Merge pull request #920 from jkczyz/2021-05-event-processing

Background processing of ChannelManager and ChannelMonitor events

Author: TheBlueMatt

fuzz/src/chanmon_consistency.rs

@@ -44,7 +44,7 @@ use lightning::util::errors::APIError;
 use lightning::util::events;
 use lightning::util::logger::Logger;
 use lightning::util::config::UserConfig;
-use lightning::util::events::{EventsProvider, MessageSendEventsProvider};
+use lightning::util::events::MessageSendEventsProvider;
 use lightning::util::ser::{Readable, ReadableArgs, Writeable, Writer};
 use lightning::routing::router::{Route, RouteHop};
 

fuzz/src/full_stack.rs

@@ -39,7 +39,7 @@ use lightning::ln::msgs::DecodeError;
 use lightning::routing::router::get_route;
 use lightning::routing::network_graph::NetGraphMsgHandler;
 use lightning::util::config::UserConfig;
-use lightning::util::events::{EventsProvider,Event};
+use lightning::util::events::Event;
 use lightning::util::enforcing_trait_impls::EnforcingSigner;
 use lightning::util::logger::Logger;
 use lightning::util::ser::Readable;

lightning-background-processor/src/lib.rs

@@ -12,21 +12,19 @@
 //!
 //! Designed to be as simple as possible, the high-level usage is almost as simple as "hand over a
 //! TcpStream and a reference to a PeerManager and the rest is handled", except for the
-//! [Event](../lightning/util/events/enum.Event.html) handlng mechanism, see below.
+//! [Event](../lightning/util/events/enum.Event.html) handling mechanism; see example below.
 //!
 //! The PeerHandler, due to the fire-and-forget nature of this logic, must be an Arc, and must use
 //! the SocketDescriptor provided here as the PeerHandler's SocketDescriptor.
 //!
-//! Three methods are exposed to register a new connection for handling in tokio::spawn calls, see
-//! their individual docs for more. All three take a
-//! [mpsc::Sender<()>](../tokio/sync/mpsc/struct.Sender.html) which is sent into every time
-//! something occurs which may result in lightning [Events](../lightning/util/events/enum.Event.html).
-//! The call site should, thus, look something like this:
+//! Three methods are exposed to register a new connection for handling in tokio::spawn calls; see
+//! their individual docs for details.
+//!
+//! # Example
 //! ```
-//! use tokio::sync::mpsc;
 //! use std::net::TcpStream;
 //! use bitcoin::secp256k1::key::PublicKey;
-//! use lightning::util::events::EventsProvider;
+//! use lightning::util::events::{Event, EventHandler, EventsProvider};
 //! use std::net::SocketAddr;
 //! use std::sync::Arc;
 //!
@@ -43,32 +41,30 @@
 //!
 //! // Connect to node with pubkey their_node_id at addr:
 //! async fn connect_to_node(peer_manager: PeerManager, chain_monitor: Arc<ChainMonitor>, channel_manager: ChannelManager, their_node_id: PublicKey, addr: SocketAddr) {
-//!     let (sender, mut receiver) = mpsc::channel(2);
-//!     lightning_net_tokio::connect_outbound(peer_manager, sender, their_node_id, addr).await;
-//!     loop {
-//!         receiver.recv().await;
-//!         for _event in channel_manager.get_and_clear_pending_events().drain(..) {
-//!             // Handle the event!
-//!         }
-//!         for _event in chain_monitor.get_and_clear_pending_events().drain(..) {
-//!             // Handle the event!
-//!         }
-//!     }
+//! 	lightning_net_tokio::connect_outbound(peer_manager, their_node_id, addr).await;
+//! 	loop {
+//! 		channel_manager.await_persistable_update();
+//! 		channel_manager.process_pending_events(&|event| {
+//! 			// Handle the event!
+//! 		});
+//! 		chain_monitor.process_pending_events(&|event| {
+//! 			// Handle the event!
+//! 		});
+//! 	}
 //! }
 //!
 //! // Begin reading from a newly accepted socket and talk to the peer:
 //! async fn accept_socket(peer_manager: PeerManager, chain_monitor: Arc<ChainMonitor>, channel_manager: ChannelManager, socket: TcpStream) {
-//!     let (sender, mut receiver) = mpsc::channel(2);
-//!     lightning_net_tokio::setup_inbound(peer_manager, sender, socket);
-//!     loop {
-//!         receiver.recv().await;
-//!         for _event in channel_manager.get_and_clear_pending_events().drain(..) {
-//!             // Handle the event!
-//!         }
-//!         for _event in chain_monitor.get_and_clear_pending_events().drain(..) {
-//!             // Handle the event!
-//!         }
-//!     }
+//! 	lightning_net_tokio::setup_inbound(peer_manager, socket);
+//! 	loop {
+//! 		channel_manager.await_persistable_update();
+//! 		channel_manager.process_pending_events(&|event| {
+//! 			// Handle the event!
+//! 		});
+//! 		chain_monitor.process_pending_events(&|event| {
+//! 			// Handle the event!
+//! 		});
+//! 	}
 //! }
 //! ```
 
