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 //! Utilities for scoring payment channels.
12 //! [`Scorer`] may be given to [`find_route`] to score payment channels during path finding when a
13 //! custom [`Score`] implementation is not needed.
18 //! # extern crate secp256k1;
20 //! # use lightning::routing::network_graph::NetworkGraph;
21 //! # use lightning::routing::router::{RouteParameters, find_route};
22 //! # use lightning::routing::scoring::{Scorer, ScoringParameters};
23 //! # use lightning::util::logger::{Logger, Record};
24 //! # use secp256k1::key::PublicKey;
26 //! # struct FakeLogger {};
27 //! # impl Logger for FakeLogger {
28 //! # fn log(&self, record: &Record) { unimplemented!() }
30 //! # fn find_scored_route(payer: PublicKey, params: RouteParameters, network_graph: NetworkGraph) {
31 //! # let logger = FakeLogger {};
33 //! // Use the default channel penalties.
34 //! let scorer = Scorer::default();
36 //! // Or use custom channel penalties.
37 //! let scorer = Scorer::new(ScoringParameters {
38 //! base_penalty_msat: 1000,
39 //! failure_penalty_msat: 2 * 1024 * 1000,
40 //! ..ScoringParameters::default()
43 //! let route = find_route(&payer, ¶ms, &network_graph, None, &logger, &scorer);
49 //! If persisting [`Scorer`], it must be restored using the same [`Time`] parameterization. Using a
50 //! different type results in undefined behavior. Specifically, persisting when built with feature
51 //! `no-std` and restoring without it, or vice versa, uses different types and thus is undefined.
53 //! [`find_route`]: crate::routing::router::find_route
55 use ln::msgs::DecodeError;
56 use routing::network_graph::NodeId;
57 use routing::router::RouteHop;
58 use util::ser::{Readable, Writeable, Writer};
61 use core::cell::{RefCell, RefMut};
62 use core::ops::{DerefMut, Sub};
63 use core::time::Duration;
64 use io::{self, Read}; use sync::{Mutex, MutexGuard};
66 /// An interface used to score payment channels for path finding.
68 /// Scoring is in terms of fees willing to be paid in order to avoid routing through a channel.
70 /// Returns the fee in msats willing to be paid to avoid routing `send_amt_msat` through the
71 /// given channel in the direction from `source` to `target`.
73 /// The channel's capacity (less any other MPP parts which are also being considered for use in
74 /// the same payment) is given by `channel_capacity_msat`. It may be guessed from various
75 /// sources or assumed from no data at all.
77 /// For hints provided in the invoice, we assume the channel has sufficient capacity to accept
78 /// the invoice's full amount, and provide a `channel_capacity_msat` of `None`. In all other
79 /// cases it is set to `Some`, even if we're guessing at the channel value.
81 /// Your code should be overflow-safe through a `channel_capacity_msat` of 21 million BTC.
82 fn channel_penalty_msat(&self, short_channel_id: u64, send_amt_msat: u64, channel_capacity_msat: Option<u64>, source: &NodeId, target: &NodeId) -> u64;
84 /// Handles updating channel penalties after failing to route through a channel.
85 fn payment_path_failed(&mut self, path: &[&RouteHop], short_channel_id: u64);
88 /// A scorer that is accessed under a lock.
90 /// Needed so that calls to [`Score::channel_penalty_msat`] in [`find_route`] can be made while
91 /// having shared ownership of a scorer but without requiring internal locking in [`Score`]
92 /// implementations. Internal locking would be detrimental to route finding performance and could
93 /// result in [`Score::channel_penalty_msat`] returning a different value for the same channel.
95 /// [`find_route`]: crate::routing::router::find_route
96 pub trait LockableScore<'a> {
97 /// The locked [`Score`] type.
98 type Locked: 'a + Score;
100 /// Returns the locked scorer.
101 fn lock(&'a self) -> Self::Locked;
104 impl<'a, T: 'a + Score> LockableScore<'a> for Mutex<T> {
105 type Locked = MutexGuard<'a, T>;
107 fn lock(&'a self) -> MutexGuard<'a, T> {
108 Mutex::lock(self).unwrap()
112 impl<'a, T: 'a + Score> LockableScore<'a> for RefCell<T> {
113 type Locked = RefMut<'a, T>;
115 fn lock(&'a self) -> RefMut<'a, T> {
120 impl<S: Score, T: DerefMut<Target=S>> Score for T {
121 fn channel_penalty_msat(&self, short_channel_id: u64, send_amt_msat: u64, channel_capacity_msat: Option<u64>, source: &NodeId, target: &NodeId) -> u64 {
122 self.deref().channel_penalty_msat(short_channel_id, send_amt_msat, channel_capacity_msat, source, target)
125 fn payment_path_failed(&mut self, path: &[&RouteHop], short_channel_id: u64) {
126 self.deref_mut().payment_path_failed(path, short_channel_id)
130 /// [`Score`] implementation that provides reasonable default behavior.
