Make all internal signatures accept LowerBoundedFeeEstimator

fuzz/src/chanmon_consistency.rs

@@ -33,7 +33,7 @@ use lightning::chain;
 use lightning::chain::{BestBlock, ChannelMonitorUpdateErr, chainmonitor, channelmonitor, Confirm, Watch};
 use lightning::chain::channelmonitor::{ChannelMonitor, MonitorEvent};
 use lightning::chain::transaction::OutPoint;
-use lightning::chain::chaininterface::{BroadcasterInterface, ConfirmationTarget, FeeEstimator};
+use lightning::chain::chaininterface::{BroadcasterInterface, ConfirmationTarget, FeeEstimator, LowerBoundedFeeEstimator};
 use lightning::chain::keysinterface::{KeyMaterial, KeysInterface, InMemorySigner, Recipient};
 use lightning::ln::{PaymentHash, PaymentPreimage, PaymentSecret};
 use lightning::ln::channelmanager::{ChainParameters, ChannelManager, PaymentSendFailure, ChannelManagerReadArgs};
@@ -140,7 +140,7 @@ impl chain::Watch<EnforcingSigner> for TestChainMonitor {
 		};
 		let deserialized_monitor = <(BlockHash, channelmonitor::ChannelMonitor<EnforcingSigner>)>::
 			read(&mut Cursor::new(&map_entry.get().1), &*self.keys).unwrap().1;
-		deserialized_monitor.update_monitor(&update, &&TestBroadcaster{}, &&FuzzEstimator { ret_val: atomic::AtomicU32::new(253) }, &self.logger).unwrap();
+		deserialized_monitor.update_monitor(&update, &&TestBroadcaster{}, &LowerBoundedFeeEstimator::new(&FuzzEstimator { ret_val: atomic::AtomicU32::new(253) }), &self.logger).unwrap();
 		let mut ser = VecWriter(Vec::new());
 		deserialized_monitor.write(&mut ser).unwrap();
 		map_entry.insert((update.update_id, ser.0));

lightning-block-sync/src/init.rs

@@ -45,7 +45,7 @@ BlockSourceResult<ValidatedBlockHeader> where B::Target: BlockSource {
 /// use lightning::chain::chainmonitor;
 /// use lightning::chain::chainmonitor::ChainMonitor;
 /// use lightning::chain::channelmonitor::ChannelMonitor;
-/// use lightning::chain::chaininterface::BroadcasterInterface;
+/// use lightning::chain::chaininterface::{BroadcasterInterface, LowerBoundedFeeEstimator};
 /// use lightning::chain::chaininterface::FeeEstimator;
 /// use lightning::chain::keysinterface;
 /// use lightning::chain::keysinterface::KeysInterface;

lightning/src/chain/chainmonitor.rs

@@ -28,7 +28,7 @@ use bitcoin::hash_types::Txid;
 
 use chain;
 use chain::{ChannelMonitorUpdateErr, Filter, WatchedOutput};
-use chain::chaininterface::{BroadcasterInterface, FeeEstimator};
+use chain::chaininterface::{BroadcasterInterface, FeeEstimator, LowerBoundedFeeEstimator};
 use chain::channelmonitor::{ChannelMonitor, ChannelMonitorUpdate, Balance, MonitorEvent, TransactionOutputs, LATENCY_GRACE_PERIOD_BLOCKS};
 use chain::transaction::{OutPoint, TransactionData};
 use chain::keysinterface::Sign;
@@ -231,7 +231,7 @@ pub struct ChainMonitor<ChannelSigner: Sign, C: Deref, T: Deref, F: Deref, L: De
 	chain_source: Option<C>,
 	broadcaster: T,
 	logger: L,
-	fee_estimator: F,
+	fee_estimator: LowerBoundedFeeEstimator<F>,
 	persister: P,
 	/// "User-provided" (ie persistence-completion/-failed) [`MonitorEvent`]s. These came directly
 	/// from the user and not from a [`ChannelMonitor`].
@@ -354,7 +354,7 @@ where C::Target: chain::Filter,
 			chain_source,
 			broadcaster,
 			logger,
-			fee_estimator: feeest,
+			fee_estimator: LowerBoundedFeeEstimator::new(feeest),
 			persister,
 			pending_monitor_events: Mutex::new(Vec::new()),
 			highest_chain_height: AtomicUsize::new(0),
@@ -505,7 +505,7 @@ where
 		log_debug!(self.logger, "New best block {} at height {} provided via block_connected", header.block_hash(), height);
 		self.process_chain_data(header, Some(height), &txdata, |monitor, txdata| {
 			monitor.block_connected(
-				header, txdata, height, &*self.broadcaster, &*self.fee_estimator, &*self.logger)
+				header, txdata, height, &*self.broadcaster, &self.fee_estimator, &*self.logger)
 		});
 	}
 