@@ -90,7 +86,7 @@ use lightning::util::logger::Logger;
 use std::{task, thread};
 use std::net::SocketAddr;
 use std::net::TcpStream as StdTcpStream;
-use std::sync::{Arc, Mutex, MutexGuard};
+use std::sync::{Arc, Mutex};
 use std::sync::atomic::{AtomicU64, Ordering};
 use std::time::Duration;
 use std::hash::Hash;
@@ -102,7 +98,6 @@ static ID_COUNTER: AtomicU64 = AtomicU64::new(0);
 /// read future (which is returned by schedule_read).
 struct Connection {
 	writer: Option<io::WriteHalf<TcpStream>>,
-	event_notify: mpsc::Sender<()>,
 	// Because our PeerManager is templated by user-provided types, and we can't (as far as I can
 	// tell) have a const RawWakerVTable built out of templated functions, we need some indirection
 	// between being woken up with write-ready and calling PeerManager::write_buffer_space_avail.
@@ -129,21 +124,10 @@ struct Connection {
 	id: u64,
 }
 impl Connection {
-	fn event_trigger(us: &mut MutexGuard<Self>) {
-		match us.event_notify.try_send(()) {
-			Ok(_) => {},
-			Err(mpsc::error::TrySendError::Full(_)) => {
-				// Ignore full errors as we just need the user to poll after this point, so if they
-				// haven't received the last send yet, it doesn't matter.
-			},
-			_ => panic!()
-		}
-	}
 	async fn schedule_read<CMH, RMH, L>(peer_manager: Arc<peer_handler::PeerManager<SocketDescriptor, Arc<CMH>, Arc<RMH>, Arc<L>>>, us: Arc<Mutex<Self>>, mut reader: io::ReadHalf<TcpStream>, mut read_wake_receiver: mpsc::Receiver<()>, mut write_avail_receiver: mpsc::Receiver<()>) where
 			CMH: ChannelMessageHandler + 'static,
 			RMH: RoutingMessageHandler + 'static,
 			L: Logger + 'static + ?Sized {
-		let peer_manager_ref = peer_manager.clone();
 		// 8KB is nice and big but also should never cause any issues with stack overflowing.
 		let mut buf = [0; 8192];
 
