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[WIP] refactor: remove add_node_addr API #3338

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[WIP] refactor: remove add_node_addr API #3338

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87 changes: 41 additions & 46 deletions iroh/src/discovery.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -114,15 +114,17 @@ use n0_future::{
stream::StreamExt,
task::{self, AbortOnDropHandle},
time::{self, Duration},
Stream, TryStreamExt,
Stream,
};
use nested_enum_utils::common_fields;
use snafu::{ensure, IntoError, Snafu};
use tokio::sync::oneshot;
use tracing::{debug, error_span, warn, Instrument};

pub use crate::node_info::{NodeData, NodeInfo, ParseError, UserData};
use crate::Endpoint;
use crate::{
watcher::{self, Watcher},
Endpoint,
};

#[cfg(not(wasm_browser))]
pub mod dns;
Expand Down Expand Up @@ -258,7 +260,7 @@ impl<T: Discovery> Discovery for Arc<T> {}
///
/// This struct derefs to [`NodeData`], so you can access the methods from [`NodeData`]
/// directly from [`DiscoveryItem`].
#[derive(Debug, Clone)]
#[derive(Debug, Clone, PartialEq, Eq)]
pub struct DiscoveryItem {
/// The node info for the node, as discovered by the the discovery service.
node_info: NodeInfo,
Expand Down Expand Up @@ -412,24 +414,31 @@ const MAX_AGE: Duration = Duration::from_secs(10);

/// A wrapper around a tokio task which runs a node discovery.
pub(super) struct DiscoveryTask {
on_first_rx: oneshot::Receiver<Result<(), DiscoveryError>>,
watcher: watcher::Direct<Option<DiscoveryItem>>,
_task: AbortOnDropHandle<()>,
}

impl DiscoveryTask {
/// Starts a discovery task.
pub(super) fn start(ep: Endpoint, node_id: NodeId) -> Result<Self, DiscoveryError> {
ensure!(ep.discovery().is_some(), NoServiceConfiguredSnafu);
let (on_first_tx, on_first_rx) = oneshot::channel();
let watchable = watcher::Watchable::default();
let watcher = watchable.watch();
let me = ep.node_id();
let task = task::spawn(
async move { Self::run(ep, node_id, on_first_tx).await }.instrument(
async move {
if let Err(err) = Self::run(ep, node_id, watchable).await {
// TODO: propagate err
warn!("discovery failed: {:?}", err);
}
}
.instrument(
error_span!("discovery", me = %me.fmt_short(), node = %node_id.fmt_short()),
),
);
Ok(Self {
_task: AbortOnDropHandle::new(task),
on_first_rx,
watcher,
})
}

Expand All @@ -451,36 +460,39 @@ impl DiscoveryTask {
return Ok(None);
}
ensure!(ep.discovery().is_some(), NoServiceConfiguredSnafu);
let (on_first_tx, on_first_rx) = oneshot::channel();
let watchable = watcher::Watchable::default();
let watcher = watchable.watch();
let ep = ep.clone();
let me = ep.node_id();

let task = task::spawn(
async move {
// If delay is set, wait and recheck if discovery is needed. If not, early-exit.
if let Some(delay) = delay {
time::sleep(delay).await;
if !Self::needs_discovery(&ep, node_id) {
debug!("no discovery needed, abort");
on_first_tx.send(Ok(())).ok();
return;
}
}
Self::run(ep, node_id, on_first_tx).await
if let Err(err) = Self::run(ep, node_id, watchable).await {
// TODO: propagate error
warn!("failed discovery: {:?}", err);
}
}
.instrument(
error_span!("discovery", me = %me.fmt_short(), node = %node_id.fmt_short()),
),
);
Ok(Some(Self {
_task: AbortOnDropHandle::new(task),
on_first_rx,
watcher,
}))
}

