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};
17 use core::convert::TryInto;
19 use bitcoin::blockdata::transaction::Transaction;
21 // TODO: Define typed abstraction over feerates to handle their conversions.
22 pub(crate) fn compute_feerate_sat_per_1000_weight(fee_sat: u64, weight: u64) -> u32 {
23 (fee_sat * 1000 / weight).try_into().unwrap_or(u32::max_value())
25 pub(crate) const fn fee_for_weight(feerate_sat_per_1000_weight: u32, weight: u64) -> u64 {
26 ((feerate_sat_per_1000_weight as u64 * weight) + 1000 - 1) / 1000
29 /// An interface to send a transaction to the Bitcoin network.
30 pub trait BroadcasterInterface {
31 /// Sends a list of transactions out to (hopefully) be mined.
32 /// This only needs to handle the actual broadcasting of transactions, LDK will automatically
33 /// rebroadcast transactions that haven't made it into a block.
35 /// In some cases LDK may attempt to broadcast a transaction which double-spends another
36 /// and this isn't a bug and can be safely ignored.
38 /// If more than one transaction is given, these transactions should be considered to be a
39 /// package and broadcast together. Some of the transactions may or may not depend on each other,
40 /// be sure to manage both cases correctly.
42 /// Bitcoin transaction packages are defined in BIP 331 and here:
43 /// https://github.com/bitcoin/bitcoin/blob/master/doc/policy/packages.md
44 fn broadcast_transactions(&self, txs: &[&Transaction]);
47 /// An enum that represents the priority at which we want a transaction to confirm used for feerate
49 #[derive(Clone, Copy, Debug, Hash, PartialEq, Eq)]
50 pub enum ConfirmationTarget {
51 /// We'd like a transaction to confirm in the future, but don't want to commit most of the fees
52 /// required to do so yet. The remaining fees will come via a Child-Pays-For-Parent (CPFP) fee
53 /// bump of the transaction.
55 /// The feerate returned should be the absolute minimum feerate required to enter most node
56 /// mempools across the network. Note that if you are not able to obtain this feerate estimate,
57 /// you should likely use the furthest-out estimate allowed by your fee estimator.
59 /// We are happy with a transaction confirming slowly, at least within a day or so worth of
62 /// We'd like a transaction to confirm without major delayed, i.e., within the next 12-24 blocks.
64 /// We'd like a transaction to confirm in the next few blocks.
68 /// A trait which should be implemented to provide feerate information on a number of time
71 /// Note that all of the functions implemented here *must* be reentrant-safe (obviously - they're
72 /// called from inside the library in response to chain events, P2P events, or timer events).
73 pub trait FeeEstimator {
74 /// Gets estimated satoshis of fee required per 1000 Weight-Units.
76 /// LDK will wrap this method and ensure that the value returned is no smaller than 253
77 /// (ie 1 satoshi-per-byte rounded up to ensure later round-downs don't put us below 1 satoshi-per-byte).
79 /// The following unit conversions can be used to convert to sats/KW:
80 /// * satoshis-per-byte * 250
81 /// * satoshis-per-kbyte / 4
82 fn get_est_sat_per_1000_weight(&self, confirmation_target: ConfirmationTarget) -> u32;
85 /// Minimum relay fee as required by bitcoin network mempool policy.
86 pub const MIN_RELAY_FEE_SAT_PER_1000_WEIGHT: u64 = 4000;
87 /// Minimum feerate that takes a sane approach to bitcoind weight-to-vbytes rounding.
88 /// See the following Core Lightning commit for an explanation:
89 /// <https://github.com/ElementsProject/lightning/commit/2e687b9b352c9092b5e8bd4a688916ac50b44af0>
90 pub const FEERATE_FLOOR_SATS_PER_KW: u32 = 253;
92 /// Wraps a `Deref` to a `FeeEstimator` so that any fee estimations provided by it
93 /// are bounded below by `FEERATE_FLOOR_SATS_PER_KW` (253 sats/KW).
95 /// Note that this does *not* implement [`FeeEstimator`] to make it harder to accidentally mix the
97 pub(crate) struct LowerBoundedFeeEstimator<F: Deref>(pub F) where F::Target: FeeEstimator;
99 impl<F: Deref> LowerBoundedFeeEstimator<F> where F::Target: FeeEstimator {
100 /// Creates a new `LowerBoundedFeeEstimator` which wraps the provided fee_estimator
101 pub fn new(fee_estimator: F) -> Self {
102 LowerBoundedFeeEstimator(fee_estimator)
105 pub fn bounded_sat_per_1000_weight(&self, confirmation_target: ConfirmationTarget) -> u32 {
107 self.0.get_est_sat_per_1000_weight(confirmation_target),
108 FEERATE_FLOOR_SATS_PER_KW,
115 use super::{FEERATE_FLOOR_SATS_PER_KW, LowerBoundedFeeEstimator, ConfirmationTarget, FeeEstimator};
117 struct TestFeeEstimator {
121 impl FeeEstimator for TestFeeEstimator {
122 fn get_est_sat_per_1000_weight(&self, _: ConfirmationTarget) -> u32 {
128 fn test_fee_estimator_less_than_floor() {
129 let sat_per_kw = FEERATE_FLOOR_SATS_PER_KW - 1;
130 let test_fee_estimator = &TestFeeEstimator { sat_per_kw };
131 let fee_estimator = LowerBoundedFeeEstimator::new(test_fee_estimator);
133 assert_eq!(fee_estimator.bounded_sat_per_1000_weight(ConfirmationTarget::Background), FEERATE_FLOOR_SATS_PER_KW);
137 fn test_fee_estimator_greater_than_floor() {
138 let sat_per_kw = FEERATE_FLOOR_SATS_PER_KW + 1;
139 let test_fee_estimator = &TestFeeEstimator { sat_per_kw };
140 let fee_estimator = LowerBoundedFeeEstimator::new(test_fee_estimator);
142 assert_eq!(fee_estimator.bounded_sat_per_1000_weight(ConfirmationTarget::Background), sat_per_kw);