Struct async_lock::Semaphore

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

A counter for limiting the number of concurrent operations.

Implementations§

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impl Semaphore

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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);
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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());
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pub fn acquire(&self) -> Acquire<'_>

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;
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impl Semaphore

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pub fn try_acquire_arc(self: &Arc<Self>) -> 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());
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pub fn acquire_arc(self: &Arc<Self>) -> AcquireArc

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§

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impl Debug for Semaphore

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

Formats the value using the given formatter. Read more

Auto Trait Implementations§

Blanket Implementations§

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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,

const: unstable · source§

fn borrow(&self) -> &T

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

const: unstable · source§

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

Mutably borrows from an owned value. Read more
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impl<T> From<T> for T

const: unstable · source§

fn from(t: T) -> T

Returns the argument unchanged.

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

const: unstable · source§

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.