pub struct Barrier { /* private fields */ }
Expand description

A barrier enables multiple tasks to synchronize the beginning of some computation.

use tokio::sync::Barrier;
use std::sync::Arc;

let mut handles = Vec::with_capacity(10);
let barrier = Arc::new(Barrier::new(10));
for _ in 0..10 {
    let c = barrier.clone();
    // The same messages will be printed together.
    // You will NOT see any interleaving.
    handles.push(tokio::spawn(async move {
        println!("before wait");
        let wait_result = c.wait().await;
        println!("after wait");
        wait_result
    }));
}

// Will not resolve until all "after wait" messages have been printed
let mut num_leaders = 0;
for handle in handles {
    let wait_result = handle.await.unwrap();
    if wait_result.is_leader() {
        num_leaders += 1;
    }
}

// Exactly one barrier will resolve as the "leader"
assert_eq!(num_leaders, 1);

Implementations

Creates a new barrier that can block a given number of tasks.

A barrier will block n-1 tasks which call Barrier::wait and then wake up all tasks at once when the nth task calls wait.

Does not resolve until all tasks have rendezvoused here.

Barriers are re-usable after all tasks have rendezvoused once, and can be used continuously.

A single (arbitrary) future will receive a BarrierWaitResult that returns true from BarrierWaitResult::is_leader when returning from this function, and all other tasks will receive a result that will return false from is_leader.

Trait Implementations

Formats the value using the given formatter. Read more

Auto Trait Implementations

Blanket Implementations

Gets the TypeId of self. Read more

Immutably borrows from an owned value. Read more

Mutably borrows from an owned value. Read more

Returns the argument unchanged.

Calls U::from(self).

That is, this conversion is whatever the implementation of From<T> for U chooses to do.

The type returned in the event of a conversion error.

Performs the conversion.

The type returned in the event of a conversion error.

Performs the conversion.