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tokiorace: improvements

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This commit is contained in:
J. Fernando Sánchez 2025-01-23 08:39:21 +01:00
parent e227e387f4
commit 6b68928eab
1 changed files with 184 additions and 128 deletions
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312
rust/tokiorace/src/main.rs
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@ -1,19 +1,18 @@
use tokio::{
task,
time::{Instant, Duration, sleep},
sync::{oneshot,
mpsc::{Receiver, Sender, channel}
}
};
use std::collections::{HashMap};
use anyhow::Result; use anyhow::Result;
use anyhow::{bail, Context}; use anyhow::{bail, Context};
use tracing::{info, debug, instrument}; use std::collections::HashMap;
use tracing_subscriber::{fmt, EnvFilter};
use tracing_subscriber::prelude::*;
use std::future::Future; use std::future::Future;
use tokio::{
sync::{
mpsc::{channel, Receiver, Sender},
oneshot,
},
task,
time::{sleep, timeout_at, Duration, Instant},
};
use tracing::{debug, error, warn, info, instrument};
use tracing_subscriber::prelude::*;
use tracing_subscriber::{filter::LevelFilter, fmt, EnvFilter};
/// Simplified version of a maelstrom event /// Simplified version of a maelstrom event
#[derive(Debug)] #[derive(Debug)]
@ -22,130 +21,144 @@ struct Event {
in_reply_to: Option<usize>, in_reply_to: Option<usize>,
} }
type BoxFuture<'a, T> = Box<dyn Future<Output = T> + 'a>;
type CallbackDyn = dyn for<'a> Fn(Event, &'a mut Transport) -> BoxFuture<'a, Result<()>>;
enum Handler {
Callback(Box<CallbackDyn>),
Channel(oneshot::Sender<Event>)
}
/// Very simplified transport that receives from a channel and sends to another channel. In practice, /// Very simplified transport that receives from a channel and sends to another channel. In practice,
/// this would be replaced with a transport that reads/writes events from/to files or a connection. /// this would be replaced with a transport that reads/writes events from/to files or a connection.
struct Transport { struct Transport {
erx: Receiver<anyhow::Error>,
etx: Sender<anyhow::Error>,
msg_id: usize, msg_id: usize,
outbox: Sender<Event>, outbox: Sender<Event>,
inbox: Receiver<Option<Event>>, inbox: Receiver<Option<Event>>,
callbacks: HashMap<usize, (Handler, Instant)>, callbacks: HashMap<usize, (oneshot::Sender<Option<Event>>, Instant)>,
} }
impl Transport { impl Transport {
fn new() -> (Self, Sender<Option<Event>>, Receiver<Event>) { fn new() -> (Self, Sender<Option<Event>>, Receiver<Event>) {
let (itx, irx) = channel::<Option<Event>>(1); let (itx, irx) = channel::<Option<Event>>(1);
let (otx, orx) = channel::<Event>(1); let (otx, orx) = channel::<Event>(1);
(Self { let (etx, erx) = channel(1);
msg_id: 0, (
outbox: otx, Self {
inbox: irx, erx,
callbacks: Default::default(), etx,
}, itx, orx) msg_id: 0,
outbox: otx,
inbox: irx,
callbacks: Default::default(),
},
itx,
orx,
)
} }
#[instrument(level="debug",skip(self),ret)] #[instrument(level = "debug", skip(self))]
fn close(&mut self) -> Result<()> { async fn close(mut self) -> Result<()> {
self.inbox.close(); self.inbox.close();
let i = Instant::now(); let i = Instant::now();
self.callbacks.retain(|_, (_, t)| *t >= i); self.callbacks.retain(|_, (_, t)| *t >= i);
if self.callbacks.is_empty() { drop(self.etx);
Ok(()) debug!("Waiting for errors to propagate");
} else { for (c, _t) in self.callbacks.into_values() {
bail!("some callbacks failed to launch.") let _ = c.send(None);
} }
if let Some(e) = self.erx.recv().await {
return Err(e);
}
Ok(())
} }
#[instrument(level="debug",skip(self),ret)] #[instrument(level = "debug", skip(self))]
async fn send(&self, e: Event) -> Result<()> { async fn send(&mut self, mut e: Event) -> Result<()> {
e.id = self.msg_id;
self.msg_id += 1;
self.outbox.send(e).await.context("unable to send message") self.outbox.send(e).await.context("unable to send message")
} }
