Struct StartSignal

pub(crate) struct StartSignal {
    fut: Shared<Receiver<Infallible>>,
    token_ref: Weak<RefCell<Box<dyn Any>>>,
}

A signal that can be awaited by operators to suspend them prior to startup.

Creating a signal also yields a token, dropping of which causes the signal to fire.

StartSignal is designed to be usable by both async and sync Timely operators.

• Async operators can simply await it.
• Sync operators should register an ActivateOnDrop value via StartSignal::drop_on_fire and then check StartSignal::has_fired() on each activation.

Fields

fut: Shared<Receiver<Infallible>>

A future that completes when the signal fires.

The inner type is Infallible because no data is ever expected on this channel. Instead the signal is activated by dropping the corresponding Sender.

token_ref: Weak<RefCell<Box<dyn Any>>>

A weak reference to the token, to register drop-on-fire values.

Implementations

impl StartSignal

pub fn new() -> (Self, Rc<dyn Any>)

Create a new StartSignal and a corresponding token that activates the signal when dropped.

pub fn has_fired(&self) -> bool

pub fn drop_on_fire(&self, to_drop: Box<dyn Any>)

Trait Implementations

impl Clone for StartSignal

fn clone(&self) -> StartSignal

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Future for StartSignal

type Output = ()

The type of value produced on completion.

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

Attempts to resolve the future to a final value, registering the current task for wakeup if the value is not yet available.