Add probing service

bindings/ldk_node.udl

@@ -13,6 +13,8 @@ typedef dictionary TorConfig;
 
 typedef interface NodeEntropy;
 
+typedef interface ProbingConfig;
+
 typedef enum WordCount;
 
 [Remote]
@@ -32,6 +34,18 @@ interface LogWriter {
 	void log(LogRecord record);
 };
 
+interface ProbingConfigBuilder {
+	[Name=high_degree]
+	constructor(u64 top_node_count);
+	[Name=random_walk]
+	constructor(u64 max_hops);
+	void set_interval(u64 secs);
+	void set_max_locked_msat(u64 max_msat);
+	void set_diversity_penalty_msat(u64 penalty_msat);
+	void set_cooldown(u64 secs);
+	ProbingConfig build();
+};
+
 interface Builder {
 	constructor();
 	[Name=from_config]
@@ -59,6 +73,7 @@ interface Builder {
 	void set_node_alias(string node_alias);
 	[Throws=BuildError]
 	void set_async_payments_role(AsyncPaymentsRole? role);
+	void set_probing_config(ProbingConfig config);
 	[Throws=BuildError]
 	Node build(NodeEntropy node_entropy);
 	[Throws=BuildError]

src/builder.rs

@@ -50,6 +50,7 @@ use crate::config::{
 	default_user_config, may_announce_channel, AnnounceError, AsyncPaymentsRole,
 	BitcoindRestClientConfig, Config, ElectrumSyncConfig, EsploraSyncConfig, HRNResolverConfig,
 	TorConfig, DEFAULT_ESPLORA_SERVER_URL, DEFAULT_LOG_FILENAME, DEFAULT_LOG_LEVEL,
+	DEFAULT_MAX_PROBE_AMOUNT_MSAT, DEFAULT_MIN_PROBE_AMOUNT_MSAT,
 };
 use crate::connection::ConnectionManager;
 use crate::entropy::NodeEntropy;
@@ -74,6 +75,10 @@ use crate::logger::{log_error, LdkLogger, LogLevel, LogWriter, Logger};
 use crate::message_handler::NodeCustomMessageHandler;
 use crate::payment::asynchronous::om_mailbox::OnionMessageMailbox;
 use crate::peer_store::PeerStore;
+use crate::probing::{
+	HighDegreeStrategy, Prober, ProbingConfig, ProbingStrategy, ProbingStrategyKind,
+	RandomWalkStrategy,
+};
 use crate::runtime::{Runtime, RuntimeSpawner};
 use crate::tx_broadcaster::TransactionBroadcaster;
 use crate::types::{
@@ -306,6 +311,7 @@ pub struct NodeBuilder {
 	async_payments_role: Option<AsyncPaymentsRole>,
 	runtime_handle: Option<tokio::runtime::Handle>,
 	pathfinding_scores_sync_config: Option<PathfindingScoresSyncConfig>,
+	probing_config: Option<ProbingConfig>,
 }
 
 impl NodeBuilder {
@@ -323,6 +329,7 @@ impl NodeBuilder {
  let log_writer_config = None;
  let runtime_handle = None;
  let pathfinding_scores_sync_config = None;
+ let probing_config = None;
  Self {
  config,
  chain_data_source_config,
@@ -332,6 +339,7 @@ impl NodeBuilder {
  runtime_handle,
  async_payments_role: None,
  pathfinding_scores_sync_config,
+ probing_config,
  }
 	}
 
@@ -629,6 +637,31 @@ impl NodeBuilder {
  Ok(self)
 	}
 
+	/// Sets background probing config.
+	///
+	/// Use [`ProbingConfigBuilder`] to build the configuration:
+	/// ```no_run
+	/// # #[cfg(not(feature = "uniffi"))]
+	/// # {
+	/// use std::time::Duration;
+	/// use ldk_node::Builder;
+	/// use ldk_node::probing::ProbingConfigBuilder;
+	///
+	/// let mut builder = Builder::new();
+	/// builder.set_probing_config(
+	/// ProbingConfigBuilder::high_degree(100)
+	/// .interval(Duration::from_secs(30))
+	/// .build()
+	/// );
+	/// # }
+	/// ```
+	///
+	/// [`ProbingConfigBuilder`]: crate::probing::ProbingConfigBuilder
+	pub fn set_probing_config(&mut self, config: ProbingConfig) -> &mut Self {
+ self.probing_config = Some(config);
+ self
+	}
+
 	/// Builds a [`Node`] instance with a [`SqliteStore`] backend and according to the options
 	/// previously configured.
 	pub fn build(&self, node_entropy: NodeEntropy) -> Result<Node, BuildError> {
@@ -868,6 +901,7 @@ impl NodeBuilder {
  self.gossip_source_config.as_ref(),
  self.liquidity_source_config.as_ref(),
  self.pathfinding_scores_sync_config.as_ref(),
+ self.probing_config.as_ref(),
  self.async_payments_role,
  seed_bytes,
  runtime,
@@ -1166,6 +1200,15 @@ impl ArcedNodeBuilder {
  self.inner.write().expect("lock").set_async_payments_role(role).map(|_| ())
 	}
 
+	/// Configures background probing.
+	///
+	/// Use [`ProbingConfigBuilder`] to build the configuration.
+	///
+	/// [`ProbingConfigBuilder`]: crate::probing::ProbingConfigBuilder
+	pub fn set_probing_config(&self, config: Arc<ProbingConfig>) {
+ self.inner.write().expect("lock").set_probing_config((*config).clone());
+	}
+
 	/// Builds a [`Node`] instance with a [`SqliteStore`] backend and according to the options
 	/// previously configured.
 	pub fn build(&self, node_entropy: Arc<NodeEntropy>) -> Result<Arc<Node>, BuildError> {
@@ -1361,8 +1404,8 @@ fn build_with_store_internal(
 	gossip_source_config: Option<&GossipSourceConfig>,
 	liquidity_source_config: Option<&LiquiditySourceConfig>,
 	pathfinding_scores_sync_config: Option<&PathfindingScoresSyncConfig>,
-async_payments_role: Option<AsyncPaymentsRole>, seed_bytes: [u8; 64], runtime: Arc<Runtime>,
-	logger: Arc<Logger>, kv_store: Arc<DynStore>,
+probing_config: Option<&ProbingConfig>, async_payments_role: Option<AsyncPaymentsRole>,
+seed_bytes: [u8; 64], runtime: Arc<Runtime>, logger: Arc<Logger>, kv_store: Arc<DynStore>,
 ) -> Result<Node, BuildError> {
 	optionally_install_rustls_cryptoprovider();
 
@@ -2219,6 +2262,51 @@ fn build_with_store_internal(
  _leak_checker.0.push(Arc::downgrade(&wallet) as Weak<dyn Any + Send + Sync>);
 	}
 
+	let prober = probing_config.map(|probing_cfg| {
+ let strategy: Arc<dyn ProbingStrategy> = match &probing_cfg.kind {
+ ProbingStrategyKind::HighDegree { top_node_count } => {
+ // Dedicated router for probing so the diversity penalty doesn't interfere
+ // with real payments; shares the scorer so probe results still train it.
+ let mut probing_fee_params = ProbabilisticScoringFeeParameters::default();
+ if let Some(penalty) = probing_cfg.diversity_penalty_msat {
+ probing_fee_params.probing_diversity_penalty_msat = penalty;
+ }
+ let probing_router = Arc::new(DefaultRouter::new(
+ Arc::clone(&network_graph),
+ Arc::clone(&logger),
+ Arc::clone(&keys_manager),
+ Arc::clone(&scorer),
+ probing_fee_params,
+ ));
+ Arc::new(HighDegreeStrategy::new(
+ Arc::clone(&network_graph),
+ Arc::clone(&channel_manager),
+ probing_router,
+ *top_node_count,
+ DEFAULT_MIN_PROBE_AMOUNT_MSAT,
+ DEFAULT_MAX_PROBE_AMOUNT_MSAT,
+ probing_cfg.cooldown,
+ config.probing_liquidity_limit_multiplier,
+ ))
+ },
+ ProbingStrategyKind::RandomWalk { max_hops } => Arc::new(RandomWalkStrategy::new(
+ Arc::clone(&network_graph),
+ Arc::clone(&channel_manager),
+ *max_hops,
+ DEFAULT_MIN_PROBE_AMOUNT_MSAT,
+ DEFAULT_MAX_PROBE_AMOUNT_MSAT,
+ )),
+ ProbingStrategyKind::Custom(s) => Arc::clone(s),
+ };
+ Arc::new(Prober {
+ channel_manager: Arc::clone(&channel_manager),
+ logger: Arc::clone(&logger),
+ strategy,
+ interval: probing_cfg.interval,
+ max_locked_msat: probing_cfg.max_locked_msat,
+ })
+	});
+
 	Ok(Node {
  runtime,
  stop_sender,
@@ -2252,6 +2340,7 @@ fn build_with_store_internal(
  om_mailbox,
  async_payments_role,
  hrn_resolver,
+ prober,
  #[cfg(cycle_tests)]
  _leak_checker,
 	})

src/config.rs

@@ -28,6 +28,12 @@ const DEFAULT_BDK_WALLET_SYNC_INTERVAL_SECS: u64 = 80;
 const DEFAULT_LDK_WALLET_SYNC_INTERVAL_SECS: u64 = 30;
 const DEFAULT_FEE_RATE_CACHE_UPDATE_INTERVAL_SECS: u64 = 60 * 10;
 const DEFAULT_PROBING_LIQUIDITY_LIMIT_MULTIPLIER: u64 = 3;
+pub(crate) const DEFAULT_PROBING_INTERVAL_SECS: u64 = 10;
+pub(crate) const MIN_PROBING_INTERVAL: Duration = Duration::from_millis(100);
+pub(crate) const DEFAULT_PROBED_NODE_COOLDOWN_SECS: u64 = 60 * 60; // 1 hour
+pub(crate) const DEFAULT_MAX_PROBE_LOCKED_MSAT: u64 = 100_000_000; // 100k sats
+pub(crate) const DEFAULT_MIN_PROBE_AMOUNT_MSAT: u64 = 1_000_000; // 1k sats
+pub(crate) const DEFAULT_MAX_PROBE_AMOUNT_MSAT: u64 = 10_000_000; // 10k sats
 const DEFAULT_ANCHOR_PER_CHANNEL_RESERVE_SATS: u64 = 25_000;
 
 // The default timeout after which we abort a wallet syncing operation.

src/event.rs

@@ -52,6 +52,7 @@ use crate::payment::store::{
 	PaymentDetails, PaymentDetailsUpdate, PaymentDirection, PaymentKind, PaymentStatus,
 };
 use crate::payment::PaymentMetadata;
+use crate::probing::Prober;
 use crate::runtime::Runtime;
 use crate::types::{
 	CustomTlvRecord, DynStore, KeysManager, OnionMessenger, PaymentStore, Sweeper, Wallet,
@@ -536,12 +537,13 @@ where
 	payment_store: Arc<PaymentStore>,
 	peer_store: Arc<PeerStore<L>>,
 	keys_manager: Arc<KeysManager>,
-	runtime: Arc<Runtime>,
-	logger: L,
-	config: Arc<Config>,
 	static_invoice_store: Option<StaticInvoiceStore>,
 	onion_messenger: Arc<OnionMessenger>,
 	om_mailbox: Option<Arc<OnionMessageMailbox>>,
+	prober: Option<Arc<Prober>>,
+	runtime: Arc<Runtime>,
+	logger: L,
+	config: Arc<Config>,
 }
 
 impl<L: Deref + Clone + Sync + Send + 'static> EventHandler<L>
@@ -556,8 +558,8 @@ where
  liquidity_source: Arc<LiquiditySource<Arc<Logger>>>, payment_store: Arc<PaymentStore>,
  peer_store: Arc<PeerStore<L>>, keys_manager: Arc<KeysManager>,
  static_invoice_store: Option<StaticInvoiceStore>, onion_messenger: Arc<OnionMessenger>,
- om_mailbox: Option<Arc<OnionMessageMailbox>>, runtime: Arc<Runtime>, logger: L,
- config: Arc<Config>,
+ om_mailbox: Option<Arc<OnionMessageMailbox>>, prober: Option<Arc<Prober>>,
+runtime: Arc<Runtime>, logger: L, config: Arc<Config>,
 	) -> Self {
  Self {
  event_queue,
@@ -571,12 +573,13 @@ where
  payment_store,
  peer_store,
  keys_manager,
- logger,
- runtime,
- config,
  static_invoice_store,
  onion_messenger,
  om_mailbox,
+ prober,
+ runtime,
+ logger,
+ config,
  }
 	}
 
@@ -1208,8 +1211,16 @@ where
 
  LdkEvent::PaymentPathSuccessful { .. } => {},
  LdkEvent::PaymentPathFailed { .. } => {},
- LdkEvent::ProbeSuccessful { .. } => {},
- LdkEvent::ProbeFailed { .. } => {},
+ LdkEvent::ProbeSuccessful { path, payment_id, .. } => {
+ if let Some(prober) = &self.prober {
+ prober.handle_background_probe_successful(&path, payment_id);
+ }
+ },
+ LdkEvent::ProbeFailed { path, payment_id, .. } => {
+ if let Some(prober) = &self.prober {
+ prober.handle_background_probe_failed(&path, payment_id);
+ }
+ },
  LdkEvent::HTLCHandlingFailed { failure_type, .. } => {
  self.liquidity_source
  .lsps2_service()

src/ffi/types.rs

@@ -149,6 +149,7 @@ pub use crate::entropy::{generate_entropy_mnemonic, NodeEntropy, WordCount};
 use crate::error::Error;
 pub use crate::liquidity::LSPS1OrderStatus;
 pub use crate::logger::{LogLevel, LogRecord, LogWriter};
+pub use crate::probing::ProbingConfig;
 use crate::{hex_utils, SocketAddress, UserChannelId};
 
 uniffi::custom_type!(PublicKey, String, {

src/lib.rs

@@ -101,10 +101,12 @@ pub mod logger;
 mod message_handler;
 pub mod payment;
 mod peer_store;
+pub mod probing;
 mod runtime;
 mod scoring;
 mod tx_broadcaster;
 mod types;
+mod util;
 mod wallet;
 
 use std::default::Default;
@@ -172,6 +174,9 @@ use payment::{
 	UnifiedPayment,
 };
 use peer_store::{PeerInfo, PeerStore};
+#[cfg(feature = "uniffi")]
+pub use probing::ArcedProbingConfigBuilder as ProbingConfigBuilder;
+use probing::{run_prober, Prober};
 use runtime::Runtime;
 pub use tokio;
 use types::{
@@ -250,6 +255,7 @@ pub struct Node {
 	om_mailbox: Option<Arc<OnionMessageMailbox>>,
 	async_payments_role: Option<AsyncPaymentsRole>,
 	hrn_resolver: HRNResolver,
+	prober: Option<Arc<Prober>>,
 	#[cfg(cycle_tests)]
 	_leak_checker: LeakChecker,
 }
@@ -610,11 +616,19 @@ impl Node {
  static_invoice_store,
  Arc::clone(&self.onion_messenger),
  self.om_mailbox.clone(),
+ self.prober.clone(),
  Arc::clone(&self.runtime),
  Arc::clone(&self.logger),
  Arc::clone(&self.config),
  ));
 
+ if let Some(prober) = self.prober.clone() {
+ let stop_rx = self.stop_sender.subscribe();
+ self.runtime.spawn_cancellable_background_task(async move {
+ run_prober(prober, stop_rx).await;
+ });
+ }
+
  // Setup background processing
  let background_persister = Arc::clone(&self.kv_store);
  let background_event_handler = Arc::clone(&event_handler);
@@ -1145,6 +1159,11 @@ impl Node {
  ))
 	}
 
+	/// Returns a reference to the [`Prober`], or `None` if no probing strategy is configured.
+	pub fn prober(&self) -> Option<&Prober> {
+ self.prober.as_deref()
+	}
+
 	/// Retrieve a list of known channels.
 	pub fn list_channels(&self) -> Vec<ChannelDetails> {
  self.channel_manager

bindings/ldk_node.udl

@@ -13,6 +13,8 @@ typedef dictionary TorConfig;
 
 typedef interface NodeEntropy;
 
