Crate mpi

Message Passing Interface bindings for Rust

The Message Passing Interface (MPI) is a specification for a message-passing style concurrency library. Implementations of MPI are often used to structure parallel computation on High Performance Computing systems. The MPI specification describes bindings for the C programming language (and through it C++) as well as for the Fortran programming language. This library tries to bridge the gap into a more rustic world.

Usage

Add the mpi crate as a dependency in your Cargo.toml:

[dependencies]
mpi = "0.5"

Then use it in your program like this:

extern crate mpi;

use mpi::traits::*;

fn main() {
    let universe = mpi::initialize().unwrap();
    let world = universe.world();
    let size = world.size();
    let rank = world.rank();

    if size != 2 {
        panic!("Size of MPI_COMM_WORLD must be 2, but is {}!", size);
     }

    match rank {
        0 => {
            let msg = vec![4.0f64, 8.0, 15.0];
            world.process_at_rank(rank + 1).send(&msg[..]);
        }
        1 => {
            let (msg, status) = world.any_process().receive_vec::<f64>();
            println!("Process {} got message {:?}.\nStatus is: {:?}", rank, msg, status);
        }
        _ => unreachable!()
    }
}

Features

The bindings follow the MPI 3.1 specification.

Currently supported:

• Groups, Contexts, Communicators:
  • Group and (Intra-)Communicator management from section 6 is mostly complete.
  • no Inter-Communicators
  • no process topologies
• Point to point communication:
  • standard, buffered, synchronous and ready mode send in blocking and non-blocking variants
  • receive in blocking and non-blocking variants
  • send-receive
  • probe
  • matched probe/receive
• Collective communication:
  • barrier
  • broadcast
  • (all) gather
  • scatter
  • all to all
  • varying counts operations
  • reductions/scans
  • blocking and non-blocking variants
• Datatypes: Bridging between Rust types and MPI basic types as well as custom MPI datatypes which can act as views into buffers.

Not supported (yet):

• Process management
• One-sided communication (RMA)
• MPI parallel I/O
• A million small things

The sub-modules contain a more detailed description of which features are and are not supported.

Further Reading

While every publicly defined item in this crate should have some documentation attached to it, most of the descriptions are quite terse for now and to the uninitiated will only make sense in combination with the MPI specification.

Modules

collective	Collective communication
datatype	Describing data
environment	Environmental management
ffi	The raw C language MPI API
point_to_point	Point to point communication
raw	Bridge between rust types and raw values
request	Request objects for non-blocking operations
topology	Organizing processes as groups and communicators
traits	Re-exports all traits.

Enums

Threading

Describes the various levels of multithreading that can be supported by an MPI library.

Functions

initialize	Initialize MPI.
initialize_with_threading	Initialize MPI with desired level of multithreading support.
time	Time in seconds since an arbitrary time in the past.
time_resolution	Resolution of timer used in time() in seconds

Type Definitions

Address	An address in memory
Count	Encodes number of values in multi-value messages.
Error	Encodes error values returned by MPI functions.
Tag	Can be used to tag messages on the sender side and match on the receiver side.