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

Inheritance diagram for Utilities::MPI::ConsensusAlgorithms::PEX< RequestType, AnswerType >:

Public Member Functions
	PEX ()=default

	PEX (Process< RequestType, AnswerType > &process, const MPI_Comm comm)

virtual	~PEX ()=default

virtual std::vector< unsigned int >	run (const std::vector< unsigned int > &targets, const std::function< RequestType(const unsigned int)> &create_request, const std::function< AnswerType(const unsigned int, const RequestType &)> &answer_request, const std::function< void(const unsigned int, const AnswerType &)> &process_answer, const MPI_Comm comm) override

std::vector< unsigned int >	run ()

std::vector< unsigned int >	run (Process< RequestType, AnswerType > &process, const MPI_Comm comm)

Private Member Functions
unsigned int	start_communication (const std::vector< unsigned int > &targets, const std::function< RequestType(const unsigned int)> &create_request, const MPI_Comm comm)

void	answer_one_request (const unsigned int index, const std::function< AnswerType(const unsigned int, const RequestType &)> &answer_request, const MPI_Comm comm)

void	process_incoming_answers (const unsigned int n_targets, const std::function< void(const unsigned int, const AnswerType &)> &process_answer, const MPI_Comm comm)

void	clean_up_and_end_communication ()

Private Attributes
std::vector< std::vector< char > >	send_buffers

std::vector< std::vector< char > >	recv_buffers

std::vector< MPI_Request >	send_request_requests

std::vector< std::vector< char > >	requests_buffers

std::vector< MPI_Request >	send_answer_requests

std::set< unsigned int >	requesting_processes

Process< RequestType, AnswerType > *	process

MPI_Comm	comm

Detailed Description

template<typename RequestType, typename AnswerType>
class Utilities::MPI::ConsensusAlgorithms::PEX< RequestType, AnswerType >

This class implements a concrete algorithm for the ConsensusAlgorithms::Interface base class, using a two step approach. In the first step the source ranks are determined and in the second step a static sparse data exchange is performed. This algorithm is most suitable for relatively small process counts – say, less than 100.

Note: In contrast to NBX, this class splits the same task into two distinct steps. In the first step, all processes are identified who want to send a request to this process. In the second step, the data is exchanged. However, since - in the second step - now it is clear how many requests have to be answered, i.e. when this process can stop waiting for requests, no IBarrier is needed.; Under the hood, this function uses Utilities::MPI::compute_point_to_point_communication_pattern() to determine the source processes, which itself is based on the NBX-algorithm from [98] that is implemented in the ConsensusAlgorithms::NBX class (a sister class to the current one).

Template Parameters

RequestType	The type of the elements of the vector to be sent.
AnswerType	The type of the elements of the vector to be received.

Definition at line 622 of file mpi_consensus_algorithms.h.

Constructor & Destructor Documentation

◆ PEX() [1/2]

template<typename RequestType , typename AnswerType >

Utilities::MPI::ConsensusAlgorithms::PEX< RequestType, AnswerType >::PEX ( )

default

Default constructor.

◆ PEX() [2/2]

template<typename RequestType , typename AnswerType >

Utilities::MPI::ConsensusAlgorithms::PEX< RequestType, AnswerType >::PEX	(	Process< RequestType, AnswerType > &	process,
		const MPI_Comm	comm
	)

Constructor.

Parameters

process	Process to be run during consensus algorithm.
comm	MPI Communicator

Deprecated:: This constructor stores the Process object and the communicator so that one can later call the run() function without arguments. This approach is deprecated. Instead, use the default constructor of this class along with the run() function that takes an argument.

◆ ~PEX()

template<typename RequestType , typename AnswerType >

virtual Utilities::MPI::ConsensusAlgorithms::PEX< RequestType, AnswerType >::~PEX ( )

virtualdefault

Destructor.

Member Function Documentation

◆ run() [1/3]

template<typename RequestType , typename AnswerType >

virtual std::vector< unsigned int > Utilities::MPI::ConsensusAlgorithms::PEX< RequestType, AnswerType >::run	(	const std::vector< unsigned int > &	targets,
		const std::function< RequestType(const unsigned int)> &	create_request,
		const std::function< AnswerType(const unsigned int, const RequestType &)> &	answer_request,
		const std::function< void(const unsigned int, const AnswerType &)> &	process_answer,
		const MPI_Comm	comm
	)

overridevirtual

Run the consensus algorithm and return a vector of process ranks that have requested answers from the current process.

Deprecated:: This function is deprecated. It can be called if the Process object and communicator to be used have previously been provided to the non-default constructor. Use the run() functions taking arguments instead.

Implements Utilities::MPI::ConsensusAlgorithms::Interface< RequestType, AnswerType >.

◆ start_communication()

template<typename RequestType , typename AnswerType >

unsigned int Utilities::MPI::ConsensusAlgorithms::PEX< RequestType, AnswerType >::start_communication	(	const std::vector< unsigned int > &	targets,
		const std::function< RequestType(const unsigned int)> &	create_request,
		const MPI_Comm	comm
	)

private

Start to send all requests via ISend and post IRecvs for the incoming answer messages.

