Merge pull request #813 from jkczyz/2021-02-channel-monitor-mutex

Use interior mutability in ChannelMonitor

Author: TheBlueMatt

fuzz/src/chanmon_consistency.rs

@@ -126,7 +126,7 @@ impl chain::Watch<EnforcingSigner> for TestChainMonitor {
 			hash_map::Entry::Occupied(entry) => entry,
 			hash_map::Entry::Vacant(_) => panic!("Didn't have monitor on update call"),
 		};
-		let mut deserialized_monitor = <(BlockHash, channelmonitor::ChannelMonitor<EnforcingSigner>)>::
+		let deserialized_monitor = <(BlockHash, channelmonitor::ChannelMonitor<EnforcingSigner>)>::
 			read(&mut Cursor::new(&map_entry.get().1), &OnlyReadsKeysInterface {}).unwrap().1;
 		deserialized_monitor.update_monitor(&update, &&TestBroadcaster{}, &&FuzzEstimator{}, &self.logger).unwrap();
 		let mut ser = VecWriter(Vec::new());

lightning-block-sync/src/init.rs

@@ -38,7 +38,6 @@ use lightning::chain;
 ///
 /// use lightning_block_sync::*;
 ///
-/// use std::cell::RefCell;
 /// use std::io::Cursor;
 ///
 /// async fn init_sync<
@@ -83,7 +82,7 @@ use lightning::chain;
 ///
 /// 	// Synchronize any channel monitors and the channel manager to be on the best block.
 /// 	let mut cache = UnboundedCache::new();
-/// 	let mut monitor_listener = (RefCell::new(monitor), &*tx_broadcaster, &*fee_estimator, &*logger);
+/// 	let mut monitor_listener = (monitor, &*tx_broadcaster, &*fee_estimator, &*logger);
 /// 	let listeners = vec![
 /// 		(monitor_block_hash, &mut monitor_listener as &mut dyn chain::Listen),
 /// 		(manager_block_hash, &mut manager as &mut dyn chain::Listen),
@@ -92,7 +91,7 @@ use lightning::chain;
 /// 		block_source, Network::Bitcoin, &mut cache, listeners).await.unwrap();
 ///
 /// 	// Allow the chain monitor to watch any channels.
-/// 	let monitor = monitor_listener.0.into_inner();
+/// 	let monitor = monitor_listener.0;
 /// 	chain_monitor.watch_channel(monitor.get_funding_txo().0, monitor);
 ///
 /// 	// Create an SPV client to notify the chain monitor and channel manager of block events.

lightning/src/chain/chainmonitor.rs

@@ -43,7 +43,7 @@ use util::events;
 use util::events::Event;
 
 use std::collections::{HashMap, hash_map};
-use std::sync::Mutex;
+use std::sync::RwLock;
 use std::ops::Deref;
 
 /// An implementation of [`chain::Watch`] for monitoring channels.
@@ -64,7 +64,7 @@ pub struct ChainMonitor<ChannelSigner: Sign, C: Deref, T: Deref, F: Deref, L: De
         P::Target: channelmonitor::Persist<ChannelSigner>,
 {
 	/// The monitors
-	pub monitors: Mutex<HashMap<OutPoint, ChannelMonitor<ChannelSigner>>>,
+	pub monitors: RwLock<HashMap<OutPoint, ChannelMonitor<ChannelSigner>>>,
 	chain_source: Option<C>,
 	broadcaster: T,
 	logger: L,
@@ -93,8 +93,8 @@ where C::Target: chain::Filter,
 	/// [`chain::Watch::release_pending_monitor_events`]: ../trait.Watch.html#tymethod.release_pending_monitor_events
 	/// [`chain::Filter`]: ../trait.Filter.html
 	pub fn block_connected(&self, header: &BlockHeader, txdata: &TransactionData, height: u32) {
-		let mut monitors = self.monitors.lock().unwrap();
-		for monitor in monitors.values_mut() {
+		let monitors = self.monitors.read().unwrap();
+		for monitor in monitors.values() {
 			let mut txn_outputs = monitor.block_connected(header, txdata, height, &*self.broadcaster, &*self.fee_estimator, &*self.logger);
 