@@ -201,7 +185,6 @@ impl Connection {
 								if pause_read {
 									us_lock.read_paused = true;
 								}
-								Self::event_trigger(&mut us_lock);
 							},
 							Err(e) => shutdown_socket!(e, Disconnect::CloseConnection),
 						}
@@ -210,19 +193,20 @@ impl Connection {
 					Err(e) => shutdown_socket!(e, Disconnect::PeerDisconnected),
 				},
 			}
+			peer_manager.process_events();
 		};
 		let writer_option = us.lock().unwrap().writer.take();
 		if let Some(mut writer) = writer_option {
 			// If the socket is already closed, shutdown() will fail, so just ignore it.
 			let _ = writer.shutdown().await;
 		}
 		if let Disconnect::PeerDisconnected = disconnect_type {
-			peer_manager_ref.socket_disconnected(&our_descriptor);
-			Self::event_trigger(&mut us.lock().unwrap());
+			peer_manager.socket_disconnected(&our_descriptor);
+			peer_manager.process_events();
 		}
 	}
 
-	fn new(event_notify: mpsc::Sender<()>, stream: StdTcpStream) -> (io::ReadHalf<TcpStream>, mpsc::Receiver<()>, mpsc::Receiver<()>, Arc<Mutex<Self>>) {
+	fn new(stream: StdTcpStream) -> (io::ReadHalf<TcpStream>, mpsc::Receiver<()>, mpsc::Receiver<()>, Arc<Mutex<Self>>) {
 		// We only ever need a channel of depth 1 here: if we returned a non-full write to the
 		// PeerManager, we will eventually get notified that there is room in the socket to write
 		// new bytes, which will generate an event. That event will be popped off the queue before
@@ -238,7 +222,7 @@ impl Connection {
 
 		(reader, write_receiver, read_receiver,
 		Arc::new(Mutex::new(Self {
-			writer: Some(writer), event_notify, write_avail, read_waker, read_paused: false,
+			writer: Some(writer), write_avail, read_waker, read_paused: false,
 			block_disconnect_socket: false, rl_requested_disconnect: false,
 			id: ID_COUNTER.fetch_add(1, Ordering::AcqRel)
 		})))
@@ -251,13 +235,11 @@ impl Connection {
 /// The returned future will complete when the peer is disconnected and associated handling
 /// futures are freed, though, because all processing futures are spawned with tokio::spawn, you do
 /// not need to poll the provided future in order to make progress.
-///
-/// See the module-level documentation for how to handle the event_notify mpsc::Sender.
-pub fn setup_inbound<CMH, RMH, L>(peer_manager: Arc<peer_handler::PeerManager<SocketDescriptor, Arc<CMH>, Arc<RMH>, Arc<L>>>, event_notify: mpsc::Sender<()>, stream: StdTcpStream) -> impl std::future::Future<Output=()> where
+pub fn setup_inbound<CMH, RMH, L>(peer_manager: Arc<peer_handler::PeerManager<SocketDescriptor, Arc<CMH>, Arc<RMH>, Arc<L>>>, stream: StdTcpStream) -> impl std::future::Future<Output=()> where
 		CMH: ChannelMessageHandler + 'static + Send + Sync,
 		RMH: RoutingMessageHandler + 'static + Send + Sync,
 		L: Logger + 'static + ?Sized + Send + Sync {
-	let (reader, write_receiver, read_receiver, us) = Connection::new(event_notify, stream);
+	let (reader, write_receiver, read_receiver, us) = Connection::new(stream);
 	#[cfg(debug_assertions)]
 	let last_us = Arc::clone(&us);
 
