[−][src]Crate component_future
This crate implements the inner future protocol documented in the tokio docs.
Overview
If you are implementing a complicated future or stream which contains many
inner futures and streams, it can be difficult to keep track of when
looping is necessary, when it is safe to return NotReady
, etc. This
provides an interface similar to the existing poll
interface for futures
and streams, but extended to include additional state about how the inner
future or stream affected the outer future or stream's state. This allows
you to easily split your poll
implementation into multiple methods, and
ensure that they interact properly.
Synopsis
enum OutputEvent { // ... } struct Server { // ... } impl Server { fn process_thing(&self, thing: OutputEvent) { // ... } fn process_other_thing(&self, thing: OutputEvent) -> OutputEvent { // ... } } impl Server { const POLL_FNS: &'static [&'static dyn for<'a> Fn( &'a mut Self, ) -> component_future::Poll< Option<OutputEvent>, String, >] = &[&Self::poll_thing, &Self::poll_other_thing]; fn poll_thing( &mut self, ) -> component_future::Poll<Option<OutputEvent>, String> { let thing = component_future::try_ready!(self.some_future.poll()); self.process_thing(thing); Ok(component_future::Async::DidWork) } fn poll_other_thing( &mut self, ) -> component_future::Poll<Option<OutputEvent>, String> { if let Some(other_future) = &mut self.other_future { let other_thing = component_future::try_ready!( other_future.poll() ); let processed_thing = self.process_other_thing(other_thing); self.other_future.take(); Ok(component_future::Async::Ready(Some(processed_thing))) } else { Ok(component_future::Async::NothingToDo) } } } impl futures::stream::Stream for Server { type Item = OutputEvent; type Error = String; fn poll(&mut self) -> futures::Poll<Option<Self::Item>, Self::Error> { component_future::poll_stream(self, Self::POLL_FNS) } }
Macros
try_ready | A macro for extracting the successful type of a |
Enums
Async | Return type of a component of a future or stream, indicating whether a value is ready, or if not, what actions were taken. |
Functions
poll_future | The body of a |
poll_stream | The body of a |
Type Definitions
Poll | Each component poll method should return a value of this type. |