Remove all batches related to a peer on disconnect

beacon_node/lighthouse_network/src/rpc/handler.rs

@@ -352,37 +352,6 @@ where
         !matches!(self.state, HandlerState::Deactivated)
     }
 
-    // NOTE: This function gets polled to completion upon a connection close.
-    fn poll_close(&mut self, _: &mut Context<'_>) -> Poll<Option<Self::ToBehaviour>> {
-        // Inform the network behaviour of any failed requests
-
-        while let Some(substream_id) = self.outbound_substreams.keys().next().cloned() {
-            let outbound_info = self
-                .outbound_substreams
-                .remove(&substream_id)
-                .expect("The value must exist for a key");
-            // If the state of the connection is closing, we do not need to report this case to
-            // the behaviour, as the connection has just closed non-gracefully
-            if matches!(outbound_info.state, OutboundSubstreamState::Closing(_)) {
-                continue;
-            }
-
-            // Register this request as an RPC Error
-            return Poll::Ready(Some(HandlerEvent::Err(HandlerErr::Outbound {
-                error: RPCError::Disconnected,
-                proto: outbound_info.proto,
-                id: outbound_info.req_id,
-            })));
-        }
-
-        // Also handle any events that are awaiting to be sent to the behaviour
-        if !self.events_out.is_empty() {
-            return Poll::Ready(Some(self.events_out.remove(0)));
-        }
-
-        Poll::Ready(None)
-    }
-
     fn poll(
         &mut self,
         cx: &mut Context<'_>,

beacon_node/lighthouse_network/tests/rpc_tests.rs

@@ -3,7 +3,7 @@
 mod common;
 
 use common::Protocol;
-use lighthouse_network::rpc::{methods::*, RPCError};
+use lighthouse_network::rpc::methods::*;
 use lighthouse_network::{rpc::max_rpc_size, NetworkEvent, ReportSource, Request, Response};
 use slog::{debug, warn, Level};
 use ssz::Encode;
@@ -1012,98 +1012,6 @@ fn test_tcp_blocks_by_root_chunked_rpc_terminates_correctly() {
     })
 }
 
-#[test]
-fn test_disconnect_triggers_rpc_error() {
-    // set up the logging. The level and enabled logging or not
-    let log_level = Level::Debug;
-    let enable_logging = false;
-
-    let log = common::build_log(log_level, enable_logging);
-    let spec = E::default_spec();
-
-    let rt = Arc::new(Runtime::new().unwrap());
-    // get sender/receiver
-    rt.block_on(async {
-        let (mut sender, mut receiver) = common::build_node_pair(
-            Arc::downgrade(&rt),
-            &log,
-            ForkName::Base,
-            &spec,
-            Protocol::Tcp,
-        )
-        .await;
-
-        // BlocksByRoot Request
-        let rpc_request = Request::BlocksByRoot(BlocksByRootRequest::new(
-            // Must have at least one root for the request to create a stream
-            vec![Hash256::from_low_u64_be(0)],
-            &spec,
-        ));
-
-        // build the sender future
-        let sender_future = async {
-            loop {
-                match sender.next_event().await {
-                    NetworkEvent::PeerConnectedOutgoing(peer_id) => {
-                        // Send a STATUS message
-                        debug!(log, "Sending RPC");
-                        sender
-                            .send_request(peer_id, 42, rpc_request.clone())
-                            .unwrap();
-                    }
-                    NetworkEvent::RPCFailed { error, id: 42, .. } => match error {
-                        RPCError::Disconnected => return,
-                        other => panic!("received unexpected error {:?}", other),
-                    },
-                    other => {
-                        warn!(log, "Ignoring other event {:?}", other);
-                    }
-                }
-            }
-        };
-
-        // determine messages to send (PeerId, RequestId). If some, indicates we still need to send
-        // messages
-        let mut sending_peer = None;
-        let receiver_future = async {
-            loop {
-                // this future either drives the sending/receiving or times out allowing messages to be
-                // sent in the timeout
-                match futures::future::select(
-                    Box::pin(receiver.next_event()),
-                    Box::pin(tokio::time::sleep(Duration::from_secs(1))),
-                )
-                .await
-                {
-                    futures::future::Either::Left((ev, _)) => match ev {
-                        NetworkEvent::RequestReceived { peer_id, .. } => {
-                            sending_peer = Some(peer_id);
-                        }
-                        other => {
-                            warn!(log, "Ignoring other event {:?}", other);
-                        }
-                    },
-                    futures::future::Either::Right((_, _)) => {} // The timeout hit, send messages if required
-                }
-
-                // if we need to send messages send them here. This will happen after a delay
-                if let Some(peer_id) = sending_peer.take() {
-                    warn!(log, "Receiver got request, disconnecting peer");
-                    receiver.__hard_disconnect_testing_only(peer_id);
-                }
-            }
-        };
-
-        tokio::select! {
-            _ = sender_future => {}
-            _ = receiver_future => {}
-            _ = sleep(Duration::from_secs(30)) => {
-                panic!("Future timed out");
-            }
-        }
-    })
-}
-
 /// Establishes a pair of nodes and disconnects the pair based on the selected protocol via an RPC
 /// Goodbye message.
 fn goodbye_test(log_level: Level, enable_logging: bool, protocol: Protocol) {

