Struct tokio::sync::Barrier

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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§

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impl Barrier

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pub fn new(n: usize) -> Barrier

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.

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pub async fn wait(&self) -> BarrierWaitResult

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§

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impl Debug for Barrier

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

Formats the value using the given formatter. Read more

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

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fn type_id(&self) -> TypeId

Gets the TypeId of self. Read more
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impl<T> Borrow<T> for Twhere
    T: ?Sized,

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fn borrow(&self) -> &T

Immutably borrows from an owned value. Read more
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impl<T> BorrowMut<T> for Twhere
    T: ?Sized,

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fn borrow_mut(&mut self) -> &mut T

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impl<T> From<T> for T

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fn from(t: T) -> T

Returns the argument unchanged.

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

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fn into(self) -> U

Calls U::from(self).

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

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

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type Error = Infallible

The type returned in the event of a conversion error.
const: unstable · source§

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

Performs the conversion.
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impl<T, U> TryInto<U> for Twhere
    U: TryFrom<T>,

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

The type returned in the event of a conversion error.
const: unstable · source§

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

Performs the conversion.