pub struct Semaphore { /* private fields */ }
Expand description

A counter for limiting the number of concurrent operations.

Implementations

Creates a new semaphore with a limit of n concurrent operations.

Examples
use async_lock::Semaphore;

let s = Semaphore::new(5);

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());

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;

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());

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

Formats the value using the given formatter. Read more

Auto Trait Implementations

Blanket Implementations

Gets the TypeId of self. Read more

Immutably borrows from an owned value. Read more

Mutably borrows from an owned value. Read more

Returns the argument unchanged.

Calls U::from(self).

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

The type returned in the event of a conversion error.

Performs the conversion.

The type returned in the event of a conversion error.

Performs the conversion.