Enforce successful initial fee update

So far we'd immediately start background syncing wallets and the fee
cache upon `start()` which
would work fine, except when these initial syncs failed, in which case
we'd use our fallback fee. This might lead to being disconnected
from peers as our fallback values are likely out of current fee ranges.

To mitigate this we here simply enforce that an initial fee rate update in
`start()` is successful.

Additionally, we make the fee rate cache update
interval configurable.

Author: tnull

bindings/ldk_node.udl

@@ -8,6 +8,7 @@ dictionary Config {
 	u32 default_cltv_expiry_delta;
 	u64 onchain_wallet_sync_interval_secs;
 	u64 wallet_sync_interval_secs;
+	u64 fee_rate_cache_update_interval_secs;
 	LogLevel log_level;
 };
 

src/lib.rs

@@ -175,6 +175,7 @@ const DEFAULT_LISTENING_ADDR: &str = "0.0.0.0:9735";
 const DEFAULT_CLTV_EXPIRY_DELTA: u32 = 144;
 const DEFAULT_BDK_WALLET_SYNC_INTERVAL_SECS: u64 = 60;
 const DEFAULT_LDK_WALLET_SYNC_INTERVAL_SECS: u64 = 20;
+const DEFAULT_FEE_RATE_CACHE_UPDATE_INTERVAL_SECS: u64 = 60 * 60;
 const DEFAULT_LOG_LEVEL: LogLevel = LogLevel::Debug;
 
 // The 'stop gap' parameter used by BDK's wallet sync. This seems to configure the threshold
@@ -218,6 +219,7 @@ const WALLET_KEYS_SEED_LEN: usize = 64;
 /// | `default_cltv_expiry_delta`            | 144              |
 /// | `onchain_wallet_sync_interval_secs`    | 60               |
 /// | `wallet_sync_interval_secs`            | 20               |
+/// | `fee_rate_cache_update_interval_secs`  | 3600             |
 /// | `log_level`                            | `Debug`          |
 ///
 pub struct Config {
@@ -237,6 +239,10 @@ pub struct Config {
 	///
 	/// **Note:** A minimum of 10 seconds is always enforced.
 	pub wallet_sync_interval_secs: u64,
+	/// The time in-between background update attempts to our fee rate cache, in seconds.
+	///
+	/// **Note:** A minimum of 10 seconds is always enforced.
+	pub fee_rate_cache_update_interval_secs: u64,
 	/// The level at which we log messages.
 	///
 	/// Any messages below this level will be excluded from the logs.
@@ -252,6 +258,7 @@ impl Default for Config {
 			default_cltv_expiry_delta: DEFAULT_CLTV_EXPIRY_DELTA,
 			onchain_wallet_sync_interval_secs: DEFAULT_BDK_WALLET_SYNC_INTERVAL_SECS,
 			wallet_sync_interval_secs: DEFAULT_LDK_WALLET_SYNC_INTERVAL_SECS,
+			fee_rate_cache_update_interval_secs: DEFAULT_FEE_RATE_CACHE_UPDATE_INTERVAL_SECS,
 			log_level: DEFAULT_LOG_LEVEL,
 		}
 	}
@@ -785,12 +792,35 @@ impl<K: KVStore + Sync + Send + 'static> Node<K> {
 
 		let runtime = tokio::runtime::Builder::new_multi_thread().enable_all().build().unwrap();
 
+		// Block to ensure we update our fee rate cache once on startup
+		let wallet = Arc::clone(&self.wallet);
+		let sync_logger = Arc::clone(&self.logger);
+		runtime.block_on(async move {
+			let now = Instant::now();
+			match wallet.update_fee_estimates().await {
+				Ok(()) => {
+					log_info!(
+						sync_logger,
+						"Initial fee rate cache update finished in {}ms.",
+						now.elapsed().as_millis()
+					);
+					Ok(())
+				}
+				Err(e) => {
+					log_error!(sync_logger, "Initial fee rate cache update failed: {}", e,);
+					Err(e)
+				}
+			}
+		})?;
+
 		// Setup wallet sync
 		let wallet = Arc::clone(&self.wallet);
 		let sync_logger = Arc::clone(&self.logger);
 		let mut stop_sync = self.stop_receiver.clone();
 		let onchain_wallet_sync_interval_secs =
 			self.config.onchain_wallet_sync_interval_secs.max(WALLET_SYNC_INTERVAL_MINIMUM_SECS);
+		let fee_rate_cache_update_interval_secs =
+			self.config.fee_rate_cache_update_interval_secs.max(WALLET_SYNC_INTERVAL_MINIMUM_SECS);
 		std::thread::spawn(move || {
 			tokio::runtime::Builder::new_current_thread().enable_all().build().unwrap().block_on(
 				async move {
@@ -799,6 +829,11 @@ impl<K: KVStore + Sync + Send + 'static> Node<K> {
 					);
 					onchain_wallet_sync_interval
 						.set_missed_tick_behavior(tokio::time::MissedTickBehavior::Skip);
+					let mut fee_rate_update_interval = tokio::time::interval(Duration::from_secs(
+						fee_rate_cache_update_interval_secs,
+					));
+					// We just blocked on updating, so skip the first tick.
+					fee_rate_update_interval.reset();
 					loop {
 						let now = Instant::now();
 						tokio::select! {
@@ -821,6 +856,22 @@ impl<K: KVStore + Sync + Send + 'static> Node<K> {
 									}
 								}
 							}
+							_ = fee_rate_update_interval.tick() => {
+								match wallet.update_fee_estimates().await {
+									Ok(()) => log_trace!(
+										sync_logger,
+										"Background update of fee rate cache finished in {}ms.",
+										now.elapsed().as_millis()
+										),
+									Err(err) => {
+										log_error!(
+											sync_logger,
+											"Background update of fee rate cache failed: {}",
+											err
+											)
+									}
+								}
+							}
 						}
 					}
 				},

src/test/functional_tests.rs

@@ -399,7 +399,7 @@ fn onchain_spend_receive() {
 
 #[test]
 fn sign_verify_msg() {
-	let (_, electrsd) = setup_bitcoind_and_electrsd();
+	let (_bitcoind, electrsd) = setup_bitcoind_and_electrsd();
 	let esplora_url = format!("http://{}", electrsd.esplora_url.as_ref().unwrap());
 	let config = random_config();
 	let builder = Builder::from_config(config.clone());

src/wallet.rs

@@ -73,14 +73,6 @@ where
 			}
 		};
 
-		match self.update_fee_estimates().await {
-			Ok(()) => (),
-			Err(e) => {
-				log_error!(self.logger, "Fee estimation error: {}", e);
-				return Err(e);
-			}
-		}
-
 		let sync_options = SyncOptions { progress: None };
 		let wallet_lock = self.inner.lock().unwrap();
 		let res = match wallet_lock.sync(&self.blockchain, sync_options).await {