beacon_node/network/src/sync/backfill_sync/mod.rs

@@ -307,15 +307,49 @@ impl<T: BeaconChainTypes> BackFillSync<T> {
     /// A peer has disconnected.
     /// If the peer has active batches, those are considered failed and re-requested.
     #[must_use = "A failure here indicates the backfill sync has failed and the global sync state should be updated"]
-    pub fn peer_disconnected(&mut self, peer_id: &PeerId) -> Result<(), BackFillError> {
+    pub fn peer_disconnected(
+        &mut self,
+        peer_id: &PeerId,
+        network: &mut SyncNetworkContext<T>,
+    ) -> Result<(), BackFillError> {
         if matches!(
             self.state(),
             BackFillState::Failed | BackFillState::NotRequired
         ) {
             return Ok(());
         }
 
-        self.active_requests.remove(peer_id);
+        if let Some(batch_ids) = self.active_requests.remove(peer_id) {
+            // fail the batches.
+            for id in batch_ids {
+                if let Some(batch) = self.batches.get_mut(&id) {
+                    match batch.download_failed(false) {
+                        Ok(BatchOperationOutcome::Failed { blacklist: _ }) => {
+                            self.fail_sync(BackFillError::BatchDownloadFailed(id))?;
+                        }
+                        Ok(BatchOperationOutcome::Continue) => {}
+                        Err(e) => {
+                            self.fail_sync(BackFillError::BatchInvalidState(id, e.0))?;
+                        }
+                    }
+                    // If we have run out of peers in which to retry this batch, the backfill state
+                    // transitions to a paused state.
+                    // We still need to reset the state for all the affected batches, so we should not
+                    // short circuit early.
+                    if self.retry_batch_download(network, id).is_err() {
+                        debug!(
+                            self.log,
+                            "Batch could not be retried";
+                            "batch_id" => id,
+                            "error" => "no synced peers"
+                        );
+                    }
+                } else {
+                    debug!(self.log, "Batch not found while removing peer";
+                        "peer" => %peer_id, "batch" => id)
+                }
+            }
+        }
 
         // Remove the peer from the participation list
         self.participating_peers.remove(peer_id);

beacon_node/network/src/sync/block_lookups/mod.rs

@@ -1,3 +1,25 @@
+//! Implements block lookup sync.
+//!
+//! Block lookup sync is triggered when a peer claims to have imported a block we don't know about.
+//! For example, a peer attesting to a head block root that is not in our fork-choice. Lookup sync
+//! is recursive in nature, as we may discover that this attested head block root has a parent that
+//! is also unknown to us.
+//!
+//! Block lookup is implemented as an event-driven state machine. It sends events to the network and
+//! beacon processor, and expects some set of events back. A discrepancy in the expected event API
+//! will result in lookups getting "stuck". A lookup becomes stuck when there is no future event
+//! that will trigger the lookup to make progress. There's a fallback mechanism that drops lookups
+//! that live for too long, logging the line "Notify the devs a sync lookup is stuck".
+//!
+//! The expected event API is documented in the code paths that are making assumptions  with the
+//! comment prefix "Lookup sync event safety:"
+//!
+//! Block lookup sync attempts to not re-download or re-process data that we already have. Block
+//! components are cached temporarily in multiple places before they are imported into fork-choice.
+//! Therefore, block lookup sync must peek these caches correctly to decide when to skip a download
+//! or consider a lookup complete. These caches are read from the `SyncNetworkContext` and its state
+//! returned to this module as `LookupRequestResult` variants.
+
 use self::parent_chain::{compute_parent_chains, NodeChain};
 pub use self::single_block_lookup::DownloadResult;
 use self::single_block_lookup::{LookupRequestError, LookupResult, SingleBlockLookup};
@@ -410,21 +432,9 @@ impl<T: BeaconChainTypes> BlockLookups<T> {
     /* Error responses */
 
     pub fn peer_disconnected(&mut self, peer_id: &PeerId) {
-        self.single_block_lookups.retain(|_, lookup| {
+        for (_, lookup) in self.single_block_lookups.iter_mut() {
             lookup.remove_peer(peer_id);
-
-            // Note: this condition should be removed in the future. It's not strictly necessary to drop a
-            // lookup if there are no peers left. Lookup should only be dropped if it can not make progress
-            if lookup.has_no_peers() {
-                debug!(self.log,
-                    "Dropping single lookup after peer disconnection";
-                    "block_root" => ?lookup.block_root()
-                );
-                false
-            } else {
-                true
-            }
-        });
+        }
     }
 
