feat(node): Generate syncing related events

cli/src/native.rs

@@ -68,7 +68,7 @@ pub(crate) async fn run(args: Params) -> Result<()> {
         info!("Initialised store, present headers: {stored_ranges}");
     }
 
-    let node = Node::new(NodeConfig {
+    let (_node, mut events) = Node::new_subscribed(NodeConfig {
         network_id,
         genesis_hash,
         p2p_local_keypair,
@@ -80,14 +80,13 @@ pub(crate) async fn run(args: Params) -> Result<()> {
     .await
     .context("Failed to start node")?;
 
-    node.wait_connected_trusted().await?;
-    let mut events = node.event_subscriber();
-
-    // We have nothing else to do, but we want to keep main alive
     while let Ok(ev) = events.recv().await {
         match ev.event {
             // Skip noisy events
             NodeEvent::ShareSamplingResult { .. } => continue,
+            event @ (NodeEvent::FatalDaserError { .. } | NodeEvent::NetworkCompromised) => {
+                warn!("{event}");
+            }
             event => info!("{event}"),
         }
     }

node-wasm/src/worker.rs

@@ -55,7 +55,7 @@ struct NodeWorker {
 }
 
 impl NodeWorker {
-    async fn new(config: WasmNodeConfig) -> Result<Self> {
+    async fn new(events_channel_name: &str, config: WasmNodeConfig) -> Result<Self> {
         let config = config.into_node_config().await?;
 
         if let Ok(store_height) = config.store.head_height().await {
@@ -64,18 +64,16 @@ impl NodeWorker {
             info!("Initialised new empty store");
         }
 
-        let node = Node::new(config).await?;
+        let (node, events_sub) = Node::new_subscribed(config).await?;
 
-        let events_channel_name = format!("NodeEventChannel-{}", get_crypto()?.random_uuid());
-        let events_channel = BroadcastChannel::new(&events_channel_name)
+        let events_channel = BroadcastChannel::new(events_channel_name)
             .context("Failed to allocate BroadcastChannel")?;
 
-        let events_sub = node.event_subscriber();
         spawn_local(event_forwarder_task(events_sub, events_channel));
 
         Ok(Self {
             node,
-            events_channel_name,
+            events_channel_name: events_channel_name.to_owned(),
         })
     }
 
@@ -238,9 +236,10 @@ impl NodeWorker {
 }
 
 #[wasm_bindgen]
-pub async fn run_worker(queued_events: Vec<MessageEvent>) {
+pub async fn run_worker(queued_events: Vec<MessageEvent>) -> Result<()> {
     info!("Entered run_worker");
     let (tx, mut rx) = mpsc::channel(WORKER_MESSAGE_SERVER_INCOMING_QUEUE_LENGTH);
+    let events_channel_name = format!("NodeEventChannel-{}", get_crypto()?.random_uuid());
 
     let mut message_server: Box<dyn MessageServer> = if SharedWorker::is_worker_type() {
         Box::new(SharedWorkerMessageServer::new(tx.clone(), queued_events))
@@ -265,8 +264,14 @@ pub async fn run_worker(queued_events: Vec<MessageEvent>) {
                         NodeCommand::IsRunning => {
                             message_server.respond_to(client_id, WorkerResponse::IsRunning(false));
                         }
+                        NodeCommand::GetEventsChannelName => {
+                            message_server.respond_to(
+                                client_id,
+                                WorkerResponse::EventsChannelName(events_channel_name.clone()),
+                            );
+                        }
                         NodeCommand::StartNode(config) => {
-                            match NodeWorker::new(config).await {
+                            match NodeWorker::new(&events_channel_name, config).await {
                                 Ok(node) => {
                                     worker = Some(node);
                                     message_server
@@ -293,6 +298,8 @@ pub async fn run_worker(queued_events: Vec<MessageEvent>) {
     }
 
     info!("Channel to WorkerMessageServer closed, exiting the SharedWorker");
+
+    Ok(())
 }
 
 async fn event_forwarder_task(mut events_sub: EventSubscriber, events_channel: BroadcastChannel) {

node/src/events.rs

@@ -72,6 +72,11 @@ impl EventChannel {
             rx: self.tx.subscribe(),
         }
     }
+
+    /// Returns if there are any active subscribers or not.
+    pub fn has_subscribers(&self) -> bool {
+        self.tx.receiver_count() > 0
+    }
 }
 
 impl Default for EventChannel {
@@ -94,6 +99,10 @@ impl EventPublisher {
             file_line: location.line(),
         });
     }
+
+    pub(crate) fn has_subscribers(&self) -> bool {
+        self.tx.receiver_count() > 0
+    }
 }
 