+typedef interface ProbingConfig;
+
 typedef enum WordCount;
 
 [Remote]
@@ -32,6 +34,18 @@ interface LogWriter {
 	void log(LogRecord record);
 };
 
+interface ProbingConfigBuilder {
+	[Name=high_degree]
+	constructor(u64 top_node_count);
+	[Name=random_walk]
+	constructor(u64 max_hops);
+	void set_interval(u64 secs);
+	void set_max_locked_msat(u64 max_msat);
+	void set_diversity_penalty_msat(u64 penalty_msat);
+	void set_cooldown(u64 secs);
+	ProbingConfig build();
+};
+
 interface Builder {
 	constructor();
 	[Name=from_config]
@@ -59,6 +73,7 @@ interface Builder {
 	void set_node_alias(string node_alias);
 	[Throws=BuildError]
 	void set_async_payments_role(AsyncPaymentsRole? role);
+	void set_probing_config(ProbingConfig config);
 	[Throws=BuildError]
 	Node build(NodeEntropy node_entropy);
 	[Throws=BuildError]

src/builder.rs

@@ -50,6 +50,7 @@ use crate::config::{
 	default_user_config, may_announce_channel, AnnounceError, AsyncPaymentsRole,
 	BitcoindRestClientConfig, Config, ElectrumSyncConfig, EsploraSyncConfig, HRNResolverConfig,
 	TorConfig, DEFAULT_ESPLORA_SERVER_URL, DEFAULT_LOG_FILENAME, DEFAULT_LOG_LEVEL,
+	DEFAULT_MAX_PROBE_AMOUNT_MSAT, DEFAULT_MIN_PROBE_AMOUNT_MSAT,
 };
 use crate::connection::ConnectionManager;
 use crate::entropy::NodeEntropy;
@@ -74,6 +75,10 @@ use crate::logger::{log_error, LdkLogger, LogLevel, LogWriter, Logger};
 use crate::message_handler::NodeCustomMessageHandler;
 use crate::payment::asynchronous::om_mailbox::OnionMessageMailbox;
 use crate::peer_store::PeerStore;
+use crate::probing::{
+	HighDegreeStrategy, Prober, ProbingConfig, ProbingStrategy, ProbingStrategyKind,
+	RandomWalkStrategy,
+};
 use crate::runtime::{Runtime, RuntimeSpawner};
 use crate::tx_broadcaster::TransactionBroadcaster;
 use crate::types::{
@@ -306,6 +311,7 @@ pub struct NodeBuilder {
 	async_payments_role: Option<AsyncPaymentsRole>,
 	runtime_handle: Option<tokio::runtime::Handle>,
 	pathfinding_scores_sync_config: Option<PathfindingScoresSyncConfig>,
+	probing_config: Option<ProbingConfig>,
 }
 
 impl NodeBuilder {
@@ -323,6 +329,7 @@ impl NodeBuilder {
  let log_writer_config = None;
  let runtime_handle = None;
  let pathfinding_scores_sync_config = None;
+ let probing_config = None;
  Self {
  config,
  chain_data_source_config,
@@ -332,6 +339,7 @@ impl NodeBuilder {
  runtime_handle,
  async_payments_role: None,
  pathfinding_scores_sync_config,
+ probing_config,
  }
 	}
 
@@ -629,6 +637,31 @@ impl NodeBuilder {
  Ok(self)
 	}
 
+	/// Sets background probing config.
+	///
+	/// Use [`ProbingConfigBuilder`] to build the configuration:
+	/// ```no_run
+	/// # #[cfg(not(feature = "uniffi"))]
+	/// # {
+	/// use std::time::Duration;
+	/// use ldk_node::Builder;
+	/// use ldk_node::probing::ProbingConfigBuilder;
+	///
+	/// let mut builder = Builder::new();
+	/// builder.set_probing_config(
+	/// ProbingConfigBuilder::high_degree(100)
+	/// .interval(Duration::from_secs(30))
+	/// .build()
+	/// );
+	/// # }
+	/// ```
+	///
+	/// [`ProbingConfigBuilder`]: crate::probing::ProbingConfigBuilder
+	pub fn set_probing_config(&mut self, config: ProbingConfig) -> &mut Self {
+ self.probing_config = Some(config);
+ self
+	}
+
 	/// Builds a [`Node`] instance with a [`SqliteStore`] backend and according to the options
 	/// previously configured.
 	pub fn build(&self, node_entropy: NodeEntropy) -> Result<Node, BuildError> {
@@ -868,6 +901,7 @@ impl NodeBuilder {
  self.gossip_source_config.as_ref(),
  self.liquidity_source_config.as_ref(),
  self.pathfinding_scores_sync_config.as_ref(),
+ self.probing_config.as_ref(),
  self.async_payments_role,
  seed_bytes,
  runtime,
@@ -1166,6 +1200,15 @@ impl ArcedNodeBuilder {
  self.inner.write().expect("lock").set_async_payments_role(role).map(|_| ())
 	}
 
+	/// Configures background probing.
+	///
+	/// Use [`ProbingConfigBuilder`] to build the configuration.
+	///
+	/// [`ProbingConfigBuilder`]: crate::probing::ProbingConfigBuilder
+	pub fn set_probing_config(&self, config: Arc<ProbingConfig>) {
+ self.inner.write().expect("lock").set_probing_config((*config).clone());
+	}
+
 	/// Builds a [`Node`] instance with a [`SqliteStore`] backend and according to the options
 	/// previously configured.
 	pub fn build(&self, node_entropy: Arc<NodeEntropy>) -> Result<Arc<Node>, BuildError> {
@@ -1361,8 +1404,8 @@ fn build_with_store_internal(
 	gossip_source_config: Option<&GossipSourceConfig>,
 	liquidity_source_config: Option<&LiquiditySourceConfig>,
 	pathfinding_scores_sync_config: Option<&PathfindingScoresSyncConfig>,
-async_payments_role: Option<AsyncPaymentsRole>, seed_bytes: [u8; 64], runtime: Arc<Runtime>,
-	logger: Arc<Logger>, kv_store: Arc<DynStore>,
+probing_config: Option<&ProbingConfig>, async_payments_role: Option<AsyncPaymentsRole>,
+seed_bytes: [u8; 64], runtime: Arc<Runtime>, logger: Arc<Logger>, kv_store: Arc<DynStore>,
 ) -> Result<Node, BuildError> {
 	optionally_install_rustls_cryptoprovider();
 
@@ -2219,6 +2262,51 @@ fn build_with_store_internal(
  _leak_checker.0.push(Arc::downgrade(&wallet) as Weak<dyn Any + Send + Sync>);
 	}
 
+	let prober = probing_config.map(|probing_cfg| {
+ let strategy: Arc<dyn ProbingStrategy> = match &probing_cfg.kind {
+ ProbingStrategyKind::HighDegree { top_node_count } => {
+ // Dedicated router for probing so the diversity penalty doesn't interfere
+ // with real payments; shares the scorer so probe results still train it.
+ let mut probing_fee_params = ProbabilisticScoringFeeParameters::default();
+ if let Some(penalty) = probing_cfg.diversity_penalty_msat {
+ probing_fee_params.probing_diversity_penalty_msat = penalty;
+ }
+ let probing_router = Arc::new(DefaultRouter::new(
+ Arc::clone(&network_graph),
+ Arc::clone(&logger),
+ Arc::clone(&keys_manager),
+ Arc::clone(&scorer),
+ probing_fee_params,
+ ));
+ Arc::new(HighDegreeStrategy::new(
+ Arc::clone(&network_graph),
+ Arc::clone(&channel_manager),
+ probing_router,
+ *top_node_count,
+ DEFAULT_MIN_PROBE_AMOUNT_MSAT,
+ DEFAULT_MAX_PROBE_AMOUNT_MSAT,
+ probing_cfg.cooldown,
+ config.probing_liquidity_limit_multiplier,
+ ))
+ },
+ ProbingStrategyKind::RandomWalk { max_hops } => Arc::new(RandomWalkStrategy::new(
+ Arc::clone(&network_graph),
+ Arc::clone(&channel_manager),
+ *max_hops,
+ DEFAULT_MIN_PROBE_AMOUNT_MSAT,
+ DEFAULT_MAX_PROBE_AMOUNT_MSAT,
+ )),
+ ProbingStrategyKind::Custom(s) => Arc::clone(s),
+ };
+ Arc::new(Prober {
+ channel_manager: Arc::clone(&channel_manager),
+ logger: Arc::clone(&logger),
+ strategy,
+ interval: probing_cfg.interval,
+ max_locked_msat: probing_cfg.max_locked_msat,
+ })
+	});
+
 	Ok(Node {
  runtime,
  stop_sender,
@@ -2252,6 +2340,7 @@ fn build_with_store_internal(
  om_mailbox,
  async_payments_role,
  hrn_resolver,
+ prober,
  #[cfg(cycle_tests)]
  _leak_checker,
 	})

src/config.rs

@@ -28,6 +28,12 @@ const DEFAULT_BDK_WALLET_SYNC_INTERVAL_SECS: u64 = 80;
 const DEFAULT_LDK_WALLET_SYNC_INTERVAL_SECS: u64 = 30;
 const DEFAULT_FEE_RATE_CACHE_UPDATE_INTERVAL_SECS: u64 = 60 * 10;
 const DEFAULT_PROBING_LIQUIDITY_LIMIT_MULTIPLIER: u64 = 3;
+pub(crate) const DEFAULT_PROBING_INTERVAL_SECS: u64 = 10;
+pub(crate) const MIN_PROBING_INTERVAL: Duration = Duration::from_millis(100);
+pub(crate) const DEFAULT_PROBED_NODE_COOLDOWN_SECS: u64 = 60 * 60; // 1 hour
+pub(crate) const DEFAULT_MAX_PROBE_LOCKED_MSAT: u64 = 100_000_000; // 100k sats
+pub(crate) const DEFAULT_MIN_PROBE_AMOUNT_MSAT: u64 = 1_000_000; // 1k sats
+pub(crate) const DEFAULT_MAX_PROBE_AMOUNT_MSAT: u64 = 10_000_000; // 10k sats
 const DEFAULT_ANCHOR_PER_CHANNEL_RESERVE_SATS: u64 = 25_000;
 
 // The default timeout after which we abort a wallet syncing operation.

src/event.rs

@@ -52,6 +52,7 @@ use crate::payment::store::{
 	PaymentDetails, PaymentDetailsUpdate, PaymentDirection, PaymentKind, PaymentStatus,
 };
 use crate::payment::PaymentMetadata;
+use crate::probing::Prober;
 use crate::runtime::Runtime;
 use crate::types::{
 	CustomTlvRecord, DynStore, KeysManager, OnionMessenger, PaymentStore, Sweeper, Wallet,
@@ -536,12 +537,13 @@ where
 	payment_store: Arc<PaymentStore>,
 	peer_store: Arc<PeerStore<L>>,
 	keys_manager: Arc<KeysManager>,
-	runtime: Arc<Runtime>,
-	logger: L,
-	config: Arc<Config>,
 	static_invoice_store: Option<StaticInvoiceStore>,
 	onion_messenger: Arc<OnionMessenger>,
 	om_mailbox: Option<Arc<OnionMessageMailbox>>,
+	prober: Option<Arc<Prober>>,
+	runtime: Arc<Runtime>,
+	logger: L,
+	config: Arc<Config>,
 }
 
 impl<L: Deref + Clone + Sync + Send + 'static> EventHandler<L>
@@ -556,8 +558,8 @@ where
  liquidity_source: Arc<LiquiditySource<Arc<Logger>>>, payment_store: Arc<PaymentStore>,
  peer_store: Arc<PeerStore<L>>, keys_manager: Arc<KeysManager>,
  static_invoice_store: Option<StaticInvoiceStore>, onion_messenger: Arc<OnionMessenger>,
- om_mailbox: Option<Arc<OnionMessageMailbox>>, runtime: Arc<Runtime>, logger: L,
- config: Arc<Config>,
+ om_mailbox: Option<Arc<OnionMessageMailbox>>, prober: Option<Arc<Prober>>,
+runtime: Arc<Runtime>, logger: L, config: Arc<Config>,
 	) -> Self {
  Self {
  event_queue,
@@ -571,12 +573,13 @@ where
  payment_store,
  peer_store,
  keys_manager,
- logger,
- runtime,
- config,
  static_invoice_store,
  onion_messenger,
  om_mailbox,
+ prober,
+ runtime,
+ logger,
+ config,
  }
 	}
 
@@ -1208,8 +1211,16 @@ where
 
  LdkEvent::PaymentPathSuccessful { .. } => {},
  LdkEvent::PaymentPathFailed { .. } => {},
- LdkEvent::ProbeSuccessful { .. } => {},
- LdkEvent::ProbeFailed { .. } => {},
+ LdkEvent::ProbeSuccessful { path, payment_id, .. } => {
+ if let Some(prober) = &self.prober {
+ prober.handle_background_probe_successful(&path, payment_id);
+ }
+ },
+ LdkEvent::ProbeFailed { path, payment_id, .. } => {
+ if let Some(prober) = &self.prober {
+ prober.handle_background_probe_failed(&path, payment_id);
+ }
+ },
  LdkEvent::HTLCHandlingFailed { failure_type, .. } => {
  self.liquidity_source
  .lsps2_service()

src/ffi/types.rs

@@ -149,6 +149,7 @@ pub use crate::entropy::{generate_entropy_mnemonic, NodeEntropy, WordCount};
 use crate::error::Error;
 pub use crate::liquidity::LSPS1OrderStatus;
 pub use crate::logger::{LogLevel, LogRecord, LogWriter};
+pub use crate::probing::ProbingConfig;
 use crate::{hex_utils, SocketAddress, UserChannelId};
 
 uniffi::custom_type!(PublicKey, String, {

src/lib.rs

@@ -101,10 +101,12 @@ pub mod logger;
 mod message_handler;
 pub mod payment;
 mod peer_store;
+pub mod probing;
 mod runtime;
 mod scoring;
 mod tx_broadcaster;
 mod types;
+mod util;
 mod wallet;
 
 use std::default::Default;
@@ -172,6 +174,9 @@ use payment::{
 	UnifiedPayment,
 };
 use peer_store::{PeerInfo, PeerStore};
+#[cfg(feature = "uniffi")]
+pub use probing::ArcedProbingConfigBuilder as ProbingConfigBuilder;
+use probing::{run_prober, Prober};
 use runtime::Runtime;
 pub use tokio;
 use types::{
@@ -250,6 +255,7 @@ pub struct Node {
 	om_mailbox: Option<Arc<OnionMessageMailbox>>,
 	async_payments_role: Option<AsyncPaymentsRole>,
 	hrn_resolver: HRNResolver,
+	prober: Option<Arc<Prober>>,
 	#[cfg(cycle_tests)]
 	_leak_checker: LeakChecker,
 }
@@ -610,11 +616,19 @@ impl Node {
  static_invoice_store,
  Arc::clone(&self.onion_messenger),
  self.om_mailbox.clone(),
+ self.prober.clone(),
  Arc::clone(&self.runtime),
  Arc::clone(&self.logger),
  Arc::clone(&self.config),
  ));
 
+ if let Some(prober) = self.prober.clone() {
+ let stop_rx = self.stop_sender.subscribe();
+ self.runtime.spawn_cancellable_background_task(async move {
+ run_prober(prober, stop_rx).await;
+ });
+ }
+
  // Setup background processing
  let background_persister = Arc::clone(&self.kv_store);
  let background_event_handler = Arc::clone(&event_handler);
@@ -1145,6 +1159,11 @@ impl Node {
  ))
 	}
 
+	/// Returns a reference to the [`Prober`], or `None` if no probing strategy is configured.
+	pub fn prober(&self) -> Option<&Prober> {
+ self.prober.as_deref()
+	}
+
 	/// Retrieve a list of known channels.
 	pub fn list_channels(&self) -> Vec<ChannelDetails> {
  self.channel_manager

bindings/ldk_node.udl

@@ -13,6 +13,8 @@ typedef dictionary TorConfig;
 
 typedef interface NodeEntropy;
 
