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