@@ -293,13 +275,11 @@ pub fn setup_inbound<CMH, RMH, L>(peer_manager: Arc<peer_handler::PeerManager<So
 /// The returned future will complete when the peer is disconnected and associated handling
 /// futures are freed, though, because all processing futures are spawned with tokio::spawn, you do
 /// not need to poll the provided future in order to make progress.
-///
-/// See the module-level documentation for how to handle the event_notify mpsc::Sender.
-pub fn setup_outbound<CMH, RMH, L>(peer_manager: Arc<peer_handler::PeerManager<SocketDescriptor, Arc<CMH>, Arc<RMH>, Arc<L>>>, event_notify: mpsc::Sender<()>, their_node_id: PublicKey, stream: StdTcpStream) -> impl std::future::Future<Output=()> where
+pub fn setup_outbound<CMH, RMH, L>(peer_manager: Arc<peer_handler::PeerManager<SocketDescriptor, Arc<CMH>, Arc<RMH>, Arc<L>>>, their_node_id: PublicKey, stream: StdTcpStream) -> impl std::future::Future<Output=()> where
 		CMH: ChannelMessageHandler + 'static + Send + Sync,
 		RMH: RoutingMessageHandler + 'static + Send + Sync,
 		L: Logger + 'static + ?Sized + Send + Sync {
-	let (reader, mut write_receiver, read_receiver, us) = Connection::new(event_notify, stream);
+	let (reader, mut write_receiver, read_receiver, us) = Connection::new(stream);
 	#[cfg(debug_assertions)]
 	let last_us = Arc::clone(&us);
 
@@ -365,14 +345,12 @@ pub fn setup_outbound<CMH, RMH, L>(peer_manager: Arc<peer_handler::PeerManager<S
 /// disconnected and associated handling futures are freed, though, because all processing in said
 /// futures are spawned with tokio::spawn, you do not need to poll the second future in order to
 /// make progress.
-///
-/// See the module-level documentation for how to handle the event_notify mpsc::Sender.
-pub async fn connect_outbound<CMH, RMH, L>(peer_manager: Arc<peer_handler::PeerManager<SocketDescriptor, Arc<CMH>, Arc<RMH>, Arc<L>>>, event_notify: mpsc::Sender<()>, their_node_id: PublicKey, addr: SocketAddr) -> Option<impl std::future::Future<Output=()>> where
+pub async fn connect_outbound<CMH, RMH, L>(peer_manager: Arc<peer_handler::PeerManager<SocketDescriptor, Arc<CMH>, Arc<RMH>, Arc<L>>>, their_node_id: PublicKey, addr: SocketAddr) -> Option<impl std::future::Future<Output=()>> where
 		CMH: ChannelMessageHandler + 'static + Send + Sync,
 		RMH: RoutingMessageHandler + 'static + Send + Sync,
 		L: Logger + 'static + ?Sized + Send + Sync {
 	if let Ok(Ok(stream)) = time::timeout(Duration::from_secs(10), async { TcpStream::connect(&addr).await.map(|s| s.into_std().unwrap()) }).await {
-		Some(setup_outbound(peer_manager, event_notify, their_node_id, stream))
+		Some(setup_outbound(peer_manager, their_node_id, stream))
 	} else { None }
 }
 
@@ -634,9 +612,8 @@ mod tests {
 			(std::net::TcpStream::connect("127.0.0.1:46926").unwrap(), listener.accept().unwrap().0)
 		} else { panic!("Failed to bind to v4 localhost on common ports"); };
 
-		let (sender, _receiver) = mpsc::channel(2);
-		let fut_a = super::setup_outbound(Arc::clone(&a_manager), sender.clone(), b_pub, conn_a);
-		let fut_b = super::setup_inbound(b_manager, sender, conn_b);
+		let fut_a = super::setup_outbound(Arc::clone(&a_manager), b_pub, conn_a);
+		let fut_b = super::setup_inbound(b_manager, conn_b);
 
 		tokio::time::timeout(Duration::from_secs(10), a_connected.recv()).await.unwrap();
 		tokio::time::timeout(Duration::from_secs(1), b_connected.recv()).await.unwrap();

lightning-net-tokio/src/lib.rs

@@ -35,7 +35,7 @@ use chain::transaction::{OutPoint, TransactionData};
 use chain::keysinterface::Sign;
 use util::logger::Logger;
 use util::events;
-use util::events::Event;
+use util::events::EventHandler;
 
