Pass Event by reference to EventHandler

Passing an Event by reference rather and by move gives more flexibility
for composing event handlers without needing to clone events.

Author: jkczyz

lightning-background-processor/src/lib.rs

@@ -336,7 +336,7 @@ mod tests {
 			begin_open_channel!($node_a, $node_b, $channel_value);
 			let events = $node_a.node.get_and_clear_pending_events();
 			assert_eq!(events.len(), 1);
-			let (temporary_channel_id, tx) = handle_funding_generation_ready!(events[0], $channel_value);
+			let (temporary_channel_id, tx) = handle_funding_generation_ready!(&events[0], $channel_value);
 			end_open_channel!($node_a, $node_b, temporary_channel_id, tx);
 			tx
 		}}
@@ -353,14 +353,14 @@ mod tests {
 	macro_rules! handle_funding_generation_ready {
 		($event: expr, $channel_value: expr) => {{
 			match $event {
-				Event::FundingGenerationReady { ref temporary_channel_id, ref channel_value_satoshis, ref output_script, user_channel_id } => {
-					assert_eq!(*channel_value_satoshis, $channel_value);
+				&Event::FundingGenerationReady { temporary_channel_id, channel_value_satoshis, ref output_script, user_channel_id } => {
+					assert_eq!(channel_value_satoshis, $channel_value);
 					assert_eq!(user_channel_id, 42);
 
 					let tx = Transaction { version: 1 as i32, lock_time: 0, input: Vec::new(), output: vec![TxOut {
-						value: *channel_value_satoshis, script_pubkey: output_script.clone(),
+						value: channel_value_satoshis, script_pubkey: output_script.clone(),
 					}]};
-					(*temporary_channel_id, tx)
+					(temporary_channel_id, tx)
 				},
 				_ => panic!("Unexpected event"),
 			}
@@ -414,7 +414,7 @@ mod tests {
 		// Initiate the background processors to watch each node.
 		let data_dir = nodes[0].persister.get_data_dir();
 		let persister = move |node: &ChannelManager<InMemorySigner, Arc<ChainMonitor>, Arc<test_utils::TestBroadcaster>, Arc<KeysManager>, Arc<test_utils::TestFeeEstimator>, Arc<test_utils::TestLogger>>| FilesystemPersister::persist_manager(data_dir.clone(), node);
-		let event_handler = |_| {};
+		let event_handler = |_: &_| {};
 		let bg_processor = BackgroundProcessor::start(persister, event_handler, nodes[0].chain_monitor.clone(), nodes[0].node.clone(), nodes[0].peer_manager.clone(), nodes[0].logger.clone());
 
 		macro_rules! check_persisted_data {
@@ -467,7 +467,7 @@ mod tests {
 		let nodes = create_nodes(1, "test_timer_tick_called".to_string());
 		let data_dir = nodes[0].persister.get_data_dir();
 		let persister = move |node: &ChannelManager<InMemorySigner, Arc<ChainMonitor>, Arc<test_utils::TestBroadcaster>, Arc<KeysManager>, Arc<test_utils::TestFeeEstimator>, Arc<test_utils::TestLogger>>| FilesystemPersister::persist_manager(data_dir.clone(), node);
-		let event_handler = |_| {};
+		let event_handler = |_: &_| {};
 		let bg_processor = BackgroundProcessor::start(persister, event_handler, nodes[0].chain_monitor.clone(), nodes[0].node.clone(), nodes[0].peer_manager.clone(), nodes[0].logger.clone());
 		loop {
 			let log_entries = nodes[0].logger.lines.lock().unwrap();
@@ -489,7 +489,7 @@ mod tests {
 		open_channel!(nodes[0], nodes[1], 100000);
 
 		let persister = |_: &_| Err(std::io::Error::new(std::io::ErrorKind::Other, "test"));
-		let event_handler = |_| {};
+		let event_handler = |_: &_| {};
 		let bg_processor = BackgroundProcessor::start(persister, event_handler, nodes[0].chain_monitor.clone(), nodes[0].node.clone(), nodes[0].peer_manager.clone(), nodes[0].logger.clone());
 		match bg_processor.join() {
 			Ok(_) => panic!("Expected error persisting manager"),
@@ -509,7 +509,7 @@ mod tests {
 