132 /// Used to apply a fixed penalty to each channel, thus avoiding long paths when shorter paths with
133 /// slightly higher fees are available. Will further penalize channels that fail to relay payments.
135 /// See [module-level documentation] for usage.
137 /// [module-level documentation]: crate::routing::scoring
138 pub type Scorer = ScorerUsingTime::<DefaultTime>;
140 /// Time used by [`Scorer`].
141 #[cfg(not(feature = "no-std"))]
142 pub type DefaultTime = std::time::Instant;
144 /// Time used by [`Scorer`].
145 #[cfg(feature = "no-std")]
146 pub type DefaultTime = Eternity;
148 /// [`Score`] implementation parameterized by [`Time`].
150 /// See [`Scorer`] for details.
154 /// Mixing [`Time`] types between serialization and deserialization results in undefined behavior.
155 pub struct ScorerUsingTime<T: Time> {
156 params: ScoringParameters,
157 // TODO: Remove entries of closed channels.
158 channel_failures: HashMap<u64, ChannelFailure<T>>,
161 /// Parameters for configuring [`Scorer`].
162 pub struct ScoringParameters {
163 /// A fixed penalty in msats to apply to each channel.
165 /// Default value: 500 msat
166 pub base_penalty_msat: u64,
168 /// A penalty in msats to apply to a channel upon failing to relay a payment.
170 /// This accumulates for each failure but may be reduced over time based on
171 /// [`failure_penalty_half_life`].
173 /// Default value: 1,024,000 msat
175 /// [`failure_penalty_half_life`]: Self::failure_penalty_half_life
176 pub failure_penalty_msat: u64,
178 /// When the amount being sent over a channel is this many 1024ths of the total channel
179 /// capacity, we begin applying [`overuse_penalty_msat_per_1024th`].
181 /// Default value: 128 1024ths (i.e. begin penalizing when an HTLC uses 1/8th of a channel)
183 /// [`overuse_penalty_msat_per_1024th`]: Self::overuse_penalty_msat_per_1024th
184 pub overuse_penalty_start_1024th: u16,
186 /// A penalty applied, per whole 1024ths of the channel capacity which the amount being sent
187 /// over the channel exceeds [`overuse_penalty_start_1024th`] by.
189 /// Default value: 20 msat (i.e. 2560 msat penalty to use 1/4th of a channel, 7680 msat penalty
190 /// to use half a channel, and 12,560 msat penalty to use 3/4ths of a channel)
192 /// [`overuse_penalty_start_1024th`]: Self::overuse_penalty_start_1024th
193 pub overuse_penalty_msat_per_1024th: u64,
195 /// The time required to elapse before any accumulated [`failure_penalty_msat`] penalties are
200 /// When time is an [`Eternity`], as is default when enabling feature `no-std`, it will never
201 /// elapse. Therefore, this penalty will never decay.
203 /// [`failure_penalty_msat`]: Self::failure_penalty_msat
204 pub failure_penalty_half_life: Duration,
207 impl_writeable_tlv_based!(ScoringParameters, {
208 (0, base_penalty_msat, required),
209 (1, overuse_penalty_start_1024th, (default_value, 128)),
210 (2, failure_penalty_msat, required),
211 (3, overuse_penalty_msat_per_1024th, (default_value, 20)),
212 (4, failure_penalty_half_life, required),
215 /// Accounting for penalties against a channel for failing to relay any payments.
217 /// Penalties decay over time, though accumulate as more failures occur.
218 struct ChannelFailure<T: Time> {
219 /// Accumulated penalty in msats for the channel as of `last_failed`.
220 undecayed_penalty_msat: u64,
222 /// Last time the channel failed. Used to decay `undecayed_penalty_msat`.
226 /// A measurement of time.
227 pub trait Time: Sub<Duration, Output = Self> where Self: Sized {
228 /// Returns an instance corresponding to the current moment.
231 /// Returns the amount of time elapsed since `self` was created.
232 fn elapsed(&self) -> Duration;
234 /// Returns the amount of time passed since the beginning of [`Time`].
236 /// Used during (de-)serialization.
237 fn duration_since_epoch() -> Duration;
240 impl<T: Time> ScorerUsingTime<T> {
241 /// Creates a new scorer using the given scoring parameters.
242 pub fn new(params: ScoringParameters) -> Self {
245 channel_failures: HashMap::new(),
249 /// Creates a new scorer using `penalty_msat` as a fixed channel penalty.
