Remove last_synced_height from cbf

Previously we tracked synced height and also had dirty flag for rescan
which was made from the genesis block. This was removed in favor of
block heights from channel manager and onchain wallet.

Safety reorg interval of 7 blocks (look-back) is added.

Force tests use CBF config with 1 required peers, as otherwise it would
die if one of two required peers went offline (which made impossible
testing of scenarios with 2 nodes on which goes offline).

Author: randomlogin

src/chain/cbf.rs

@@ -7,7 +7,7 @@
 
 use std::collections::{BTreeMap, HashMap};
 use std::net::SocketAddr;
-use std::sync::atomic::{AtomicBool, AtomicU32, Ordering};
+use std::sync::atomic::{AtomicU32, Ordering};
 use std::sync::{Arc, Mutex, RwLock};
 use std::time::{Duration, Instant, SystemTime, UNIX_EPOCH};
 
@@ -43,6 +43,11 @@ const MIN_FEERATE_SAT_PER_KWU: u64 = 250;
 /// Number of recent blocks to look back for per-target fee rate estimation.
 const FEE_RATE_LOOKBACK_BLOCKS: usize = 6;
 
+/// Number of blocks to walk back from a component's persisted best block height
+/// for reorg safety when computing the incremental scan skip height.
+/// Matches bdk-kyoto's `IMPOSSIBLE_REORG_DEPTH`.
+const REORG_SAFETY_BLOCKS: u32 = 7;
+
 /// The fee estimation back-end used by the CBF chain source.
 enum FeeSource {
 	/// Derive fee rates from the coinbase reward of recent blocks.
@@ -82,12 +87,6 @@ pub(super) struct CbfChainSource {
 	scan_lock: tokio::sync::Mutex<()>,
 	/// Scripts registered by LDK's Filter trait for lightning channel monitoring.
 	registered_scripts: Mutex<Vec<ScriptBuf>>,
-	/// Set when new scripts are registered; forces a full rescan on next lightning sync.
-	lightning_scripts_dirty: AtomicBool,
-	/// Last block height reached by on-chain wallet sync, used for incremental scans.
-	last_onchain_synced_height: Mutex<Option<u32>>,
-	/// Last block height reached by lightning wallet sync, used for incremental scans.
-	last_lightning_synced_height: Mutex<Option<u32>>,
 	/// Deduplicates concurrent on-chain wallet sync requests.
 	onchain_wallet_sync_status: Mutex<WalletSyncStatus>,
 	/// Deduplicates concurrent lightning wallet sync requests.
@@ -146,10 +145,7 @@ impl CbfChainSource {
 		let sync_completion_tx = Arc::new(Mutex::new(None));
 		let filter_skip_height = Arc::new(AtomicU32::new(0));
 		let registered_scripts = Mutex::new(Vec::new());
-		let lightning_scripts_dirty = AtomicBool::new(true);
 		let scan_lock = tokio::sync::Mutex::new(());
-		let last_onchain_synced_height = Mutex::new(None);
-		let last_lightning_synced_height = Mutex::new(None);
 		let onchain_wallet_sync_status = Mutex::new(WalletSyncStatus::Completed);
 		let lightning_wallet_sync_status = Mutex::new(WalletSyncStatus::Completed);
 		Ok(Self {
@@ -163,10 +159,7 @@ impl CbfChainSource {
 			sync_completion_tx,
 			filter_skip_height,
 			registered_scripts,
-			lightning_scripts_dirty,
 			scan_lock,
-			last_onchain_synced_height,
-			last_lightning_synced_height,
 			onchain_wallet_sync_status,
 			lightning_wallet_sync_status,
 			fee_estimator,
@@ -309,6 +302,10 @@ impl CbfChainSource {
 							reorganized.len(),
 							accepted.len(),
 						);
+
+						// No height reset needed: skip heights are derived from
+						// BDK's checkpoint (on-chain) and LDK's best block
+						// (lightning), both walked back by REORG_SAFETY_BLOCKS.
 					},
 					BlockHeaderChanges::Connected(header) => {
 						log_trace!(logger, "CBF block connected at height {}", header.height,);
@@ -353,13 +350,11 @@ impl CbfChainSource {
 	/// Register a transaction script for Lightning channel monitoring.
 	pub(crate) fn register_tx(&self, _txid: &Txid, script_pubkey: &Script) {
 		self.registered_scripts.lock().unwrap().push(script_pubkey.to_owned());
-		self.lightning_scripts_dirty.store(true, Ordering::Release);
 	}
 