+typedef interface ProbingConfig;
+
 typedef enum WordCount;
 
 [Remote]
@@ -32,6 +34,18 @@ interface LogWriter {
 	void log(LogRecord record);
 };
 
+interface ProbingConfigBuilder {
+	[Name=high_degree]
+	constructor(u64 top_node_count);
+	[Name=random_walk]
+	constructor(u64 max_hops);
+	void set_interval(u64 secs);
+	void set_max_locked_msat(u64 max_msat);
+	void set_diversity_penalty_msat(u64 penalty_msat);
+	void set_cooldown(u64 secs);
+	ProbingConfig build();
+};
+
 interface Builder {
 	constructor();
 	[Name=from_config]
@@ -59,6 +73,7 @@ interface Builder {
 	void set_node_alias(string node_alias);
 	[Throws=BuildError]
 	void set_async_payments_role(AsyncPaymentsRole? role);
+	void set_probing_config(ProbingConfig config);
 	[Throws=BuildError]
 	Node build(NodeEntropy node_entropy);
 	[Throws=BuildError]

src/builder.rs

@@ -50,6 +50,7 @@ use crate::config::{
 	default_user_config, may_announce_channel, AnnounceError, AsyncPaymentsRole,
 	BitcoindRestClientConfig, Config, ElectrumSyncConfig, EsploraSyncConfig, HRNResolverConfig,
 	TorConfig, DEFAULT_ESPLORA_SERVER_URL, DEFAULT_LOG_FILENAME, DEFAULT_LOG_LEVEL,
+	DEFAULT_MAX_PROBE_AMOUNT_MSAT, DEFAULT_MIN_PROBE_AMOUNT_MSAT,
 };
 use crate::connection::ConnectionManager;
 use crate::entropy::NodeEntropy;
@@ -74,6 +75,10 @@ use crate::logger::{log_error, LdkLogger, LogLevel, LogWriter, Logger};
 use crate::message_handler::NodeCustomMessageHandler;
 use crate::payment::asynchronous::om_mailbox::OnionMessageMailbox;
 use crate::peer_store::PeerStore;
+use crate::probing::{
+	HighDegreeStrategy, Prober, ProbingConfig, ProbingStrategy, ProbingStrategyKind,
+	RandomWalkStrategy,
+};
 use crate::runtime::{Runtime, RuntimeSpawner};
 use crate::tx_broadcaster::TransactionBroadcaster;
 use crate::types::{
@@ -306,6 +311,7 @@ pub struct NodeBuilder {
 	async_payments_role: Option<AsyncPaymentsRole>,
 	runtime_handle: Option<tokio::runtime::Handle>,
 	pathfinding_scores_sync_config: Option<PathfindingScoresSyncConfig>,
+	probing_config: Option<ProbingConfig>,
 }
 
 impl NodeBuilder {
@@ -323,6 +329,7 @@ impl NodeBuilder {
  let log_writer_config = None;
  let runtime_handle = None;
  let pathfinding_scores_sync_config = None;
+ let probing_config = None;
  Self {
  config,
  chain_data_source_config,
@@ -332,6 +339,7 @@ impl NodeBuilder {
  runtime_handle,
  async_payments_role: None,
  pathfinding_scores_sync_config,
+ probing_config,
  }
 	}
 
@@ -629,6 +637,31 @@ impl NodeBuilder {
  Ok(self)
 	}
 
+	/// Sets background probing config.
+	///
+	/// Use [`ProbingConfigBuilder`] to build the configuration:
+	/// ```no_run
+	/// # #[cfg(not(feature = "uniffi"))]
+	/// # {
+	/// use std::time::Duration;
+	/// use ldk_node::Builder;
+	/// use ldk_node::probing::ProbingConfigBuilder;
+	///
+	/// let mut builder = Builder::new();
+	/// builder.set_probing_config(
+	/// ProbingConfigBuilder::high_degree(100)
+	/// .interval(Duration::from_secs(30))
+	/// .build()
+	/// );
+	/// # }
+	/// ```
+	///
+	/// [`ProbingConfigBuilder`]: crate::probing::ProbingConfigBuilder
+	pub fn set_probing_config(&mut self, config: ProbingConfig) -> &mut Self {
+ self.probing_config = Some(config);
+ self
+	}
+
 	/// Builds a [`Node`] instance with a [`SqliteStore`] backend and according to the options
 	/// previously configured.
 	pub fn build(&self, node_entropy: NodeEntropy) -> Result<Node, BuildError> {
@@ -868,6 +901,7 @@ impl NodeBuilder {
  self.gossip_source_config.as_ref(),
  self.liquidity_source_config.as_ref(),
  self.pathfinding_scores_sync_config.as_ref(),
+ self.probing_config.as_ref(),
  self.async_payments_role,
  seed_bytes,
  runtime,
@@ -1166,6 +1200,15 @@ impl ArcedNodeBuilder {
  self.inner.write().expect("lock").set_async_payments_role(role).map(|_| ())
 	}
 
+	/// Configures background probing.
+	///
+	/// Use [`ProbingConfigBuilder`] to build the configuration.
+	///
+	/// [`ProbingConfigBuilder`]: crate::probing::ProbingConfigBuilder
+	pub fn set_probing_config(&self, config: Arc<ProbingConfig>) {
+ self.inner.write().expect("lock").set_probing_config((*config).clone());
+	}
+
 	/// Builds a [`Node`] instance with a [`SqliteStore`] backend and according to the options
 	/// previously configured.
 	pub fn build(&self, node_entropy: Arc<NodeEntropy>) -> Result<Arc<Node>, BuildError> {
@@ -1361,8 +1404,8 @@ fn build_with_store_internal(
 	gossip_source_config: Option<&GossipSourceConfig>,
 	liquidity_source_config: Option<&LiquiditySourceConfig>,
 	pathfinding_scores_sync_config: Option<&PathfindingScoresSyncConfig>,
-async_payments_role: Option<AsyncPaymentsRole>, seed_bytes: [u8; 64], runtime: Arc<Runtime>,
-	logger: Arc<Logger>, kv_store: Arc<DynStore>,
+probing_config: Option<&ProbingConfig>, async_payments_role: Option<AsyncPaymentsRole>,
+seed_bytes: [u8; 64], runtime: Arc<Runtime>, logger: Arc<Logger>, kv_store: Arc<DynStore>,
 ) -> Result<Node, BuildError> {
 	optionally_install_rustls_cryptoprovider();
 
@@ -2219,6 +2262,51 @@ fn build_with_store_internal(
  _leak_checker.0.push(Arc::downgrade(&wallet) as Weak<dyn Any + Send + Sync>);
 	}
 
+	let prober = probing_config.map(|probing_cfg| {
+ let strategy: Arc<dyn ProbingStrategy> = match &probing_cfg.kind {
+ ProbingStrategyKind::HighDegree { top_node_count } => {
+ // Dedicated router for probing so the diversity penalty doesn't interfere
+ // with real payments; shares the scorer so probe results still train it.
+ let mut probing_fee_params = ProbabilisticScoringFeeParameters::default();
+ if let Some(penalty) = probing_cfg.diversity_penalty_msat {
+ probing_fee_params.probing_diversity_penalty_msat = penalty;
+ }
+ let probing_router = Arc::new(DefaultRouter::new(
+ Arc::clone(&network_graph),
+ Arc::clone(&logger),
+ Arc::clone(&keys_manager),
+ Arc::clone(&scorer),
+ probing_fee_params,
+ ));
+ Arc::new(HighDegreeStrategy::new(
+ Arc::clone(&network_graph),
+ Arc::clone(&channel_manager),
+ probing_router,
+ *top_node_count,
+ DEFAULT_MIN_PROBE_AMOUNT_MSAT,
+ DEFAULT_MAX_PROBE_AMOUNT_MSAT,
+ probing_cfg.cooldown,
+ config.probing_liquidity_limit_multiplier,
+ ))
+ },
+ ProbingStrategyKind::RandomWalk { max_hops } => Arc::new(RandomWalkStrategy::new(
+ Arc::clone(&network_graph),
+ Arc::clone(&channel_manager),
+ *max_hops,
+ DEFAULT_MIN_PROBE_AMOUNT_MSAT,
+ DEFAULT_MAX_PROBE_AMOUNT_MSAT,
+ )),
+ ProbingStrategyKind::Custom(s) => Arc::clone(s),
+ };
+ Arc::new(Prober {
+ channel_manager: Arc::clone(&channel_manager),
+ logger: Arc::clone(&logger),
+ strategy,
+ interval: probing_cfg.interval,
+ max_locked_msat: probing_cfg.max_locked_msat,
+ })
+	});
+
 	Ok(Node {
  runtime,
  stop_sender,
@@ -2252,6 +2340,7 @@ fn build_with_store_internal(
  om_mailbox,
  async_payments_role,
  hrn_resolver,
+ prober,
  #[cfg(cycle_tests)]
  _leak_checker,
 	})

src/config.rs

@@ -28,6 +28,12 @@ const DEFAULT_BDK_WALLET_SYNC_INTERVAL_SECS: u64 = 80;
 const DEFAULT_LDK_WALLET_SYNC_INTERVAL_SECS: u64 = 30;
 const DEFAULT_FEE_RATE_CACHE_UPDATE_INTERVAL_SECS: u64 = 60 * 10;
 const DEFAULT_PROBING_LIQUIDITY_LIMIT_MULTIPLIER: u64 = 3;
+pub(crate) const DEFAULT_PROBING_INTERVAL_SECS: u64 = 10;
+pub(crate) const MIN_PROBING_INTERVAL: Duration = Duration::from_millis(100);
+pub(crate) const DEFAULT_PROBED_NODE_COOLDOWN_SECS: u64 = 60 * 60; // 1 hour
+pub(crate) const DEFAULT_MAX_PROBE_LOCKED_MSAT: u64 = 100_000_000; // 100k sats
+pub(crate) const DEFAULT_MIN_PROBE_AMOUNT_MSAT: u64 = 1_000_000; // 1k sats
+pub(crate) const DEFAULT_MAX_PROBE_AMOUNT_MSAT: u64 = 10_000_000; // 10k sats
 const DEFAULT_ANCHOR_PER_CHANNEL_RESERVE_SATS: u64 = 25_000;
 
 // The default timeout after which we abort a wallet syncing operation.

src/event.rs

@@ -52,6 +52,7 @@ use crate::payment::store::{
 	PaymentDetails, PaymentDetailsUpdate, PaymentDirection, PaymentKind, PaymentStatus,
 };
 use crate::payment::PaymentMetadata;
+use crate::probing::Prober;
 use crate::runtime::Runtime;
 use crate::types::{
 	CustomTlvRecord, DynStore, KeysManager, OnionMessenger, PaymentStore, Sweeper, Wallet,
@@ -536,12 +537,13 @@ where
 	payment_store: Arc<PaymentStore>,
 	peer_store: Arc<PeerStore<L>>,
 	keys_manager: Arc<KeysManager>,
-	runtime: Arc<Runtime>,
-	logger: L,
-	config: Arc<Config>,
 	static_invoice_store: Option<StaticInvoiceStore>,
 	onion_messenger: Arc<OnionMessenger>,
 	om_mailbox: Option<Arc<OnionMessageMailbox>>,
+	prober: Option<Arc<Prober>>,
+	runtime: Arc<Runtime>,
+	logger: L,
+	config: Arc<Config>,
 }
 
 impl<L: Deref + Clone + Sync + Send + 'static> EventHandler<L>
@@ -556,8 +558,8 @@ where
  liquidity_source: Arc<LiquiditySource<Arc<Logger>>>, payment_store: Arc<PaymentStore>,
  peer_store: Arc<PeerStore<L>>, keys_manager: Arc<KeysManager>,
  static_invoice_store: Option<StaticInvoiceStore>, onion_messenger: Arc<OnionMessenger>,
- om_mailbox: Option<Arc<OnionMessageMailbox>>, runtime: Arc<Runtime>, logger: L,
- config: Arc<Config>,
+ om_mailbox: Option<Arc<OnionMessageMailbox>>, prober: Option<Arc<Prober>>,
+runtime: Arc<Runtime>, logger: L, config: Arc<Config>,
 	) -> Self {
  Self {
  event_queue,
@@ -571,12 +573,13 @@ where
  payment_store,
  peer_store,
  keys_manager,
- logger,
- runtime,
- config,
  static_invoice_store,
  onion_messenger,
  om_mailbox,
+ prober,
+ runtime,
+ logger,
+ config,
  }
 	}
 
@@ -1208,8 +1211,16 @@ where
 
  LdkEvent::PaymentPathSuccessful { .. } => {},
  LdkEvent::PaymentPathFailed { .. } => {},
- LdkEvent::ProbeSuccessful { .. } => {},
- LdkEvent::ProbeFailed { .. } => {},
+ LdkEvent::ProbeSuccessful { path, payment_id, .. } => {
+ if let Some(prober) = &self.prober {
+ prober.handle_background_probe_successful(&path, payment_id);
+ }
+ },
+ LdkEvent::ProbeFailed { path, payment_id, .. } => {
+ if let Some(prober) = &self.prober {
+ prober.handle_background_probe_failed(&path, payment_id);
+ }
+ },
  LdkEvent::HTLCHandlingFailed { failure_type, .. } => {
  self.liquidity_source
  .lsps2_service()

src/ffi/types.rs

@@ -149,6 +149,7 @@ pub use crate::entropy::{generate_entropy_mnemonic, NodeEntropy, WordCount};
 use crate::error::Error;
 pub use crate::liquidity::LSPS1OrderStatus;
 pub use crate::logger::{LogLevel, LogRecord, LogWriter};
+pub use crate::probing::ProbingConfig;
 use crate::{hex_utils, SocketAddress, UserChannelId};
 
 uniffi::custom_type!(PublicKey, String, {

src/lib.rs

@@ -101,10 +101,12 @@ pub mod logger;
 mod message_handler;
 pub mod payment;
 mod peer_store;
+pub mod probing;
 mod runtime;
 mod scoring;
 mod tx_broadcaster;
 mod types;
+mod util;
 mod wallet;
 
 use std::default::Default;
@@ -172,6 +174,9 @@ use payment::{
 	UnifiedPayment,
 };
 use peer_store::{PeerInfo, PeerStore};
+#[cfg(feature = "uniffi")]
+pub use probing::ArcedProbingConfigBuilder as ProbingConfigBuilder;
+use probing::{run_prober, Prober};
 use runtime::Runtime;
 pub use tokio;
 use types::{
@@ -250,6 +255,7 @@ pub struct Node {
 	om_mailbox: Option<Arc<OnionMessageMailbox>>,
 	async_payments_role: Option<AsyncPaymentsRole>,
 	hrn_resolver: HRNResolver,
+	prober: Option<Arc<Prober>>,
 	#[cfg(cycle_tests)]
 	_leak_checker: LeakChecker,
 }
@@ -610,11 +616,19 @@ impl Node {
  static_invoice_store,
  Arc::clone(&self.onion_messenger),
  self.om_mailbox.clone(),
+ self.prober.clone(),
  Arc::clone(&self.runtime),
  Arc::clone(&self.logger),
  Arc::clone(&self.config),
  ));
 
+ if let Some(prober) = self.prober.clone() {
+ let stop_rx = self.stop_sender.subscribe();
+ self.runtime.spawn_cancellable_background_task(async move {
+ run_prober(prober, stop_rx).await;
+ });
+ }
+
  // Setup background processing
  let background_persister = Arc::clone(&self.kv_store);
  let background_event_handler = Arc::clone(&event_handler);
@@ -1145,6 +1159,11 @@ impl Node {
  ))
 	}
 
+	/// Returns a reference to the [`Prober`], or `None` if no probing strategy is configured.
+	pub fn prober(&self) -> Option<&Prober> {
+ self.prober.as_deref()
+	}
+
 	/// Retrieve a list of known channels.
 	pub fn list_channels(&self) -> Vec<ChannelDetails> {
  self.channel_manager

bindings/ldk_node.udl

@@ -13,6 +13,8 @@ typedef dictionary TorConfig;
 
 typedef interface NodeEntropy;
 