#[instrument(level="debug",skip(self),ret)] #[instrument(level = "debug", skip(self))]
async fn rpc(&mut self, e: Event) -> Result<Event> { async fn rpc_chan(
let rx = self.rpc_chan(e).await?; &mut self,
let resp = rx.await?; e: Event,
Ok(resp) expiration: Instant,
} ) -> Result<oneshot::Receiver<Option<Event>>> {
#[instrument(level="debug",skip(self),ret)]
async fn rpc_chan(&mut self, e: Event) -> Result<oneshot::Receiver<Event>> {
let id = e.id; let id = e.id;
self.send(e).await?; self.send(e).await?;
let (tx, rx) = oneshot::channel(); let (tx, rx) = oneshot::channel();
self.callbacks.insert(id, (Handler::Channel(tx), Instant::now() + Duration::from_millis(1000))); self.callbacks.insert(id, (tx, expiration));
Ok(rx) Ok(rx)
} }
async fn rpc_callback<C>(&mut self, e: Event, cb: C) -> Result<()> async fn rpc_callback<C, F>(&mut self, e: Event, cb: C, expiration: Instant) -> Result<()>
where where
C: for<'a> Fn(Event, &'a mut Transport) -> BoxFuture<'a, Result<()>> + 'static C: 'static + Send + FnOnce(oneshot::Receiver<Option<Event>>, Sender<Event>) -> F,
F: Future<Output = Result<()>> + Send + 'static,
{ {
self.callbacks.insert(e.id, (Handler::Callback(Box::new(cb)), (Instant::now() + Duration::from_millis(1000)))); let rec = self.rpc_chan(e, expiration).await?;
self.send(e).await let sender = self.outbox.clone();
let tx = self.etx.clone();
task::spawn(async move {
if let Ok(Err(e)) = timeout_at(expiration, cb(rec, sender)).await {
error!("propagating error '{e:?}'");
tx.send(e)
.await
.expect("could not propagate error to transport.");
}
});
Ok(())
} }
/// #Cancellation safety: This method is **not** cancellation safe, because it deals with callbacks /// #Cancellation safety: This method is cancellation safe
#[instrument(level="debug",skip(self),ret)] #[instrument(level = "debug", skip(self))]
async fn recv(&mut self) -> Result<Option<Event>> { async fn recv(&mut self) -> Result<Option<Event>> {
loop { loop {
let Some(nxt) = self.inbox.recv().await else { tokio::select! {
return Ok(None); rec = self.inbox.recv() => {
}; let Some(Some(nxt)) = rec else {
let Some(nxt) = nxt else { break;
return Ok(None); };
}; if let Some(e) = self.process_event(nxt).await? {
let Some(original) = nxt.in_reply_to else { return Ok(Some(e));
return Ok(Some(nxt));
};
let sp = match self.callbacks.remove(&original) {
None => {
return Ok(Some(nxt));
},
Some((h, t)) => {
if t < Instant::now() {
continue;
} }
h
}
};
match sp {
Handler::Callback(cb) => {
let f = Box::into_pin(cb(nxt, self));
f.await?;
}, },
Handler::Channel(c) => { e = self.erx.recv() => {
if let Err(e) = c.send(nxt) { error!("OHNOES, we have received an error");
bail!("could not send event to callback {e:?}") if let Some(e) = e {
return Err(e);
} }
info!("no more errors");
break;
} }
} }
} }
Ok(None)
} }
}
/// Simple macro to generate a dyn-safe closure from an async block. async fn process_event(&mut self, nxt: Event) -> Result<Option<Event>> {
macro_rules! callback { let Some(original) = nxt.in_reply_to else {
(|$e:ident, $svc:ident| $blk:block) => { return Ok(Some(nxt));
|$e, $svc| { };
Box::new(async move { if let Some((c, t)) = self.callbacks.remove(&original) {
$blk if t >= Instant::now() {
}) if let Err(e) = c.send(Some(nxt)) {
bail!("could not send event to callback {e:?}")
}
}
} }
Ok(None)
} }
} }
///// Simple macro to generate a dyn-safe closure from an async block.
//macro_rules! callback {
// (|$e:ident, $svc:ident| $blk:block) => {
// move |$e, $svc| {
// async move {
// $blk
// }
// }
// }
//
//}
struct Service { struct Service {
t: Transport, t: Transport,
} }
@ -153,77 +166,120 @@ struct Service {
/// All-in-one implementation of a service. In practice, this would be a trait where the `serve` /// All-in-one implementation of a service. In practice, this would be a trait where the `serve`
/// part is kind of generic, and the process varies between implementers. /// part is kind of generic, and the process varies between implementers.
