Utilities::MPI::ConsensusAlgorithms::NBX< RequestType, AnswerType > Class Template Reference

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

Detailed Description

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

This class implements a concrete algorithm for the ConsensusAlgorithms::Interface base class, using only point-to-point communications and a single IBarrier. This algorithm is suitable for very large process counts because it does not require the allocation of arrays with size proportional to the number of processes.

Note

This class closely follows [133], but our implementation also deals with payloads.

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 209 of file mpi_consensus_algorithms.h.

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

Public Member Functions
	NBX ()=default
virtual	~NBX ()=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

Private Member Functions
bool	all_locally_originated_receives_are_completed (const std::function< void(const unsigned int, const AnswerType &)> &process_answer, const MPI_Comm comm)
void	signal_finish (const MPI_Comm comm)
bool	all_remotely_originated_receives_are_completed ()
void	maybe_answer_one_request (const std::function< AnswerType(const unsigned int, const RequestType &)> &answer_request, const MPI_Comm comm)
void	start_communication (const std::vector< unsigned int > &targets, const std::function< RequestType(const unsigned int)> &create_request, const MPI_Comm comm)
void	clean_up_and_end_communication (const MPI_Comm comm)

Private Attributes
std::vector< std::vector< char > >	send_buffers
std::vector< MPI_Request >	send_requests
std::vector< std::unique_ptr< std::vector< char > > >	request_buffers
std::vector< std::unique_ptr< MPI_Request > >	request_requests
unsigned int	n_outstanding_answers
MPI_Request	barrier_request
std::set< unsigned int >	requesting_processes

Constructor & Destructor Documentation

NBX()

template<typename RequestType , typename AnswerType >

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

default

Default constructor.

~NBX()

template<typename RequestType , typename AnswerType >

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

virtualdefault

Destructor.

Member Function Documentation

run()

template<typename RequestType , typename AnswerType >

virtual std::vector< unsigned int > Utilities::MPI::ConsensusAlgorithms::NBX< 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.

Parameters

[in]	targets	A vector that contains the ranks of processes to which requests should be sent and from which answers need to be received.
[in]	create_request	A function object that takes the rank of a target process as argument and returns the message that forms the request to this target.
[in]	answer_request	A function that takes as arguments the rank of the process that has sent a request to us, along with the message of the request, and returns the message that forms the answer that should be sent back to the requesting process.
[in]	process_answer	A function object that takes as argument the rank of a process from which we have received an answer to a previously sent request, along with the message that forms this answer. This function is used to describe what the caller of the consensus algorithm wants to do with the received answer.
[in]	comm	The MPI communicator on which the whole algorithm is to be performed.

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

all_locally_originated_receives_are_completed()

template<typename RequestType , typename AnswerType >

bool Utilities::MPI::ConsensusAlgorithms::NBX< RequestType, AnswerType >::all_locally_originated_receives_are_completed ( const std::function< void(const unsigned int, const AnswerType &)> &  process_answer, const MPI_Comm  comm  )

private

Check whether all of the requests for answers that were created by the communication posted from the current process to other ranks have been satisfied.

signal_finish()

template<typename RequestType , typename AnswerType >

void Utilities::MPI::ConsensusAlgorithms::NBX< RequestType, AnswerType >::signal_finish ( const MPI_Comm  comm )

private

Signal to all other ranks that this rank has received all request answers via entering IBarrier.

all_remotely_originated_receives_are_completed()

template<typename RequestType , typename AnswerType >

bool Utilities::MPI::ConsensusAlgorithms::NBX< RequestType, AnswerType >::all_remotely_originated_receives_are_completed ( )

private

Check whether all of the requests for answers that were created by communication posted from other processes to the current rank have been satisfied.

maybe_answer_one_request()

template<typename RequestType , typename AnswerType >

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

private

Check whether a request message from another rank has been received, and if so, process the request by storing the data and sending an answer.

start_communication()

template<typename RequestType , typename AnswerType >

void Utilities::MPI::ConsensusAlgorithms::NBX< 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.

clean_up_and_end_communication()

template<typename RequestType , typename AnswerType >

void Utilities::MPI::ConsensusAlgorithms::NBX< RequestType, AnswerType >::clean_up_and_end_communication ( const MPI_Comm  comm )

private

After all rank has received all answers, the MPI data structures can be freed and the received answers can be processed.

Member Data Documentation

send_buffers

template<typename RequestType , typename AnswerType >

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

private

Buffers for sending requests.

Definition at line 240 of file mpi_consensus_algorithms.h.

send_requests

template<typename RequestType , typename AnswerType >

std::vector<MPI_Request> Utilities::MPI::ConsensusAlgorithms::NBX< RequestType, AnswerType >::send_requests

private

Requests for sending requests.

Definition at line 245 of file mpi_consensus_algorithms.h.

request_buffers

template<typename RequestType , typename AnswerType >

std::vector<std::unique_ptr<std::vector<char> > > Utilities::MPI::ConsensusAlgorithms::NBX< RequestType, AnswerType >::request_buffers

private

Buffers for sending answers to requests. We use a vector of pointers because that guarantees that the buffers themselves are newer moved around in memory, even if the vector is resized and consequently its elements (the pointers) are moved around.

Definition at line 254 of file mpi_consensus_algorithms.h.

request_requests

template<typename RequestType , typename AnswerType >

std::vector<std::unique_ptr<MPI_Request> > Utilities::MPI::ConsensusAlgorithms::NBX< RequestType, AnswerType >::request_requests

private

Requests for sending answers to requests.

Definition at line 259 of file mpi_consensus_algorithms.h.

n_outstanding_answers

template<typename RequestType , typename AnswerType >

unsigned int Utilities::MPI::ConsensusAlgorithms::NBX< RequestType, AnswerType >::n_outstanding_answers

private

The number of processes from which we are still expecting answers.

Definition at line 264 of file mpi_consensus_algorithms.h.

barrier_request

template<typename RequestType , typename AnswerType >

MPI_Request Utilities::MPI::ConsensusAlgorithms::NBX< RequestType, AnswerType >::barrier_request

private

Definition at line 267 of file mpi_consensus_algorithms.h.

requesting_processes

template<typename RequestType , typename AnswerType >

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

private

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

Definition at line 273 of file mpi_consensus_algorithms.h.

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

• include/deal.II/base/mpi_consensus_algorithms.h