Struct OwnedSemaphorePermit

Source

pub struct OwnedSemaphorePermit { /* private fields */ }

Expand description

An owned permit from the semaphore.

This type is created by the acquire_owned method.

Implementations§

Source §

impl OwnedSemaphorePermit

Source

pub fn forget(self)

Forgets the permit without releasing it back to the semaphore.

This can be used to permanently reduce the number of permits available from a semaphore.

§Examples

use std::sync::Arc;

use asyncband::semaphore::Semaphore;

let sem = Arc::new(Semaphore::new(10));
{
    let permit = sem.clone().try_acquire_owned(5).unwrap();
    assert_eq!(sem.available_permits(), 5);
    permit.forget();
}

// Since we forgot the permit, available permits won't go back to
// its initial value even after the permit is dropped
assert_eq!(sem.available_permits(), 5);

Source

pub fn merge(&mut self, other: Self)

Merge two OwnedSemaphorePermit instances together, consuming other without releasing the permits it holds.

Permits held by both self and other are released when self drops.

§Panics

This function panics if permits from different Semaphore instances are merged or if their combined permit count exceeds usize::MAX.

§Examples

use std::sync::Arc;

use asyncband::semaphore::Semaphore;

let sem = Arc::new(Semaphore::new(10));
let mut permit = sem.clone().try_acquire_owned(1).unwrap();

for _ in 0..9 {
    let new_permit = sem.clone().try_acquire_owned(1).unwrap();
    // Merge individual permits into a single one.
    permit.merge(new_permit)
}

assert_eq!(sem.available_permits(), 0);

// Release all permits in a single batch.
drop(permit);

assert_eq!(sem.available_permits(), 10);

Source

pub fn split(&mut self, n: usize) -> Option<Self>

Splits n permits from self and returns a new OwnedSemaphorePermit instance that holds n permits.

If there are insufficient permits, and it is impossible to reduce by n, returns None.

§Note

It will clone the owned Arc<Semaphore> to construct the new instance.

§Examples

use std::sync::Arc;

use asyncband::semaphore::Semaphore;

let sem = Arc::new(Semaphore::new(3));

let mut p1 = sem.try_acquire_owned(3).unwrap();
let p2 = p1.split(1).unwrap();

assert_eq!(p1.permits(), 2);
assert_eq!(p2.permits(), 1);

Source

pub fn permits(&self) -> usize

Returns the number of permits this permit holds.

§Examples

use std::sync::Arc;

use asyncband::semaphore::Semaphore;

let sem = Arc::new(Semaphore::new(5));
let permit = sem.try_acquire_owned(3).unwrap();
assert_eq!(permit.permits(), 3);