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use futures::{Async, Poll, Stream};
use std::marker::PhantomData;
use actor::{Actor, ActorContext, ActorState, AsyncContext, Running, SpawnHandle};
use fut::ActorFuture;
/// Stream handler
///
/// This is helper trait that allows to handle `Stream` in
/// a similar way as normal actor messages.
/// When stream resolves to a next item, `handle()` method of this trait
/// get called. If stream produces error, `error()` method get called.
/// Depends on result of the `error()` method, actor could continue to
/// process stream items or stop stream processing.
/// When stream completes, `finished()` method get called. By default
/// `finished()` method stops actor execution.
#[allow(unused_variables)]
pub trait StreamHandler<I, E>
where
Self: Actor,
{
/// Method is called for every message received by this Actor
fn handle(&mut self, item: I, ctx: &mut Self::Context);
/// Method is called when stream get polled first time.
fn started(&mut self, ctx: &mut Self::Context) {}
/// Method is called when stream emits error.
///
/// If this method returns `ErrorAction::Continue` stream processing
/// continues otherwise stream processing stops. Default method
/// implementation returns `ErrorAction::Stop`
fn error(&mut self, err: E, ctx: &mut Self::Context) -> Running {
Running::Stop
}
/// Method is called when stream finishes.
///
/// By default this method stops actor execution.
fn finished(&mut self, ctx: &mut Self::Context) {
ctx.stop()
}
/// This method register stream to an actor context and
/// allows to handle `Stream` in similar way as normal actor messages.
///
/// ```rust
/// # #[macro_use] extern crate actix;
/// # extern crate futures;
/// # use std::io;
/// use actix::prelude::*;
/// use futures::stream::once;
///
/// #[derive(Message)]
/// struct Ping;
///
/// struct MyActor;
///
/// impl StreamHandler<Ping, io::Error> for MyActor {
///
/// fn handle(&mut self, item: Ping, ctx: &mut Context<MyActor>) {
/// println!("PING");
/// # System::current().stop()
/// }
///
/// fn finished(&mut self, ctx: &mut Self::Context) {
/// println!("finished");
/// }
/// }
///
/// impl Actor for MyActor {
/// type Context = Context<Self>;
///
/// fn started(&mut self, ctx: &mut Context<Self>) {
/// // add stream
/// Self::add_stream(once::<Ping, io::Error>(Ok(Ping)), ctx);
/// }
/// }
/// # fn main() {
/// # let sys = System::new("example");
/// # let addr = MyActor.start();
/// # sys.run();
/// # }
/// ```
fn add_stream<S>(fut: S, ctx: &mut Self::Context) -> SpawnHandle
where
Self::Context: AsyncContext<Self>,
S: Stream<Item = I, Error = E> + 'static,
I: 'static,
E: 'static,
{
if ctx.state() == ActorState::Stopped {
error!("Context::add_stream called for stopped actor.");
SpawnHandle::default()
} else {
ctx.spawn(ActorStream::new(fut))
}
}
}
pub(crate) struct ActorStream<A, M, E, S> {
stream: S,
started: bool,
act: PhantomData<A>,
msg: PhantomData<M>,
error: PhantomData<E>,
}
impl<A, M, E, S> ActorStream<A, M, E, S> {
pub fn new(fut: S) -> Self {
ActorStream {
stream: fut,
started: false,
act: PhantomData,
msg: PhantomData,
error: PhantomData,
}
}
}
impl<A, M, E, S> ActorFuture for ActorStream<A, M, E, S>
where
S: Stream<Item = M, Error = E>,
A: Actor + StreamHandler<M, E>,
A::Context: AsyncContext<A>,
{
type Item = ();
type Error = ();
type Actor = A;
fn poll(
&mut self, act: &mut A, ctx: &mut A::Context,
) -> Poll<Self::Item, Self::Error> {
if !self.started {
self.started = true;
<A as StreamHandler<M, E>>::started(act, ctx);
}
loop {
match self.stream.poll() {
Ok(Async::Ready(Some(msg))) => {
A::handle(act, msg, ctx);
if ctx.waiting() {
return Ok(Async::NotReady);
}
}
Err(err) => {
if A::error(act, err, ctx) == Running::Stop {
A::finished(act, ctx);
return Ok(Async::Ready(()));
}
}
Ok(Async::Ready(None)) => {
A::finished(act, ctx);
return Ok(Async::Ready(()));
}
Ok(Async::NotReady) => return Ok(Async::NotReady),
}
}
}
}