webrtc
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webrtc-rs
[All] change callback fn from Box<dyn ...> to Arc<dyn ..>
example:
pub type FnTimeGen = Arc<dyn (Fn() -> Pin<Box<dyn Future<Output = SystemTime> + Send + 'static>>) + Send + Sync>;
The purpose is to avoid potential deadlock by allowing callback fn cloneable and using tokio::spawn to call it without locking
It would be nicer for the external interfaces if the signature of functions that specify callbacks didn't require specifying the smart pointer type e.g.
instead of
pub type FnTimeGen = Arc<dyn (Fn() -> Pin<Box<dyn Future<Output = SystemTime> + Send + 'static>>) + Send + Sync>;
fn set_callback(&self, fn: FnTimeGen)
use
fn set_callback<F>(&self, fn: F)
where F: (Fn() -> Pin<Box<dyn Future<Output = SystemTime> + Send + 'static>>) + Send + Sync
This way it's simpler for the caller and a change like this doesn't change the public interface.
I think one further step from what @k0nserv suggests would be to have an interface like so:
trait TimeGen {
type Future: Future<Output = SystemTime> + Unpin; // other bounds may be necessary
fn call() -> Self::Future;
I think that such a trait is object safe, and can be stored in the same way it is done now.
There are 3 major advantages to this:
- No need to box the future
- Easier to pass along state, in tidier ways (boxed closure returning a boxed future is rather unergonomic)
- We can still implement the trait for Fn, so changes to existing codebases would be minor.
Yes, I'm having some major trouble calling async functions from inside the Boxed closure... I either get 'static lifetime issues, or cycle detected issues.
