[−][src]Struct tokio::sync::Semaphore
sync
only.Counting semaphore performing asynchronous permit aquisition.
A semaphore maintains a set of permits. Permits are used to synchronize access to a shared resource. A semaphore differs from a mutex in that it can allow more than one concurrent caller to access the shared resource at a time.
When acquire
is called and the semaphore has remaining permits, the
function immediately returns a permit. However, if no remaining permits are
available, acquire
(asynchronously) waits until an outstanding permit is
dropped. At this point, the freed permit is assigned to the caller.
Implementations
impl Semaphore
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pub fn new(permits: usize) -> Self
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Creates a new semaphore with the initial number of permits.
pub fn available_permits(&self) -> usize
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Returns the current number of available permits.
pub fn add_permits(&self, n: usize)
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Adds n
new permits to the semaphore.
The maximum number of permits is usize::MAX >> 3
, and this function will panic if the limit is exceeded.
pub async fn acquire(&self) -> SemaphorePermit<'_>
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Acquires permit from the semaphore.
pub fn try_acquire(&self) -> Result<SemaphorePermit<'_>, TryAcquireError>
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Tries to acquire a permit from the semaphore.
pub async fn acquire_owned(self: Arc<Self>) -> OwnedSemaphorePermit
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Acquires permit from the semaphore.
The semaphore must be wrapped in an Arc
to call this method.
pub fn try_acquire_owned(
self: Arc<Self>
) -> Result<OwnedSemaphorePermit, TryAcquireError>
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self: Arc<Self>
) -> Result<OwnedSemaphorePermit, TryAcquireError>
Tries to acquire a permit from the semaphore.
The semaphore must be wrapped in an Arc
to call this method.
Trait Implementations
Auto Trait Implementations
impl !RefUnwindSafe for Semaphore
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impl Send for Semaphore
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impl Sync for Semaphore
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impl Unpin for Semaphore
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impl !UnwindSafe for Semaphore
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Blanket Implementations
impl<T> Any for T where
T: 'static + ?Sized,
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T: 'static + ?Sized,
impl<T> Borrow<T> for T where
T: ?Sized,
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T: ?Sized,
impl<T> BorrowMut<T> for T where
T: ?Sized,
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T: ?Sized,
pub fn borrow_mut(&mut self) -> &mut Tⓘ
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impl<T> From<T> for T
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impl<T> Instrument for T
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pub fn instrument(self, span: Span) -> Instrumented<Self>ⓘNotable traits for Instrumented<T>
impl<T> Future for Instrumented<T> where
T: Future, type Output = <T as Future>::Output;
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Notable traits for Instrumented<T>
impl<T> Future for Instrumented<T> where
T: Future, type Output = <T as Future>::Output;
pub fn in_current_span(self) -> Instrumented<Self>ⓘNotable traits for Instrumented<T>
impl<T> Future for Instrumented<T> where
T: Future, type Output = <T as Future>::Output;
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Notable traits for Instrumented<T>
impl<T> Future for Instrumented<T> where
T: Future, type Output = <T as Future>::Output;
impl<T, U> Into<U> for T where
U: From<T>,
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U: From<T>,
impl<T, U> TryFrom<U> for T where
U: Into<T>,
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U: Into<T>,
type Error = Infallible
The type returned in the event of a conversion error.
pub fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>
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impl<T, U> TryInto<U> for T where
U: TryFrom<T>,
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U: TryFrom<T>,