+typedef interface ProbingConfig;
+
 typedef enum WordCount;
 
 [Remote]
@@ -32,6 +34,18 @@ interface LogWriter {
 	void log(LogRecord record);
 };
 
+interface ProbingConfigBuilder {
+	[Name=high_degree]
+	constructor(u64 top_node_count);
+	[Name=random_walk]
+	constructor(u64 max_hops);
+	void set_interval(u64 secs);
+	void set_max_locked_msat(u64 max_msat);
+	void set_diversity_penalty_msat(u64 penalty_msat);
+	void set_cooldown(u64 secs);
+	ProbingConfig build();
+};
+
 interface Builder {
 	constructor();
 	[Name=from_config]
@@ -59,6 +73,7 @@ interface Builder {
 	void set_node_alias(string node_alias);
 	[Throws=BuildError]
 	void set_async_payments_role(AsyncPaymentsRole? role);
+	void set_probing_config(ProbingConfig config);
 	[Throws=BuildError]
 	Node build(NodeEntropy node_entropy);
 	[Throws=BuildError]

src/builder.rs

@@ -50,6 +50,7 @@ use crate::config::{
 	default_user_config, may_announce_channel, AnnounceError, AsyncPaymentsRole,
 	BitcoindRestClientConfig, Config, ElectrumSyncConfig, EsploraSyncConfig, HRNResolverConfig,
 	TorConfig, DEFAULT_ESPLORA_SERVER_URL, DEFAULT_LOG_FILENAME, DEFAULT_LOG_LEVEL,
+	DEFAULT_MAX_PROBE_AMOUNT_MSAT, DEFAULT_MIN_PROBE_AMOUNT_MSAT,
 };
 use crate::connection::ConnectionManager;
 use crate::entropy::NodeEntropy;
@@ -74,6 +75,10 @@ use crate::logger::{log_error, LdkLogger, LogLevel, LogWriter, Logger};
 use crate::message_handler::NodeCustomMessageHandler;
 use crate::payment::asynchronous::om_mailbox::OnionMessageMailbox;
 use crate::peer_store::PeerStore;
+use crate::probing::{
+	HighDegreeStrategy, Prober, ProbingConfig, ProbingStrategy, ProbingStrategyKind,
+	RandomWalkStrategy,
+};
 use crate::runtime::{Runtime, RuntimeSpawner};
 use crate::tx_broadcaster::TransactionBroadcaster;
 use crate::types::{
@@ -306,6 +311,7 @@ pub struct NodeBuilder {
 	async_payments_role: Option<AsyncPaymentsRole>,
 	runtime_handle: Option<tokio::runtime::Handle>,
 	pathfinding_scores_sync_config: Option<PathfindingScoresSyncConfig>,
+	probing_config: Option<ProbingConfig>,
 }
 
 impl NodeBuilder {
@@ -323,6 +329,7 @@ impl NodeBuilder {
  let log_writer_config = None;
  let runtime_handle = None;
  let pathfinding_scores_sync_config = None;
+ let probing_config = None;
  Self {
  config,
  chain_data_source_config,
@@ -332,6 +339,7 @@ impl NodeBuilder {
  runtime_handle,
  async_payments_role: None,
  pathfinding_scores_sync_config,
+ probing_config,
  }
 	}
 
@@ -629,6 +637,31 @@ impl NodeBuilder {
  Ok(self)
 	}
 
+	/// Sets background probing config.
+	///
+	/// Use [`ProbingConfigBuilder`] to build the configuration:
+	/// ```no_run
+	/// # #[cfg(not(feature = "uniffi"))]
+	/// # {
+	/// use std::time::Duration;
+	/// use ldk_node::Builder;
+	/// use ldk_node::probing::ProbingConfigBuilder;
+	///
+	/// let mut builder = Builder::new();
+	/// builder.set_probing_config(
+	/// ProbingConfigBuilder::high_degree(100)
+	/// .interval(Duration::from_secs(30))
+	/// .build()
+	/// );
+	/// # }
+	/// ```
+	///
+	/// [`ProbingConfigBuilder`]: crate::probing::ProbingConfigBuilder
+	pub fn set_probing_config(&mut self, config: ProbingConfig) -> &mut Self {
+ self.probing_config = Some(config);
+ self
+	}
+
 	/// Builds a [`Node`] instance with a [`SqliteStore`] backend and according to the options
 	/// previously configured.
 	pub fn build(&self, node_entropy: NodeEntropy) -> Result<Node, BuildError> {
@@ -868,6 +901,7 @@ impl NodeBuilder {
  self.gossip_source_config.as_ref(),
  self.liquidity_source_config.as_ref(),
  self.pathfinding_scores_sync_config.as_ref(),
+ self.probing_config.as_ref(),
  self.async_payments_role,
  seed_bytes,
  runtime,
@@ -1166,6 +1200,15 @@ impl ArcedNodeBuilder {
  self.inner.write().expect("lock").set_async_payments_role(role).map(|_| ())
 	}
 
+	/// Configures background probing.
+	///
+	/// Use [`ProbingConfigBuilder`] to build the configuration.
+	///
+	/// [`ProbingConfigBuilder`]: crate::probing::ProbingConfigBuilder
+	pub fn set_probing_config(&self, config: Arc<ProbingConfig>) {
+ self.inner.write().expect("lock").set_probing_config((*config).clone());
+	}
+
 	/// Builds a [`Node`] instance with a [`SqliteStore`] backend and according to the options
 	/// previously configured.
 	pub fn build(&self, node_entropy: Arc<NodeEntropy>) -> Result<Arc<Node>, BuildError> {
@@ -1361,8 +1404,8 @@ fn build_with_store_internal(
 	gossip_source_config: Option<&GossipSourceConfig>,
 	liquidity_source_config: Option<&LiquiditySourceConfig>,
 	pathfinding_scores_sync_config: Option<&PathfindingScoresSyncConfig>,
-async_payments_role: Option<AsyncPaymentsRole>, seed_bytes: [u8; 64], runtime: Arc<Runtime>,
-	logger: Arc<Logger>, kv_store: Arc<DynStore>,
+probing_config: Option<&ProbingConfig>, async_payments_role: Option<AsyncPaymentsRole>,
+seed_bytes: [u8; 64], runtime: Arc<Runtime>, logger: Arc<Logger>, kv_store: Arc<DynStore>,
 ) -> Result<Node, BuildError> {
 	optionally_install_rustls_cryptoprovider();
 
@@ -2219,6 +2262,51 @@ fn build_with_store_internal(
  _leak_checker.0.push(Arc::downgrade(&wallet) as Weak<dyn Any + Send + Sync>);
 	}
 
+	let prober = probing_config.map(|probing_cfg| {
+ let strategy: Arc<dyn ProbingStrategy> = match &probing_cfg.kind {
+ ProbingStrategyKind::HighDegree { top_node_count } => {
+ // Dedicated router for probing so the diversity penalty doesn't interfere
+ // with real payments; shares the scorer so probe results still train it.
+ let mut probing_fee_params = ProbabilisticScoringFeeParameters::default();
+ if let Some(penalty) = probing_cfg.diversity_penalty_msat {
+ probing_fee_params.probing_diversity_penalty_msat = penalty;
+ }
+ let probing_router = Arc::new(DefaultRouter::new(
+ Arc::clone(&network_graph),
+ Arc::clone(&logger),
+ Arc::clone(&keys_manager),
+ Arc::clone(&scorer),
+ probing_fee_params,
+ ));
+ Arc::new(HighDegreeStrategy::new(
+ Arc::clone(&network_graph),
+ Arc::clone(&channel_manager),
+ probing_router,
+ *top_node_count,
+ DEFAULT_MIN_PROBE_AMOUNT_MSAT,
+ DEFAULT_MAX_PROBE_AMOUNT_MSAT,
+ probing_cfg.cooldown,
+ config.probing_liquidity_limit_multiplier,
+ ))
+ },
+ ProbingStrategyKind::RandomWalk { max_hops } => Arc::new(RandomWalkStrategy::new(
+ Arc::clone(&network_graph),
+ Arc::clone(&channel_manager),
+ *max_hops,
+ DEFAULT_MIN_PROBE_AMOUNT_MSAT,
+ DEFAULT_MAX_PROBE_AMOUNT_MSAT,
+ )),
+ ProbingStrategyKind::Custom(s) => Arc::clone(s),
+ };
+ Arc::new(Prober {
+ channel_manager: Arc::clone(&channel_manager),
+ logger: Arc::clone(&logger),
+ strategy,
+ interval: probing_cfg.interval,
+ max_locked_msat: probing_cfg.max_locked_msat,
+ })
+	});
+
 	Ok(Node {
  runtime,
  stop_sender,
@@ -2252,6 +2340,7 @@ fn build_with_store_internal(
  om_mailbox,
  async_payments_role,
  hrn_resolver,
+ prober,
  #[cfg(cycle_tests)]
  _leak_checker,
 	})

src/config.rs

@@ -28,6 +28,12 @@ const DEFAULT_BDK_WALLET_SYNC_INTERVAL_SECS: u64 = 80;
 const DEFAULT_LDK_WALLET_SYNC_INTERVAL_SECS: u64 = 30;
 const DEFAULT_FEE_RATE_CACHE_UPDATE_INTERVAL_SECS: u64 = 60 * 10;
 const DEFAULT_PROBING_LIQUIDITY_LIMIT_MULTIPLIER: u64 = 3;
+pub(crate) const DEFAULT_PROBING_INTERVAL_SECS: u64 = 10;
+pub(crate) const MIN_PROBING_INTERVAL: Duration = Duration::from_millis(100);
+pub(crate) const DEFAULT_PROBED_NODE_COOLDOWN_SECS: u64 = 60 * 60; // 1 hour
+pub(crate) const DEFAULT_MAX_PROBE_LOCKED_MSAT: u64 = 100_000_000; // 100k sats
+pub(crate) const DEFAULT_MIN_PROBE_AMOUNT_MSAT: u64 = 1_000_000; // 1k sats
+pub(crate) const DEFAULT_MAX_PROBE_AMOUNT_MSAT: u64 = 10_000_000; // 10k sats
 const DEFAULT_ANCHOR_PER_CHANNEL_RESERVE_SATS: u64 = 25_000;
 
 // The default timeout after which we abort a wallet syncing operation.

src/event.rs

@@ -52,6 +52,7 @@ use crate::payment::store::{
 	PaymentDetails, PaymentDetailsUpdate, PaymentDirection, PaymentKind, PaymentStatus,
 };
 use crate::payment::PaymentMetadata;
+use crate::probing::Prober;
 use crate::runtime::Runtime;
 use crate::types::{
 	CustomTlvRecord, DynStore, KeysManager, OnionMessenger, PaymentStore, Sweeper, Wallet,
@@ -536,12 +537,13 @@ where
 	payment_store: Arc<PaymentStore>,
 	peer_store: Arc<PeerStore<L>>,
 	keys_manager: Arc<KeysManager>,
-	runtime: Arc<Runtime>,
-	logger: L,
-	config: Arc<Config>,
 	static_invoice_store: Option<StaticInvoiceStore>,
 	onion_messenger: Arc<OnionMessenger>,
 	om_mailbox: Option<Arc<OnionMessageMailbox>>,
+	prober: Option<Arc<Prober>>,
+	runtime: Arc<Runtime>,
+	logger: L,
+	config: Arc<Config>,
 }
 
 impl<L: Deref + Clone + Sync + Send + 'static> EventHandler<L>
@@ -556,8 +558,8 @@ where
  liquidity_source: Arc<LiquiditySource<Arc<Logger>>>, payment_store: Arc<PaymentStore>,
  peer_store: Arc<PeerStore<L>>, keys_manager: Arc<KeysManager>,
  static_invoice_store: Option<StaticInvoiceStore>, onion_messenger: Arc<OnionMessenger>,
- om_mailbox: Option<Arc<OnionMessageMailbox>>, runtime: Arc<Runtime>, logger: L,
- config: Arc<Config>,
+ om_mailbox: Option<Arc<OnionMessageMailbox>>, prober: Option<Arc<Prober>>,
+runtime: Arc<Runtime>, logger: L, config: Arc<Config>,
 	) -> Self {
  Self {
  event_queue,
@@ -571,12 +573,13 @@ where
  payment_store,
  peer_store,
  keys_manager,
- logger,
- runtime,
- config,
  static_invoice_store,
  onion_messenger,
  om_mailbox,
+ prober,
+ runtime,
+ logger,
+ config,
  }
 	}
 
@@ -1208,8 +1211,16 @@ where
 
  LdkEvent::PaymentPathSuccessful { .. } => {},
  LdkEvent::PaymentPathFailed { .. } => {},
- LdkEvent::ProbeSuccessful { .. } => {},
- LdkEvent::ProbeFailed { .. } => {},
+ LdkEvent::ProbeSuccessful { path, payment_id, .. } => {
+ if let Some(prober) = &self.prober {
+ prober.handle_background_probe_successful(&path, payment_id);
+ }
+ },
+ LdkEvent::ProbeFailed { path, payment_id, .. } => {
+ if let Some(prober) = &self.prober {
+ prober.handle_background_probe_failed(&path, payment_id);
+ }
+ },
  LdkEvent::HTLCHandlingFailed { failure_type, .. } => {
  self.liquidity_source
  .lsps2_service()

src/ffi/types.rs

@@ -149,6 +149,7 @@ pub use crate::entropy::{generate_entropy_mnemonic, NodeEntropy, WordCount};
 use crate::error::Error;
 pub use crate::liquidity::LSPS1OrderStatus;
 pub use crate::logger::{LogLevel, LogRecord, LogWriter};
+pub use crate::probing::ProbingConfig;
 use crate::{hex_utils, SocketAddress, UserChannelId};
 
 uniffi::custom_type!(PublicKey, String, {

src/lib.rs

@@ -101,10 +101,12 @@ pub mod logger;
 mod message_handler;
 pub mod payment;
 mod peer_store;
+pub mod probing;
 mod runtime;
 mod scoring;
 mod tx_broadcaster;
 mod types;
+mod util;
 mod wallet;
 
 use std::default::Default;
@@ -172,6 +174,9 @@ use payment::{
 	UnifiedPayment,
 };
 use peer_store::{PeerInfo, PeerStore};
+#[cfg(feature = "uniffi")]
+pub use probing::ArcedProbingConfigBuilder as ProbingConfigBuilder;
+use probing::{run_prober, Prober};
 use runtime::Runtime;
 pub use tokio;
 use types::{
@@ -250,6 +255,7 @@ pub struct Node {
 	om_mailbox: Option<Arc<OnionMessageMailbox>>,
 	async_payments_role: Option<AsyncPaymentsRole>,
 	hrn_resolver: HRNResolver,
+	prober: Option<Arc<Prober>>,
 	#[cfg(cycle_tests)]
 	_leak_checker: LeakChecker,
 }
@@ -610,11 +616,19 @@ impl Node {
  static_invoice_store,
  Arc::clone(&self.onion_messenger),
  self.om_mailbox.clone(),
+ self.prober.clone(),
  Arc::clone(&self.runtime),
  Arc::clone(&self.logger),
  Arc::clone(&self.config),
  ));
 
+ if let Some(prober) = self.prober.clone() {
+ let stop_rx = self.stop_sender.subscribe();
+ self.runtime.spawn_cancellable_background_task(async move {
+ run_prober(prober, stop_rx).await;
+ });
+ }
+
  // Setup background processing
  let background_persister = Arc::clone(&self.kv_store);
  let background_event_handler = Arc::clone(&event_handler);
@@ -1145,6 +1159,11 @@ impl Node {
  ))
 	}
 
+	/// Returns a reference to the [`Prober`], or `None` if no probing strategy is configured.
+	pub fn prober(&self) -> Option<&Prober> {
+ self.prober.as_deref()
+	}
+
 	/// Retrieve a list of known channels.
 	pub fn list_channels(&self) -> Vec<ChannelDetails> {
  self.channel_manager

bindings/ldk_node.udl

@@ -13,6 +13,8 @@ typedef dictionary TorConfig;
 
 typedef interface NodeEntropy;
 
