#include <deal.II/base/communication_pattern_base.h>

Inheritance diagram for Utilities::MPI::CommunicationPatternBase:

[legend]

Public Member Functions
virtual	~CommunicationPatternBase ()=default

virtual void	reinit (const IndexSet &locally_owned_indices, const IndexSet &ghost_indices, const MPI_Comm communicator)=0

virtual MPI_Comm	get_mpi_communicator () const =0

Detailed Description

CommunicationPattern is an abstract class that is used to define a communication plan that can be called repeatedly to efficiently obtain off-processor elements. The idea is to decouple the communication pattern from the data that needs to be communicated. The goal is to reuse the same communication pattern for different containers. This is similar to the way SparseMatrix and SparsityPattern works.

Conceptually, this class operates under the assumption that data are stored in one linearly indexed array of which every MPI process stores some elements (or possibly none). In practice it does of course not matter whether the elements are stored in contiguous arrays; the point is simply that a single integer index can be used to access a specific element. The elements of this logical array are (or at least may be) stored on different processes in a parallel MPI universe.

In this world view, every process has a set of elements and their indices in the array form the "locally owned indices". Next, every process will as part of executing an algorithm require access to some of the elements stored elsewhere; we call the indices of these elements the "ghost indices", in analogy to how vectors and triangulations partition vector elements and mesh cells into locally owned ones and ghost ones (along, of course, with cells and ghosts stored on other processes that the current process simply does not care about and consequently needs not know anything about).

The point of this class (and its implementations in derived classes) is to set up communication infrastructure whereby one process can inquire efficiently about the "ghost elements" stored on other processes, and to send those locally owned elements to those other processes that require knowledge of their value because they list these elements among their respective "ghost indices".

Definition at line 66 of file communication_pattern_base.h.

Constructor & Destructor Documentation

◆ ~CommunicationPatternBase()

virtual Utilities::MPI::CommunicationPatternBase::~CommunicationPatternBase ( )

virtualdefault

Destructor.

Member Function Documentation

◆ reinit()

virtual void Utilities::MPI::CommunicationPatternBase::reinit	(	const IndexSet &	locally_owned_indices,
		const IndexSet &	ghost_indices,
		const MPI_Comm	communicator )

pure virtual

Reinitialize the communication pattern.

Parameters

[in]	locally_owned_indices	The set of indices of elements in the array mentioned in the class documentation that are stored on the current process.
[in]	ghost_indices	The set of indices of elements in the array mentioned in the class documentation that the current process will need to be able to import.
[in]	communicator	The MPI communicator used to describe the entire set of processes that participate in the storage and access to elements of the array.

Implemented in LinearAlgebra::EpetraWrappers::CommunicationPattern, LinearAlgebra::TpetraWrappers::CommunicationPattern< MemorySpace >, PETScWrappers::CommunicationPattern, PETScWrappers::Partitioner, Utilities::MPI::NoncontiguousPartitioner, and Utilities::MPI::Partitioner.

◆ get_mpi_communicator()

virtual MPI_Comm Utilities::MPI::CommunicationPatternBase::get_mpi_communicator ( ) const