util: add PollSemaphore::{add_permits, available_permits}
#3683
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## Motivation The `tokio::sync::Semaphore` type provides a [`Semaphore::available_permits` method][1] which returns the current number of permits available on the semaphore. `tokio_util::sync::PollSemaphore` [does not expose such a method][2]. It is possible to use `PollSemaphore::into_inner` or `PollSemaphore::clone_inner` to unwrap the inner semaphore, but this may require cloning/dropping the semaphore's `Arc` which shouldn't be necessary to access the permits. ## Solution This commit adds `PollSemaphore::available_permits`. It also adds `PollSemaphore::add_permits` while we're here. [1]: https://docs.rs/tokio/1.4.0/tokio/sync/struct.Semaphore.html#method.available_permits [2]: https://docs.rs/tokio-util/0.6.5/tokio_util/sync/struct.PollSemaphore.html#implementations
Contributor
|
Do you want to add |
Darksonn
approved these changes
Apr 7, 2021
Member
Author
Can do, I wasn't sure whether or not we wanted to expose all the API surface of the |
Member
Author
|
FreeBSD build failure looks unrelated? |
Contributor
|
I am fine with exposing access to the |
Darksonn
approved these changes
Apr 7, 2021
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Motivation
The
tokio::sync::Semaphoretype provides aSemaphore::available_permitsmethod which returns the currentnumber of permits available on the semaphore.
tokio_util::sync::PollSemaphoredoes not expose such a method. Itis possible to use
PollSemaphore::into_innerorPollSemaphore::clone_innerto unwrap the inner semaphore, but this mayrequire cloning/dropping the semaphore's
Arcwhich shouldn't benecessary to access the permits.
Solution
This commit adds
PollSemaphore::available_permits. It also addsPollSemaphore::add_permitswhile we're here.Closes #3682