mpi::communicator

#include <mpi/communicator.hpp>

Detailed Description

C++ wrapper around MPI_Comm providing various convenience functions.

It stores an MPI_Comm object as its only member which by default is set to MPI_COMM_WORLD. Note that copying the communicator simply copies the MPI_Comm object, without calling MPI_Comm_dup.

All functions that make direct calls to the MPI C library throw an exception in case the call fails.

Definition at line 43 of file communicator.hpp.

Public Member Functions
	communicator ()=default
	Construct a communicator with MPI_COMM_WORLD.
	communicator (MPI_Comm c)
	Construct a communicator with a given MPI_Comm object.
void	abort (int error_code) const
	If mpi::has_env is true, MPI_Abort is called with the given error code, otherwise std::abort is called.
void	barrier (long poll_msec=1) const
	Barrier synchronization.
communicator	duplicate () const
	Duplicate the communicator.
void	free ()
	Free the communicator.
MPI_Comm	get () const noexcept
	Get the wrapped MPI_Comm object.
int	rank () const
	Get the rank of the calling process in the communicator.
int	size () const
	Get the size of the communicator.
communicator	split (int color, int key=0) const
	Split the communicator into disjoint subgroups.

Constructor & Destructor Documentation

communicator()

mpi::communicator::communicator ( MPI_Comm c )

inline

Construct a communicator with a given MPI_Comm object.

The MPI_Comm object is copied without calling MPI_Comm_dup.

Definition at line 55 of file communicator.hpp.

Member Function Documentation

abort()

void mpi::communicator::abort ( int error_code ) const

inline

If mpi::has_env is true, MPI_Abort is called with the given error code, otherwise std::abort is called.

Parameters

error_code

The error code to pass to MPI_Abort.

Definition at line 145 of file communicator.hpp.

barrier()

void mpi::communicator::barrier ( long poll_msec = 1 ) const

inline

Barrier synchronization.

Does nothing if mpi::has_env is false. Otherwise, it either uses a blocking MPI_Barrier (if the given argument is 0) or a non-blocking MPI_Ibarrier call. The given parameter determines in milliseconds how often each process calls MPI_Test to check if all processes have reached the barrier. This can considerably reduce the CPU load:

• 1 msec ~ 1% cpu load
• 10 msec ~ 0.5% cpu load
• 100 msec ~ 0.01% cpu load

For a very unbalanced load that takes a long time to finish, 1000 msec is a good choice.

Parameters

poll_msec

The polling interval in milliseconds. If set to 0, a simple MPI_Barrier call is used.

Definition at line 173 of file communicator.hpp.

duplicate()

communicator mpi::communicator::duplicate ( ) const

inlinenodiscard

Duplicate the communicator.

Calls MPI_Comm_dup to duplicate the communicator. See the MPI documentation for more details, e.g. open-mpi docs.

Warning

This allocates a new communicator object. Make sure to call free on the returned communicator when it is no longer needed.

Returns

If mpi::has_env is true, return the duplicated MPI_Comm object wrapped in a new mpi::communicator, otherwise return a default constructed mpi::communicator.

Definition at line 119 of file communicator.hpp.

free()

void mpi::communicator::free ( )

inline

Free the communicator.

Calls MPI_Comm_free to mark the communicator for deallocation. See the MPI documentation for more details, e.g. open-mpi docs .

Does nothing, if mpi::has_env is false.

Definition at line 137 of file communicator.hpp.

rank()

int mpi::communicator::rank ( ) const

inlinenodiscard

Get the rank of the calling process in the communicator.

Returns

The result of MPI_Comm_rank if mpi::has_env is true, otherwise 0.

Definition at line 64 of file communicator.hpp.

size()

int mpi::communicator::size ( ) const

inlinenodiscard

Get the size of the communicator.

Returns

The result of MPI_Comm_size if mpi::has_env is true, otherwise 1.

Definition at line 77 of file communicator.hpp.

split()

communicator mpi::communicator::split ( int color, int key = 0 ) const

inlinenodiscard

Split the communicator into disjoint subgroups.

Calls MPI_Comm_split with the given color and key arguments. See the MPI documentation for more details, e.g. open-mpi docs.

Warning

This allocates a new communicator object. Make sure to call free on the returned communicator when it is no longer needed.

Returns

If mpi::has_env is true, return the split MPI_Comm object wrapped in a new mpi::communicator, otherwise return a default constructed mpi::communicator.

Definition at line 98 of file communicator.hpp.

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

• mpi/communicator.hpp