pub trait ActorFuture<A: Actor> {
type Output;
fn poll(
self: Pin<&mut Self>,
srv: &mut A,
ctx: &mut A::Context,
task: &mut Context<'_>
) -> Poll<Self::Output>;
}Expand description
Trait for types which are a placeholder of a value that may become available at some later point in time.
ActorFuture is very similar to a regular Future, only with subsequent combinator closures accepting the actor and its context, in addition to the result.
ActorFuture allows for use cases where future processing requires access to the actor or its context.
Here is an example of a handler on a single actor, deferring work to another actor, and then updating the initiating actor’s state:
use actix::prelude::*;
// The response type returned by the actor future
type OriginalActorResponse = ();
// The error type returned by the actor future
type MessageError = ();
// This is the needed result for the DeferredWork message
// It's a result that combine both Response and Error from the future response.
type DeferredWorkResult = Result<OriginalActorResponse, MessageError>;
impl Handler<DeferredWork> for OriginalActor {
// Notice the `Response` is an `ActorFuture`-ized version of `Self::Message::Result`.
type Result = ResponseActFuture<Self, Result<OriginalActorResponse, MessageError>>;
fn handle(&mut self, _msg: DeferredWork, _ctx: &mut Context<Self>) -> Self::Result {
// this creates a `Future` representing the `.send` and subsequent `Result` from
// `other_actor`
let send_to_other = self.other_actor
.send(OtherMessage {});
// Wrap that `Future` so subsequent chained handlers can access
// the `actor` (`self` in the synchronous code) as well as the context.
let send_to_other = actix::fut::wrap_future::<_, Self>(send_to_other);
// once the wrapped future resolves, update this actor's state
let update_self = send_to_other.map(|result, actor, _ctx| {
// Actor's state updated here
match result {
Ok(v) => {
actor.inner_state.update_from(v);
Ok(())
},
// Failed to send message to other_actor
Err(_e) => Err(()),
}
});
// return the wrapped future
Box::pin(update_self)
}
}
See also into_actor, which provides future conversion using trait