//! Includes traits for monitoring and receiving notifications of new blocks and block
//! disconnections, transaction broadcasting, and feerate information requests.
+use core::{cmp, ops::Deref};
+
use bitcoin::blockdata::transaction::Transaction;
/// An interface to send a transaction to the Bitcoin network.
/// An enum that represents the speed at which we want a transaction to confirm used for feerate
/// estimation.
+#[derive(Clone, Copy, Debug, Hash, PartialEq, Eq)]
pub enum ConfirmationTarget {
/// We are happy with this transaction confirming slowly when feerate drops some.
Background,
pub trait FeeEstimator {
/// Gets estimated satoshis of fee required per 1000 Weight-Units.
///
- /// Must be no smaller than 253 (ie 1 satoshi-per-byte rounded up to ensure later round-downs
- /// don't put us below 1 satoshi-per-byte).
+ /// LDK will wrap this method and ensure that the value returned is no smaller than 253
+ /// (ie 1 satoshi-per-byte rounded up to ensure later round-downs don't put us below 1 satoshi-per-byte).
///
- /// This translates to:
+ /// The following unit conversions can be used to convert to sats/KW:
/// * satoshis-per-byte * 250
- /// * ceil(satoshis-per-kbyte / 4)
+ /// * satoshis-per-kbyte / 4
fn get_est_sat_per_1000_weight(&self, confirmation_target: ConfirmationTarget) -> u32;
}
/// Minimum relay fee as required by bitcoin network mempool policy.
pub const MIN_RELAY_FEE_SAT_PER_1000_WEIGHT: u64 = 4000;
+/// Minimum feerate that takes a sane approach to bitcoind weight-to-vbytes rounding.
+/// See the following Core Lightning commit for an explanation:
+/// <https://github.com/ElementsProject/lightning/commit/2e687b9b352c9092b5e8bd4a688916ac50b44af0>
+pub const FEERATE_FLOOR_SATS_PER_KW: u32 = 253;
+
+/// Wraps a `Deref` to a `FeeEstimator` so that any fee estimations provided by it
+/// are bounded below by `FEERATE_FLOOR_SATS_PER_KW` (253 sats/KW).
+///
+/// Note that this does *not* implement [`FeeEstimator`] to make it harder to accidentally mix the
+/// two.
+pub(crate) struct LowerBoundedFeeEstimator<F: Deref>(pub F) where F::Target: FeeEstimator;
+
+impl<F: Deref> LowerBoundedFeeEstimator<F> where F::Target: FeeEstimator {
+ /// Creates a new `LowerBoundedFeeEstimator` which wraps the provided fee_estimator
+ pub fn new(fee_estimator: F) -> Self {
+ LowerBoundedFeeEstimator(fee_estimator)
+ }
+
+ pub fn bounded_sat_per_1000_weight(&self, confirmation_target: ConfirmationTarget) -> u32 {
+ cmp::max(
+ self.0.get_est_sat_per_1000_weight(confirmation_target),
+ FEERATE_FLOOR_SATS_PER_KW,
+ )
+ }
+}
+
+#[cfg(test)]
+mod tests {
+ use super::{FEERATE_FLOOR_SATS_PER_KW, LowerBoundedFeeEstimator, ConfirmationTarget, FeeEstimator};
+
+ struct TestFeeEstimator {
+ sat_per_kw: u32,
+ }
+
+ impl FeeEstimator for TestFeeEstimator {
+ fn get_est_sat_per_1000_weight(&self, _: ConfirmationTarget) -> u32 {
+ self.sat_per_kw
+ }
+ }
+
+ #[test]
+ fn test_fee_estimator_less_than_floor() {
+ let sat_per_kw = FEERATE_FLOOR_SATS_PER_KW - 1;
+ let test_fee_estimator = &TestFeeEstimator { sat_per_kw };
+ let fee_estimator = LowerBoundedFeeEstimator::new(test_fee_estimator);
+
+ assert_eq!(fee_estimator.bounded_sat_per_1000_weight(ConfirmationTarget::Background), FEERATE_FLOOR_SATS_PER_KW);
+ }
+
+ #[test]
+ fn test_fee_estimator_greater_than_floor() {
+ let sat_per_kw = FEERATE_FLOOR_SATS_PER_KW + 1;
+ let test_fee_estimator = &TestFeeEstimator { sat_per_kw };
+ let fee_estimator = LowerBoundedFeeEstimator::new(test_fee_estimator);
+
+ assert_eq!(fee_estimator.bounded_sat_per_1000_weight(ConfirmationTarget::Background), sat_per_kw);
+ }
+}