 	/// Register a watched output script for Lightning channel monitoring.
 	pub(crate) fn register_output(&self, output: WatchedOutput) {
 		self.registered_scripts.lock().unwrap().push(output.script_pubkey.clone());
-		self.lightning_scripts_dirty.store(true, Ordering::Release);
 	}
 
 	/// Run a CBF filter scan: set watched scripts, trigger a rescan, wait for
@@ -429,7 +424,7 @@ impl CbfChainSource {
 				Duration::from_secs(
 					self.sync_config.timeouts_config.onchain_wallet_sync_timeout_secs,
 				),
-				self.sync_onchain_wallet_op(requester, scripts),
+				self.sync_onchain_wallet_op(requester, &onchain_wallet, scripts),
 			);
 
 			let (tx_update, sync_update) = match timeout_fut.await {
@@ -484,12 +479,11 @@ impl CbfChainSource {
 	}
 
 	async fn sync_onchain_wallet_op(
-		&self, requester: Requester, scripts: Vec<ScriptBuf>,
+		&self, requester: Requester, onchain_wallet: &Wallet, scripts: Vec<ScriptBuf>,
 	) -> Result<(TxUpdate<ConfirmationBlockTime>, SyncUpdate), Error> {
-		// Always do a full scan (skip_height=None) for the on-chain wallet.
-		// Unlike the Lightning wallet which can rely on reorg_queue events,
-		// the on-chain wallet needs to see all blocks to correctly detect
-		// reorgs via checkpoint comparison in the caller.
+		// Derive skip height from BDK's persisted checkpoint, walked back by
+		// REORG_SAFETY_BLOCKS for reorg safety (same approach as bdk-kyoto).
+		// This survives restarts since BDK persists its checkpoint chain.
 		//
 		// We include LDK-registered scripts (e.g., channel funding output
 		// scripts) alongside the wallet scripts. This ensures the on-chain
@@ -501,9 +495,10 @@ impl CbfChainSource {
 		// unknown. This mirrors what the Bitcoind chain source does in
 		// `Wallet::block_connected` by inserting registered tx outputs.
 		let mut all_scripts = scripts;
-		// we query all registered scripts, not only BDK-related
 		all_scripts.extend(self.registered_scripts.lock().unwrap().iter().cloned());
-		let (sync_update, matched) = self.run_filter_scan(all_scripts, None).await?;
+		let skip_height =
+			onchain_wallet.latest_checkpoint().height().checked_sub(REORG_SAFETY_BLOCKS);
+		let (sync_update, matched) = self.run_filter_scan(all_scripts, skip_height).await?;
 
 		log_debug!(
 			self.logger,
@@ -532,9 +527,6 @@ impl CbfChainSource {
 			}
 		}
 
-		let tip = sync_update.tip();
-		*self.last_onchain_synced_height.lock().unwrap() = Some(tip.height);
-
 		Ok((tx_update, sync_update))
 	}
 
@@ -615,9 +607,8 @@ impl CbfChainSource {
 		&self, requester: Requester, channel_manager: Arc<ChannelManager>,
 		chain_monitor: Arc<ChainMonitor>, output_sweeper: Arc<Sweeper>, scripts: Vec<ScriptBuf>,
 	) -> Result<(), Error> {
-		let scripts_dirty = self.lightning_scripts_dirty.load(Ordering::Acquire);
 		let skip_height =
-			if scripts_dirty { None } else { *self.last_lightning_synced_height.lock().unwrap() };
+			channel_manager.current_best_block().height.checked_sub(REORG_SAFETY_BLOCKS);
 		let (sync_update, matched) = self.run_filter_scan(scripts, skip_height).await?;
 
 		log_debug!(
@@ -652,9 +643,6 @@ impl CbfChainSource {
 			}
 		}
 
-		*self.last_lightning_synced_height.lock().unwrap() = Some(tip.height);
-		self.lightning_scripts_dirty.store(false, Ordering::Release);
-
 		Ok(())
 	}
 

tests/common/mod.rs

@@ -509,6 +509,7 @@ pub(crate) fn setup_node(chain_source: &TestChainSource, config: TestConfig) ->
 			let sync_config = CbfSyncConfig {
 				background_sync_config: None,
 				timeouts_config,
+				required_peers: 1,
 				..Default::default()
 			};
 			builder.set_chain_source_cbf(vec![peer_addr], Some(sync_config), None);