Add ChannelMonitor::is_fully_resolved function

  Checks if the monitor is fully resolved. Resolved monitor is one that has claimed all of
  its ouputs and balacnes.

  This function returns true only if `get_claimable_balances` has been empty for at least
  2016 blocks.

Author: jbesraa

lightning/src/chain/channelmonitor.rs

@@ -934,6 +934,9 @@ pub(crate) struct ChannelMonitorImpl<Signer: WriteableEcdsaChannelSigner> {
 	/// Ordering of tuple data: (their_per_commitment_point, feerate_per_kw, to_broadcaster_sats,
 	/// to_countersignatory_sats)
 	initial_counterparty_commitment_info: Option<(PublicKey, u32, u64, u64)>,
+
+	/// The first block height at which we had no remaining claimable balances.
+	balances_empty_height: Option<u32>,
 }
 
 /// Transaction outputs to watch for on-chain spends.
@@ -1327,6 +1330,7 @@ impl<Signer: WriteableEcdsaChannelSigner> ChannelMonitor<Signer> {
 			best_block,
 			counterparty_node_id: Some(counterparty_node_id),
 			initial_counterparty_commitment_info: None,
+			balances_empty_height: None,
 		})
 	}
 
@@ -1855,6 +1859,42 @@ impl<Signer: WriteableEcdsaChannelSigner> ChannelMonitor<Signer> {
 		spendable_outputs
 	}
 
+	/// Checks if the monitor is fully resolved. Resolved monitor is one that has claimed all of
+	/// its ouputs and balacnes.
+	///
+	/// This function returns true only if `get_claimable_balances` has been empty for at least
+	/// 2016 blocks.
+	pub(crate) fn is_fully_resolved(&self) -> bool {
+		let is_all_funds_claimed = self.get_claimable_balances().is_empty();
+		let current_height = self.current_best_block().height;
+		let mut inner = self.inner.lock().unwrap();
+
+		match (inner.balances_empty_height, is_all_funds_claimed) {
+			(Some(h), true) => {
+				// Claimed all funds, Check if reached the threshold.
+				let threshold = 2016; // two weeks
+				return current_height >= h + threshold;
+			},
+			(Some(_), false) => {
+				// previously assumed we claimed all funds, but we have new funds to claim.
+				// Should not happen in practice.
+				debug_assert!(!is_all_funds_claimed, "Trying to check if monitor is fully resolved before all funds are claimed. Aborting.");
+				inner.balances_empty_height = None;
+				return false;
+			},
+			(None, true) => {
+				// Claimed all funds but `balances_empty_height` is None. It is set to the
+				// current block height.
+				inner.balances_empty_height = Some(current_height);
+				return false;
+			},
+			(None, false) => {
+				// Have funds to claim.
+				return false;
+			},
+		}
+	}
+
 	#[cfg(test)]
 	pub fn get_counterparty_payment_script(&self) -> ScriptBuf {
 		self.inner.lock().unwrap().counterparty_payment_script.clone()
@@ -4721,6 +4761,7 @@ impl<'a, 'b, ES: EntropySource, SP: SignerProvider> ReadableArgs<(&'a ES, &'b SP
 			best_block,
 			counterparty_node_id,
 			initial_counterparty_commitment_info,
+			balances_empty_height: None,
 		})))
 	}
 }

lightning/src/ln/monitor_tests.rs

@@ -259,6 +259,9 @@ fn do_chanmon_claim_value_coop_close(anchors: bool) {
 
 	check_closed_event!(nodes[0], 1, ClosureReason::LocallyInitiatedCooperativeClosure, [nodes[1].node.get_our_node_id()], 1000000);
 	check_closed_event!(nodes[1], 1, ClosureReason::CounterpartyInitiatedCooperativeClosure, [nodes[0].node.get_our_node_id()], 1000000);
+
+	assert!(nodes[0].chain_monitor.chain_monitor.get_and_clear_pending_events().is_empty());
+	assert!(nodes[1].chain_monitor.chain_monitor.get_and_clear_pending_events().is_empty());
 }
 
 #[test]