@@ -514,7 +514,7 @@ where
 		log_debug!(self.logger, "Latest block {} at height {} removed via block_disconnected", header.block_hash(), height);
 		for monitor_state in monitor_states.values() {
 			monitor_state.monitor.block_disconnected(
-				header, height, &*self.broadcaster, &*self.fee_estimator, &*self.logger);
+				header, height, &*self.broadcaster, &self.fee_estimator, &*self.logger);
 		}
 	}
 }
@@ -532,15 +532,15 @@ where
 		log_debug!(self.logger, "{} provided transactions confirmed at height {} in block {}", txdata.len(), height, header.block_hash());
 		self.process_chain_data(header, None, txdata, |monitor, txdata| {
 			monitor.transactions_confirmed(
-				header, txdata, height, &*self.broadcaster, &*self.fee_estimator, &*self.logger)
+				header, txdata, height, &*self.broadcaster, &self.fee_estimator, &*self.logger)
 		});
 	}
 
 	fn transaction_unconfirmed(&self, txid: &Txid) {
 		log_debug!(self.logger, "Transaction {} reorganized out of chain", txid);
 		let monitor_states = self.monitors.read().unwrap();
 		for monitor_state in monitor_states.values() {
-			monitor_state.monitor.transaction_unconfirmed(txid, &*self.broadcaster, &*self.fee_estimator, &*self.logger);
+			monitor_state.monitor.transaction_unconfirmed(txid, &*self.broadcaster, &self.fee_estimator, &*self.logger);
 		}
 	}
 
@@ -551,7 +551,7 @@ where
 			// it's still possible if a chain::Filter implementation returns a transaction.
 			debug_assert!(txdata.is_empty());
 			monitor.best_block_updated(
-				header, height, &*self.broadcaster, &*self.fee_estimator, &*self.logger)
+				header, height, &*self.broadcaster, &self.fee_estimator, &*self.logger)
 		});
 	}
 

lightning/src/chain/channelmonitor.rs

@@ -40,7 +40,7 @@ use ln::chan_utils::{CounterpartyCommitmentSecrets, HTLCOutputInCommitment, HTLC
 use ln::channelmanager::HTLCSource;
 use chain;
 use chain::{BestBlock, WatchedOutput};
-use chain::chaininterface::{BroadcasterInterface, FeeEstimator};
+use chain::chaininterface::{BroadcasterInterface, FeeEstimator, LowerBoundedFeeEstimator};
 use chain::transaction::{OutPoint, TransactionData};
 use chain::keysinterface::{SpendableOutputDescriptor, StaticPaymentOutputDescriptor, DelayedPaymentOutputDescriptor, Sign, KeysInterface};
 use chain::onchaintx::OnchainTxHandler;
@@ -1099,7 +1099,7 @@ impl<Signer: Sign> ChannelMonitor<Signer> {
 		payment_hash: &PaymentHash,
 		payment_preimage: &PaymentPreimage,
 		broadcaster: &B,
-		fee_estimator: &F,
+		fee_estimator: &LowerBoundedFeeEstimator<F>,
 		logger: &L,
 	) where
 		B::Target: BroadcasterInterface,
@@ -1129,7 +1129,7 @@ impl<Signer: Sign> ChannelMonitor<Signer> {
 		&self,
 		updates: &ChannelMonitorUpdate,
 		broadcaster: &B,
-		fee_estimator: &F,
+		fee_estimator: &LowerBoundedFeeEstimator<F>,
 		logger: &L,
 	) -> Result<(), ()>
 	where
@@ -1295,8 +1295,9 @@ impl<Signer: Sign> ChannelMonitor<Signer> {
 		F::Target: FeeEstimator,
 		L::Target: Logger,
 	{
+		let bounded_fee_estimator = LowerBoundedFeeEstimator::new(fee_estimator);
 		self.inner.lock().unwrap().transactions_confirmed(
-			header, txdata, height, broadcaster, fee_estimator, logger)
+			header, txdata, height, broadcaster, &bounded_fee_estimator, logger)
 	}
 