 			if let Some(ref chain_source) = self.chain_source {
@@ -113,8 +113,8 @@ where C::Target: chain::Filter,
 	///
 	/// [`ChannelMonitor::block_disconnected`]: ../channelmonitor/struct.ChannelMonitor.html#method.block_disconnected
 	pub fn block_disconnected(&self, header: &BlockHeader, disconnected_height: u32) {
-		let mut monitors = self.monitors.lock().unwrap();
-		for monitor in monitors.values_mut() {
+		let monitors = self.monitors.read().unwrap();
+		for monitor in monitors.values() {
 			monitor.block_disconnected(header, disconnected_height, &*self.broadcaster, &*self.fee_estimator, &*self.logger);
 		}
 	}
@@ -130,7 +130,7 @@ where C::Target: chain::Filter,
 	/// [`chain::Filter`]: ../trait.Filter.html
 	pub fn new(chain_source: Option<C>, broadcaster: T, logger: L, feeest: F, persister: P) -> Self {
 		Self {
-			monitors: Mutex::new(HashMap::new()),
+			monitors: RwLock::new(HashMap::new()),
 			chain_source,
 			broadcaster,
 			logger,
@@ -177,7 +177,7 @@ where C::Target: chain::Filter,
 	///
 	/// [`chain::Filter`]: ../trait.Filter.html
 	fn watch_channel(&self, funding_outpoint: OutPoint, monitor: ChannelMonitor<ChannelSigner>) -> Result<(), ChannelMonitorUpdateErr> {
-		let mut monitors = self.monitors.lock().unwrap();
+		let mut monitors = self.monitors.write().unwrap();
 		let entry = match monitors.entry(funding_outpoint) {
 			hash_map::Entry::Occupied(_) => {
 				log_error!(self.logger, "Failed to add new channel data: channel monitor for given outpoint is already present");
@@ -209,8 +209,8 @@ where C::Target: chain::Filter,
 	/// `ChainMonitor` monitors lock.
 	fn update_channel(&self, funding_txo: OutPoint, update: ChannelMonitorUpdate) -> Result<(), ChannelMonitorUpdateErr> {
 		// Update the monitor that watches the channel referred to by the given outpoint.
-		let mut monitors = self.monitors.lock().unwrap();
-		match monitors.get_mut(&funding_txo) {
+		let monitors = self.monitors.read().unwrap();
+		match monitors.get(&funding_txo) {
 			None => {
 				log_error!(self.logger, "Failed to update channel monitor: no such monitor registered");
 
@@ -222,15 +222,15 @@ where C::Target: chain::Filter,
 				#[cfg(not(any(test, feature = "fuzztarget")))]
 				Err(ChannelMonitorUpdateErr::PermanentFailure)
 			},
-			Some(orig_monitor) => {
-				log_trace!(self.logger, "Updating Channel Monitor for channel {}", log_funding_info!(orig_monitor));
-				let update_res = orig_monitor.update_monitor(&update, &self.broadcaster, &self.fee_estimator, &self.logger);
+			Some(monitor) => {
+				log_trace!(self.logger, "Updating Channel Monitor for channel {}", log_funding_info!(monitor));
+				let update_res = monitor.update_monitor(&update, &self.broadcaster, &self.fee_estimator, &self.logger);
 				if let Err(e) = &update_res {
 					log_error!(self.logger, "Failed to update channel monitor: {:?}", e);
 				}
 				// Even if updating the monitor returns an error, the monitor's state will
 				// still be changed. So, persist the updated monitor despite the error.
-				let persist_res = self.persister.update_persisted_channel(funding_txo, &update, orig_monitor);
+				let persist_res = self.persister.update_persisted_channel(funding_txo, &update, monitor);
 				if let Err(ref e) = persist_res {
 					log_error!(self.logger, "Failed to persist channel monitor update: {:?}", e);
 				}
@@ -245,8 +245,8 @@ where C::Target: chain::Filter,
 
 	fn release_pending_monitor_events(&self) -> Vec<MonitorEvent> {
 		let mut pending_monitor_events = Vec::new();
-		for chan in self.monitors.lock().unwrap().values_mut() {
-			pending_monitor_events.append(&mut chan.get_and_clear_pending_monitor_events());
+		for monitor in self.monitors.read().unwrap().values() {
+			pending_monitor_events.append(&mut monitor.get_and_clear_pending_monitor_events());
 		}
 		pending_monitor_events
 	}
@@ -261,8 +261,8 @@ impl<ChannelSigner: Sign, C: Deref, T: Deref, F: Deref, L: Deref, P: Deref> even
 {
 	fn get_and_clear_pending_events(&self) -> Vec<Event> {
 		let mut pending_events = Vec::new();
-		for chan in self.monitors.lock().unwrap().values_mut() {
-			pending_events.append(&mut chan.get_and_clear_pending_events());
+		for monitor in self.monitors.read().unwrap().values() {
+			pending_events.append(&mut monitor.get_and_clear_pending_events());
 		}
 		pending_events
 	}