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
sourceimpl Barrier
impl Barrier
sourcepub fn new(n: usize) -> Barrier
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 n
th task calls wait
.
sourcepub async fn wait(&self) -> BarrierWaitResult
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
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
sourceimpl<T> BorrowMut<T> for T where
T: ?Sized,
impl<T> BorrowMut<T> for T where
T: ?Sized,
const: unstable · sourcefn borrow_mut(&mut self) -> &mut T
fn borrow_mut(&mut self) -> &mut T
Mutably borrows from an owned value. Read more