+typedef interface ProbingConfig;
+
 typedef enum WordCount;
 
 [Remote]
@@ -32,6 +34,18 @@ interface LogWriter {
 	void log(LogRecord record);
 };
 
+interface ProbingConfigBuilder {
+	[Name=high_degree]
+	constructor(u64 top_node_count);
+	[Name=random_walk]
+	constructor(u64 max_hops);
+	void set_interval(u64 secs);
+	void set_max_locked_msat(u64 max_msat);
+	void set_diversity_penalty_msat(u64 penalty_msat);
+	void set_cooldown(u64 secs);
+	ProbingConfig build();
+};
+
 interface Builder {
 	constructor();
 	[Name=from_config]
@@ -59,6 +73,7 @@ interface Builder {
 	void set_node_alias(string node_alias);
 	[Throws=BuildError]
 	void set_async_payments_role(AsyncPaymentsRole? role);
+	void set_probing_config(ProbingConfig config);
 	[Throws=BuildError]
 	Node build(NodeEntropy node_entropy);
 	[Throws=BuildError]

src/builder.rs

@@ -50,6 +50,7 @@ use crate::config::{
 	default_user_config, may_announce_channel, AnnounceError, AsyncPaymentsRole,
 	BitcoindRestClientConfig, Config, ElectrumSyncConfig, EsploraSyncConfig, HRNResolverConfig,
 	TorConfig, DEFAULT_ESPLORA_SERVER_URL, DEFAULT_LOG_FILENAME, DEFAULT_LOG_LEVEL,
+	DEFAULT_MAX_PROBE_AMOUNT_MSAT, DEFAULT_MIN_PROBE_AMOUNT_MSAT,
 };
 use crate::connection::ConnectionManager;
 use crate::entropy::NodeEntropy;
@@ -74,6 +75,10 @@ use crate::logger::{log_error, LdkLogger, LogLevel, LogWriter, Logger};
 use crate::message_handler::NodeCustomMessageHandler;
 use crate::payment::asynchronous::om_mailbox::OnionMessageMailbox;
 use crate::peer_store::PeerStore;
+use crate::probing::{
+	HighDegreeStrategy, Prober, ProbingConfig, ProbingStrategy, ProbingStrategyKind,
+	RandomWalkStrategy,
+};
 use crate::runtime::{Runtime, RuntimeSpawner};
 use crate::tx_broadcaster::TransactionBroadcaster;
 use crate::types::{
@@ -306,6 +311,7 @@ pub struct NodeBuilder {
 	async_payments_role: Option<AsyncPaymentsRole>,
 	runtime_handle: Option<tokio::runtime::Handle>,
 	pathfinding_scores_sync_config: Option<PathfindingScoresSyncConfig>,
+	probing_config: Option<ProbingConfig>,
 }
 
 impl NodeBuilder {
@@ -323,6 +329,7 @@ impl NodeBuilder {
  let log_writer_config = None;
  let runtime_handle = None;
  let pathfinding_scores_sync_config = None;
+ let probing_config = None;
  Self {
  config,
  chain_data_source_config,
@@ -332,6 +339,7 @@ impl NodeBuilder {
  runtime_handle,
  async_payments_role: None,
  pathfinding_scores_sync_config,
+ probing_config,
  }
 	}
 
@@ -629,6 +637,31 @@ impl NodeBuilder {
  Ok(self)
 	}
 
+	/// Sets background probing config.
+	///
+	/// Use [`ProbingConfigBuilder`] to build the configuration:
+	/// ```no_run
+	/// # #[cfg(not(feature = "uniffi"))]
+	/// # {
+	/// use std::time::Duration;
+	/// use ldk_node::Builder;
+	/// use ldk_node::probing::ProbingConfigBuilder;
+	///
+	/// let mut builder = Builder::new();
+	/// builder.set_probing_config(
+	/// ProbingConfigBuilder::high_degree(100)
+	/// .interval(Duration::from_secs(30))
+	/// .build()
+	/// );
+	/// # }
+	/// ```
+	///
+	/// [`ProbingConfigBuilder`]: crate::probing::ProbingConfigBuilder
+	pub fn set_probing_config(&mut self, config: ProbingConfig) -> &mut Self {
+ self.probing_config = Some(config);
+ self
+	}
+
 	/// Builds a [`Node`] instance with a [`SqliteStore`] backend and according to the options
 	/// previously configured.
 	pub fn build(&self, node_entropy: NodeEntropy) -> Result<Node, BuildError> {
@@ -868,6 +901,7 @@ impl NodeBuilder {
  self.gossip_source_config.as_ref(),
  self.liquidity_source_config.as_ref(),
  self.pathfinding_scores_sync_config.as_ref(),
+ self.probing_config.as_ref(),
  self.async_payments_role,
  seed_bytes,
  runtime,
@@ -1166,6 +1200,15 @@ impl ArcedNodeBuilder {
  self.inner.write().expect("lock").set_async_payments_role(role).map(|_| ())
 	}
 
+	/// Configures background probing.
+	///
+	/// Use [`ProbingConfigBuilder`] to build the configuration.
+	///
+	/// [`ProbingConfigBuilder`]: crate::probing::ProbingConfigBuilder
+	pub fn set_probing_config(&self, config: Arc<ProbingConfig>) {
+ self.inner.write().expect("lock").set_probing_config((*config).clone());
+	}
+
 	/// Builds a [`Node`] instance with a [`SqliteStore`] backend and according to the options
 	/// previously configured.
 	pub fn build(&self, node_entropy: Arc<NodeEntropy>) -> Result<Arc<Node>, BuildError> {
@@ -1361,8 +1404,8 @@ fn build_with_store_internal(
 	gossip_source_config: Option<&GossipSourceConfig>,
 	liquidity_source_config: Option<&LiquiditySourceConfig>,
 	pathfinding_scores_sync_config: Option<&PathfindingScoresSyncConfig>,
-async_payments_role: Option<AsyncPaymentsRole>, seed_bytes: [u8; 64], runtime: Arc<Runtime>,
-	logger: Arc<Logger>, kv_store: Arc<DynStore>,
+probing_config: Option<&ProbingConfig>, async_payments_role: Option<AsyncPaymentsRole>,
+seed_bytes: [u8; 64], runtime: Arc<Runtime>, logger: Arc<Logger>, kv_store: Arc<DynStore>,
 ) -> Result<Node, BuildError> {
 	optionally_install_rustls_cryptoprovider();
 
@@ -2219,6 +2262,51 @@ fn build_with_store_internal(
  _leak_checker.0.push(Arc::downgrade(&wallet) as Weak<dyn Any + Send + Sync>);
 	}
 
+	let prober = probing_config.map(|probing_cfg| {
+ let strategy: Arc<dyn ProbingStrategy> = match &probing_cfg.kind {
+ ProbingStrategyKind::HighDegree { top_node_count } => {
+ // Dedicated router for probing so the diversity penalty doesn't interfere
+ // with real payments; shares the scorer so probe results still train it.
+ let mut probing_fee_params = ProbabilisticScoringFeeParameters::default();
+ if let Some(penalty) = probing_cfg.diversity_penalty_msat {
+ probing_fee_params.probing_diversity_penalty_msat = penalty;
+ }
+ let probing_router = Arc::new(DefaultRouter::new(
+ Arc::clone(&network_graph),
+ Arc::clone(&logger),
+ Arc::clone(&keys_manager),
+ Arc::clone(&scorer),
+ probing_fee_params,
+ ));
+ Arc::new(HighDegreeStrategy::new(
+ Arc::clone(&network_graph),
+ Arc::clone(&channel_manager),
+ probing_router,
+ *top_node_count,
+ DEFAULT_MIN_PROBE_AMOUNT_MSAT,
+ DEFAULT_MAX_PROBE_AMOUNT_MSAT,
+ probing_cfg.cooldown,
+ config.probing_liquidity_limit_multiplier,
+ ))
+ },
+ ProbingStrategyKind::RandomWalk { max_hops } => Arc::new(RandomWalkStrategy::new(
+ Arc::clone(&network_graph),
+ Arc::clone(&channel_manager),
+ *max_hops,
+ DEFAULT_MIN_PROBE_AMOUNT_MSAT,
+ DEFAULT_MAX_PROBE_AMOUNT_MSAT,
+ )),
+ ProbingStrategyKind::Custom(s) => Arc::clone(s),
+ };
+ Arc::new(Prober {
+ channel_manager: Arc::clone(&channel_manager),
+ logger: Arc::clone(&logger),
+ strategy,
+ interval: probing_cfg.interval,
+ max_locked_msat: probing_cfg.max_locked_msat,
+ })
+	});
+
 	Ok(Node {
  runtime,
  stop_sender,
@@ -2252,6 +2340,7 @@ fn build_with_store_internal(
  om_mailbox,
  async_payments_role,
  hrn_resolver,
+ prober,
  #[cfg(cycle_tests)]
  _leak_checker,
 	})

src/config.rs

@@ -28,6 +28,12 @@ const DEFAULT_BDK_WALLET_SYNC_INTERVAL_SECS: u64 = 80;
 const DEFAULT_LDK_WALLET_SYNC_INTERVAL_SECS: u64 = 30;
 const DEFAULT_FEE_RATE_CACHE_UPDATE_INTERVAL_SECS: u64 = 60 * 10;
 const DEFAULT_PROBING_LIQUIDITY_LIMIT_MULTIPLIER: u64 = 3;
+pub(crate) const DEFAULT_PROBING_INTERVAL_SECS: u64 = 10;
+pub(crate) const MIN_PROBING_INTERVAL: Duration = Duration::from_millis(100);
+pub(crate) const DEFAULT_PROBED_NODE_COOLDOWN_SECS: u64 = 60 * 60; // 1 hour
+pub(crate) const DEFAULT_MAX_PROBE_LOCKED_MSAT: u64 = 100_000_000; // 100k sats
+pub(crate) const DEFAULT_MIN_PROBE_AMOUNT_MSAT: u64 = 1_000_000; // 1k sats
+pub(crate) const DEFAULT_MAX_PROBE_AMOUNT_MSAT: u64 = 10_000_000; // 10k sats
 const DEFAULT_ANCHOR_PER_CHANNEL_RESERVE_SATS: u64 = 25_000;
 
 // The default timeout after which we abort a wallet syncing operation.

src/event.rs

@@ -52,6 +52,7 @@ use crate::payment::store::{
 	PaymentDetails, PaymentDetailsUpdate, PaymentDirection, PaymentKind, PaymentStatus,
 };
 use crate::payment::PaymentMetadata;
+use crate::probing::Prober;
 use crate::runtime::Runtime;
 use crate::types::{
 	CustomTlvRecord, DynStore, KeysManager, OnionMessenger, PaymentStore, Sweeper, Wallet,
@@ -536,12 +537,13 @@ where
 	payment_store: Arc<PaymentStore>,
 	peer_store: Arc<PeerStore<L>>,
 	keys_manager: Arc<KeysManager>,
-	runtime: Arc<Runtime>,
-	logger: L,
-	config: Arc<Config>,
 	static_invoice_store: Option<StaticInvoiceStore>,
 	onion_messenger: Arc<OnionMessenger>,
 	om_mailbox: Option<Arc<OnionMessageMailbox>>,
+	prober: Option<Arc<Prober>>,
+	runtime: Arc<Runtime>,
+	logger: L,
+	config: Arc<Config>,
 }
 
 impl<L: Deref + Clone + Sync + Send + 'static> EventHandler<L>
@@ -556,8 +558,8 @@ where
  liquidity_source: Arc<LiquiditySource<Arc<Logger>>>, payment_store: Arc<PaymentStore>,
  peer_store: Arc<PeerStore<L>>, keys_manager: Arc<KeysManager>,
  static_invoice_store: Option<StaticInvoiceStore>, onion_messenger: Arc<OnionMessenger>,
- om_mailbox: Option<Arc<OnionMessageMailbox>>, runtime: Arc<Runtime>, logger: L,
- config: Arc<Config>,
+ om_mailbox: Option<Arc<OnionMessageMailbox>>, prober: Option<Arc<Prober>>,
+runtime: Arc<Runtime>, logger: L, config: Arc<Config>,
 	) -> Self {
  Self {
  event_queue,
@@ -571,12 +573,13 @@ where
  payment_store,
  peer_store,
  keys_manager,
- logger,
- runtime,
- config,
  static_invoice_store,
  onion_messenger,
  om_mailbox,
+ prober,
+ runtime,
+ logger,
+ config,
  }
 	}
 
@@ -1208,8 +1211,16 @@ where
 
  LdkEvent::PaymentPathSuccessful { .. } => {},
  LdkEvent::PaymentPathFailed { .. } => {},
- LdkEvent::ProbeSuccessful { .. } => {},
- LdkEvent::ProbeFailed { .. } => {},
+ LdkEvent::ProbeSuccessful { path, payment_id, .. } => {
+ if let Some(prober) = &self.prober {
+ prober.handle_background_probe_successful(&path, payment_id);
+ }
+ },
+ LdkEvent::ProbeFailed { path, payment_id, .. } => {
+ if let Some(prober) = &self.prober {
+ prober.handle_background_probe_failed(&path, payment_id);
+ }
+ },
  LdkEvent::HTLCHandlingFailed { failure_type, .. } => {
  self.liquidity_source
  .lsps2_service()

src/ffi/types.rs

@@ -149,6 +149,7 @@ pub use crate::entropy::{generate_entropy_mnemonic, NodeEntropy, WordCount};
 use crate::error::Error;
 pub use crate::liquidity::LSPS1OrderStatus;
 pub use crate::logger::{LogLevel, LogRecord, LogWriter};
+pub use crate::probing::ProbingConfig;
 use crate::{hex_utils, SocketAddress, UserChannelId};
 
 uniffi::custom_type!(PublicKey, String, {

src/lib.rs

@@ -101,10 +101,12 @@ pub mod logger;
 mod message_handler;
 pub mod payment;
 mod peer_store;
+pub mod probing;
 mod runtime;
 mod scoring;
 mod tx_broadcaster;
 mod types;
+mod util;
 mod wallet;
 
 use std::default::Default;
@@ -172,6 +174,9 @@ use payment::{
 	UnifiedPayment,
 };
 use peer_store::{PeerInfo, PeerStore};
+#[cfg(feature = "uniffi")]
+pub use probing::ArcedProbingConfigBuilder as ProbingConfigBuilder;
+use probing::{run_prober, Prober};
 use runtime::Runtime;
 pub use tokio;
 use types::{
@@ -250,6 +255,7 @@ pub struct Node {
 	om_mailbox: Option<Arc<OnionMessageMailbox>>,
 	async_payments_role: Option<AsyncPaymentsRole>,
 	hrn_resolver: HRNResolver,
+	prober: Option<Arc<Prober>>,
 	#[cfg(cycle_tests)]
 	_leak_checker: LeakChecker,
 }
@@ -610,11 +616,19 @@ impl Node {
  static_invoice_store,
  Arc::clone(&self.onion_messenger),
  self.om_mailbox.clone(),
+ self.prober.clone(),
  Arc::clone(&self.runtime),
  Arc::clone(&self.logger),
  Arc::clone(&self.config),
  ));
 
+ if let Some(prober) = self.prober.clone() {
+ let stop_rx = self.stop_sender.subscribe();
+ self.runtime.spawn_cancellable_background_task(async move {
+ run_prober(prober, stop_rx).await;
+ });
+ }
+
  // Setup background processing
  let background_persister = Arc::clone(&self.kv_store);
  let background_event_handler = Arc::clone(&event_handler);
@@ -1145,6 +1159,11 @@ impl Node {
  ))
 	}
 
+	/// Returns a reference to the [`Prober`], or `None` if no probing strategy is configured.
+	pub fn prober(&self) -> Option<&Prober> {
+ self.prober.as_deref()
+	}
+
 	/// Retrieve a list of known channels.
 	pub fn list_channels(&self) -> Vec<ChannelDetails> {
  self.channel_manager

bindings/ldk_node.udl

@@ -13,6 +13,8 @@ typedef dictionary TorConfig;
 
 typedef interface NodeEntropy;
 
