Struct tokio::sync::Barrier[][src]

pub struct Barrier { /* fields omitted */ }
This is supported on crate feature sync only.
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");

// 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);


impl Barrier[src]

pub fn new(n: usize) -> Barrier[src]

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.

pub async fn wait(&self) -> BarrierWaitResult[src]

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

impl Debug for Barrier[src]

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

Formats the value using the given formatter. Read more

Auto Trait Implementations

impl !RefUnwindSafe for Barrier

impl Send for Barrier

impl Sync for Barrier

impl Unpin for Barrier

impl !UnwindSafe for Barrier

Blanket Implementations

impl<T> Any for T where
    T: 'static + ?Sized

pub fn type_id(&self) -> TypeId[src]

Gets the TypeId of self. Read more

impl<T> Borrow<T> for T where
    T: ?Sized

pub fn borrow(&self) -> &T[src]

Immutably borrows from an owned value. Read more

impl<T> BorrowMut<T> for T where
    T: ?Sized

pub fn borrow_mut(&mut self) -> &mut T[src]

Mutably borrows from an owned value. Read more

impl<T> From<T> for T[src]

pub fn from(t: T) -> T[src]

Performs the conversion.

impl<T, U> Into<U> for T where
    U: From<T>, 

pub fn into(self) -> U[src]

Performs the conversion.

impl<T, U> TryFrom<U> for T where
    U: Into<T>, 

type Error = Infallible

The type returned in the event of a conversion error.

pub fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>[src]

Performs the conversion.

impl<T, U> TryInto<U> for T where
    U: TryFrom<T>, 

type Error = <U as TryFrom<T>>::Error

The type returned in the event of a conversion error.

pub fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>[src]

Performs the conversion.