Extend OnchainTxHandler::generate_claim to optionally force feerate bump
[rust-lightning] / lightning / src / chain / package.rs
index 786451ee50c834923f79e34bae478e7800f12c2b..5974a65d2a3e7527102c57cd8781a66d4a4b21e6 100644 (file)
@@ -762,16 +762,23 @@ 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: &LowerBoundedFeeEstimator<F>, logger: &L) -> Option<(u64, u64)>
-               where F::Target: FeeEstimator,
-                     L::Target: Logger,
+       pub(crate) fn compute_package_output<F: Deref, L: Deref>(
+               &self, predicted_weight: usize, dust_limit_sats: u64, force_feerate_bump: bool,
+               fee_estimator: &LowerBoundedFeeEstimator<F>, logger: &L,
+       ) -> Option<(u64, u64)>
+       where
+               F::Target: FeeEstimator,
+               L::Target: Logger,
        {
                debug_assert!(self.malleability == PackageMalleability::Malleable, "The package output is fixed for non-malleable packages");
                let input_amounts = self.package_amount();
                assert!(dust_limit_sats as i64 > 0, "Output script must be broadcastable/have a 'real' dust limit.");
                // If old feerate is 0, first iteration of this claim, use normal fee calculation
                if self.feerate_previous != 0 {
-                       if let Some((new_fee, feerate)) = feerate_bump(predicted_weight, input_amounts, self.feerate_previous, fee_estimator, logger) {
+                       if let Some((new_fee, feerate)) = feerate_bump(
+                               predicted_weight, input_amounts, self.feerate_previous, force_feerate_bump,
+                               fee_estimator, logger,
+                       ) {
                                return Some((cmp::max(input_amounts as i64 - new_fee as i64, dust_limit_sats as i64) as u64, feerate));
                        }
                } else {
@@ -784,16 +791,19 @@ impl PackageTemplate {
 
        #[cfg(anchors)]
        /// Computes a feerate based on the given confirmation target. If a previous feerate was used,
-       /// and the new feerate is below it, we'll use a 25% increase of the previous feerate instead of
-       /// the new one.
+       /// the new feerate is below it, and `force_feerate_bump` is set, we'll use a 25% increase of
+       /// the previous feerate instead of the new feerate.
        pub(crate) fn compute_package_feerate<F: Deref>(
                &self, fee_estimator: &LowerBoundedFeeEstimator<F>, conf_target: ConfirmationTarget,
+               force_feerate_bump: bool,
        ) -> u32 where F::Target: FeeEstimator {
                let feerate_estimate = fee_estimator.bounded_sat_per_1000_weight(conf_target);
                if self.feerate_previous != 0 {
                        // If old feerate inferior to actual one given back by Fee Estimator, use it to compute new fee...
                        if feerate_estimate as u64 > self.feerate_previous {
                                feerate_estimate
+                       } else if !force_feerate_bump {
+                               self.feerate_previous.try_into().unwrap_or(u32::max_value())
                        } else {
                                // ...else just increase the previous feerate by 25% (because that's a nice number)
                                (self.feerate_previous + (self.feerate_previous / 4)).try_into().unwrap_or(u32::max_value())
@@ -945,32 +955,47 @@ fn compute_fee_from_spent_amounts<F: Deref, L: Deref>(input_amounts: u64, predic
 
 /// Attempt to propose a bumping fee for a transaction from its spent output's values and predicted
 /// weight. If feerates proposed by the fee-estimator have been increasing since last fee-bumping
-/// 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: &LowerBoundedFeeEstimator<F>, logger: &L) -> Option<(u64, u64)>
-       where F::Target: FeeEstimator,
-             L::Target: Logger,
+/// attempt, use them. If `force_feerate_bump` is set, we bump the feerate by 25% of the previous
+/// feerate, or just use the previous feerate otherwise. If a feerate bump did happen, 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, force_feerate_bump: bool,
+       fee_estimator: &LowerBoundedFeeEstimator<F>, logger: &L,
+) -> Option<(u64, u64)>
+where
+       F::Target: FeeEstimator,
+       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 let Some((new_fee, _)) = compute_fee_from_spent_amounts(input_amounts, predicted_weight, fee_estimator, logger) {
-               let updated_feerate = new_fee / (predicted_weight as u64 * 1000);
-               if updated_feerate > previous_feerate {
-                       new_fee
+       let (new_fee, new_feerate) = if let Some((new_fee, new_feerate)) = compute_fee_from_spent_amounts(input_amounts, predicted_weight, fee_estimator, logger) {
+               if new_feerate > previous_feerate {
+                       (new_fee, new_feerate)
+               } else if !force_feerate_bump {
+                       let previous_fee = previous_feerate * (predicted_weight as u64) / 1000;
+                       (previous_fee, previous_feerate)
                } else {
                        // ...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 {
+                       let bumped_feerate = previous_feerate + (previous_feerate / 4);
+                       let bumped_fee = bumped_feerate * (predicted_weight as u64) / 1000;
+                       if input_amounts <= bumped_fee {
                                log_warn!(logger, "Can't 25% bump new claiming tx, amount {} is too small", input_amounts);
                                return None;
                        }
-                       new_fee
+                       (bumped_fee, bumped_feerate)
                }
        } else {
                log_warn!(logger, "Can't new-estimation bump new claiming tx, amount {} is too small", input_amounts);
                return None;
        };
 
+       // Our feerates should never decrease. If it hasn't changed though, we just need to
+       // rebroadcast/re-sign the previous claim.
+       debug_assert!(new_feerate >= previous_feerate);
+       if new_feerate == previous_feerate {
+               return Some((new_fee, new_feerate));
+       }
+
        let previous_fee = previous_feerate * (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