Extract/refactor fee computation utilities out of OnchainTxHandler

Author: Antoine Riard

lightning/src/ln/onchain_utils.rs

@@ -782,21 +782,22 @@ fn feerate_bump<F: Deref, L: Deref>(predicted_weight: usize, input_amounts: u64,
 	      L::Target: Logger,
 {
 	// If old feerate inferior to actual one given back by Fee Estimator, use it to compute new fee...
-	let new_fee = if previous_feerate < fee_estimator.get_est_sat_per_1000_weight(ConfirmationTarget::HighPriority) as u64 {
-		if let Some((new_fee, _)) = subtract_high_prio_fee(input_amounts, predicted_weight, fee_estimator, logger) {
+	let new_fee = if let Some((new_fee, _)) = subtract_high_prio_fee(input_amounts, predicted_weight, fee_estimator, logger) {
+		let updated_feerate = new_fee / (predicted_weight as u64 * 1000);
+		if updated_feerate > previous_feerate {
 			new_fee
 		} else {
-			log_trace!(logger, "Can't new-estimation bump new claiming tx, amount {} is too small", input_amounts);
-			return None;
+			// ...else just increase the previous feerate by 25% (because that's a nice number)
+			let new_fee = previous_feerate * (predicted_weight as u64) / 750;
+			if input_amounts <= new_fee {
+				log_trace!(logger, "Can't 25% bump new claiming tx, amount {} is too small", input_amounts);
+				return None;
+			}
+			new_fee
 		}
-	// ...else just increase the previous feerate by 25% (because that's a nice number)
 	} else {
-		let fee = previous_feerate * (predicted_weight as u64) / 750;
-		if input_amounts <= fee {
-			log_trace!(logger, "Can't 25% bump new claiming tx, amount {} is too small", input_amounts);
-			return None;
-		}
-		fee
+		log_trace!(logger, "Can't new-estimation bump new claiming tx, amount {} is too small", input_amounts);
+		return None;
 	};
 
 	let previous_fee = previous_feerate * (predicted_weight as u64) / 1000;

lightning/src/ln/onchaintx.rs

@@ -78,41 +78,6 @@ enum OnchainEvent {
 	}
 }
 
-macro_rules! subtract_high_prio_fee {
-	($logger: ident, $fee_estimator: expr, $value: expr, $predicted_weight: expr, $used_feerate: expr) => {
-		{
-			$used_feerate = $fee_estimator.get_est_sat_per_1000_weight(ConfirmationTarget::HighPriority).into();
-			let mut fee = $used_feerate as u64 * $predicted_weight / 1000;
-			if $value <= fee {
-				$used_feerate = $fee_estimator.get_est_sat_per_1000_weight(ConfirmationTarget::Normal).into();
-				fee = $used_feerate as u64 * $predicted_weight / 1000;
-				if $value <= fee.into() {
-					$used_feerate = $fee_estimator.get_est_sat_per_1000_weight(ConfirmationTarget::Background).into();
-					fee = $used_feerate as u64 * $predicted_weight / 1000;
-					if $value <= fee {
-						log_error!($logger, "Failed to generate an on-chain punishment tx as even low priority fee ({} sat) was more than the entire claim balance ({} sat)",
-							fee, $value);
-						false
-					} else {
-						log_warn!($logger, "Used low priority fee for on-chain punishment tx as high priority fee was more than the entire claim balance ({} sat)",
-							$value);
-						$value -= fee;
-						true
-					}
-				} else {
-					log_warn!($logger, "Used medium priority fee for on-chain punishment tx as high priority fee was more than the entire claim balance ({} sat)",
-						$value);
-					$value -= fee;
-					true
-				}
-			} else {
-				$value -= fee;
-				true
-			}
-		}
-	}
-}
-
 impl Readable for Option<Vec<Option<(usize, Signature)>>> {
 	fn read<R: ::std::io::Read>(reader: &mut R) -> Result<Self, DecodeError> {
 		match Readable::read(reader)? {
@@ -380,45 +345,6 @@ impl<ChannelSigner: Sign> OnchainTxHandler<ChannelSigner> {
 	{
 		if cached_request.outpoints().len() == 0 { return None } // But don't prune pending claiming request yet, we may have to resurrect HTLCs
 
-		macro_rules! RBF_bump {
-			($amount: expr, $old_feerate: expr, $fee_estimator: expr, $predicted_weight: expr) => {
-				{
-					let mut used_feerate: u32;
-					// If old feerate inferior to actual one given back by Fee Estimator, use it to compute new fee...
-					let new_fee = if $old_feerate < $fee_estimator.get_est_sat_per_1000_weight(ConfirmationTarget::HighPriority) as u64 {
-						let mut value = $amount;
-						if subtract_high_prio_fee!(logger, $fee_estimator, value, $predicted_weight, used_feerate) {
-							// Overflow check is done in subtract_high_prio_fee
-							($amount - value)
-						} else {
-							log_trace!(logger, "Can't new-estimation bump new claiming tx, amount {} is too small", $amount);
-							return None;
-						}
-					// ...else just increase the previous feerate by 25% (because that's a nice number)
-					} else {
-						let fee = $old_feerate as u64 * ($predicted_weight as u64) / 750;
-						if $amount <= fee {
-							log_trace!(logger, "Can't 25% bump new claiming tx, amount {} is too small", $amount);
-							return None;
-						}
-						fee
-					};
-
-					let previous_fee = $old_feerate as u64 * ($predicted_weight as u64) / 1000;
-					let min_relay_fee = MIN_RELAY_FEE_SAT_PER_1000_WEIGHT * ($predicted_weight as u64) / 1000;
-					// BIP 125 Opt-in Full Replace-by-Fee Signaling
-					// 	* 3. The replacement transaction pays an absolute fee of at least the sum paid by the original transactions.
-					//	* 4. The replacement transaction must also pay for its own bandwidth at or above the rate set by the node's minimum relay fee setting.
-					let new_fee = if new_fee < previous_fee + min_relay_fee {
-						new_fee + previous_fee + min_relay_fee - new_fee
-					} else {
-						new_fee
-					};
-					Some((new_fee, new_fee * 1000 / ($predicted_weight as u64)))
-				}
-			}
-		}
-
 		// Compute new height timer to decide when we need to regenerate a new bumped version of the claim tx (if we
 		// didn't receive confirmation of it before, or not enough reorg-safe depth on top of it).
 		let new_timer = Some(Self::get_height_timer(height, cached_request.timelock()));