 	/// Processes a transaction that was reorganized out of the chain.
@@ -1316,8 +1317,9 @@ impl<Signer: Sign> ChannelMonitor<Signer> {
 		F::Target: FeeEstimator,
 		L::Target: Logger,
 	{
+		let bounded_fee_estimator = LowerBoundedFeeEstimator::new(fee_estimator);
 		self.inner.lock().unwrap().transaction_unconfirmed(
-			txid, broadcaster, fee_estimator, logger);
+			txid, broadcaster, &bounded_fee_estimator, logger);
 	}
 
 	/// Updates the monitor with the current best chain tip, returning new outputs to watch. See
@@ -1340,8 +1342,9 @@ impl<Signer: Sign> ChannelMonitor<Signer> {
 		F::Target: FeeEstimator,
 		L::Target: Logger,
 	{
+		let bounded_fee_estimator = LowerBoundedFeeEstimator::new(fee_estimator);
 		self.inner.lock().unwrap().best_block_updated(
-			header, height, broadcaster, fee_estimator, logger)
+			header, height, broadcaster, &bounded_fee_estimator, logger)
 	}
 
 	/// Returns the set of txids that should be monitored for re-organization out of the chain.
@@ -1857,7 +1860,9 @@ impl<Signer: Sign> ChannelMonitorImpl<Signer> {
 
 	/// Provides a payment_hash->payment_preimage mapping. Will be automatically pruned when all
 	/// commitment_tx_infos which contain the payment hash have been revoked.
-	fn provide_payment_preimage<B: Deref, F: Deref, L: Deref>(&mut self, payment_hash: &PaymentHash, payment_preimage: &PaymentPreimage, broadcaster: &B, fee_estimator: &F, logger: &L)
+	fn provide_payment_preimage<B: Deref, F: Deref, L: Deref>(
+		&mut self, payment_hash: &PaymentHash, payment_preimage: &PaymentPreimage, broadcaster: &B,
+		fee_estimator: &LowerBoundedFeeEstimator<F>, logger: &L)
 	where B::Target: BroadcasterInterface,
 		    F::Target: FeeEstimator,
 		    L::Target: Logger,
@@ -1914,7 +1919,7 @@ impl<Signer: Sign> ChannelMonitorImpl<Signer> {
 		self.pending_monitor_events.push(MonitorEvent::CommitmentTxConfirmed(self.funding_info.0));
 	}
 
-	pub fn update_monitor<B: Deref, F: Deref, L: Deref>(&mut self, updates: &ChannelMonitorUpdate, broadcaster: &B, fee_estimator: &F, logger: &L) -> Result<(), ()>
+	pub(crate) fn update_monitor<B: Deref, F: Deref, L: Deref>(&mut self, updates: &ChannelMonitorUpdate, broadcaster: &B, fee_estimator: &LowerBoundedFeeEstimator<F>, logger: &L) -> Result<(), ()>
 	where B::Target: BroadcasterInterface,
 		    F::Target: FeeEstimator,
 		    L::Target: Logger,
@@ -1955,7 +1960,8 @@ impl<Signer: Sign> ChannelMonitorImpl<Signer> {
 				},
 				ChannelMonitorUpdateStep::PaymentPreimage { payment_preimage } => {
 					log_trace!(logger, "Updating ChannelMonitor with payment preimage");
-					self.provide_payment_preimage(&PaymentHash(Sha256::hash(&payment_preimage.0[..]).into_inner()), &payment_preimage, broadcaster, fee_estimator, logger)
+					let bounded_fee_estimator = LowerBoundedFeeEstimator::new(fee_estimator);
+					self.provide_payment_preimage(&PaymentHash(Sha256::hash(&payment_preimage.0[..]).into_inner()), &payment_preimage, broadcaster, &bounded_fee_estimator, logger)
 				},
 				ChannelMonitorUpdateStep::CommitmentSecret { idx, secret } => {
 					log_trace!(logger, "Updating ChannelMonitor with commitment secret");
@@ -2381,15 +2387,16 @@ impl<Signer: Sign> ChannelMonitorImpl<Signer> {
 		let block_hash = header.block_hash();
 		self.best_block = BestBlock::new(block_hash, height);
 