+typedef interface ProbingConfig;
+
 typedef enum WordCount;
 
 [Remote]
@@ -32,6 +34,18 @@ interface LogWriter {
 	void log(LogRecord record);
 };
 
+interface ProbingConfigBuilder {
+	[Name=high_degree]
+	constructor(u64 top_node_count);
+	[Name=random_walk]
+	constructor(u64 max_hops);
+	void set_interval(u64 secs);
+	void set_max_locked_msat(u64 max_msat);
+	void set_diversity_penalty_msat(u64 penalty_msat);
+	void set_cooldown(u64 secs);
+	ProbingConfig build();
+};
+
 interface Builder {
 	constructor();
 	[Name=from_config]
@@ -59,6 +73,7 @@ interface Builder {
 	void set_node_alias(string node_alias);
 	[Throws=BuildError]
 	void set_async_payments_role(AsyncPaymentsRole? role);
+	void set_probing_config(ProbingConfig config);
 	[Throws=BuildError]
 	Node build(NodeEntropy node_entropy);
 	[Throws=BuildError]

src/builder.rs

@@ -50,6 +50,7 @@ use crate::config::{
 	default_user_config, may_announce_channel, AnnounceError, AsyncPaymentsRole,
 	BitcoindRestClientConfig, Config, ElectrumSyncConfig, EsploraSyncConfig, HRNResolverConfig,
 	TorConfig, DEFAULT_ESPLORA_SERVER_URL, DEFAULT_LOG_FILENAME, DEFAULT_LOG_LEVEL,
+	DEFAULT_MAX_PROBE_AMOUNT_MSAT, DEFAULT_MIN_PROBE_AMOUNT_MSAT,
 };
 use crate::connection::ConnectionManager;
 use crate::entropy::NodeEntropy;
@@ -74,6 +75,10 @@ use crate::logger::{log_error, LdkLogger, LogLevel, LogWriter, Logger};
 use crate::message_handler::NodeCustomMessageHandler;
 use crate::payment::asynchronous::om_mailbox::OnionMessageMailbox;
 use crate::peer_store::PeerStore;
+use crate::probing::{
+	HighDegreeStrategy, Prober, ProbingConfig, ProbingStrategy, ProbingStrategyKind,
+	RandomWalkStrategy,
+};
 use crate::runtime::{Runtime, RuntimeSpawner};
 use crate::tx_broadcaster::TransactionBroadcaster;
 use crate::types::{
@@ -306,6 +311,7 @@ pub struct NodeBuilder {
 	async_payments_role: Option<AsyncPaymentsRole>,
 	runtime_handle: Option<tokio::runtime::Handle>,
 	pathfinding_scores_sync_config: Option<PathfindingScoresSyncConfig>,
+	probing_config: Option<ProbingConfig>,
 }
 
 impl NodeBuilder {
@@ -323,6 +329,7 @@ impl NodeBuilder {
  let log_writer_config = None;
  let runtime_handle = None;
  let pathfinding_scores_sync_config = None;
+ let probing_config = None;
  Self {
  config,
  chain_data_source_config,
@@ -332,6 +339,7 @@ impl NodeBuilder {
  runtime_handle,
  async_payments_role: None,
  pathfinding_scores_sync_config,
+ probing_config,
  }
 	}
 
@@ -629,6 +637,31 @@ impl NodeBuilder {
  Ok(self)
 	}
 
+	/// Sets background probing config.
+	///
+	/// Use [`ProbingConfigBuilder`] to build the configuration:
+	/// ```no_run
+	/// # #[cfg(not(feature = "uniffi"))]
+	/// # {
+	/// use std::time::Duration;
+	/// use ldk_node::Builder;
+	/// use ldk_node::probing::ProbingConfigBuilder;
+	///
+	/// let mut builder = Builder::new();
+	/// builder.set_probing_config(
+	/// ProbingConfigBuilder::high_degree(100)
+	/// .interval(Duration::from_secs(30))
+	/// .build()
+	/// );
+	/// # }
+	/// ```
+	///
+	/// [`ProbingConfigBuilder`]: crate::probing::ProbingConfigBuilder
+	pub fn set_probing_config(&mut self, config: ProbingConfig) -> &mut Self {
+ self.probing_config = Some(config);
+ self
+	}
+
 	/// Builds a [`Node`] instance with a [`SqliteStore`] backend and according to the options
 	/// previously configured.
 	pub fn build(&self, node_entropy: NodeEntropy) -> Result<Node, BuildError> {
@@ -868,6 +901,7 @@ impl NodeBuilder {
  self.gossip_source_config.as_ref(),
  self.liquidity_source_config.as_ref(),
  self.pathfinding_scores_sync_config.as_ref(),
+ self.probing_config.as_ref(),
  self.async_payments_role,
  seed_bytes,
  runtime,
@@ -1166,6 +1200,15 @@ impl ArcedNodeBuilder {
  self.inner.write().expect("lock").set_async_payments_role(role).map(|_| ())
 	}
 
+	/// Configures background probing.
+	///
+	/// Use [`ProbingConfigBuilder`] to build the configuration.
+	///
+	/// [`ProbingConfigBuilder`]: crate::probing::ProbingConfigBuilder
+	pub fn set_probing_config(&self, config: Arc<ProbingConfig>) {
+ self.inner.write().expect("lock").set_probing_config((*config).clone());
+	}
+
 	/// Builds a [`Node`] instance with a [`SqliteStore`] backend and according to the options
 	/// previously configured.
 	pub fn build(&self, node_entropy: Arc<NodeEntropy>) -> Result<Arc<Node>, BuildError> {
@@ -1361,8 +1404,8 @@ fn build_with_store_internal(
 	gossip_source_config: Option<&GossipSourceConfig>,
 	liquidity_source_config: Option<&LiquiditySourceConfig>,
 	pathfinding_scores_sync_config: Option<&PathfindingScoresSyncConfig>,
-async_payments_role: Option<AsyncPaymentsRole>, seed_bytes: [u8; 64], runtime: Arc<Runtime>,
-	logger: Arc<Logger>, kv_store: Arc<DynStore>,
+probing_config: Option<&ProbingConfig>, async_payments_role: Option<AsyncPaymentsRole>,
+seed_bytes: [u8; 64], runtime: Arc<Runtime>, logger: Arc<Logger>, kv_store: Arc<DynStore>,
 ) -> Result<Node, BuildError> {
 	optionally_install_rustls_cryptoprovider();
 
@@ -2219,6 +2262,51 @@ fn build_with_store_internal(
  _leak_checker.0.push(Arc::downgrade(&wallet) as Weak<dyn Any + Send + Sync>);
 	}
 
+	let prober = probing_config.map(|probing_cfg| {
+ let strategy: Arc<dyn ProbingStrategy> = match &probing_cfg.kind {
+ ProbingStrategyKind::HighDegree { top_node_count } => {
+ // Dedicated router for probing so the diversity penalty doesn't interfere
+ // with real payments; shares the scorer so probe results still train it.
+ let mut probing_fee_params = ProbabilisticScoringFeeParameters::default();
+ if let Some(penalty) = probing_cfg.diversity_penalty_msat {
+ probing_fee_params.probing_diversity_penalty_msat = penalty;
+ }
+ let probing_router = Arc::new(DefaultRouter::new(
+ Arc::clone(&network_graph),
+ Arc::clone(&logger),
+ Arc::clone(&keys_manager),
+ Arc::clone(&scorer),
+ probing_fee_params,
+ ));
+ Arc::new(HighDegreeStrategy::new(
+ Arc::clone(&network_graph),
+ Arc::clone(&channel_manager),
+ probing_router,
+ *top_node_count,
+ DEFAULT_MIN_PROBE_AMOUNT_MSAT,
+ DEFAULT_MAX_PROBE_AMOUNT_MSAT,
+ probing_cfg.cooldown,
+ config.probing_liquidity_limit_multiplier,
+ ))
+ },
+ ProbingStrategyKind::RandomWalk { max_hops } => Arc::new(RandomWalkStrategy::new(
+ Arc::clone(&network_graph),
+ Arc::clone(&channel_manager),
+ *max_hops,
+ DEFAULT_MIN_PROBE_AMOUNT_MSAT,
+ DEFAULT_MAX_PROBE_AMOUNT_MSAT,
+ )),
+ ProbingStrategyKind::Custom(s) => Arc::clone(s),
+ };
+ Arc::new(Prober {
+ channel_manager: Arc::clone(&channel_manager),
+ logger: Arc::clone(&logger),
+ strategy,
+ interval: probing_cfg.interval,
+ max_locked_msat: probing_cfg.max_locked_msat,
+ })
+	});
+
 	Ok(Node {
  runtime,
  stop_sender,
@@ -2252,6 +2340,7 @@ fn build_with_store_internal(
  om_mailbox,
  async_payments_role,
  hrn_resolver,
+ prober,
  #[cfg(cycle_tests)]
  _leak_checker,
 	})

src/config.rs

@@ -28,6 +28,12 @@ const DEFAULT_BDK_WALLET_SYNC_INTERVAL_SECS: u64 = 80;
 const DEFAULT_LDK_WALLET_SYNC_INTERVAL_SECS: u64 = 30;
 const DEFAULT_FEE_RATE_CACHE_UPDATE_INTERVAL_SECS: u64 = 60 * 10;
 const DEFAULT_PROBING_LIQUIDITY_LIMIT_MULTIPLIER: u64 = 3;
+pub(crate) const DEFAULT_PROBING_INTERVAL_SECS: u64 = 10;
+pub(crate) const MIN_PROBING_INTERVAL: Duration = Duration::from_millis(100);
+pub(crate) const DEFAULT_PROBED_NODE_COOLDOWN_SECS: u64 = 60 * 60; // 1 hour
+pub(crate) const DEFAULT_MAX_PROBE_LOCKED_MSAT: u64 = 100_000_000; // 100k sats
+pub(crate) const DEFAULT_MIN_PROBE_AMOUNT_MSAT: u64 = 1_000_000; // 1k sats
+pub(crate) const DEFAULT_MAX_PROBE_AMOUNT_MSAT: u64 = 10_000_000; // 10k sats
 const DEFAULT_ANCHOR_PER_CHANNEL_RESERVE_SATS: u64 = 25_000;
 
 // The default timeout after which we abort a wallet syncing operation.

src/event.rs

@@ -52,6 +52,7 @@ use crate::payment::store::{
 	PaymentDetails, PaymentDetailsUpdate, PaymentDirection, PaymentKind, PaymentStatus,
 };
 use crate::payment::PaymentMetadata;
+use crate::probing::Prober;
 use crate::runtime::Runtime;
 use crate::types::{
 	CustomTlvRecord, DynStore, KeysManager, OnionMessenger, PaymentStore, Sweeper, Wallet,
@@ -536,12 +537,13 @@ where
 	payment_store: Arc<PaymentStore>,
 	peer_store: Arc<PeerStore<L>>,
 	keys_manager: Arc<KeysManager>,
-	runtime: Arc<Runtime>,
-	logger: L,
-	config: Arc<Config>,
 	static_invoice_store: Option<StaticInvoiceStore>,
 	onion_messenger: Arc<OnionMessenger>,
 	om_mailbox: Option<Arc<OnionMessageMailbox>>,
+	prober: Option<Arc<Prober>>,
+	runtime: Arc<Runtime>,
+	logger: L,
+	config: Arc<Config>,
 }
 
 impl<L: Deref + Clone + Sync + Send + 'static> EventHandler<L>
@@ -556,8 +558,8 @@ where
  liquidity_source: Arc<LiquiditySource<Arc<Logger>>>, payment_store: Arc<PaymentStore>,
  peer_store: Arc<PeerStore<L>>, keys_manager: Arc<KeysManager>,
  static_invoice_store: Option<StaticInvoiceStore>, onion_messenger: Arc<OnionMessenger>,
- om_mailbox: Option<Arc<OnionMessageMailbox>>, runtime: Arc<Runtime>, logger: L,
- config: Arc<Config>,
+ om_mailbox: Option<Arc<OnionMessageMailbox>>, prober: Option<Arc<Prober>>,
+runtime: Arc<Runtime>, logger: L, config: Arc<Config>,
 	) -> Self {
  Self {
  event_queue,
@@ -571,12 +573,13 @@ where
  payment_store,
  peer_store,
  keys_manager,
- logger,
- runtime,
- config,
  static_invoice_store,
  onion_messenger,
  om_mailbox,
+ prober,
+ runtime,
+ logger,
+ config,
  }
 	}
 
@@ -1208,8 +1211,16 @@ where
 
  LdkEvent::PaymentPathSuccessful { .. } => {},
  LdkEvent::PaymentPathFailed { .. } => {},
- LdkEvent::ProbeSuccessful { .. } => {},
- LdkEvent::ProbeFailed { .. } => {},
+ LdkEvent::ProbeSuccessful { path, payment_id, .. } => {
+ if let Some(prober) = &self.prober {
+ prober.handle_background_probe_successful(&path, payment_id);
+ }
+ },
+ LdkEvent::ProbeFailed { path, payment_id, .. } => {
+ if let Some(prober) = &self.prober {
+ prober.handle_background_probe_failed(&path, payment_id);
+ }
+ },
  LdkEvent::HTLCHandlingFailed { failure_type, .. } => {
  self.liquidity_source
  .lsps2_service()

src/ffi/types.rs

@@ -149,6 +149,7 @@ pub use crate::entropy::{generate_entropy_mnemonic, NodeEntropy, WordCount};
 use crate::error::Error;
 pub use crate::liquidity::LSPS1OrderStatus;
 pub use crate::logger::{LogLevel, LogRecord, LogWriter};
+pub use crate::probing::ProbingConfig;
 use crate::{hex_utils, SocketAddress, UserChannelId};
 
 uniffi::custom_type!(PublicKey, String, {

src/lib.rs

@@ -101,10 +101,12 @@ pub mod logger;
 mod message_handler;
 pub mod payment;
 mod peer_store;
+pub mod probing;
 mod runtime;
 mod scoring;
 mod tx_broadcaster;
 mod types;
+mod util;
 mod wallet;
 
 use std::default::Default;
@@ -172,6 +174,9 @@ use payment::{
 	UnifiedPayment,
 };
 use peer_store::{PeerInfo, PeerStore};
+#[cfg(feature = "uniffi")]
+pub use probing::ArcedProbingConfigBuilder as ProbingConfigBuilder;
+use probing::{run_prober, Prober};
 use runtime::Runtime;
 pub use tokio;
 use types::{
@@ -250,6 +255,7 @@ pub struct Node {
 	om_mailbox: Option<Arc<OnionMessageMailbox>>,
 	async_payments_role: Option<AsyncPaymentsRole>,
 	hrn_resolver: HRNResolver,
+	prober: Option<Arc<Prober>>,
 	#[cfg(cycle_tests)]
 	_leak_checker: LeakChecker,
 }
@@ -610,11 +616,19 @@ impl Node {
  static_invoice_store,
  Arc::clone(&self.onion_messenger),
  self.om_mailbox.clone(),
+ self.prober.clone(),
  Arc::clone(&self.runtime),
  Arc::clone(&self.logger),
  Arc::clone(&self.config),
  ));
 
+ if let Some(prober) = self.prober.clone() {
+ let stop_rx = self.stop_sender.subscribe();
+ self.runtime.spawn_cancellable_background_task(async move {
+ run_prober(prober, stop_rx).await;
+ });
+ }
+
  // Setup background processing
  let background_persister = Arc::clone(&self.kv_store);
  let background_event_handler = Arc::clone(&event_handler);
@@ -1145,6 +1159,11 @@ impl Node {
  ))
 	}
 
+	/// Returns a reference to the [`Prober`], or `None` if no probing strategy is configured.
+	pub fn prober(&self) -> Option<&Prober> {
+ self.prober.as_deref()
+	}
+
 	/// Retrieve a list of known channels.
 	pub fn list_channels(&self) -> Vec<ChannelDetails> {
  self.channel_manager

bindings/ldk_node.udl

@@ -13,6 +13,8 @@ typedef dictionary TorConfig;
 
 typedef interface NodeEntropy;
 