 use std::collections::{HashMap, hash_map};
 use std::sync::RwLock;
@@ -139,6 +139,15 @@ where C::Target: chain::Filter,
 			persister,
 		}
 	}
+
+	#[cfg(any(test, feature = "fuzztarget", feature = "_test_utils"))]
+	pub fn get_and_clear_pending_events(&self) -> Vec<events::Event> {
+		use util::events::EventsProvider;
+		let events = std::cell::RefCell::new(Vec::new());
+		let event_handler = |event| events.borrow_mut().push(event);
+		self.process_pending_events(&event_handler);
+		events.into_inner()
+	}
 }
 
 impl<ChannelSigner: Sign, C: Deref, T: Deref, F: Deref, L: Deref, P: Deref>
@@ -306,12 +315,20 @@ impl<ChannelSigner: Sign, C: Deref, T: Deref, F: Deref, L: Deref, P: Deref> even
 	      L::Target: Logger,
 	      P::Target: channelmonitor::Persist<ChannelSigner>,
 {
-	fn get_and_clear_pending_events(&self) -> Vec<Event> {
+	/// Processes [`SpendableOutputs`] events produced from each [`ChannelMonitor`] upon maturity.
+	///
+	/// An [`EventHandler`] may safely call back to the provider, though this shouldn't be needed in
+	/// order to handle these events.
+	///
+	/// [`SpendableOutputs`]: events::Event::SpendableOutputs
+	fn process_pending_events<H: Deref>(&self, handler: H) where H::Target: EventHandler {
 		let mut pending_events = Vec::new();
 		for monitor in self.monitors.read().unwrap().values() {
 			pending_events.append(&mut monitor.get_and_clear_pending_events());
 		}
-		pending_events
+		for event in pending_events.drain(..) {
+			handler.handle_event(event);
+		}
 	}
 }
 
@@ -320,7 +337,6 @@ mod tests {
 	use ::{check_added_monitors, get_local_commitment_txn};
 	use ln::features::InitFeatures;
 	use ln::functional_test_utils::*;
-	use util::events::EventsProvider;
 	use util::events::MessageSendEventsProvider;
 	use util::test_utils::{OnRegisterOutput, TxOutReference};
 

lightning/src/chain/chainmonitor.rs

@@ -222,11 +222,11 @@ pub(crate) const CLTV_CLAIM_BUFFER: u32 = 18;
 pub(crate) const LATENCY_GRACE_PERIOD_BLOCKS: u32 = 3;
 /// Number of blocks we wait on seeing a HTLC output being solved before we fail corresponding inbound
 /// HTLCs. This prevents us from failing backwards and then getting a reorg resulting in us losing money.
-/// We use also this delay to be sure we can remove our in-flight claim txn from bump candidates buffer.
-/// It may cause spurrious generation of bumped claim txn but that's allright given the outpoint is already
-/// solved by a previous claim tx. What we want to avoid is reorg evicting our claim tx and us not
-/// keeping bumping another claim tx to solve the outpoint.
-pub(crate) const ANTI_REORG_DELAY: u32 = 6;
+// We also use this delay to be sure we can remove our in-flight claim txn from bump candidates buffer.
+// It may cause spurious generation of bumped claim txn but that's alright given the outpoint is already
+// solved by a previous claim tx. What we want to avoid is reorg evicting our claim tx and us not
+// keep bumping another claim tx to solve the outpoint.
+pub const ANTI_REORG_DELAY: u32 = 6;
 /// Number of blocks before confirmation at which we fail back an un-relayed HTLC or at which we
 /// refuse to accept a new HTLC.
 ///

lightning/src/chain/channelmonitor.rs

@@ -27,7 +27,7 @@ use ln::msgs::{ChannelMessageHandler, ErrorAction, RoutingMessageHandler};
 use routing::router::get_route;
 use util::config::UserConfig;
 use util::enforcing_trait_impls::EnforcingSigner;
-use util::events::{Event, EventsProvider, MessageSendEvent, MessageSendEventsProvider};
+use util::events::{Event, MessageSendEvent, MessageSendEventsProvider};
 use util::errors::APIError;
 use util::ser::{ReadableArgs, Writeable};