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use crate::transport::{ConnectionOrigin, Transport};
use diem_types::{network_address::NetworkAddress, PeerId};
use futures::{future::Future, stream::Stream};
use pin_project::pin_project;
use std::{
pin::Pin,
task::{Context, Poll},
};
pub struct AndThen<T, F> {
transport: T,
function: F,
}
impl<T, F> AndThen<T, F> {
pub(crate) fn new(transport: T, function: F) -> Self {
Self {
transport,
function,
}
}
}
impl<T, F, Fut, O> Transport for AndThen<T, F>
where
T: Transport,
F: (FnOnce(T::Output, NetworkAddress, ConnectionOrigin) -> Fut) + Send + Unpin + Clone,
Fut: Future<Output = Result<O, T::Error>> + Send,
{
type Output = O;
type Error = T::Error;
type Listener = AndThenStream<T::Listener, F>;
type Inbound = AndThenFuture<T::Inbound, Fut, F>;
type Outbound = AndThenFuture<T::Outbound, Fut, F>;
fn listen_on(
&self,
addr: NetworkAddress,
) -> Result<(Self::Listener, NetworkAddress), Self::Error> {
let (listener, addr) = self.transport.listen_on(addr)?;
let listener = AndThenStream::new(listener, self.function.clone());
Ok((listener, addr))
}
fn dial(&self, peer_id: PeerId, addr: NetworkAddress) -> Result<Self::Outbound, Self::Error> {
let fut = self.transport.dial(peer_id, addr.clone())?;
let origin = ConnectionOrigin::Outbound;
let f = self.function.clone();
Ok(AndThenFuture::new(fut, f, addr, origin))
}
}
#[pin_project]
#[derive(Debug)]
#[must_use = "streams do nothing unless polled"]
pub struct AndThenStream<St, F> {
#[pin]
stream: St,
f: F,
}
impl<St, Fut1, O1, Fut2, O2, E, F> AndThenStream<St, F>
where
St: Stream<Item = Result<(Fut1, NetworkAddress), E>>,
Fut1: Future<Output = Result<O1, E>>,
Fut2: Future<Output = Result<O2, E>>,
F: FnOnce(O1, NetworkAddress, ConnectionOrigin) -> Fut2 + Clone,
E: ::std::error::Error,
{
fn new(stream: St, f: F) -> Self {
Self { stream, f }
}
}
impl<St, Fut1, O1, Fut2, O2, E, F> Stream for AndThenStream<St, F>
where
St: Stream<Item = Result<(Fut1, NetworkAddress), E>>,
Fut1: Future<Output = Result<O1, E>>,
Fut2: Future<Output = Result<O2, E>>,
F: FnOnce(O1, NetworkAddress, ConnectionOrigin) -> Fut2 + Clone,
E: ::std::error::Error,
{
type Item = Result<(AndThenFuture<Fut1, Fut2, F>, NetworkAddress), E>;
fn poll_next(mut self: Pin<&mut Self>, context: &mut Context) -> Poll<Option<Self::Item>> {
match self.as_mut().project().stream.poll_next(context) {
Poll::Pending => Poll::Pending,
Poll::Ready(None) => Poll::Ready(None),
Poll::Ready(Some(Err(e))) => Poll::Ready(Some(Err(e))),
Poll::Ready(Some(Ok((fut1, addr)))) => Poll::Ready(Some(Ok((
AndThenFuture::new(
fut1,
self.f.clone(),
addr.clone(),
ConnectionOrigin::Inbound,
),
addr,
)))),
}
}
}
#[pin_project(project = AndThenChainProj)]
#[derive(Debug)]
enum AndThenChain<Fut1, Fut2, F> {
First(#[pin] Fut1, Option<(F, NetworkAddress, ConnectionOrigin)>),
Second(#[pin] Fut2),
Empty,
}
#[pin_project]
#[derive(Debug)]
#[must_use = "futures do nothing unless polled"]
pub struct AndThenFuture<Fut1, Fut2, F> {
#[pin]
chain: AndThenChain<Fut1, Fut2, F>,
}
impl<Fut1, O1, Fut2, O2, E, F> AndThenFuture<Fut1, Fut2, F>
where
Fut1: Future<Output = Result<O1, E>>,
Fut2: Future<Output = Result<O2, E>>,
F: FnOnce(O1, NetworkAddress, ConnectionOrigin) -> Fut2,
E: ::std::error::Error,
{
fn new(fut1: Fut1, f: F, addr: NetworkAddress, origin: ConnectionOrigin) -> Self {
Self {
chain: AndThenChain::First(fut1, Some((f, addr, origin))),
}
}
}
impl<Fut1, O1, Fut2, O2, E, F> Future for AndThenFuture<Fut1, Fut2, F>
where
Fut1: Future<Output = Result<O1, E>>,
Fut2: Future<Output = Result<O2, E>>,
F: FnOnce(O1, NetworkAddress, ConnectionOrigin) -> Fut2,
E: ::std::error::Error,
{
type Output = Result<O2, E>;
fn poll(self: Pin<&mut Self>, context: &mut Context) -> Poll<Self::Output> {
let mut this = self.project();
loop {
let (output, (f, addr, origin)) = match this.chain.as_mut().project() {
AndThenChainProj::First(fut1, data) => match fut1.poll(context) {
Poll::Pending => return Poll::Pending,
Poll::Ready(Err(e)) => return Poll::Ready(Err(e)),
Poll::Ready(Ok(output)) => (output, data.take().expect("must be initialized")),
},
AndThenChainProj::Second(fut2) => return fut2.poll(context),
AndThenChainProj::Empty => unreachable!(),
};
this.chain.set(AndThenChain::Empty);
let fut2 = f(output, addr, origin);
this.chain.set(AndThenChain::Second(fut2));
}
}
}