From: Wilmer Paulino Date: Thu, 20 Apr 2023 21:16:24 +0000 (-0700) Subject: Extend OnchainTxHandler::generate_claim to optionally force feerate bump X-Git-Tag: v0.0.115~8^2~2 X-Git-Url: http://git.bitcoin.ninja/index.cgi?a=commitdiff_plain;h=e496d62b98b7d7cd1800fe0dbf70684866fed7e7;p=rust-lightning Extend OnchainTxHandler::generate_claim to optionally force feerate bump In the next commit, we plan to extend the `OnchainTxHandler` to retry pending claims on a timer. This timer may fire with much more frequency than incoming blocks, so we want to avoid manually bumping feerates (currently by 25%) each time our fee estimator provides a lower feerate than before. --- diff --git a/lightning/src/chain/onchaintx.rs b/lightning/src/chain/onchaintx.rs index cd0cb08ea..aece19c83 100644 --- a/lightning/src/chain/onchaintx.rs +++ b/lightning/src/chain/onchaintx.rs @@ -489,9 +489,13 @@ impl OnchainTxHandler /// /// 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(&mut self, cur_height: u32, cached_request: &PackageTemplate, fee_estimator: &LowerBoundedFeeEstimator, logger: &L) -> Option<(u32, u64, OnchainClaim)> - where F::Target: FeeEstimator, - L::Target: Logger, + fn generate_claim( + &mut self, cur_height: u32, cached_request: &PackageTemplate, force_feerate_bump: bool, + fee_estimator: &LowerBoundedFeeEstimator, logger: &L, + ) -> Option<(u32, u64, OnchainClaim)> + where + F::Target: FeeEstimator, + L::Target: Logger, { let request_outpoints = cached_request.outpoints(); if request_outpoints.is_empty() { @@ -538,8 +542,9 @@ impl OnchainTxHandler #[cfg(anchors)] { // Attributes are not allowed on if expressions on our current MSRV of 1.41. if cached_request.requires_external_funding() { - let target_feerate_sat_per_1000_weight = cached_request - .compute_package_feerate(fee_estimator, ConfirmationTarget::HighPriority); + let target_feerate_sat_per_1000_weight = cached_request.compute_package_feerate( + fee_estimator, ConfirmationTarget::HighPriority, force_feerate_bump + ); if let Some(htlcs) = cached_request.construct_malleable_package_with_external_funding(self) { return Some(( new_timer, @@ -558,7 +563,8 @@ impl OnchainTxHandler let predicted_weight = cached_request.package_weight(&self.destination_script); if let Some((output_value, new_feerate)) = cached_request.compute_package_output( - predicted_weight, self.destination_script.dust_value().to_sat(), fee_estimator, logger, + predicted_weight, self.destination_script.dust_value().to_sat(), + force_feerate_bump, fee_estimator, logger, ) { assert!(new_feerate != 0); @@ -601,7 +607,7 @@ impl OnchainTxHandler // counterparty's latest commitment don't have any HTLCs present. let conf_target = ConfirmationTarget::HighPriority; let package_target_feerate_sat_per_1000_weight = cached_request - .compute_package_feerate(fee_estimator, conf_target); + .compute_package_feerate(fee_estimator, conf_target, force_feerate_bump); Some(( new_timer, package_target_feerate_sat_per_1000_weight as u64, @@ -700,7 +706,9 @@ impl OnchainTxHandler // Generate claim transactions and track them to bump if necessary at // height timer expiration (i.e in how many blocks we're going to take action). for mut req in preprocessed_requests { - if let Some((new_timer, new_feerate, claim)) = self.generate_claim(cur_height, &req, &*fee_estimator, &*logger) { + if let Some((new_timer, new_feerate, claim)) = self.generate_claim( + cur_height, &req, true /* force_feerate_bump */, &*fee_estimator, &*logger, + ) { req.set_timer(new_timer); req.set_feerate(new_feerate); let package_id = match claim { @@ -893,7 +901,9 @@ impl OnchainTxHandler // Build, bump and rebroadcast tx accordingly log_trace!(logger, "Bumping {} candidates", bump_candidates.len()); for (package_id, request) in bump_candidates.iter() { - if let Some((new_timer, new_feerate, bump_claim)) = self.generate_claim(cur_height, &request, &*fee_estimator, &*logger) { + if let Some((new_timer, new_feerate, bump_claim)) = self.generate_claim( + cur_height, &request, true /* force_feerate_bump */, &*fee_estimator, &*logger, + ) { match bump_claim { OnchainClaim::Tx(bump_tx) => { log_info!(logger, "Broadcasting RBF-bumped onchain {}", log_tx!(bump_tx)); @@ -973,7 +983,9 @@ impl OnchainTxHandler } } for ((_package_id, _), ref mut request) in bump_candidates.iter_mut() { - if let Some((new_timer, new_feerate, bump_claim)) = self.generate_claim(height, &request, fee_estimator, &&*logger) { + if let Some((new_timer, new_feerate, bump_claim)) = self.generate_claim( + height, &request, true /* force_feerate_bump */, fee_estimator, &&*logger + ) { request.set_timer(new_timer); request.set_feerate(new_feerate); match bump_claim { diff --git a/lightning/src/chain/package.rs b/lightning/src/chain/package.rs index 786451ee5..5974a65d2 100644 --- a/lightning/src/chain/package.rs +++ b/lightning/src/chain/package.rs @@ -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(&self, predicted_weight: usize, dust_limit_sats: u64, fee_estimator: &LowerBoundedFeeEstimator, logger: &L) -> Option<(u64, u64)> - where F::Target: FeeEstimator, - L::Target: Logger, + pub(crate) fn compute_package_output( + &self, predicted_weight: usize, dust_limit_sats: u64, force_feerate_bump: bool, + fee_estimator: &LowerBoundedFeeEstimator, 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( &self, fee_estimator: &LowerBoundedFeeEstimator, 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(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(predicted_weight: usize, input_amounts: u64, previous_feerate: u64, fee_estimator: &LowerBoundedFeeEstimator, 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( + predicted_weight: usize, input_amounts: u64, previous_feerate: u64, force_feerate_bump: bool, + fee_estimator: &LowerBoundedFeeEstimator, 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 diff --git a/lightning/src/ln/functional_tests.rs b/lightning/src/ln/functional_tests.rs index 401667f31..17f8e1597 100644 --- a/lightning/src/ln/functional_tests.rs +++ b/lightning/src/ln/functional_tests.rs @@ -2991,9 +2991,9 @@ fn do_test_htlc_on_chain_timeout(connect_style: ConnectStyle) { if nodes[1].connect_style.borrow().skips_blocks() { assert_eq!(txn.len(), 1); } else { - assert_eq!(txn.len(), 2); // Extra rebroadcast of timeout transaction + assert_eq!(txn.len(), 3); // Two extra fee bumps for timeout transaction } - check_spends!(txn[0], commitment_tx[0]); + txn.iter().for_each(|tx| check_spends!(tx, commitment_tx[0])); assert_eq!(txn[0].clone().input[0].witness.last().unwrap().len(), ACCEPTED_HTLC_SCRIPT_WEIGHT); txn.remove(0) }; @@ -7510,7 +7510,7 @@ fn test_bump_penalty_txn_on_remote_commitment() { assert_ne!(feerate_preimage, 0); // After exhaustion of height timer, new bumped claim txn should have been broadcast, check it - connect_blocks(&nodes[1], 15); + connect_blocks(&nodes[1], 1); { let mut node_txn = nodes[1].tx_broadcaster.txn_broadcasted.lock().unwrap(); assert_eq!(node_txn.len(), 1);