impl Service { impl Service {
#[instrument(level="debug", skip(self),ret)] fn new(t: Transport) -> Self {
async fn process(&mut self, event: Event) -> Result<()>{ Self { t }
let resp = self.t.rpc(Event{id: event.id, in_reply_to: None}).await?; }
#[instrument(level = "debug", skip(self))]
async fn process(&mut self, event: Event) -> Result<()> {
let eid = event.id;
info!("Service received event");
let resp = self
.t
.rpc_callback(
Event {
id: event.id,
in_reply_to: None,
},
move |chan: oneshot::Receiver<Option<Event>>, out: Sender<Event>| {
async move {
let Some(e) = chan.await? else {
warn!("Reply not received for event {eid}");
return Ok(());
};
info!("Received reply {e:?}");
out.send(Event {
id: 199,
in_reply_to: Some(e.id),
})
.await
.context("could not send reply.")?;
//bail!("forcing an error here!");
Ok(())
}
},
Instant::now() + Duration::from_millis(100000),
)
.await?;
debug!("{:?}", &resp); debug!("{:?}", &resp);
Ok(()) Ok(())
} }
#[instrument(level="debug", skip(self),ret)] #[instrument(level = "debug", skip(self))]
async fn process_nonblocking(&mut self, event: Event) -> Result<()>{ async fn serve(mut self) -> Result<()> {
let resp = self.t.rpc_callback(Event{id: event.id, in_reply_to: None},
callback!(|e, svc| {
svc.send(Event{id: 199, in_reply_to: Some(e.id)}).await
})).await?;
debug!("{:?}", &resp);
Ok(())
}
#[instrument(level="debug", skip(self),ret)]
async fn serve(mut self) -> Result<()>{
while let Some(e) = self.t.recv().await? { while let Some(e) = self.t.recv().await? {
self.process_nonblocking(e).await?; self.process(e).await?;
} }
self.t.close() self.t.close().await
} }
} }
#[tokio::main] #[tokio::main]
async fn main() -> Result<()> { async fn main() -> Result<()> {
let filter = EnvFilter::builder()
.with_default_directive(LevelFilter::INFO.into())
.from_env_lossy();
tracing_subscriber::registry() tracing_subscriber::registry()
.with(fmt::layer()) .with(fmt::layer())
.with(EnvFilter::from_default_env()) .with(filter)
.init(); .init();
info!("Starting example server"); info!("Starting example server");
let (t, tx, mut rx) = Transport::new(); let (t, tx, mut rx) = Transport::new();
let serv = Service{t}; let serv = Service::new(t);
let tx1 = tx.clone(); let tx1 = tx.clone();
let s = tokio::spawn(async move { let s = tokio::spawn(async move {
for i in 0..2 { for i in 0..5 {
debug!("Sending event {i}"); debug!("Main sending event {i}");
tx1.send(Some(Event{id: i, in_reply_to: None})).await.context("could not send original message")?; tx1.send(Some(Event {
id: i,
in_reply_to: None,
}))
.await
.context("could not send original message")?;
debug!("Main sent event {i}");
} }
debug!("Main done sending events");
Ok::<(), anyhow::Error>(()) Ok::<(), anyhow::Error>(())
}); });
debug!("Serving"); debug!("Serving");
let r = tokio::spawn(async move { let r = tokio::spawn(async move {
for i in 0..2 { info!("Spawning receptor");
for _i in 0..3 {
let Some(msg) = rx.recv().await else { let Some(msg) = rx.recv().await else {
break; break;
}; };
if msg.in_reply_to.is_some() { if msg.in_reply_to.is_some() {
info!("Main received response: {msg:?}");
continue; continue;
} }
sleep(Duration::from_millis(200)).await; info!("Main received request: {msg:?}");
if i < 0 { sleep(Duration::from_millis(10)).await;
let reply = Event{id: 99, in_reply_to: Some(msg.id)}; let reply = Event {
debug!("Sending reply: {:?}", &reply); id: 99,
tx.send(Some(reply)).await.context("could not send reply")?; in_reply_to: Some(msg.id),
} else { };
println!("DONE WITH REPLIES"); debug!("Sending reply: {:?}", &reply);
} let tx = tx.clone();
tokio::spawn(async move {
tx.send(Some(reply)).await.expect("could not send reply");
});
} }
sleep(Duration::from_millis(100)).await; info!("Not sending more replies. Logging outgoing messages.");
tx.send(None).await.context("could not send closing message")?; drop(tx);
sleep(Duration::from_millis(1000)).await;
while let Some(msg) = rx.recv().await {
info!("Main received: {msg:?}");
};
Ok(()) Ok(())
}); });
serv.serve().await?; if let Err(e) = serv.serve().await {
error!("Have received the error: {e:?}");
return Ok(());
};
info!("Served"); info!("Served");
s.await.context("error joining")??; s.await.context("error joining")??;