Add a method to prune stale channels from NetworkGraph

lightning-background-processor/Cargo.toml

@@ -11,7 +11,7 @@ edition = "2018"
 
 [dependencies]
 bitcoin = "0.27"
-lightning = { version = "0.0.103", path = "../lightning", features = ["allow_wallclock_use"] }
+lightning = { version = "0.0.103", path = "../lightning", features = ["std"] }
 lightning-persister = { version = "0.0.103", path = "../lightning-persister" }
 
 [dev-dependencies]

lightning-background-processor/src/lib.rs

@@ -34,6 +34,8 @@ use std::ops::Deref;
 ///   [`ChannelManager`] persistence should be done in the background.
 /// * Calling [`ChannelManager::timer_tick_occurred`] and [`PeerManager::timer_tick_occurred`]
 ///   at the appropriate intervals.
+/// * Calling [`NetworkGraph::remove_stale_channels`] (if a [`NetGraphMsgHandler`] is provided to
+///   [`BackgroundProcessor::start`]).
 ///
 /// It will also call [`PeerManager::process_events`] periodically though this shouldn't be relied
 /// upon as doing so may result in high latency.
@@ -68,6 +70,9 @@ const PING_TIMER: u64 = 30;
 #[cfg(test)]
 const PING_TIMER: u64 = 1;
 
+/// Prune the network graph of stale entries hourly.
+const NETWORK_PRUNE_TIMER: u64 = 60 * 60;
+
 /// Trait which handles persisting a [`ChannelManager`] to disk.
 ///
 /// [`ChannelManager`]: lightning::ln::channelmanager::ChannelManager
@@ -203,13 +208,16 @@ impl BackgroundProcessor {
 		let stop_thread = Arc::new(AtomicBool::new(false));
 		let stop_thread_clone = stop_thread.clone();
 		let handle = thread::spawn(move || -> Result<(), std::io::Error> {
-			let event_handler = DecoratingEventHandler { event_handler, net_graph_msg_handler };
+			let event_handler = DecoratingEventHandler { event_handler, net_graph_msg_handler: net_graph_msg_handler.as_ref().map(|t| t.deref()) };
 
 			log_trace!(logger, "Calling ChannelManager's timer_tick_occurred on startup");
 			channel_manager.timer_tick_occurred();
 
 			let mut last_freshness_call = Instant::now();
 			let mut last_ping_call = Instant::now();
+			let mut last_prune_call = Instant::now();
+			let mut have_pruned = false;
+
 			loop {
 				peer_manager.process_events();
 				channel_manager.process_pending_events(&event_handler);
@@ -247,6 +255,19 @@ impl BackgroundProcessor {
 					peer_manager.timer_tick_occurred();
 					last_ping_call = Instant::now();
 				}
+
+				// Note that we want to run a graph prune once not long after startup before
+				// falling back to our usual hourly prunes. This avoids short-lived clients never
+				// pruning their network graph. We run once 60 seconds after startup before
+				// continuing our normal cadence.
+				if last_prune_call.elapsed().as_secs() > if have_pruned { NETWORK_PRUNE_TIMER } else { 60 } {
+					if let Some(ref handler) = net_graph_msg_handler {
+						log_trace!(logger, "Pruning network graph of stale entries");
+						handler.network_graph().remove_stale_channels();
+						last_prune_call = Instant::now();
+						have_pruned = true;
+					}
+				}
 			}
 		});
 		Self { stop_thread: stop_thread_clone, thread_handle: Some(handle) }

lightning/Cargo.toml

@@ -11,7 +11,6 @@ Still missing tons of error-handling. See GitHub issues for suggested projects i
 """
 
 [features]
-allow_wallclock_use = []
 fuzztarget = ["bitcoin/fuzztarget", "regex"]
 # Internal test utilities exposed to other repo crates
 _test_utils = ["hex", "regex", "bitcoin/bitcoinconsensus"]
@@ -53,6 +52,3 @@ secp256k1 = { version = "0.20.2", default-features = false, features = ["alloc"]
 version = "0.27"
 default-features = false
 features = ["bitcoinconsensus", "secp-recovery"]
-
-[package.metadata.docs.rs]
-features = ["allow_wallclock_use"] # When https://github.com/rust-lang/rust/issues/43781 complies with our MSVR, we can add nice banners in the docs for the methods behind this feature-gate.

lightning/src/ln/channelmanager.rs

@@ -67,10 +67,11 @@ use io::{Cursor, Read};
 use sync::{Arc, Condvar, Mutex, MutexGuard, RwLock, RwLockReadGuard};
 use core::sync::atomic::{AtomicUsize, Ordering};
 use core::time::Duration;
-#[cfg(any(test, feature = "allow_wallclock_use"))]
-use std::time::Instant;
 use core::ops::Deref;
 
+#[cfg(any(test, feature = "std"))]
+use std::time::Instant;
+
 // We hold various information about HTLC relay in the HTLC objects in Channel itself:
 //
 // Upon receipt of an HTLC from a peer, we'll give it a PendingHTLCStatus indicating if it should
@@ -5110,8 +5111,9 @@ where
 	/// indicating whether persistence is necessary. Only one listener on
 	/// `await_persistable_update` or `await_persistable_update_timeout` is guaranteed to be woken
 	/// up.
-	/// Note that the feature `allow_wallclock_use` must be enabled to use this function.
-	#[cfg(any(test, feature = "allow_wallclock_use"))]
+	///
+	/// Note that this method is not available with the `no-std` feature.
+	#[cfg(any(test, feature = "std"))]
 	pub fn await_persistable_update_timeout(&self, max_wait: Duration) -> bool {
 		self.persistence_notifier.wait_timeout(max_wait)
 	}
@@ -5406,7 +5408,7 @@ impl PersistenceNotifier {
 		}
 	}
 
-	#[cfg(any(test, feature = "allow_wallclock_use"))]
+	#[cfg(any(test, feature = "std"))]
 	fn wait_timeout(&self, max_wait: Duration) -> bool {
 		let current_time = Instant::now();
 		loop {