-		self.transactions_confirmed(header, txdata, height, broadcaster, fee_estimator, logger)
+		let bounded_fee_estimator = LowerBoundedFeeEstimator::new(fee_estimator);
+		self.transactions_confirmed(header, txdata, height, broadcaster, &bounded_fee_estimator, logger)
 	}
 
 	fn best_block_updated<B: Deref, F: Deref, L: Deref>(
 		&mut self,
 		header: &BlockHeader,
 		height: u32,
 		broadcaster: B,
-		fee_estimator: F,
+		fee_estimator: &LowerBoundedFeeEstimator<F>,
 		logger: L,
 	) -> Vec<TransactionOutputs>
 	where
@@ -2416,7 +2423,7 @@ impl<Signer: Sign> ChannelMonitorImpl<Signer> {
 		txdata: &TransactionData,
 		height: u32,
 		broadcaster: B,
-		fee_estimator: F,
+		fee_estimator: &LowerBoundedFeeEstimator<F>,
 		logger: L,
 	) -> Vec<TransactionOutputs>
 	where
@@ -2513,7 +2520,7 @@ impl<Signer: Sign> ChannelMonitorImpl<Signer> {
 		mut watch_outputs: Vec<TransactionOutputs>,
 		mut claimable_outpoints: Vec<PackageTemplate>,
 		broadcaster: &B,
-		fee_estimator: &F,
+		fee_estimator: &LowerBoundedFeeEstimator<F>,
 		logger: &L,
 	) -> Vec<TransactionOutputs>
 	where
@@ -2651,7 +2658,8 @@ impl<Signer: Sign> ChannelMonitorImpl<Signer> {
 		//- maturing spendable output has transaction paying us has been disconnected
 		self.onchain_events_awaiting_threshold_conf.retain(|ref entry| entry.height < height);
 
-		self.onchain_tx_handler.block_disconnected(height, broadcaster, fee_estimator, logger);
+		let bounded_fee_estimator = LowerBoundedFeeEstimator::new(fee_estimator);
+		self.onchain_tx_handler.block_disconnected(height, broadcaster, &bounded_fee_estimator, logger);
 
 		self.best_block = BestBlock::new(header.prev_blockhash, height - 1);
 	}
@@ -2660,7 +2668,7 @@ impl<Signer: Sign> ChannelMonitorImpl<Signer> {
 		&mut self,
 		txid: &Txid,
 		broadcaster: B,
-		fee_estimator: F,
+		fee_estimator: &LowerBoundedFeeEstimator<F>,
 		logger: L,
 	) where
 		B::Target: BroadcasterInterface,
@@ -3390,6 +3398,8 @@ mod tests {
 
 	use hex;
 
+	use crate::chain::chaininterface::LowerBoundedFeeEstimator;
+
 	use super::ChannelMonitorUpdateStep;
 	use ::{check_added_monitors, check_closed_broadcast, check_closed_event, check_spends, get_local_commitment_txn, get_monitor, get_route_and_payment_hash, unwrap_send_err};
 	use chain::{BestBlock, Confirm};
@@ -3486,7 +3496,7 @@ mod tests {
 
 		let broadcaster = TestBroadcaster::new(Arc::clone(&nodes[1].blocks));
 		assert!(
-			pre_update_monitor.update_monitor(&replay_update, &&broadcaster, &&chanmon_cfgs[1].fee_estimator, &nodes[1].logger)
+			pre_update_monitor.update_monitor(&replay_update, &&broadcaster, &LowerBoundedFeeEstimator::new(&chanmon_cfgs[1].fee_estimator), &nodes[1].logger)
 			.is_err());
 		// Even though we error'd on the first update, we should still have generated an HTLC claim
 		// transaction
@@ -3511,7 +3521,7 @@ mod tests {
 		let secp_ctx = Secp256k1::new();
 		let logger = Arc::new(TestLogger::new());
 		let broadcaster = Arc::new(TestBroadcaster{txn_broadcasted: Mutex::new(Vec::new()), blocks: Arc::new(Mutex::new(Vec::new()))});
-		let fee_estimator = Arc::new(TestFeeEstimator { sat_per_kw: Mutex::new(253) });
+		let fee_estimator = TestFeeEstimator { sat_per_kw: Mutex::new(253) };
 
