Function par_stream::par_unfold_blocking

pub fn par_unfold_blocking<Item, State, P, F>(
    params: P, 
    init: State, 
    f: F
) -> RecvStream<'static, Item> where
    P: Into<ParParams>,
    F: 'static + FnMut(usize, State) -> Option<(Item, State)> + Send + Clone,
    Item: 'static + Send,
    State: 'static + Send + Clone, 

Produce stream elements from a parallel blocking task.

This function spawns a set of parallel workers. Each worker produces and places items to an output buffer. The worker pool size and buffer size is determined by params.

Each worker receives a copy of initialized state init, then iteratively calls the function f(worker_index, State) -> Option<(output, State)> to update the state and produce an output item.

If a worker receives a None, the worker with that worker index will halt, but it does not halt the other workers. The output stream terminates after every worker halts.

use futures::prelude::*;
use par_stream::prelude::*;
use std::sync::{
    atomic::{AtomicUsize, Ordering::*},
    Arc,
};

let mut vec: Vec<_> =
    par_stream::par_unfold_blocking(None, Arc::new(AtomicUsize::new(0)), move |_, counter| {
        let output = counter.fetch_add(1, SeqCst);
        (output < 1000).then(|| (output, counter))
    })
    .collect()
    .await;

vec.sort();
itertools::assert_equal(vec, 0..1000);