dolfinx::graph::build Namespace Reference

Tools for distributed graphs. More...

Functions
std::tuple< graph::AdjacencyList< std::int64_t >, std::vector< int >, std::vector< std::int64_t >, std::vector< int > >	distribute (MPI_Comm comm, const graph::AdjacencyList< std::int64_t > &list, const graph::AdjacencyList< std::int32_t > &destinations)
	Distribute adjacency list nodes to destination ranks. More...
std::vector< std::int64_t >	compute_ghost_indices (MPI_Comm comm, const std::span< const std::int64_t > &owned_indices, const std::span< const std::int64_t > &ghost_indices, const std::span< const int > &ghost_owners)
	Take a set of distributed input global indices, including ghosts, and determine the new global indices after remapping. More...
std::vector< std::int64_t >	compute_local_to_global_links (const graph::AdjacencyList< std::int64_t > &global, const graph::AdjacencyList< std::int32_t > &local)
	Given an adjacency list with global, possibly non-contiguous, link indices and a local adjacency list with contiguous link indices starting from zero, compute a local-to-global map for the links. Both adjacency lists must have the same shape. More...
std::vector< std::int32_t >	compute_local_to_local (const std::span< const std::int64_t > &local0_to_global, const std::span< const std::int64_t > &local1_to_global)
	Compute a local0-to-local1 map from two local-to-global maps with common global indices. More...

Detailed Description

Tools for distributed graphs.

Todo:

Add a function that sends data to the 'owner'

Function Documentation

compute_ghost_indices()

std::vector< std::int64_t > compute_ghost_indices	(	MPI_Comm	comm,
		const std::span< const std::int64_t > &	owned_indices,
		const std::span< const std::int64_t > &	ghost_indices,
		const std::span< const int > &	ghost_owners
	)

Take a set of distributed input global indices, including ghosts, and determine the new global indices after remapping.

Each rank receive 'input' global indices [i0, i1, ..., i(m-1), im, ..., i(n-1)], where the first m indices are owned by the caller and the remained are 'ghosts' indices that are owned by other ranks.

Each rank assigns new global indices to its owned indices. The new index is the rank offset (scan of the number of indices owned by the lower rank processes, typically computed using MPI_Exscan with MPI_SUM), i.e. i1 -> offset + 1, i2 -> offset + 2, etc. Ghost indices are number by the remote owning processes. The function returns the new ghost global indices but retrieving the new indices from the owning ranks.

Parameters

[in]	comm	MPI communicator
[in]	owned_indices	List of owned global indices. It should not contain duplicates, and these indices must now appear in owned_indices on other ranks.
[in]	ghost_indices	List of ghost global indices.
[in]	ghost_owners	The owning rank for each entry in ghost_indices.

Returns

New global indices for the ghost indices.

compute_local_to_global_links()

std::vector< std::int64_t > compute_local_to_global_links	(	const graph::AdjacencyList< std::int64_t > &	global,
		const graph::AdjacencyList< std::int32_t > &	local
	)

Given an adjacency list with global, possibly non-contiguous, link indices and a local adjacency list with contiguous link indices starting from zero, compute a local-to-global map for the links. Both adjacency lists must have the same shape.

Parameters

[in]	global	Adjacency list with global link indices
[in]	local	Adjacency list with local, contiguous link indices

Returns

Map from local index to global index, which if applied to the local adjacency list indices would yield the global adjacency list

compute_local_to_local()

std::vector< std::int32_t > compute_local_to_local	(	const std::span< const std::int64_t > &	local0_to_global,
		const std::span< const std::int64_t > &	local1_to_global
	)

Compute a local0-to-local1 map from two local-to-global maps with common global indices.

Parameters

[in]	local0_to_global	Map from local0 indices to global indices
[in]	local1_to_global	Map from local1 indices to global indices

Returns

Map from local0 indices to local1 indices

distribute()

std::tuple< graph::AdjacencyList< std::int64_t >, std::vector< int >, std::vector< std::int64_t >, std::vector< int > > distribute	(	MPI_Comm	comm,
		const graph::AdjacencyList< std::int64_t > &	list,
		const graph::AdjacencyList< std::int32_t > &	destinations
	)

Distribute adjacency list nodes to destination ranks.

The global index of each node is assumed to be the local index plus the offset for this rank.

Parameters

[in]	comm	MPI Communicator
[in]	list	The adjacency list to distribute
[in]	destinations	Destination ranks for the ith node in the adjacency list. The first rank is the 'owner' of the node.

Returns

1. Received adjacency list for this process
2. Source ranks for each node in the adjacency list
3. Original global index for each node in the adjacency list
4. Owner rank of ghost nodes