 		let dummy_key = PublicKey::from_secret_key(&secp_ctx, &SecretKey::from_slice(&[42; 32]).unwrap());
 		let dummy_tx = Transaction { version: 0, lock_time: 0, input: Vec::new(), output: Vec::new() };
@@ -3610,7 +3620,8 @@ mod tests {
 		monitor.provide_latest_counterparty_commitment_tx(dummy_txid, preimages_slice_to_htlc_outputs!(preimages[17..20]), 281474976710653, dummy_key, &logger);
 		monitor.provide_latest_counterparty_commitment_tx(dummy_txid, preimages_slice_to_htlc_outputs!(preimages[18..20]), 281474976710652, dummy_key, &logger);
 		for &(ref preimage, ref hash) in preimages.iter() {
-			monitor.provide_payment_preimage(hash, preimage, &broadcaster, &fee_estimator, &logger);
+			let bounded_fee_estimator = LowerBoundedFeeEstimator::new(&fee_estimator);
+			monitor.provide_payment_preimage(hash, preimage, &broadcaster, &bounded_fee_estimator, &logger);
 		}
 
 		// Now provide a secret, pruning preimages 10-15

lightning/src/chain/onchaintx.rs

@@ -24,7 +24,7 @@ use bitcoin::secp256k1;
 use ln::msgs::DecodeError;
 use ln::PaymentPreimage;
 use ln::chan_utils::{ChannelTransactionParameters, HolderCommitmentTransaction};
-use chain::chaininterface::{FeeEstimator, BroadcasterInterface};
+use chain::chaininterface::{FeeEstimator, BroadcasterInterface, LowerBoundedFeeEstimator};
 use chain::channelmonitor::{ANTI_REORG_DELAY, CLTV_SHARED_CLAIM_BUFFER};
 use chain::keysinterface::{Sign, KeysInterface};
 use chain::package::PackageTemplate;
@@ -377,7 +377,7 @@ impl<ChannelSigner: Sign> OnchainTxHandler<ChannelSigner> {
 	/// (CSV or CLTV following cases). In case of high-fee spikes, claim tx may stuck in the mempool, so you need to bump its feerate quickly using Replace-By-Fee or Child-Pay-For-Parent.
 	/// Panics if there are signing errors, because signing operations in reaction to on-chain events
 	/// are not expected to fail, and if they do, we may lose funds.
-	fn generate_claim_tx<F: Deref, L: Deref>(&mut self, cur_height: u32, cached_request: &PackageTemplate, fee_estimator: &F, logger: &L) -> Option<(Option<u32>, u64, Transaction)>
+	fn generate_claim_tx<F: Deref, L: Deref>(&mut self, cur_height: u32, cached_request: &PackageTemplate, fee_estimator: &LowerBoundedFeeEstimator<F>, logger: &L) -> Option<(Option<u32>, u64, Transaction)>
 		where F::Target: FeeEstimator,
 					L::Target: Logger,
 	{
@@ -415,7 +415,7 @@ impl<ChannelSigner: Sign> OnchainTxHandler<ChannelSigner> {
 	/// `conf_height` represents the height at which the transactions in `txn_matched` were
 	/// confirmed. This does not need to equal the current blockchain tip height, which should be
 	/// provided via `cur_height`, however it must never be higher than `cur_height`.
-	pub(crate) fn update_claims_view<B: Deref, F: Deref, L: Deref>(&mut self, txn_matched: &[&Transaction], requests: Vec<PackageTemplate>, conf_height: u32, cur_height: u32, broadcaster: &B, fee_estimator: &F, logger: &L)
+	pub(crate) fn update_claims_view<B: Deref, F: Deref, L: Deref>(&mut self, txn_matched: &[&Transaction], requests: Vec<PackageTemplate>, conf_height: u32, cur_height: u32, broadcaster: &B, fee_estimator: &LowerBoundedFeeEstimator<F>, logger: &L)
 		where B::Target: BroadcasterInterface,
 		      F::Target: FeeEstimator,
 					L::Target: Logger,
@@ -617,7 +617,7 @@ impl<ChannelSigner: Sign> OnchainTxHandler<ChannelSigner> {
 		&mut self,
 		txid: &Txid,
 		broadcaster: B,
-		fee_estimator: F,
+		fee_estimator: &LowerBoundedFeeEstimator<F>,
 		logger: L,
 	) where
 		B::Target: BroadcasterInterface,
@@ -637,7 +637,7 @@ impl<ChannelSigner: Sign> OnchainTxHandler<ChannelSigner> {
 		}
 	}
 