/// Waits until the discovery task produced at least one result.
pub(super) async fn first_arrived(&mut self) -> Result<(), DiscoveryError> {
let fut = &mut self.on_first_rx;
fut.await.expect("sender dropped")?;
self.watcher.initialized().await.ok();
Ok(())
}

Expand Down Expand Up @@ -522,16 +534,9 @@ impl DiscoveryTask {
async fn run(
ep: Endpoint,
node_id: NodeId,
on_first_tx: oneshot::Sender<Result<(), DiscoveryError>>,
) {
let mut stream = match Self::create_stream(&ep, node_id) {
Ok(stream) => stream,
Err(err) => {
on_first_tx.send(Err(err)).ok();
return;
}
};
let mut on_first_tx = Some(on_first_tx);
watchable: watcher::Watchable<Option<DiscoveryItem>>,
) -> Result<(), DiscoveryError> {
let mut stream = Self::create_stream(&ep, node_id)?;
debug!("starting");
loop {
match stream.next().await {
Expand All @@ -543,12 +548,12 @@ impl DiscoveryTask {
continue;
}
debug!(%provenance, addr = ?node_addr, "new address found");
ep.add_node_addr_with_source(node_addr, provenance).ok();
if let Some(tx) = on_first_tx.take() {
tx.send(Ok(())).ok();
ep.discovery_subscribers().send(r.clone());

if watchable.set(Some(r)).is_err() {
// abort if the watchable is disconnected
return Ok(());
}
// Send the discovery item to the subscribers of the discovery broadcast stream.
ep.discovery_subscribers().send(r);
}
Some(Err(err)) => {
warn!(?err, "discovery service produced error");
Expand All @@ -557,9 +562,7 @@ impl DiscoveryTask {
None => break,
}
}
if let Some(tx) = on_first_tx.take() {
tx.send(Err(NoResultsSnafu { node_id }.build())).ok();
}
Ok(())
}
}

Expand All @@ -580,30 +583,22 @@ pub struct Lagged {

#[derive(Clone, Debug)]
pub(super) struct DiscoverySubscribers {
inner: tokio::sync::broadcast::Sender<DiscoveryItem>,
inner: watcher::Watchable<Option<DiscoveryItem>>,
}

impl DiscoverySubscribers {
pub(crate) fn new() -> Self {
// TODO: Make capacity configurable from the endpoint builder?
// This is the maximum number of [`DiscoveryItem`]s held by the channel if
// subscribers are stalled.
const CAPACITY: usize = 128;
Self {
inner: tokio::sync::broadcast::Sender::new(CAPACITY),
inner: Default::default(),
}
}

pub(crate) fn subscribe(&self) -> impl Stream<Item = Result<DiscoveryItem, Lagged>> {
use tokio_stream::wrappers::{errors::BroadcastStreamRecvError, BroadcastStream};
let recv = self.inner.subscribe();
BroadcastStream::new(recv).map_err(|BroadcastStreamRecvError::Lagged(n)| Lagged { val: n })
pub(crate) fn subscribe(&self) -> impl Stream<Item = Option<DiscoveryItem>> {
self.inner.watch().stream()
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IIUC this is a quite big behaviour change: previously you'd have a reasonable chance of seeing all discovered items, now you only get a single one. Especially the ConcurrentDiscovery this could be an issue if multiple discovery services find something at the same time you'll miss one address.

}

pub(crate) fn send(&self, item: DiscoveryItem) {
// `broadcast::Sender::send` returns an error if the channel has no subscribers,
// which we don't care about.
self.inner.send(item).ok();
self.inner.set(Some(item)).ok();
}
}

Expand All @@ -624,7 +619,7 @@ mod tests {
use tracing_test::traced_test;

use super::*;
use crate::{endpoint::ConnectOptions, watcher::Watcher as _, RelayMode};
use crate::{endpoint::ConnectOptions, RelayMode};

type InfoStore = HashMap<NodeId, (NodeData, u64)>;

Expand Down
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