1 // This file is Copyright its original authors, visible in version control
4 // This file is licensed under the Apache License, Version 2.0 <LICENSE-APACHE
5 // or http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
6 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your option.
7 // You may not use this file except in accordance with one or both of these
10 //! Traits and utility impls which allow other parts of rust-lightning to interact with the
13 //! Includes traits for monitoring and receiving notifications of new blocks and block
14 //! disconnections, transaction broadcasting, and feerate information requests.
16 use core::{cmp, ops::Deref};
18 use bitcoin::blockdata::transaction::Transaction;
20 /// An interface to send a transaction to the Bitcoin network.
21 pub trait BroadcasterInterface {
22 /// Sends a transaction out to (hopefully) be mined.
23 fn broadcast_transaction(&self, tx: &Transaction);
26 /// An enum that represents the speed at which we want a transaction to confirm used for feerate
28 #[derive(Clone, Copy, PartialEq, Eq)]
29 pub enum ConfirmationTarget {
30 /// We are happy with this transaction confirming slowly when feerate drops some.
32 /// We'd like this transaction to confirm without major delay, but 12-18 blocks is fine.
34 /// We'd like this transaction to confirm in the next few blocks.
38 /// A trait which should be implemented to provide feerate information on a number of time
41 /// Note that all of the functions implemented here *must* be reentrant-safe (obviously - they're
42 /// called from inside the library in response to chain events, P2P events, or timer events).
43 pub trait FeeEstimator {
44 /// Gets estimated satoshis of fee required per 1000 Weight-Units.
46 /// LDK will wrap this method and ensure that the value returned is no smaller than 253
47 /// (ie 1 satoshi-per-byte rounded up to ensure later round-downs don't put us below 1 satoshi-per-byte).
49 /// The following unit conversions can be used to convert to sats/KW. Note that it is not
50 /// necessary to use max() as the minimum of 253 will be enforced by LDK:
51 /// * max(satoshis-per-byte * 250, 253)
52 /// * max(satoshis-per-kbyte / 4, 253)
53 fn get_est_sat_per_1000_weight(&self, confirmation_target: ConfirmationTarget) -> u32;
56 // We need `FeeEstimator` implemented so that in some places where we only have a shared
57 // reference to a `Deref` to a `FeeEstimator`, we can still wrap it.
58 impl<D: Deref> FeeEstimator for D where D::Target: FeeEstimator {
59 fn get_est_sat_per_1000_weight(&self, confirmation_target: ConfirmationTarget) -> u32 {
60 (**self).get_est_sat_per_1000_weight(confirmation_target)
64 /// Minimum relay fee as required by bitcoin network mempool policy.
65 pub const MIN_RELAY_FEE_SAT_PER_1000_WEIGHT: u64 = 4000;
66 /// Minimum feerate that takes a sane approach to bitcoind weight-to-vbytes rounding.
67 /// See the following Core Lightning commit for an explanation:
68 /// https://github.com/ElementsProject/lightning/commit/2e687b9b352c9092b5e8bd4a688916ac50b44af0
69 pub const FEERATE_FLOOR_SATS_PER_KW: u32 = 253;
71 /// Wraps a `Deref` to a `FeeEstimator` so that any fee estimations provided by it
72 /// are bounded below by `FEERATE_FLOOR_SATS_PER_KW` (253 sats/KW)
73 pub(crate) struct LowerBoundedFeeEstimator<F: Deref>(pub F) where F::Target: FeeEstimator;
75 impl<F: Deref> LowerBoundedFeeEstimator<F> where F::Target: FeeEstimator {
76 /// Creates a new `LowerBoundedFeeEstimator` which wraps the provided fee_estimator
77 pub fn new(fee_estimator: F) -> Self {
78 LowerBoundedFeeEstimator(fee_estimator)
81 pub fn get_est_sat_per_1000_weight(&self, confirmation_target: ConfirmationTarget) -> u32 {
83 self.0.get_est_sat_per_1000_weight(confirmation_target),
84 FEERATE_FLOOR_SATS_PER_KW,
91 use super::{FEERATE_FLOOR_SATS_PER_KW, LowerBoundedFeeEstimator, ConfirmationTarget, FeeEstimator};
93 struct TestFeeEstimator {
97 impl FeeEstimator for TestFeeEstimator {
98 fn get_est_sat_per_1000_weight(&self, _: ConfirmationTarget) -> u32 {
104 fn test_fee_estimator_less_than_floor() {
105 let sat_per_kw = FEERATE_FLOOR_SATS_PER_KW - 1;
106 let test_fee_estimator = &TestFeeEstimator { sat_per_kw };
107 let fee_estimator = LowerBoundedFeeEstimator::new(test_fee_estimator);
109 assert_eq!(fee_estimator.get_est_sat_per_1000_weight(ConfirmationTarget::Background), FEERATE_FLOOR_SATS_PER_KW);
113 fn test_fee_estimator_greater_than_floor() {
114 let sat_per_kw = FEERATE_FLOOR_SATS_PER_KW + 1;
115 let test_fee_estimator = &TestFeeEstimator { sat_per_kw };
116 let fee_estimator = LowerBoundedFeeEstimator::new(test_fee_estimator);
118 assert_eq!(fee_estimator.get_est_sat_per_1000_weight(ConfirmationTarget::Background), sat_per_kw);