pub struct CloneCounter(_);
Expand description

an atomic counter that increments on clone & decrements on drop

use futures_lite::future::poll_once;
let counter = CloneCounter::new();
assert_eq!(counter.current(), 0);
counter.await; // ready immediately

let counter = CloneCounter::new();
assert_eq!(counter.current(), 0);
let clone = counter.clone();
assert_eq!(counter.current(), 1);
let clone2 = counter.clone();
assert_eq!(counter.current(), 2);
assert_eq!(poll_once(clone2).await, None); // pending
assert_eq!(counter.current(), 1);
std::mem::drop(clone);

assert_eq!(counter.current(), 0);
counter.await; // ready

Implementations§

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impl CloneCounter

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pub fn new() -> Self

Constructs a new CloneCounter. Identical to CloneCounter::default()

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pub fn current(&self) -> usize

Returns the current count. The first CloneCounter is zero, so this can either be considered a zero-indexed count of the total number of CloneCounters in memory, or a one-indexed count of the number of non-original clones.

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pub fn decrement(&self)

Manually decrement the count. This is useful when taking a clone of the counter that does not represent an increase in the underlying property or resource being counted. This is called automatically on drop and is usually unnecessary to call directly

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pub fn increment(&self)

Manually increment the count. unless paired with a decrement, this will prevent the clone counter from ever reaching zero. This is called automatically on clone.

Trait Implementations§

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impl Clone for CloneCounter

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fn clone(&self) -> Self

Returns a copy of the value. Read more
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fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source. Read more
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impl Debug for CloneCounter

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

Formats the value using the given formatter. Read more
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impl Default for CloneCounter

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fn default() -> CloneCounter

Returns the “default value” for a type. Read more
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impl Drop for CloneCounter

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fn drop(&mut self)

Executes the destructor for this type. Read more
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impl Future for CloneCounter

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type Output = ()

The type of value produced on completion.
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fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output>

Attempt to resolve the future to a final value, registering the current task for wakeup if the value is not yet available. 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<F> FutureExt for Fwhere F: Future + ?Sized,

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fn poll(&mut self, cx: &mut Context<'_>) -> Poll<Self::Output>where Self: Unpin,

A convenience for calling Future::poll() on !Unpin types.
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fn or<F>(self, other: F) -> Or<Self, F>where Self: Sized, F: Future<Output = Self::Output>,

Returns the result of self or other future, preferring self if both are ready. Read more
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fn race<F>(self, other: F) -> Race<Self, F>where Self: Sized, F: Future<Output = Self::Output>,

Returns the result of self or other future, with no preference if both are ready. Read more
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fn catch_unwind(self) -> CatchUnwind<Self>where Self: Sized + UnwindSafe,

Catches panics while polling the future. Read more
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fn boxed<'a>( self ) -> Pin<Box<dyn Future<Output = Self::Output> + Send + 'a, Global>>where Self: Sized + Send + 'a,

Boxes the future and changes its type to dyn Future + Send + 'a. Read more
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fn boxed_local<'a>( self ) -> Pin<Box<dyn Future<Output = Self::Output> + 'a, Global>>where Self: Sized + 'a,

Boxes the future and changes its type to dyn Future + 'a. Read more
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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<F> IntoFuture for Fwhere F: Future,

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type Output = <F as Future>::Output

The output that the future will produce on completion.
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type IntoFuture = F

Which kind of future are we turning this into?
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fn into_future(self) -> <F as IntoFuture>::IntoFuture

Creates a future from a value. Read more
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impl<T> ToOwned for Twhere T: Clone,

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type Owned = T

The resulting type after obtaining ownership.
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fn to_owned(&self) -> T

Creates owned data from borrowed data, usually by cloning. Read more
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fn clone_into(&self, target: &mut T)

Uses borrowed data to replace owned data, usually by cloning. Read more
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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.