Function scope

pub fn scope<'a, F, R>(f: F) -> R
where
    F: FnOnce(&LocalScope<'a>) -> R,

Used to create a LocalScope

The function creates a LocalScope and then passes it into the given closure as an argument.

For safety reasons, all variables and buffers associated with a request must exist outside the scope with which the request is registered.

It is typically used like this:

/* declare variables and buffers here ... */
mpi_fork_fnsp::request::scope(|scope| {
    /* perform sends and/or receives using 'scope' */
});
/* at end of scope, panic if there are requests that have not yet completed */

Examples

See examples/immediate.rs

Examples found in repository

examples/immediate_all_to_all.rs (lines 15-19)

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

    let u = vec![rank; size as usize];
    let mut v = vec![0; size as usize];

    mpi::request::scope(|scope| {
        world
            .immediate_all_to_all_into(scope, &u[..], &mut v[..])
            .wait();
    });

    println!("u: {:?}", u);
    println!("v: {:?}", v);

    assert!(v.into_iter().zip(0..size).all(|(i, j)| i == j));
}

examples/immediate_reduce.rs (lines 26-29)

fn test_user_operations<C: Communicator>(comm: C) {
    let op = UserOperation::commutative(|x, y| {
        let x: &[Rank] = x.downcast().unwrap();
        let y: &mut [Rank] = y.downcast().unwrap();
        for (&x_i, y_i) in x.iter().zip(y) {
            *y_i += x_i;
        }
    });
    let rank = comm.rank();
    let size = comm.size();
    let mut c = 0;
    mpi::request::scope(|scope| {
        comm.immediate_all_reduce_into(scope, &rank, &mut c, &op)
            .wait();
    });
    assert_eq!(c, size * (size - 1) / 2);
}

#[cfg(not(feature = "user-operations"))]
fn test_user_operations<C: Communicator>(_: C) {}

#[cfg(not(all(msmpi, target_arch = "x86")))]
unsafe extern "C" fn unsafe_add(
    invec: *mut c_void,
    inoutvec: *mut c_void,
    len: *mut c_int,
    _datatype: *mut MPI_Datatype,
) {
    use std::slice;

    let x: &[Rank] = slice::from_raw_parts(invec as *const Rank, *len as usize);
    let y: &mut [Rank] = slice::from_raw_parts_mut(inoutvec as *mut Rank, *len as usize);
    for (&x_i, y_i) in x.iter().zip(y) {
        *y_i += x_i;
    }
}

#[cfg(all(msmpi, target_arch = "x86"))]
unsafe extern "stdcall" fn unsafe_add(
    invec: *mut c_void,
    inoutvec: *mut c_void,
    len: *mut c_int,
    _datatype: *mut MPI_Datatype,
) {
    use std::slice;

    let x: &[Rank] = slice::from_raw_parts(invec as *const Rank, *len as usize);
    let y: &mut [Rank] = slice::from_raw_parts_mut(inoutvec as *mut Rank, *len as usize);
    for (&x_i, y_i) in x.iter().zip(y) {
        *y_i += x_i;
    }
}

fn main() {
    let universe = mpi::initialize().unwrap();
    let world = universe.world();
    let rank = world.rank();
    let size = world.size();
    let root_rank = 0;

    if rank == root_rank {
        let mut sum: Rank = 0;
        mpi::request::scope(|scope| {
            world
                .process_at_rank(root_rank)
                .immediate_reduce_into_root(scope, &rank, &mut sum, SystemOperation::sum())
                .wait();
        });
        assert_eq!(sum, size * (size - 1) / 2);
    } else {
        mpi::request::scope(|scope| {
            world
                .process_at_rank(root_rank)
                .immediate_reduce_into(scope, &rank, SystemOperation::sum())
                .wait();
        });
    }

    let mut max: Rank = -1;

    mpi::request::scope(|scope| {
        world
            .immediate_all_reduce_into(scope, &rank, &mut max, SystemOperation::max())
            .wait();
    });
    assert_eq!(max, size - 1);