-	pub(crate) fn block_disconnected<B: Deref, F: Deref, L: Deref>(&mut self, height: u32, broadcaster: B, fee_estimator: F, logger: L)
+	pub(crate) fn block_disconnected<B: Deref, F: Deref, L: Deref>(&mut self, height: u32, broadcaster: B, fee_estimator: &LowerBoundedFeeEstimator<F>, logger: L)
 		where B::Target: BroadcasterInterface,
 		      F::Target: FeeEstimator,
 					L::Target: Logger,
@@ -667,7 +667,7 @@ impl<ChannelSigner: Sign> OnchainTxHandler<ChannelSigner> {
 			}
 		}
 		for (_, request) in bump_candidates.iter_mut() {
-			if let Some((new_timer, new_feerate, bump_tx)) = self.generate_claim_tx(height, &request, &&*fee_estimator, &&*logger) {
+			if let Some((new_timer, new_feerate, bump_tx)) = self.generate_claim_tx(height, &request, &fee_estimator, &&*logger) {
 				request.set_timer(new_timer);
 				request.set_feerate(new_feerate);
 				log_info!(logger, "Broadcasting onchain {}", log_tx!(bump_tx));

lightning/src/chain/package.rs

@@ -38,6 +38,8 @@ use core::mem;
 use core::ops::Deref;
 use bitcoin::Witness;
 
+use super::chaininterface::LowerBoundedFeeEstimator;
+
 const MAX_ALLOC_SIZE: usize = 64*1024;
 
 
@@ -665,7 +667,7 @@ impl PackageTemplate {
 	/// Returns value in satoshis to be included as package outgoing output amount and feerate
 	/// which was used to generate the value. Will not return less than `dust_limit_sats` for the
 	/// value.
-	pub(crate) fn compute_package_output<F: Deref, L: Deref>(&self, predicted_weight: usize, dust_limit_sats: u64, fee_estimator: &F, logger: &L) -> Option<(u64, u64)>
+	pub(crate) fn compute_package_output<F: Deref, L: Deref>(&self, predicted_weight: usize, dust_limit_sats: u64, fee_estimator: &LowerBoundedFeeEstimator<F>, logger: &L) -> Option<(u64, u64)>
 		where F::Target: FeeEstimator,
 		      L::Target: Logger,
 	{
@@ -772,7 +774,7 @@ impl Readable for PackageTemplate {
 /// If the proposed fee is less than the available spent output's values, we return the proposed
 /// fee and the corresponding updated feerate. If the proposed fee is equal or more than the
 /// available spent output's values, we return nothing
-fn compute_fee_from_spent_amounts<F: Deref, L: Deref>(input_amounts: u64, predicted_weight: usize, fee_estimator: &F, logger: &L) -> Option<(u64, u64)>
+fn compute_fee_from_spent_amounts<F: Deref, L: Deref>(input_amounts: u64, predicted_weight: usize, fee_estimator: &LowerBoundedFeeEstimator<F>, logger: &L) -> Option<(u64, u64)>
 	where F::Target: FeeEstimator,
 	      L::Target: Logger,
 {
@@ -808,7 +810,7 @@ fn compute_fee_from_spent_amounts<F: Deref, L: Deref>(input_amounts: u64, predic
 /// attempt, use them. Otherwise, blindly bump the feerate by 25% of the previous feerate. We also
 /// verify that those bumping heuristics respect BIP125 rules 3) and 4) and if required adjust
 /// the new fee to meet the RBF policy requirement.
-fn feerate_bump<F: Deref, L: Deref>(predicted_weight: usize, input_amounts: u64, previous_feerate: u64, fee_estimator: &F, logger: &L) -> Option<(u64, u64)>
+fn feerate_bump<F: Deref, L: Deref>(predicted_weight: usize, input_amounts: u64, previous_feerate: u64, fee_estimator: &LowerBoundedFeeEstimator<F>, logger: &L) -> Option<(u64, u64)>
 	where F::Target: FeeEstimator,
 	      L::Target: Logger,
 {