Struct FallbackCoordinator 

pub struct FallbackCoordinator { /* private fields */ }

Coordinates fallback across the components of a runtime generation.

Fallback is signalled through a CancellationToken and acknowledged by lifetime: a future wrapped with FallbackCoordinator::track counts as pending until it is dropped, whether it returned, was cancelled or panicked, so there is nothing a component has to remember to call on its way out. FallbackCoordinator::trigger_fallback_and_wait cancels the token and resolves once no tracked future is left, which it checks rather than infers from a wakeup: a future tracked after the trigger, or after every other one already finished, is still waited for.

This is meant to be used together with crate::task_manager::TaskManager:

task_manager.spawn(fallback_coordinator.track(async move {
    tokio::select! {
        _ = fallback_token.cancelled() => { /* clean up */ }
        // ...
    }
}));

A coordinator serves one fallback cycle: once the wait returned, the runtime instantiates a fresh one for the next generation.

Implementations

impl FallbackCoordinator

pub fn new() -> Self

pub fn token(&self) -> CancellationToken

Get the cancellation token that signals fallback.

pub fn track<F: Future>( &self, fut: F, ) -> impl Future<Output = F::Output> + use<F>

Wrap a fallback-relevant future so that fallback waits for it until it is dropped.

Tracking starts here, not when the future is first polled, so a tracked future handed to a spawner is pending from the moment it exists. Track before fallback is triggered or from inside a future that is itself tracked: a future tracked after the wait has observed the tracker empty belongs to no generation and is not waited for.

pub async fn trigger_fallback_and_wait(&self)

Trigger fallback and wait until every tracked future has been dropped.

Trait Implementations

impl Clone for FallbackCoordinator

fn clone(&self) -> Self

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for FallbackCoordinator

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

Formats the value using the given formatter.

impl Default for FallbackCoordinator

fn default() -> Self

Returns the “default value” for a type.