    let a = (0..size).collect::<Vec<_>>();
    let mut b: Rank = 0;

    mpi::request::scope(|scope| {
        world
            .immediate_reduce_scatter_block_into(scope, &a[..], &mut b, SystemOperation::product())
            .wait();
    });
    assert_eq!(b, rank.wrapping_pow(size as u32));

    test_user_operations(universe.world());

    let mut d = 0;
    let op = unsafe { UnsafeUserOperation::commutative(unsafe_add) };
    mpi::request::scope(|scope| {
        world
            .immediate_all_reduce_into(scope, &rank, &mut d, &op)
            .wait();
    });
    assert_eq!(d, size * (size - 1) / 2);
}

examples/immediate_scan.rs (lines 18-22)

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

    let mut x = 0;
    mpi::request::scope(|scope| {
        world
            .immediate_scan_into(scope, &rank, &mut x, SystemOperation::sum())
            .wait();
    });
    assert_eq!(x, (rank * (rank + 1)) / 2);

    let y = rank + 1;
    let mut z = 0;
    mpi::request::scope(|scope| {
        world
            .immediate_exclusive_scan_into(scope, &y, &mut z, SystemOperation::product())
            .wait();
    });
    if rank > 0 {
        assert_eq!(z, fac(y - 1));
    }
}

examples/immediate_scatter.rs (lines 18-21)

fn main() {
    let universe = mpi::initialize().unwrap();
    let world = universe.world();
    let rank = world.rank();
    let size = world.size();
    let root_rank = 0;
    let root_process = world.process_at_rank(root_rank);

    let mut x = 0 as Rank;
    if rank == root_rank {
        let v = (0..size).collect::<Vec<_>>();
        mpi::request::scope(|scope| {
            let req = root_process.immediate_scatter_into_root(scope, &v[..], &mut x);
            req.wait();
        });
    } else {
        mpi::request::scope(|scope| {
            let req = root_process.immediate_scatter_into(scope, &mut x);
            req.wait();
        });
    }
    assert_eq!(x, rank);
}

examples/buffered.rs (lines 24-31)

fn main() {
    let mut universe = mpi::initialize().unwrap();
    // Try to attach a buffer.
    universe.set_buffer_size(BUFFER_SIZE);
    // Check buffer size matches.
    assert_eq!(universe.buffer_size(), BUFFER_SIZE);
    // Try to detach the buffer.
    universe.detach_buffer();
    // Attach another buffer.
    universe.set_buffer_size(BUFFER_SIZE);

    let world = universe.world();

    let x = vec![std::f32::consts::PI; 1024];
    let mut y = vec![0.0; 1024];
    mpi::request::scope(|scope| {
        let _rreq = WaitGuard::from(
            world
                .any_process()
                .immediate_receive_into(scope, &mut y[..]),
        );
        world.this_process().buffered_send(&x[..]);
    });
    assert_eq!(x, y);
}

examples/ready_send.rs (lines 19-33)

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

    if rank > 0 {
        let msg = rank as u8;
        world.barrier();
        world.process_at_rank(0).ready_send(&msg);
    } else {
        let mut v = vec![0u8; (size - 1) as usize];
        mpi::request::scope(|scope| {
            let reqs = v
                .iter_mut()
                .zip(1..)
                .map(|(x, i)| {
                    world
                        .process_at_rank(i as Rank)
                        .immediate_receive_into(scope, x)
                })
                .collect::<Vec<_>>();
            world.barrier();
            for req in reqs {
                req.wait();
            }
        });
        println!("Got message: {:?}", v);
        assert!(v.iter().zip(1..).all(|(x, i)| i == *x as usize));
    }
}

Additional examples can be found in:

• examples/immediate_all_gather_varcount.rs
• examples/wait_any.rs
• examples/immediate_broadcast.rs
• examples/immediate_scatter_varcount.rs
• examples/immediate_gather_varcount.rs
• examples/readme.rs
• examples/immediate_all_gather.rs
• examples/immediate.rs
• examples/immediate_gather.rs