A simple communication infrastructure providing typed exchange channels.

This crate is part of the timely dataflow system, used primarily for its inter-worker communication. It may be independently useful, but it is separated out mostly to make clear boundaries in the project.

Threads are spawned with an allocator::Generic, whose allocate method returns a pair of several send endpoints and one receive endpoint. Messages sent into a send endpoint will eventually be received by the corresponding worker, if it receives often enough. The point-to-point channels are each FIFO, but with no fairness guarantees.

To be communicated, a type must implement the Serialize trait. A default implementation of Serialize is provided for any type implementing Abomonation. To implement other serialization strategies, wrap your type and implement Serialize for your wrapper.

Channel endpoints also implement a lower-level push and pull interface (through the Push and Pull traits), which is used for more precise control of resources.

Examples

use timely_communication::Allocate;

// configure for two threads, just one process.
let config = timely_communication::Configuration::Process(2);

// initializes communication, spawns workers
let guards = timely_communication::initialize(config, |mut allocator| {
println!("worker {} started", allocator.index());

// allocates pair of senders list and one receiver.
let (mut senders, mut receiver) = allocator.allocate(0);

// send typed data along each channel
use timely_communication::Message;
senders[0].send(Message::from_typed(format!("hello, {}", 0)));
senders[1].send(Message::from_typed(format!("hello, {}", 1)));

// no support for termination notification,
// we have to count down ourselves.
let mut expecting = 2;
while expecting > 0 {

allocator.receive();
if let Some(message) = receiver.recv() {
use std::ops::Deref;
println!("worker {}: received: <{}>", allocator.index(), message.deref());
expecting -= 1;
}
allocator.release();
}

// optionally, return something
allocator.index()
});

// computation runs until guards are joined or dropped.
if let Ok(guards) = guards {
for guard in guards.join() {
println!("result: {:?}", guard);
}
}
else { println!("error in computation"); }

The should produce output like:

worker 0 started
worker 1 started
worker 0: received: <hello, 0>
worker 1: received: <hello, 1>
worker 0: received: <hello, 0>
worker 1: received: <hello, 1>
result: Ok(0)
result: Ok(1)