Add prune_persisted_channel to Persist trait

Author: jbesraa

lightning/src/chain/chainmonitor.rs

@@ -194,6 +194,12 @@ pub trait Persist<ChannelSigner: WriteableEcdsaChannelSigner> {
 	///
 	/// [`Writeable::write`]: crate::util::ser::Writeable::write
 	fn update_persisted_channel(&self, channel_funding_outpoint: OutPoint, update: Option<&ChannelMonitorUpdate>, data: &ChannelMonitor<ChannelSigner>, update_id: MonitorUpdateId) -> ChannelMonitorUpdateStatus;
+
+	/// Prune a channel's data.
+	///
+	/// This is called when a channel is stale, ie we dont have balance to claim and its
+	/// closed.
+	fn prune_persisted_channel(&self, channel_funding_outpoint: OutPoint) -> bool;
 }
 
 struct MonitorHolder<ChannelSigner: WriteableEcdsaChannelSigner> {

lightning/src/util/persist.rs

@@ -58,6 +58,11 @@ pub const CHANNEL_MONITOR_PERSISTENCE_SECONDARY_NAMESPACE: &str = "";
 /// The primary namespace under which [`ChannelMonitorUpdate`]s will be persisted.
 pub const CHANNEL_MONITOR_UPDATE_PERSISTENCE_PRIMARY_NAMESPACE: &str = "monitor_updates";
 
+/// The primary namespace under which [`ChannelMonitor`]s will be persisted.
+pub const PRUNED_CHANNEL_MONITOR_PERSISTENCE_PRIMARY_NAMESPACE: &str = "pruned_monitors";
+/// The secondary namespace under which [`ChannelMonitor`]s will be persisted.
+pub const PRUNED_CHANNEL_MONITOR_PERSISTENCE_SECONDARY_NAMESPACE: &str = "";
+
 /// The primary namespace under which the [`NetworkGraph`] will be persisted.
 pub const NETWORK_GRAPH_PERSISTENCE_PRIMARY_NAMESPACE: &str = "";
 /// The secondary namespace under which the [`NetworkGraph`] will be persisted.
@@ -241,6 +246,18 @@ impl<ChannelSigner: WriteableEcdsaChannelSigner, K: KVStore> Persist<ChannelSign
 			Err(_) => chain::ChannelMonitorUpdateStatus::UnrecoverableError
 		}
 	}
+
+	fn prune_persisted_channel(&self, funding_txo: OutPoint) -> bool {
+		let key = format!("{}_{}", funding_txo.txid.to_string(), funding_txo.index);
+		match self.remove(
+			CHANNEL_MONITOR_PERSISTENCE_PRIMARY_NAMESPACE,
+			CHANNEL_MONITOR_PERSISTENCE_SECONDARY_NAMESPACE,
+			&key, false)
+		{
+			Ok(()) => true,
+			Err(_) => false
+		}
+	}
 }
 
 impl<ChannelSigner: WriteableEcdsaChannelSigner> Persist<ChannelSigner> for dyn KVStore + Send + Sync {
@@ -272,6 +289,18 @@ impl<ChannelSigner: WriteableEcdsaChannelSigner> Persist<ChannelSigner> for dyn
 			Err(_) => chain::ChannelMonitorUpdateStatus::UnrecoverableError
 		}
 	}
+
+	fn prune_persisted_channel(&self, funding_txo: OutPoint) -> bool {
+		let key = format!("{}_{}", funding_txo.txid.to_string(), funding_txo.index);
+		match self.remove(
+			CHANNEL_MONITOR_PERSISTENCE_PRIMARY_NAMESPACE,
+			CHANNEL_MONITOR_PERSISTENCE_SECONDARY_NAMESPACE,
+			&key, false)
+		{
+			Ok(()) => true,
+			Err(_) => false
+		}
+	}
 }
 
 /// Read previously persisted [`ChannelMonitor`]s from the store.
@@ -778,6 +807,29 @@ where
 			self.persist_new_channel(funding_txo, monitor, monitor_update_call_id)
 		}
 	}
+
+	fn prune_persisted_channel(&self, funding_txo: OutPoint) -> bool {
+		let monitor_name = MonitorName::from(funding_txo);
+		match self.kv_store.remove(
+			CHANNEL_MONITOR_PERSISTENCE_PRIMARY_NAMESPACE,
+			CHANNEL_MONITOR_PERSISTENCE_SECONDARY_NAMESPACE,
+			monitor_name.as_str(),
+			false,
+		) {
+			Ok(()) => true,
+			Err(e) => {
+				log_error!(
+					self.logger,
+					"Failed to remove ChannelMonitor {}/{}/{} reason: {}",
+					CHANNEL_MONITOR_PERSISTENCE_PRIMARY_NAMESPACE,
+					CHANNEL_MONITOR_PERSISTENCE_SECONDARY_NAMESPACE,
+					monitor_name.as_str(),
+					e
+				);
+				false
+			}
+		}
+	}
 }
 
 impl<K: Deref, L: Deref, ES: Deref, SP: Deref> MonitorUpdatingPersister<K, L, ES, SP>

lightning/src/util/test_utils.rs

@@ -501,6 +501,10 @@ impl<Signer: sign::ecdsa::WriteableEcdsaChannelSigner> chainmonitor::Persist<Sig
 		}
 		res
 	}
+
+	fn prune_persisted_channel(&self, _funding_txo: OutPoint) -> bool {
+		false
+	}
 }
 
 pub struct TestPersister {
@@ -549,6 +553,10 @@ impl<Signer: sign::ecdsa::WriteableEcdsaChannelSigner> chainmonitor::Persist<Sig
 		}
 		ret
 	}
+
+	fn prune_persisted_channel(&self, _funding_txo: OutPoint) -> bool { 
+		false
+	}
 }
 
 pub struct TestStore {