◆ answer_one_request()

template<typename RequestType , typename AnswerType >

void Utilities::MPI::ConsensusAlgorithms::PEX< RequestType, AnswerType >::answer_one_request	(	const unsigned int	index,
		const std::function< AnswerType(const unsigned int, const RequestType &)> &	answer_request,
		const MPI_Comm	comm
	)

private

The indexth request message from another rank has been received: process the request and send an answer.

◆ process_incoming_answers()

template<typename RequestType , typename AnswerType >

void Utilities::MPI::ConsensusAlgorithms::PEX< RequestType, AnswerType >::process_incoming_answers	(	const unsigned int	n_targets,
		const std::function< void(const unsigned int, const AnswerType &)> &	process_answer,
		const MPI_Comm	comm
	)

private

Receive and process all of the incoming responses to the requests we sent.

◆ clean_up_and_end_communication()

template<typename RequestType , typename AnswerType >

void Utilities::MPI::ConsensusAlgorithms::PEX< RequestType, AnswerType >::clean_up_and_end_communication ( )

private

After all answers have been exchanged, the MPI data structures can be freed and the received answers can be processed.

◆ run() [2/3]

template<typename RequestType , typename AnswerType >

std::vector< unsigned int > Utilities::MPI::ConsensusAlgorithms::Interface< RequestType, AnswerType >::run ( )

inherited

Run the consensus algorithm and return a vector of process ranks that have requested answers from the current process.

Deprecated:: This function is deprecated. It can be called if the Process object and communicator to be used have previously been provided to the non-default constructor. Use the run() functions taking arguments instead.

◆ run() [3/3]

template<typename RequestType , typename AnswerType >

std::vector< unsigned int > Utilities::MPI::ConsensusAlgorithms::Interface< RequestType, AnswerType >::run	(	Process< RequestType, AnswerType > &	process,
		const MPI_Comm	comm
	)

inherited

Run the consensus algorithm and return a vector of process ranks that have requested answers from the current process.

This version of the run() function simply unpacks the functions packaged in process and calls the version of the run() function that takes a number of std::function arguments.

Member Data Documentation

◆ send_buffers

template<typename RequestType , typename AnswerType >

std::vector<std::vector<char> > Utilities::MPI::ConsensusAlgorithms::PEX< RequestType, AnswerType >::send_buffers

private

Buffers for sending requests.

Definition at line 672 of file mpi_consensus_algorithms.h.

◆ recv_buffers

template<typename RequestType , typename AnswerType >

std::vector<std::vector<char> > Utilities::MPI::ConsensusAlgorithms::PEX< RequestType, AnswerType >::recv_buffers

private

Buffers for receiving answers to requests.

Definition at line 677 of file mpi_consensus_algorithms.h.

◆ send_request_requests

template<typename RequestType , typename AnswerType >

std::vector<MPI_Request> Utilities::MPI::ConsensusAlgorithms::PEX< RequestType, AnswerType >::send_request_requests

private

MPI request objects for sending request messages.

Definition at line 682 of file mpi_consensus_algorithms.h.

◆ requests_buffers

template<typename RequestType , typename AnswerType >

std::vector<std::vector<char> > Utilities::MPI::ConsensusAlgorithms::PEX< RequestType, AnswerType >::requests_buffers

private

Buffers for sending answers to requests.

Definition at line 687 of file mpi_consensus_algorithms.h.

◆ send_answer_requests

template<typename RequestType , typename AnswerType >

std::vector<MPI_Request> Utilities::MPI::ConsensusAlgorithms::PEX< RequestType, AnswerType >::send_answer_requests

private

Requests for sending answers to requests.

Definition at line 692 of file mpi_consensus_algorithms.h.

◆ requesting_processes

template<typename RequestType , typename AnswerType >

std::set<unsigned int> Utilities::MPI::ConsensusAlgorithms::PEX< RequestType, AnswerType >::requesting_processes

private

List of processes who have made a request to this process.

Definition at line 697 of file mpi_consensus_algorithms.h.

◆ process

template<typename RequestType , typename AnswerType >

Process<RequestType, AnswerType>* Utilities::MPI::ConsensusAlgorithms::Interface< RequestType, AnswerType >::process

privateinherited

Reference to the process provided by the user.

This member variable is only used in the deprecated constructor and the run() function without argument. It is a nullptr otherwise

Definition at line 330 of file mpi_consensus_algorithms.h.

◆ comm

template<typename RequestType , typename AnswerType >

MPI_Comm Utilities::MPI::ConsensusAlgorithms::Interface< RequestType, AnswerType >::comm

privateinherited

MPI communicator.

This member variable is only used in the deprecated constructor and the run() function without argument.

Definition at line 339 of file mpi_consensus_algorithms.h.

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

include/deal.II/base/mpi_consensus_algorithms.h

Public Member Functions

Private Member Functions

Private Attributes

Detailed Description

Constructor & Destructor Documentation

◆ PEX() [1/2]

◆ PEX() [2/2]

◆ ~PEX()

Member Function Documentation

◆ run() [1/3]

◆ start_communication()

◆ answer_one_request()

◆ process_incoming_answers()

◆ clean_up_and_end_communication()

◆ run() [2/3]

◆ run() [3/3]

Member Data Documentation

◆ send_buffers

◆ recv_buffers

◆ send_request_requests

◆ requests_buffers

◆ send_answer_requests

◆ requesting_processes

◆ process

◆ comm