Struct Semaphore 

pub struct Semaphore<S, C = Uncloseable>
where
    S: SemaphoreState + ?Sized,
    C: IsCloseable,
{ /* private fields */ }

Generic semaphore performing asynchronous permit acquisition.

See the top level docs for information about semaphores.

See Builder for methods to construct a Semaphore.

The generics on this semaphore are as follows:

• S: The SemaphoreState value that this semaphore is backed by.
• C: A type-safe configuration value for whether Semaphore::close can be called, and whether Semaphore::acquire can fail.

Implementations

impl<S> Semaphore<S, Uncloseable>

where S: SemaphoreState + ?Sized,

pub async fn must_acquire( &self, params: S::Params, ) -> Permit<'_, S, Uncloseable>

Acquire a new permit fairly with the given parameters.

If a permit is not immediately available, this task will join a queue.

impl<S, C> Semaphore<S, C>

where S: SemaphoreState + ?Sized, C: IsCloseable,

pub async fn acquire( &self, params: S::Params, ) -> Result<Permit<'_, S, C>, C::AcquireError<S::Params>>

Acquire a new permit fairly with the given parameters.

If a permit is not immediately available, this task will join a queue.

Errors

If this semaphore is_closed, then an AcquireError is returned.

pub fn try_acquire( &self, params: S::Params, ) -> Result<Permit<'_, S, C>, TryAcquireError<S::Params, C>>

Acquire a new permit fairly with the given parameters.

If this is a LIFO semaphore, and there are other tasks waiting for permits, this will still try to acquire the permit - as this task would effectively be the last in the queue.

Errors

If there are currently not enough permits available for the given request, then TryAcquireError::NoPermits is returned.

If this is a FIFO semaphore, and there are other tasks waiting for permits, then TryAcquireError::NoPermits is returned.

If this semaphore is_closed, then TryAcquireError::Closed is returned.

pub fn try_acquire_unfair( &self, params: S::Params, ) -> Result<Permit<'_, S, C>, TryAcquireError<S::Params, C>>

Acquire a new permit, potentially unfairly, with the given parameters.

If this is a FIFO semaphore, and there are other tasks waiting for permits, this will still try to acquire the permit.

Errors

If there are currently not enough permits available for the given request, then TryAcquireError::NoPermits is returned.

If this semaphore is_closed, then TryAcquireError::Closed is returned.

impl<S, C> Semaphore<S, C>

where S: SemaphoreState + ?Sized, C: IsCloseable,

pub fn with_state<T>(&self, f: impl FnOnce(&mut S) -> T) -> T

Access the state with mutable access.

This gives direct access to the state, be careful not to break any of your own state invariants. You can use this to peek at the current state, or to modify it, eg to add or remove permits from the semaphore.

pub fn is_closed(&self) -> bool

Check if the semaphore is closed

impl<S> Semaphore<S, Closeable>

where S: SemaphoreState + ?Sized,

pub fn close(&self)

Close the semaphore.

All tasks currently waiting to acquire a token will immediately stop. No new acquire attempts will succeed.

Trait Implementations

impl<S: SemaphoreState + Debug> Debug for Semaphore<S>

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

Formats the value using the given formatter.