	scatter_rev (xtl::span< T > local_data, xtl::span< const T > remote_data, int n, IndexMap::Mode op) const
	Send n values for each ghost index to owning to the process. More...

Detailed Description

This class represents the distribution index arrays across processes. An index array is a contiguous collection of N+1 indices [0, 1, . . ., N] that are distributed across M processes. On a given process, the IndexMap stores a portion of the index set using local indices [0, 1, . . . , n], and a map from the local indices to a unique global index.

Constructor & Destructor Documentation

IndexMap() [1/2]

IndexMap::IndexMap	(	MPI_Comm	comm,
		std::int32_t	local_size
	)

Create an non-overlapping index map with local_size owned on this process.

Note

Collective

Parameters

[in]	comm	The MPI communicator
[in]	local_size	Local size of the IndexMap, i.e. the number of owned entries

IndexMap() [2/2]

IndexMap::IndexMap	(	MPI_Comm	mpi_comm,
		std::int32_t	local_size,
		const std::vector< int > &	dest_ranks,
		const std::vector< std::int64_t > &	ghosts,
		const std::vector< int > &	src_ranks
	)

Create an index map with local_size owned indiced on this process.

Note

Collective

Parameters

[in]	mpi_comm	The MPI communicator
[in]	local_size	Local size of the IndexMap, i.e. the number of owned entries
[in]	dest_ranks	Ranks that 'ghost' indices that are owned by the calling rank. I.e., ranks that the caller will send data to when updating ghost values.
[in]	ghosts	The global indices of ghost entries
[in]	src_ranks	Owner rank (on global communicator) of each entry in ghosts

Member Function Documentation

comm()

MPI_Comm IndexMap::comm

(

Direction

dir = Direction::symmetric

)

const

Return a MPI communicator with attached distributed graph topology information.

Parameters

[in]

dir

Edge direction of communicator (forward, reverse, symmetric)

Returns

A neighborhood communicator for the specified edge direction

compute_shared_indices()

std::map< std::int32_t, std::set< int > > IndexMap::compute_shared_indices

(

)

const

Todo:

Aim to remove this function? If it's kept, should it work with neighborhood ranks?

Compute map from each local (owned) index to the set of ranks that have the index as a ghost

Returns

shared indices

global_indices()

std::vector< std::int64_t > IndexMap::global_indices

(

)

const

Global indices.

Returns

The global index for all local indices (0, 1, 2, ...) on this process, including ghosts

global_to_local()

void IndexMap::global_to_local	(	const xtl::span< const std::int64_t > &	global,
		const xtl::span< std::int32_t > &	local
	)		const

Compute local indices for array of global indices.

Parameters

[in]	global	Global indices
[out]	local	The local of the corresponding global index in 'global'. Returns -1 if the local index does not exist on this process.

local_to_global()

void IndexMap::local_to_global	(	const xtl::span< const std::int32_t > &	local,
		const xtl::span< std::int64_t > &	global
	)		const

Compute global indices for array of local indices.

Parameters

[in]	local	Local indices
[out]	global	The global indices

scatter_fwd()

template<typename T >

void IndexMap::scatter_fwd	(	xtl::span< const T >	local_data,
		xtl::span< T >	remote_data,
		int	n
	)		const

Send n values for each index that is owned to processes that have the index as a ghost. The size of the input array local_data must be the same as n * size_local().

Parameters

[in]	local_data	Local data associated with each owned local index to be sent to process where the data is ghosted. Size must be n * size_local().
[in,out]	remote_data	Ghost data on this process received from the owning process. Size will be n * num_ghosts().
[in]	n	Number of data items per index

scatter_rev()

template<typename T >

void IndexMap::scatter_rev	(	xtl::span< T >	local_data,
		xtl::span< const T >	remote_data,
		int	n,
		IndexMap::Mode	op
	)		const

Send n values for each ghost index to owning to the process.

Parameters

[in,out]	local_data	Local data associated with each owned local index to be sent to process where the data is ghosted. Size must be n * size_local().
[in]	remote_data	Ghost data on this process received from the owning process. Size will be n * num_ghosts().
[in]	n	Number of data items per index
[in]	op	Sum or set received values in local_data

shared_indices()

const graph::AdjacencyList< std::int32_t > & IndexMap::shared_indices ( ) const

noexcept

Todo:

Reconsider name Local (owned) indices shared with neighbor processes, i.e. are ghosts on other processes, grouped by sharing (neighbor) process(destination ranks in forward communicator and source ranks in the reverse communicator)

Returns

List of indices that are ghosted on other processes

---

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

• /__w/dolfinx/dolfinx/cpp/dolfinx/common/IndexMap.h
• /__w/dolfinx/dolfinx/cpp/dolfinx/common/IndexMap.cpp