Struct tokio::sync::SemaphorePermit
source · pub struct SemaphorePermit<'a> { /* private fields */ }
Expand description
A permit from the semaphore.
This type is created by the acquire
method.
Implementations§
source§impl<'a> SemaphorePermit<'a>
impl<'a> SemaphorePermit<'a>
sourcepub fn forget(self)
pub fn forget(self)
Forgets the permit without releasing it back to the semaphore. This can be used to reduce the amount of permits available from a semaphore.
§Examples
use std::sync::Arc;
use tokio::sync::Semaphore;
let sem = Arc::new(Semaphore::new(10));
{
let permit = sem.try_acquire_many(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);
sourcepub fn merge(&mut self, other: Self)
pub fn merge(&mut self, other: Self)
Merge two SemaphorePermit
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.
§Examples
use std::sync::Arc;
use tokio::sync::Semaphore;
let sem = Arc::new(Semaphore::new(10));
let mut permit = sem.try_acquire().unwrap();
for _ in 0..9 {
let _permit = sem.try_acquire().unwrap();
// Merge individual permits into a single one.
permit.merge(_permit)
}
assert_eq!(sem.available_permits(), 0);
// Release all permits in a single batch.
drop(permit);
assert_eq!(sem.available_permits(), 10);
sourcepub fn split(&mut self, n: usize) -> Option<Self>
pub fn split(&mut self, n: usize) -> Option<Self>
Splits n
permits from self
and returns a new SemaphorePermit
instance that holds n
permits.
If there are insufficient permits and it’s not possible to reduce by n
, returns None
.
§Examples
use std::sync::Arc;
use tokio::sync::Semaphore;
let sem = Arc::new(Semaphore::new(3));
let mut p1 = sem.try_acquire_many(3).unwrap();
let p2 = p1.split(1).unwrap();
assert_eq!(p1.num_permits(), 2);
assert_eq!(p2.num_permits(), 1);
sourcepub fn num_permits(&self) -> usize
pub fn num_permits(&self) -> usize
Returns the number of permits held by self
.
Trait Implementations§
source§impl<'a> Debug for SemaphorePermit<'a>
impl<'a> Debug for SemaphorePermit<'a>
Auto Trait Implementations§
impl<'a> Freeze for SemaphorePermit<'a>
impl<'a> !RefUnwindSafe for SemaphorePermit<'a>
impl<'a> Send for SemaphorePermit<'a>
impl<'a> Sync for SemaphorePermit<'a>
impl<'a> Unpin for SemaphorePermit<'a>
impl<'a> !UnwindSafe for SemaphorePermit<'a>
Blanket Implementations§
source§impl<T> BorrowMut<T> for Twhere
T: ?Sized,
impl<T> BorrowMut<T> for Twhere
T: ?Sized,
source§fn borrow_mut(&mut self) -> &mut T
fn borrow_mut(&mut self) -> &mut T
Mutably borrows from an owned value. Read more