Struct async_lock::Barrier

pub struct Barrier { /* private fields */ }

A counter to synchronize multiple tasks at the same time.

Implementations

impl Barrier

pub const fn new(n: usize) -> Barrier

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

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

Examples

use async_lock::Barrier;

let barrier = Barrier::new(5);

pub fn wait(&self) -> BarrierWait<'_>

Blocks the current task until all tasks reach this point.

Barriers are reusable after all tasks have synchronized, and can be used continuously.

Returns a BarrierWaitResult indicating whether this task is the “leader”, meaning the last task to call this method.

Examples

use async_lock::Barrier;
use futures_lite::future;
use std::sync::Arc;
use std::thread;

let barrier = Arc::new(Barrier::new(5));

for _ in 0..5 {
    let b = barrier.clone();
    thread::spawn(move || {
        future::block_on(async {
            // The same messages will be printed together.
            // There will NOT be interleaving of "before" and "after".
            println!("before wait");
            b.wait().await;
            println!("after wait");
        });
    });
}

pub fn wait_blocking(&self) -> BarrierWaitResult

Blocks the current thread until all tasks reach this point.

Barriers are reusable after all tasks have synchronized, and can be used continuously.

Returns a BarrierWaitResult indicating whether this task is the “leader”, meaning the last task to call this method.

Blocking

Rather than using asynchronous waiting, like the [wait] method, this method will block the current thread until the wait is complete.

This method should not be used in an asynchronous context. It is intended to be used in a way that a barrier can be used in both asynchronous and synchronous contexts. Calling this method in an asynchronous context may result in a deadlock.

Examples

use async_lock::Barrier;
use futures_lite::future;
use std::sync::Arc;
use std::thread;

let barrier = Arc::new(Barrier::new(5));

for _ in 0..5 {
    let b = barrier.clone();
    thread::spawn(move || {
        // The same messages will be printed together.
        // There will NOT be interleaving of "before" and "after".
        println!("before wait");
        b.wait_blocking();
        println!("after wait");
    });
}

Trait Implementations

impl Debug for Barrier

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.