pub struct Semaphore { /* private fields */ }
Expand description
A counter for limiting the number of concurrent operations.
Implementations
sourceimpl Semaphore
impl Semaphore
sourcepub const fn new(n: usize) -> Semaphore
pub const fn new(n: usize) -> Semaphore
Creates a new semaphore with a limit of n
concurrent operations.
Examples
use async_lock::Semaphore;
let s = Semaphore::new(5);
sourcepub fn try_acquire(&self) -> Option<SemaphoreGuard<'_>>
pub fn try_acquire(&self) -> Option<SemaphoreGuard<'_>>
Attempts to get a permit for a concurrent operation.
If the permit could not be acquired at this time, then None
is returned. Otherwise, a
guard is returned that releases the mutex when dropped.
Examples
use async_lock::Semaphore;
let s = Semaphore::new(2);
let g1 = s.try_acquire().unwrap();
let g2 = s.try_acquire().unwrap();
assert!(s.try_acquire().is_none());
drop(g2);
assert!(s.try_acquire().is_some());
sourcepub async fn acquire(&'_ self) -> SemaphoreGuard<'_>
pub async fn acquire(&'_ self) -> SemaphoreGuard<'_>
Waits for a permit for a concurrent operation.
Returns a guard that releases the permit when dropped.
Examples
use async_lock::Semaphore;
let s = Semaphore::new(2);
let guard = s.acquire().await;
sourceimpl Semaphore
impl Semaphore
sourcepub fn try_acquire_arc(self: &Arc<Semaphore>) -> Option<SemaphoreGuardArc>
pub fn try_acquire_arc(self: &Arc<Semaphore>) -> Option<SemaphoreGuardArc>
Attempts to get an owned permit for a concurrent operation.
If the permit could not be acquired at this time, then None
is returned. Otherwise, an
owned guard is returned that releases the mutex when dropped.
Examples
use async_lock::Semaphore;
use std::sync::Arc;
let s = Arc::new(Semaphore::new(2));
let g1 = s.try_acquire_arc().unwrap();
let g2 = s.try_acquire_arc().unwrap();
assert!(s.try_acquire_arc().is_none());
drop(g2);
assert!(s.try_acquire_arc().is_some());
sourcepub fn acquire_arc(
self: &Arc<Semaphore>
) -> impl Future<Output = SemaphoreGuardArc>
pub fn acquire_arc(
self: &Arc<Semaphore>
) -> impl Future<Output = SemaphoreGuardArc>
Waits for an owned permit for a concurrent operation.
Returns a guard that releases the permit when dropped.
Examples
use async_lock::Semaphore;
use std::sync::Arc;
let s = Arc::new(Semaphore::new(2));
let guard = s.acquire_arc().await;
Trait Implementations
Auto Trait Implementations
impl RefUnwindSafe for Semaphore
impl Send for Semaphore
impl Sync for Semaphore
impl Unpin for Semaphore
impl UnwindSafe for Semaphore
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