+typedef interface ProbingConfig;
+
 typedef enum WordCount;
 
 [Remote]
@@ -32,6 +34,18 @@ interface LogWriter {
 	void log(LogRecord record);
 };
 
+interface ProbingConfigBuilder {
+	[Name=high_degree]
+	constructor(u64 top_node_count);
+	[Name=random_walk]
+	constructor(u64 max_hops);
+	void set_interval(u64 secs);
+	void set_max_locked_msat(u64 max_msat);
+	void set_diversity_penalty_msat(u64 penalty_msat);
+	void set_cooldown(u64 secs);
+	ProbingConfig build();
+};
+
 interface Builder {
 	constructor();
 	[Name=from_config]
@@ -59,6 +73,7 @@ interface Builder {
 	void set_node_alias(string node_alias);
 	[Throws=BuildError]
 	void set_async_payments_role(AsyncPaymentsRole? role);
+	void set_probing_config(ProbingConfig config);
 	[Throws=BuildError]
 	Node build(NodeEntropy node_entropy);
 	[Throws=BuildError]

src/builder.rs

@@ -50,6 +50,7 @@ use crate::config::{
 	default_user_config, may_announce_channel, AnnounceError, AsyncPaymentsRole,
 	BitcoindRestClientConfig, Config, ElectrumSyncConfig, EsploraSyncConfig, HRNResolverConfig,
 	TorConfig, DEFAULT_ESPLORA_SERVER_URL, DEFAULT_LOG_FILENAME, DEFAULT_LOG_LEVEL,
+	DEFAULT_MAX_PROBE_AMOUNT_MSAT, DEFAULT_MIN_PROBE_AMOUNT_MSAT,
 };
 use crate::connection::ConnectionManager;
 use crate::entropy::NodeEntropy;
@@ -74,6 +75,10 @@ use crate::logger::{log_error, LdkLogger, LogLevel, LogWriter, Logger};
 use crate::message_handler::NodeCustomMessageHandler;
 use crate::payment::asynchronous::om_mailbox::OnionMessageMailbox;
 use crate::peer_store::PeerStore;
+use crate::probing::{
+	HighDegreeStrategy, Prober, ProbingConfig, ProbingStrategy, ProbingStrategyKind,
+	RandomWalkStrategy,
+};
 use crate::runtime::{Runtime, RuntimeSpawner};
 use crate::tx_broadcaster::TransactionBroadcaster;
 use crate::types::{
@@ -306,6 +311,7 @@ pub struct NodeBuilder {
 	async_payments_role: Option<AsyncPaymentsRole>,
 	runtime_handle: Option<tokio::runtime::Handle>,
 	pathfinding_scores_sync_config: Option<PathfindingScoresSyncConfig>,
+	probing_config: Option<ProbingConfig>,
 }
 
 impl NodeBuilder {
@@ -323,6 +329,7 @@ impl NodeBuilder {
  let log_writer_config = None;
  let runtime_handle = None;
  let pathfinding_scores_sync_config = None;
+ let probing_config = None;
  Self {
  config,
  chain_data_source_config,
@@ -332,6 +339,7 @@ impl NodeBuilder {
  runtime_handle,
  async_payments_role: None,
  pathfinding_scores_sync_config,
+ probing_config,
  }
 	}
 
@@ -629,6 +637,31 @@ impl NodeBuilder {
  Ok(self)
 	}
 
+	/// Sets background probing config.
+	///
+	/// Use [`ProbingConfigBuilder`] to build the configuration:
+	/// ```no_run
+	/// # #[cfg(not(feature = "uniffi"))]
+	/// # {
+	/// use std::time::Duration;
+	/// use ldk_node::Builder;
+	/// use ldk_node::probing::ProbingConfigBuilder;
+	///
+	/// let mut builder = Builder::new();
+	/// builder.set_probing_config(
+	/// ProbingConfigBuilder::high_degree(100)
+	/// .interval(Duration::from_secs(30))
+	/// .build()
+	/// );
+	/// # }
+	/// ```
+	///
+	/// [`ProbingConfigBuilder`]: crate::probing::ProbingConfigBuilder
+	pub fn set_probing_config(&mut self, config: ProbingConfig) -> &mut Self {
+ self.probing_config = Some(config);
+ self
+	}
+
 	/// Builds a [`Node`] instance with a [`SqliteStore`] backend and according to the options
 	/// previously configured.
 	pub fn build(&self, node_entropy: NodeEntropy) -> Result<Node, BuildError> {
@@ -868,6 +901,7 @@ impl NodeBuilder {
  self.gossip_source_config.as_ref(),
  self.liquidity_source_config.as_ref(),
  self.pathfinding_scores_sync_config.as_ref(),
+ self.probing_config.as_ref(),
  self.async_payments_role,
  seed_bytes,
  runtime,
@@ -1166,6 +1200,15 @@ impl ArcedNodeBuilder {
  self.inner.write().expect("lock").set_async_payments_role(role).map(|_| ())
 	}
 
+	/// Configures background probing.
+	///
+	/// Use [`ProbingConfigBuilder`] to build the configuration.
+	///
+	/// [`ProbingConfigBuilder`]: crate::probing::ProbingConfigBuilder
+	pub fn set_probing_config(&self, config: Arc<ProbingConfig>) {
+ self.inner.write().expect("lock").set_probing_config((*config).clone());
+	}
+
 	/// Builds a [`Node`] instance with a [`SqliteStore`] backend and according to the options
 	/// previously configured.
 	pub fn build(&self, node_entropy: Arc<NodeEntropy>) -> Result<Arc<Node>, BuildError> {
@@ -1361,8 +1404,8 @@ fn build_with_store_internal(
 	gossip_source_config: Option<&GossipSourceConfig>,
 	liquidity_source_config: Option<&LiquiditySourceConfig>,
 	pathfinding_scores_sync_config: Option<&PathfindingScoresSyncConfig>,
-async_payments_role: Option<AsyncPaymentsRole>, seed_bytes: [u8; 64], runtime: Arc<Runtime>,
-	logger: Arc<Logger>, kv_store: Arc<DynStore>,
+probing_config: Option<&ProbingConfig>, async_payments_role: Option<AsyncPaymentsRole>,
+seed_bytes: [u8; 64], runtime: Arc<Runtime>, logger: Arc<Logger>, kv_store: Arc<DynStore>,
 ) -> Result<Node, BuildError> {
 	optionally_install_rustls_cryptoprovider();
 
@@ -2219,6 +2262,51 @@ fn build_with_store_internal(
  _leak_checker.0.push(Arc::downgrade(&wallet) as Weak<dyn Any + Send + Sync>);
 	}
 
+	let prober = probing_config.map(|probing_cfg| {
+ let strategy: Arc<dyn ProbingStrategy> = match &probing_cfg.kind {
+ ProbingStrategyKind::HighDegree { top_node_count } => {
+ // Dedicated router for probing so the diversity penalty doesn't interfere
+ // with real payments; shares the scorer so probe results still train it.
+ let mut probing_fee_params = ProbabilisticScoringFeeParameters::default();
+ if let Some(penalty) = probing_cfg.diversity_penalty_msat {
+ probing_fee_params.probing_diversity_penalty_msat = penalty;
+ }
+ let probing_router = Arc::new(DefaultRouter::new(
+ Arc::clone(&network_graph),
+ Arc::clone(&logger),
+ Arc::clone(&keys_manager),
+ Arc::clone(&scorer),
+ probing_fee_params,
+ ));
+ Arc::new(HighDegreeStrategy::new(
+ Arc::clone(&network_graph),
+ Arc::clone(&channel_manager),
+ probing_router,
+ *top_node_count,
+ DEFAULT_MIN_PROBE_AMOUNT_MSAT,
+ DEFAULT_MAX_PROBE_AMOUNT_MSAT,
+ probing_cfg.cooldown,
+ config.probing_liquidity_limit_multiplier,
+ ))
+ },
+ ProbingStrategyKind::RandomWalk { max_hops } => Arc::new(RandomWalkStrategy::new(
+ Arc::clone(&network_graph),
+ Arc::clone(&channel_manager),
+ *max_hops,
+ DEFAULT_MIN_PROBE_AMOUNT_MSAT,
+ DEFAULT_MAX_PROBE_AMOUNT_MSAT,
+ )),
+ ProbingStrategyKind::Custom(s) => Arc::clone(s),
+ };
+ Arc::new(Prober {
+ channel_manager: Arc::clone(&channel_manager),
+ logger: Arc::clone(&logger),
+ strategy,
+ interval: probing_cfg.interval,
+ max_locked_msat: probing_cfg.max_locked_msat,
+ })
+	});
+
 	Ok(Node {
  runtime,
  stop_sender,
@@ -2252,6 +2340,7 @@ fn build_with_store_internal(
  om_mailbox,
  async_payments_role,
  hrn_resolver,
+ prober,
  #[cfg(cycle_tests)]
  _leak_checker,
 	})

src/config.rs

@@ -28,6 +28,12 @@ const DEFAULT_BDK_WALLET_SYNC_INTERVAL_SECS: u64 = 80;
 const DEFAULT_LDK_WALLET_SYNC_INTERVAL_SECS: u64 = 30;
 const DEFAULT_FEE_RATE_CACHE_UPDATE_INTERVAL_SECS: u64 = 60 * 10;
 const DEFAULT_PROBING_LIQUIDITY_LIMIT_MULTIPLIER: u64 = 3;
+pub(crate) const DEFAULT_PROBING_INTERVAL_SECS: u64 = 10;
+pub(crate) const MIN_PROBING_INTERVAL: Duration = Duration::from_millis(100);
+pub(crate) const DEFAULT_PROBED_NODE_COOLDOWN_SECS: u64 = 60 * 60; // 1 hour
+pub(crate) const DEFAULT_MAX_PROBE_LOCKED_MSAT: u64 = 100_000_000; // 100k sats
+pub(crate) const DEFAULT_MIN_PROBE_AMOUNT_MSAT: u64 = 1_000_000; // 1k sats
+pub(crate) const DEFAULT_MAX_PROBE_AMOUNT_MSAT: u64 = 10_000_000; // 10k sats
 const DEFAULT_ANCHOR_PER_CHANNEL_RESERVE_SATS: u64 = 25_000;
 
 // The default timeout after which we abort a wallet syncing operation.

src/event.rs

@@ -52,6 +52,7 @@ use crate::payment::store::{
 	PaymentDetails, PaymentDetailsUpdate, PaymentDirection, PaymentKind, PaymentStatus,
 };
 use crate::payment::PaymentMetadata;
+use crate::probing::Prober;
 use crate::runtime::Runtime;
 use crate::types::{
 	CustomTlvRecord, DynStore, KeysManager, OnionMessenger, PaymentStore, Sweeper, Wallet,
@@ -536,12 +537,13 @@ where
 	payment_store: Arc<PaymentStore>,
 	peer_store: Arc<PeerStore<L>>,
 	keys_manager: Arc<KeysManager>,
-	runtime: Arc<Runtime>,
-	logger: L,
-	config: Arc<Config>,
 	static_invoice_store: Option<StaticInvoiceStore>,
 	onion_messenger: Arc<OnionMessenger>,
 	om_mailbox: Option<Arc<OnionMessageMailbox>>,
+	prober: Option<Arc<Prober>>,
+	runtime: Arc<Runtime>,
+	logger: L,
+	config: Arc<Config>,
 }
 
 impl<L: Deref + Clone + Sync + Send + 'static> EventHandler<L>
@@ -556,8 +558,8 @@ where
  liquidity_source: Arc<LiquiditySource<Arc<Logger>>>, payment_store: Arc<PaymentStore>,
  peer_store: Arc<PeerStore<L>>, keys_manager: Arc<KeysManager>,
  static_invoice_store: Option<StaticInvoiceStore>, onion_messenger: Arc<OnionMessenger>,
- om_mailbox: Option<Arc<OnionMessageMailbox>>, runtime: Arc<Runtime>, logger: L,
- config: Arc<Config>,
+ om_mailbox: Option<Arc<OnionMessageMailbox>>, prober: Option<Arc<Prober>>,
+runtime: Arc<Runtime>, logger: L, config: Arc<Config>,
 	) -> Self {
  Self {
  event_queue,
@@ -571,12 +573,13 @@ where
  payment_store,
  peer_store,
  keys_manager,
- logger,
- runtime,
- config,
  static_invoice_store,
  onion_messenger,
  om_mailbox,
+ prober,
+ runtime,
+ logger,
+ config,
  }
 	}
 
@@ -1208,8 +1211,16 @@ where
 
  LdkEvent::PaymentPathSuccessful { .. } => {},
  LdkEvent::PaymentPathFailed { .. } => {},
- LdkEvent::ProbeSuccessful { .. } => {},
- LdkEvent::ProbeFailed { .. } => {},
+ LdkEvent::ProbeSuccessful { path, payment_id, .. } => {
+ if let Some(prober) = &self.prober {
+ prober.handle_background_probe_successful(&path, payment_id);
+ }
+ },
+ LdkEvent::ProbeFailed { path, payment_id, .. } => {
+ if let Some(prober) = &self.prober {
+ prober.handle_background_probe_failed(&path, payment_id);
+ }
+ },
  LdkEvent::HTLCHandlingFailed { failure_type, .. } => {
  self.liquidity_source
  .lsps2_service()

src/ffi/types.rs

@@ -149,6 +149,7 @@ pub use crate::entropy::{generate_entropy_mnemonic, NodeEntropy, WordCount};
 use crate::error::Error;
 pub use crate::liquidity::LSPS1OrderStatus;
 pub use crate::logger::{LogLevel, LogRecord, LogWriter};
+pub use crate::probing::ProbingConfig;
 use crate::{hex_utils, SocketAddress, UserChannelId};
 
 uniffi::custom_type!(PublicKey, String, {

src/lib.rs

@@ -101,10 +101,12 @@ pub mod logger;
 mod message_handler;
 pub mod payment;
 mod peer_store;
+pub mod probing;
 mod runtime;
 mod scoring;
 mod tx_broadcaster;
 mod types;
+mod util;
 mod wallet;
 
 use std::default::Default;
@@ -172,6 +174,9 @@ use payment::{
 	UnifiedPayment,
 };
 use peer_store::{PeerInfo, PeerStore};
+#[cfg(feature = "uniffi")]
+pub use probing::ArcedProbingConfigBuilder as ProbingConfigBuilder;
+use probing::{run_prober, Prober};
 use runtime::Runtime;
 pub use tokio;
 use types::{
@@ -250,6 +255,7 @@ pub struct Node {
 	om_mailbox: Option<Arc<OnionMessageMailbox>>,
 	async_payments_role: Option<AsyncPaymentsRole>,
 	hrn_resolver: HRNResolver,
+	prober: Option<Arc<Prober>>,
 	#[cfg(cycle_tests)]
 	_leak_checker: LeakChecker,
 }
@@ -610,11 +616,19 @@ impl Node {
  static_invoice_store,
  Arc::clone(&self.onion_messenger),
  self.om_mailbox.clone(),
+ self.prober.clone(),
  Arc::clone(&self.runtime),
  Arc::clone(&self.logger),
  Arc::clone(&self.config),
  ));
 
+ if let Some(prober) = self.prober.clone() {
+ let stop_rx = self.stop_sender.subscribe();
+ self.runtime.spawn_cancellable_background_task(async move {
+ run_prober(prober, stop_rx).await;
+ });
+ }
+
  // Setup background processing
  let background_persister = Arc::clone(&self.kv_store);
  let background_event_handler = Arc::clone(&event_handler);
@@ -1145,6 +1159,11 @@ impl Node {
  ))
 	}
 
+	/// Returns a reference to the [`Prober`], or `None` if no probing strategy is configured.
+	pub fn prober(&self) -> Option<&Prober> {
+ self.prober.as_deref()
+	}
+
 	/// Retrieve a list of known channels.
 	pub fn list_channels(&self) -> Vec<ChannelDetails> {
  self.channel_manager

bindings/ldk_node.udl

@@ -13,6 +13,8 @@ typedef dictionary TorConfig;
 
 typedef interface NodeEntropy;
 