 		// Set up a background event handler for FundingGenerationReady events.
 		let (sender, receiver) = std::sync::mpsc::sync_channel(1);
-		let event_handler = move |event| {
+		let event_handler = move |event: &Event| {
 			sender.send(handle_funding_generation_ready!(event, channel_value)).unwrap();
 		};
 		let bg_processor = BackgroundProcessor::start(persister.clone(), event_handler, nodes[0].chain_monitor.clone(), nodes[0].node.clone(), nodes[0].peer_manager.clone(), nodes[0].logger.clone());
@@ -535,7 +535,7 @@ mod tests {
 
 		// Set up a background event handler for SpendableOutputs events.
 		let (sender, receiver) = std::sync::mpsc::sync_channel(1);
-		let event_handler = move |event| sender.send(event).unwrap();
+		let event_handler = move |event: &Event| sender.send(event.clone()).unwrap();
 		let bg_processor = BackgroundProcessor::start(persister, event_handler, nodes[0].chain_monitor.clone(), nodes[0].node.clone(), nodes[0].peer_manager.clone(), nodes[0].logger.clone());
 
 		// Force close the channel and check that the SpendableOutputs event was handled.

lightning-net-tokio/src/lib.rs

@@ -43,27 +43,25 @@
 //! async fn connect_to_node(peer_manager: PeerManager, chain_monitor: Arc<ChainMonitor>, channel_manager: ChannelManager, their_node_id: PublicKey, addr: SocketAddr) {
 //! 	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| {
+//! 		let event_handler = |event: &Event| {
 //! 			// Handle the event!
-//! 		});
+//! 		};
+//! 		channel_manager.await_persistable_update();
+//! 		channel_manager.process_pending_events(&event_handler);
+//! 		chain_monitor.process_pending_events(&event_handler);
 //! 	}
 //! }
 //!
 //! // 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) {
 //! 	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| {
+//! 		let event_handler = |event: &Event| {
 //! 			// Handle the event!
-//! 		});
+//! 		};
+//! 		channel_manager.await_persistable_update();
+//! 		channel_manager.process_pending_events(&event_handler);
+//! 		chain_monitor.process_pending_events(&event_handler);
 //! 	}
 //! }
 //! ```

lightning/src/chain/chainmonitor.rs

@@ -144,7 +144,7 @@ where C::Target: chain::Filter,
 	pub fn get_and_clear_pending_events(&self) -> Vec<events::Event> {
 		use util::events::EventsProvider;
 		let events = core::cell::RefCell::new(Vec::new());
-		let event_handler = |event| events.borrow_mut().push(event);
+		let event_handler = |event: &events::Event| events.borrow_mut().push(event.clone());
 		self.process_pending_events(&event_handler);
 		events.into_inner()
 	}
@@ -327,7 +327,7 @@ impl<ChannelSigner: Sign, C: Deref, T: Deref, F: Deref, L: Deref, P: Deref> even
 			pending_events.append(&mut monitor.get_and_clear_pending_events());
 		}
 		for event in pending_events.drain(..) {
-			handler.handle_event(event);
+			handler.handle_event(&event);
 		}
 	}
 }

lightning/src/ln/channelmanager.rs

@@ -4065,7 +4065,7 @@ impl<Signer: Sign, M: Deref, T: Deref, K: Deref, F: Deref, L: Deref> ChannelMana
 	#[cfg(any(test, feature = "fuzztarget", feature = "_test_utils"))]
 	pub fn get_and_clear_pending_events(&self) -> Vec<events::Event> {
 		let events = core::cell::RefCell::new(Vec::new());
-		let event_handler = |event| events.borrow_mut().push(event);
+		let event_handler = |event: &events::Event| events.borrow_mut().push(event.clone());
 		self.process_pending_events(&event_handler);
 		events.into_inner()
 	}
@@ -4139,7 +4139,7 @@ where
 			}
 
 			for event in pending_events.drain(..) {
-				handler.handle_event(event);
+				handler.handle_event(&event);
 			}
 
 			result

lightning/src/util/events.rs

@@ -566,11 +566,11 @@ pub trait EventHandler {
 	/// Handles the given [`Event`].
 	///
 	/// See [`EventsProvider`] for details that must be considered when implementing this method.
-	fn handle_event(&self, event: Event);
+	fn handle_event(&self, event: &Event);
 }
 
-impl<F> EventHandler for F where F: Fn(Event) {
-	fn handle_event(&self, event: Event) {
+impl<F> EventHandler for F where F: Fn(&Event) {
+	fn handle_event(&self, event: &Event) {
 		self(event)
 	}
 }