     /* Processing responses */
@@ -787,12 +797,12 @@ impl<T: BeaconChainTypes> BlockLookups<T> {
             };
 
             if stuck_lookup.id == ancestor_stuck_lookup.id {
-                warn!(self.log, "Notify the devs, a sync lookup is stuck";
+                warn!(self.log, "Notify the devs a sync lookup is stuck";
                     "block_root" => ?stuck_lookup.block_root(),
                     "lookup" => ?stuck_lookup,
                 );
             } else {
-                warn!(self.log, "Notify the devs, a sync lookup is stuck";
+                warn!(self.log, "Notify the devs a sync lookup is stuck";
                     "block_root" => ?stuck_lookup.block_root(),
                     "lookup" => ?stuck_lookup,
                     "ancestor_block_root" => ?ancestor_stuck_lookup.block_root(),

beacon_node/network/src/sync/block_lookups/single_block_lookup.rs

@@ -197,21 +197,36 @@ impl<T: BeaconChainTypes> SingleBlockLookup<T> {
             }
 
             let Some(peer_id) = self.use_rand_available_peer() else {
-                // Allow lookup to not have any peers. In that case do nothing. If the lookup does
-                // not have peers for some time, it will be dropped.
+                // Allow lookup to not have any peers and do nothing. This is an optimization to not
+                // lose progress of lookups created from a block with unknown parent before we receive
+                // attestations for said block.
+                // Lookup sync event safety: If a lookup requires peers to make progress, and does
+                // not receive any new peers for some time it will be dropped. If it receives a new
+                // peer it must attempt to make progress.
+                R::request_state_mut(self)
+                    .get_state_mut()
+                    .update_awaiting_download_status("no peers");
                 return Ok(());
             };
 
             let request = R::request_state_mut(self);
             match request.make_request(id, peer_id, downloaded_block_expected_blobs, cx)? {
                 LookupRequestResult::RequestSent(req_id) => {
+                    // Lookup sync event safety: If make_request returns `RequestSent`, we are
+                    // guaranteed that `BlockLookups::on_download_response` will be called exactly
+                    // with this `req_id`.
                     request.get_state_mut().on_download_start(req_id)?
                 }
                 LookupRequestResult::NoRequestNeeded => {
+                    // Lookup sync event safety: Advances this request to the terminal `Processed`
+                    // state. If all requests reach this state, the request is marked as completed
+                    // in `Self::continue_requests`.
                     request.get_state_mut().on_completed_request()?
                 }
                 // Sync will receive a future event to make progress on the request, do nothing now
                 LookupRequestResult::Pending(reason) => {
+                    // Lookup sync event safety: Refer to the code paths constructing
+                    // `LookupRequestResult::Pending`
                     request
                         .get_state_mut()
                         .update_awaiting_download_status(reason);
@@ -222,16 +237,28 @@ impl<T: BeaconChainTypes> SingleBlockLookup<T> {
         // Otherwise, attempt to progress awaiting processing
         // If this request is awaiting a parent lookup to be processed, do not send for processing.
         // The request will be rejected with unknown parent error.
+        //
+        // TODO: The condition `block_is_processed || Block` can be dropped after checking for
+        // unknown parent root when import RPC blobs
         } else if !awaiting_parent
             && (block_is_processed || matches!(R::response_type(), ResponseType::Block))
         {
             // maybe_start_processing returns Some if state == AwaitingProcess. This pattern is
             // useful to conditionally access the result data.
             if let Some(result) = request.get_state_mut().maybe_start_processing() {
+                // Lookup sync event safety: If `send_for_processing` returns Ok() we are guaranteed
+                // that `BlockLookups::on_processing_result` will be called exactly once with this
+                // lookup_id
                 return R::send_for_processing(id, result, cx);
             }
+            // Lookup sync event safety: If the request is not in `AwaitingDownload` or
+            // `AwaitingProcessing` state it is guaranteed to receive some event to make progress.
         }
 
+        // Lookup sync event safety: If a lookup is awaiting a parent we are guaranteed to either:
+        // (1) attempt to make progress with `BlockLookups::continue_child_lookups` if the parent
+        // lookup completes, or (2) get dropped if the parent fails and is dropped.
+
         Ok(())
     }
 
@@ -246,10 +273,9 @@ impl<T: BeaconChainTypes> SingleBlockLookup<T> {
         self.peers.insert(peer_id)
     }
 
-    /// Remove peer from available peers. Return true if there are no more available peers and all
-    /// requests are not expecting any future event (AwaitingDownload).
-    pub fn remove_peer(&mut self, peer_id: &PeerId) -> bool {
-        self.peers.remove(peer_id)
+    /// Remove peer from available peers.
+    pub fn remove_peer(&mut self, peer_id: &PeerId) {
+        self.peers.remove(peer_id);
     }
 
     /// Returns true if this lookup has zero peers