+typedef interface ProbingConfig;
+
 typedef enum WordCount;
 
 [Remote]
@@ -32,6 +34,18 @@ interface LogWriter {
 	void log(LogRecord record);
 };
 
+interface ProbingConfigBuilder {
+	[Name=high_degree]
+	constructor(u64 top_node_count);
+	[Name=random_walk]
+	constructor(u64 max_hops);
+	void set_interval(u64 secs);
+	void set_max_locked_msat(u64 max_msat);
+	void set_diversity_penalty_msat(u64 penalty_msat);
+	void set_cooldown(u64 secs);
+	ProbingConfig build();
+};
+
 interface Builder {
 	constructor();
 	[Name=from_config]
@@ -59,6 +73,7 @@ interface Builder {
 	void set_node_alias(string node_alias);
 	[Throws=BuildError]
 	void set_async_payments_role(AsyncPaymentsRole? role);
+	void set_probing_config(ProbingConfig config);
 	[Throws=BuildError]
 	Node build(NodeEntropy node_entropy);
 	[Throws=BuildError]

src/builder.rs

@@ -50,6 +50,7 @@ use crate::config::{
 	default_user_config, may_announce_channel, AnnounceError, AsyncPaymentsRole,
 	BitcoindRestClientConfig, Config, ElectrumSyncConfig, EsploraSyncConfig, HRNResolverConfig,
 	TorConfig, DEFAULT_ESPLORA_SERVER_URL, DEFAULT_LOG_FILENAME, DEFAULT_LOG_LEVEL,
+	DEFAULT_MAX_PROBE_AMOUNT_MSAT, DEFAULT_MIN_PROBE_AMOUNT_MSAT,
 };
 use crate::connection::ConnectionManager;
 use crate::entropy::NodeEntropy;
@@ -74,6 +75,10 @@ use crate::logger::{log_error, LdkLogger, LogLevel, LogWriter, Logger};
 use crate::message_handler::NodeCustomMessageHandler;
 use crate::payment::asynchronous::om_mailbox::OnionMessageMailbox;
 use crate::peer_store::PeerStore;
+use crate::probing::{
+	HighDegreeStrategy, Prober, ProbingConfig, ProbingStrategy, ProbingStrategyKind,
+	RandomWalkStrategy,
+};
 use crate::runtime::{Runtime, RuntimeSpawner};
 use crate::tx_broadcaster::TransactionBroadcaster;
 use crate::types::{
@@ -306,6 +311,7 @@ pub struct NodeBuilder {
 	async_payments_role: Option<AsyncPaymentsRole>,
 	runtime_handle: Option<tokio::runtime::Handle>,
 	pathfinding_scores_sync_config: Option<PathfindingScoresSyncConfig>,
+	probing_config: Option<ProbingConfig>,
 }
 
 impl NodeBuilder {
@@ -323,6 +329,7 @@ impl NodeBuilder {
  let log_writer_config = None;
  let runtime_handle = None;
  let pathfinding_scores_sync_config = None;
+ let probing_config = None;
  Self {
  config,
  chain_data_source_config,
@@ -332,6 +339,7 @@ impl NodeBuilder {
  runtime_handle,
  async_payments_role: None,
  pathfinding_scores_sync_config,
+ probing_config,
  }
 	}
 
@@ -629,6 +637,31 @@ impl NodeBuilder {
  Ok(self)
 	}
 
+	/// Sets background probing config.
+	///
+	/// Use [`ProbingConfigBuilder`] to build the configuration:
+	/// ```no_run
+	/// # #[cfg(not(feature = "uniffi"))]
+	/// # {
+	/// use std::time::Duration;
+	/// use ldk_node::Builder;
+	/// use ldk_node::probing::ProbingConfigBuilder;
+	///
+	/// let mut builder = Builder::new();
+	/// builder.set_probing_config(
+	/// ProbingConfigBuilder::high_degree(100)
+	/// .interval(Duration::from_secs(30))
+	/// .build()
+	/// );
+	/// # }
+	/// ```
+	///
+	/// [`ProbingConfigBuilder`]: crate::probing::ProbingConfigBuilder
+	pub fn set_probing_config(&mut self, config: ProbingConfig) -> &mut Self {
+ self.probing_config = Some(config);
+ self
+	}
+
 	/// Builds a [`Node`] instance with a [`SqliteStore`] backend and according to the options
 	/// previously configured.
 	pub fn build(&self, node_entropy: NodeEntropy) -> Result<Node, BuildError> {
@@ -868,6 +901,7 @@ impl NodeBuilder {
  self.gossip_source_config.as_ref(),
  self.liquidity_source_config.as_ref(),
  self.pathfinding_scores_sync_config.as_ref(),
+ self.probing_config.as_ref(),
  self.async_payments_role,
  seed_bytes,
  runtime,
@@ -1166,6 +1200,15 @@ impl ArcedNodeBuilder {
  self.inner.write().expect("lock").set_async_payments_role(role).map(|_| ())
 	}
 
+	/// Configures background probing.
+	///
+	/// Use [`ProbingConfigBuilder`] to build the configuration.
+	///
+	/// [`ProbingConfigBuilder`]: crate::probing::ProbingConfigBuilder
+	pub fn set_probing_config(&self, config: Arc<ProbingConfig>) {
+ self.inner.write().expect("lock").set_probing_config((*config).clone());
+	}
+
 	/// Builds a [`Node`] instance with a [`SqliteStore`] backend and according to the options
 	/// previously configured.
 	pub fn build(&self, node_entropy: Arc<NodeEntropy>) -> Result<Arc<Node>, BuildError> {
@@ -1361,8 +1404,8 @@ fn build_with_store_internal(
 	gossip_source_config: Option<&GossipSourceConfig>,
 	liquidity_source_config: Option<&LiquiditySourceConfig>,
 	pathfinding_scores_sync_config: Option<&PathfindingScoresSyncConfig>,
-async_payments_role: Option<AsyncPaymentsRole>, seed_bytes: [u8; 64], runtime: Arc<Runtime>,
-	logger: Arc<Logger>, kv_store: Arc<DynStore>,
+probing_config: Option<&ProbingConfig>, async_payments_role: Option<AsyncPaymentsRole>,
+seed_bytes: [u8; 64], runtime: Arc<Runtime>, logger: Arc<Logger>, kv_store: Arc<DynStore>,
 ) -> Result<Node, BuildError> {
 	optionally_install_rustls_cryptoprovider();
 
@@ -2219,6 +2262,51 @@ fn build_with_store_internal(
  _leak_checker.0.push(Arc::downgrade(&wallet) as Weak<dyn Any + Send + Sync>);
 	}
 
+	let prober = probing_config.map(|probing_cfg| {
+ let strategy: Arc<dyn ProbingStrategy> = match &probing_cfg.kind {
+ ProbingStrategyKind::HighDegree { top_node_count } => {
+ // Dedicated router for probing so the diversity penalty doesn't interfere
+ // with real payments; shares the scorer so probe results still train it.
+ let mut probing_fee_params = ProbabilisticScoringFeeParameters::default();
+ if let Some(penalty) = probing_cfg.diversity_penalty_msat {
+ probing_fee_params.probing_diversity_penalty_msat = penalty;
+ }
+ let probing_router = Arc::new(DefaultRouter::new(
+ Arc::clone(&network_graph),
+ Arc::clone(&logger),
+ Arc::clone(&keys_manager),
+ Arc::clone(&scorer),
+ probing_fee_params,
+ ));
+ Arc::new(HighDegreeStrategy::new(
+ Arc::clone(&network_graph),
+ Arc::clone(&channel_manager),
+ probing_router,
+ *top_node_count,
+ DEFAULT_MIN_PROBE_AMOUNT_MSAT,
+ DEFAULT_MAX_PROBE_AMOUNT_MSAT,
+ probing_cfg.cooldown,
+ config.probing_liquidity_limit_multiplier,
+ ))
+ },
+ ProbingStrategyKind::RandomWalk { max_hops } => Arc::new(RandomWalkStrategy::new(
+ Arc::clone(&network_graph),
+ Arc::clone(&channel_manager),
+ *max_hops,
+ DEFAULT_MIN_PROBE_AMOUNT_MSAT,
+ DEFAULT_MAX_PROBE_AMOUNT_MSAT,
+ )),
+ ProbingStrategyKind::Custom(s) => Arc::clone(s),
+ };
+ Arc::new(Prober {
+ channel_manager: Arc::clone(&channel_manager),
+ logger: Arc::clone(&logger),
+ strategy,
+ interval: probing_cfg.interval,
+ max_locked_msat: probing_cfg.max_locked_msat,
+ })
+	});
+
 	Ok(Node {
  runtime,
  stop_sender,
@@ -2252,6 +2340,7 @@ fn build_with_store_internal(
  om_mailbox,
  async_payments_role,
  hrn_resolver,
+ prober,
  #[cfg(cycle_tests)]
  _leak_checker,
 	})

src/config.rs

@@ -28,6 +28,12 @@ const DEFAULT_BDK_WALLET_SYNC_INTERVAL_SECS: u64 = 80;
 const DEFAULT_LDK_WALLET_SYNC_INTERVAL_SECS: u64 = 30;
 const DEFAULT_FEE_RATE_CACHE_UPDATE_INTERVAL_SECS: u64 = 60 * 10;
 const DEFAULT_PROBING_LIQUIDITY_LIMIT_MULTIPLIER: u64 = 3;
+pub(crate) const DEFAULT_PROBING_INTERVAL_SECS: u64 = 10;
+pub(crate) const MIN_PROBING_INTERVAL: Duration = Duration::from_millis(100);
+pub(crate) const DEFAULT_PROBED_NODE_COOLDOWN_SECS: u64 = 60 * 60; // 1 hour
+pub(crate) const DEFAULT_MAX_PROBE_LOCKED_MSAT: u64 = 100_000_000; // 100k sats
+pub(crate) const DEFAULT_MIN_PROBE_AMOUNT_MSAT: u64 = 1_000_000; // 1k sats
+pub(crate) const DEFAULT_MAX_PROBE_AMOUNT_MSAT: u64 = 10_000_000; // 10k sats
 const DEFAULT_ANCHOR_PER_CHANNEL_RESERVE_SATS: u64 = 25_000;
 
 // The default timeout after which we abort a wallet syncing operation.

src/event.rs

@@ -52,6 +52,7 @@ use crate::payment::store::{
 	PaymentDetails, PaymentDetailsUpdate, PaymentDirection, PaymentKind, PaymentStatus,
 };
 use crate::payment::PaymentMetadata;
+use crate::probing::Prober;
 use crate::runtime::Runtime;
 use crate::types::{
 	CustomTlvRecord, DynStore, KeysManager, OnionMessenger, PaymentStore, Sweeper, Wallet,
@@ -536,12 +537,13 @@ where
 	payment_store: Arc<PaymentStore>,
 	peer_store: Arc<PeerStore<L>>,
 	keys_manager: Arc<KeysManager>,
-	runtime: Arc<Runtime>,
-	logger: L,
-	config: Arc<Config>,
 	static_invoice_store: Option<StaticInvoiceStore>,
 	onion_messenger: Arc<OnionMessenger>,
 	om_mailbox: Option<Arc<OnionMessageMailbox>>,
+	prober: Option<Arc<Prober>>,
+	runtime: Arc<Runtime>,
+	logger: L,
+	config: Arc<Config>,
 }
 
 impl<L: Deref + Clone + Sync + Send + 'static> EventHandler<L>
@@ -556,8 +558,8 @@ where
  liquidity_source: Arc<LiquiditySource<Arc<Logger>>>, payment_store: Arc<PaymentStore>,
  peer_store: Arc<PeerStore<L>>, keys_manager: Arc<KeysManager>,
  static_invoice_store: Option<StaticInvoiceStore>, onion_messenger: Arc<OnionMessenger>,
- om_mailbox: Option<Arc<OnionMessageMailbox>>, runtime: Arc<Runtime>, logger: L,
- config: Arc<Config>,
+ om_mailbox: Option<Arc<OnionMessageMailbox>>, prober: Option<Arc<Prober>>,
+runtime: Arc<Runtime>, logger: L, config: Arc<Config>,
 	) -> Self {
  Self {
  event_queue,
@@ -571,12 +573,13 @@ where
  payment_store,
  peer_store,
  keys_manager,
- logger,
- runtime,
- config,
  static_invoice_store,
  onion_messenger,
  om_mailbox,
+ prober,
+ runtime,
+ logger,
+ config,
  }
 	}
 
@@ -1208,8 +1211,16 @@ where
 
  LdkEvent::PaymentPathSuccessful { .. } => {},
  LdkEvent::PaymentPathFailed { .. } => {},
- LdkEvent::ProbeSuccessful { .. } => {},
- LdkEvent::ProbeFailed { .. } => {},
+ LdkEvent::ProbeSuccessful { path, payment_id, .. } => {
+ if let Some(prober) = &self.prober {
+ prober.handle_background_probe_successful(&path, payment_id);
+ }
+ },
+ LdkEvent::ProbeFailed { path, payment_id, .. } => {
+ if let Some(prober) = &self.prober {
+ prober.handle_background_probe_failed(&path, payment_id);
+ }
+ },
  LdkEvent::HTLCHandlingFailed { failure_type, .. } => {
  self.liquidity_source
  .lsps2_service()

src/ffi/types.rs

@@ -149,6 +149,7 @@ pub use crate::entropy::{generate_entropy_mnemonic, NodeEntropy, WordCount};
 use crate::error::Error;
 pub use crate::liquidity::LSPS1OrderStatus;
 pub use crate::logger::{LogLevel, LogRecord, LogWriter};
+pub use crate::probing::ProbingConfig;
 use crate::{hex_utils, SocketAddress, UserChannelId};
 
 uniffi::custom_type!(PublicKey, String, {

src/lib.rs

@@ -101,10 +101,12 @@ pub mod logger;
 mod message_handler;
 pub mod payment;
 mod peer_store;
+pub mod probing;
 mod runtime;
 mod scoring;
 mod tx_broadcaster;
 mod types;
+mod util;
 mod wallet;
 
 use std::default::Default;
@@ -172,6 +174,9 @@ use payment::{
 	UnifiedPayment,
 };
 use peer_store::{PeerInfo, PeerStore};
+#[cfg(feature = "uniffi")]
+pub use probing::ArcedProbingConfigBuilder as ProbingConfigBuilder;
+use probing::{run_prober, Prober};
 use runtime::Runtime;
 pub use tokio;
 use types::{
@@ -250,6 +255,7 @@ pub struct Node {
 	om_mailbox: Option<Arc<OnionMessageMailbox>>,
 	async_payments_role: Option<AsyncPaymentsRole>,
 	hrn_resolver: HRNResolver,
+	prober: Option<Arc<Prober>>,
 	#[cfg(cycle_tests)]
 	_leak_checker: LeakChecker,
 }
@@ -610,11 +616,19 @@ impl Node {
  static_invoice_store,
  Arc::clone(&self.onion_messenger),
  self.om_mailbox.clone(),
+ self.prober.clone(),
  Arc::clone(&self.runtime),
  Arc::clone(&self.logger),
  Arc::clone(&self.config),
  ));
 
+ if let Some(prober) = self.prober.clone() {
+ let stop_rx = self.stop_sender.subscribe();
+ self.runtime.spawn_cancellable_background_task(async move {
+ run_prober(prober, stop_rx).await;
+ });
+ }
+
  // Setup background processing
  let background_persister = Arc::clone(&self.kv_store);
  let background_event_handler = Arc::clone(&event_handler);
@@ -1145,6 +1159,11 @@ impl Node {
  ))
 	}
 
+	/// Returns a reference to the [`Prober`], or `None` if no probing strategy is configured.
+	pub fn prober(&self) -> Option<&Prober> {
+ self.prober.as_deref()
+	}
+
 	/// Retrieve a list of known channels.
 	pub fn list_channels(&self) -> Vec<ChannelDetails> {
  self.channel_manager