Struct `Barrier`

struct Barrier { ... }

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

# #[tokio::main]
# async fn main() {
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

`impl Barrier`

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.

async fn wait(self: &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.

Cancel safety

This method is not cancel safe.

`impl Debug for Barrier`

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

`impl Freeze for Barrier`

`impl RefUnwindSafe for Barrier`

`impl Send for Barrier`

`impl Sync for Barrier`

`impl Unpin for Barrier`

`impl UnsafeUnpin for Barrier`

`impl UnwindSafe for Barrier`

`impl<T> Any for Barrier`

fn type_id(self: &Self) -> TypeId

`impl<T> Borrow for Barrier`

fn borrow(self: &Self) -> &T

`impl<T> BorrowMut for Barrier`

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

`impl<T> From for Barrier`

fn from(t: T) -> T: Returns the argument unchanged.

`impl<T, U> Into for Barrier`

fn into(self: Self) -> U

Calls U::from(self).

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

`impl<T, U> TryFrom for Barrier`

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

`impl<T, U> TryInto for Barrier`

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