 impl EventSubscriber {
@@ -219,6 +228,37 @@ pub enum NodeEvent {
         /// A human readable error.
         error: String,
     },
+
+    /// A new head that was observed by the node.
+    NewSubjectiveHead {
+        /// The height of the head.
+        height: u64,
+    },
+
+    /// A new header was added from HeaderSub.
+    AddedHeaderFromHeaderSub {
+        /// The height of the header.
+        height: u64,
+    },
+
+    /// Fetching header of network head in progress.
+    FetchingHeadHeader,
+
+    /// Fetching headers for a specific block range.
+    FetchingHeaders {
+        /// Start of the range.
+        from_height: u64,
+        /// End of the range (included).
+        to_height: u64,
+    },
+
+    /// Network was compromised.
+    ///
+    /// This happens when a valid bad encoding fraud proof is received.
+    /// Ideally it would never happen, but protection needs to exist.
+    /// In case of compromised network, syncing and data sampling will
+    /// stop immediately.
+    NetworkCompromised,
 }
 
 impl fmt::Display for NodeEvent {
@@ -272,6 +312,29 @@ impl fmt::Display for NodeEvent {
             NodeEvent::FatalDaserError { error } => {
                 write!(f, "Daser stopped because of a fatal error: {error}")
             }
+            NodeEvent::NewSubjectiveHead { height } => {
+                write!(f, "New subjective head: {height}")
+            }
+            NodeEvent::AddedHeaderFromHeaderSub { height } => {
+                write!(f, "Added header {height} from HeaderSub")
+            }
+            NodeEvent::FetchingHeadHeader => {
+                write!(f, "Fetching header of network head block")
+            }
+            NodeEvent::FetchingHeaders {
+                from_height,
+                to_height,
+            } => {
+                if from_height == to_height {
+                    write!(f, "Fetching header of {from_height} block")
+                } else {
+                    write!(f, "Fetching headers of {from_height}-{to_height} blocks")
+                }
+            }
+            NodeEvent::NetworkCompromised => {
+                write!(f, "The network is compromised and should not be trusted. ")?;
+                write!(f, "Node stopped synchronizing and sampling, but you can still make some queries to the network.")
+            }
         }
     }
 }

node/src/node.rs

@@ -22,7 +22,7 @@ use tokio_util::sync::CancellationToken;
 use tracing::warn;
 
 use crate::daser::{Daser, DaserArgs, DaserError};
-use crate::events::{EventChannel, EventSubscriber};
+use crate::events::{EventChannel, EventSubscriber, NodeEvent};
 use crate::executor::spawn;
 use crate::p2p::{P2p, P2pArgs, P2pError};
 use crate::peer_tracker::PeerTrackerInfo;
@@ -92,10 +92,23 @@ where
 {
     /// Creates and starts a new celestia node with a given config.
     pub async fn new<B>(config: NodeConfig<B, S>) -> Result<Self>
+    where
+        B: Blockstore + 'static,
+    {
+        let (node, _) = Node::new_subscribed(config).await?;
+        Ok(node)
+    }
+
+    /// Creates and starts a new celestia node with a given config.
+    ///
+    /// Returns `Node` alogn with `EventSubscriber`. Use this to avoid missing any
+    /// events that will be generated on the construction of the node.
+    pub async fn new_subscribed<B>(config: NodeConfig<B, S>) -> Result<(Self, EventSubscriber)>
     where
         B: Blockstore + 'static,
     {
         let event_channel = EventChannel::new();
+        let event_sub = event_channel.subscribe();
         let store = Arc::new(config.store);
 
         let p2p = Arc::new(P2p::start(P2pArgs {
@@ -111,6 +124,7 @@ where
         let syncer = Arc::new(Syncer::start(SyncerArgs {
             store: store.clone(),
             p2p: p2p.clone(),
+            event_pub: event_channel.publisher(),
         })?);
 
         let daser = Arc::new(Daser::start(DaserArgs {
@@ -122,32 +136,42 @@ where
         // spawn the task that will stop the services when the fraud is detected
         let network_compromised_token = p2p.get_network_compromised_token().await?;
         let tasks_cancellation_token = CancellationToken::new();
+
         spawn({
             let syncer = syncer.clone();
             let daser = daser.clone();
             let tasks_cancellation_token = tasks_cancellation_token.child_token();
+            let event_pub = event_channel.publisher();
+
             async move {
                 select! {
                     _ = tasks_cancellation_token.cancelled() => (),
                     _ = network_compromised_token.cancelled() => {
-                        warn!("The network is compromised and should not be trusted.");
-                        warn!("The node will stop synchronizing and sampling.");
-                        warn!("You can still make some queries to the network.");
                         syncer.stop();
                         daser.stop();
+
+                        if event_pub.has_subscribers() {
+                            event_pub.send(NodeEvent::NetworkCompromised);
+                        } else {
+                            // This is a very important message and we want to log it if user
+                            // does not consume our events.
+                            warn!("{}", NodeEvent::NetworkCompromised);
+                        }
                     }
                 }
             }
         });
 
-        Ok(Node {
+        let node = Node {
             event_channel,
             p2p,
             store,
             syncer,
             _daser: daser,
             tasks_cancellation_token,
-        })
+        };
+
+        Ok((node, event_sub))
     }
 
     /// Returns a new `EventSubscriber`.