250 #[cfg(any(test, feature = "fuzztarget", feature = "_test_utils"))]
251 pub fn with_fixed_penalty(penalty_msat: u64) -> Self {
252 Self::new(ScoringParameters {
253 base_penalty_msat: penalty_msat,
254 failure_penalty_msat: 0,
255 failure_penalty_half_life: Duration::from_secs(0),
256 overuse_penalty_start_1024th: 1024,
257 overuse_penalty_msat_per_1024th: 0,
262 impl<T: Time> ChannelFailure<T> {
263 fn new(failure_penalty_msat: u64) -> Self {
265 undecayed_penalty_msat: failure_penalty_msat,
266 last_failed: T::now(),
270 fn add_penalty(&mut self, failure_penalty_msat: u64, half_life: Duration) {
271 self.undecayed_penalty_msat = self.decayed_penalty_msat(half_life) + failure_penalty_msat;
272 self.last_failed = T::now();
275 fn decayed_penalty_msat(&self, half_life: Duration) -> u64 {
276 let decays = self.last_failed.elapsed().as_secs().checked_div(half_life.as_secs());
278 Some(decays) => self.undecayed_penalty_msat >> decays,
284 impl<T: Time> Default for ScorerUsingTime<T> {
285 fn default() -> Self {
286 Self::new(ScoringParameters::default())
290 impl Default for ScoringParameters {
291 fn default() -> Self {
293 base_penalty_msat: 500,
294 failure_penalty_msat: 1024 * 1000,
295 failure_penalty_half_life: Duration::from_secs(3600),
296 overuse_penalty_start_1024th: 1024 / 8,
297 overuse_penalty_msat_per_1024th: 20,
302 impl<T: Time> Score for ScorerUsingTime<T> {
303 fn channel_penalty_msat(
304 &self, short_channel_id: u64, send_amt_msat: u64, chan_capacity_opt: Option<u64>, _source: &NodeId, _target: &NodeId
306 let failure_penalty_msat = self.channel_failures
307 .get(&short_channel_id)
308 .map_or(0, |value| value.decayed_penalty_msat(self.params.failure_penalty_half_life));
310 let mut penalty_msat = self.params.base_penalty_msat + failure_penalty_msat;
312 if let Some(chan_capacity_msat) = chan_capacity_opt {
313 let send_1024ths = send_amt_msat.checked_mul(1024).unwrap_or(u64::max_value()) / chan_capacity_msat;
315 if send_1024ths > self.params.overuse_penalty_start_1024th as u64 {
316 penalty_msat = penalty_msat.checked_add(
317 (send_1024ths - self.params.overuse_penalty_start_1024th as u64)
318 .checked_mul(self.params.overuse_penalty_msat_per_1024th).unwrap_or(u64::max_value()))
319 .unwrap_or(u64::max_value());
326 fn payment_path_failed(&mut self, _path: &[&RouteHop], short_channel_id: u64) {
327 let failure_penalty_msat = self.params.failure_penalty_msat;
328 let half_life = self.params.failure_penalty_half_life;
329 self.channel_failures
330 .entry(short_channel_id)
331 .and_modify(|failure| failure.add_penalty(failure_penalty_msat, half_life))
332 .or_insert_with(|| ChannelFailure::new(failure_penalty_msat));
336 #[cfg(not(feature = "no-std"))]
337 impl Time for std::time::Instant {
339 std::time::Instant::now()
342 fn duration_since_epoch() -> Duration {
343 use std::time::SystemTime;
344 SystemTime::now().duration_since(SystemTime::UNIX_EPOCH).unwrap()
347 fn elapsed(&self) -> Duration {
348 std::time::Instant::elapsed(self)
352 /// A state in which time has no meaning.
353 #[derive(Debug, PartialEq, Eq)]
356 impl Time for Eternity {
361 fn duration_since_epoch() -> Duration {
362 Duration::from_secs(0)
365 fn elapsed(&self) -> Duration {
366 Duration::from_secs(0)
370 impl Sub<Duration> for Eternity {
373 fn sub(self, _other: Duration) -> Self {
378 impl<T: Time> Writeable for ScorerUsingTime<T> {
380 fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
381 self.params.write(w)?;
382 self.channel_failures.write(w)?;
383 write_tlv_fields!(w, {});
388 impl<T: Time> Readable for ScorerUsingTime<T> {
390 fn read<R: Read>(r: &mut R) -> Result<Self, DecodeError> {
392 params: Readable::read(r)?,
393 channel_failures: Readable::read(r)?,
395 read_tlv_fields!(r, {});
400 impl<T: Time> Writeable for ChannelFailure<T> {
402 fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
403 let duration_since_epoch = T::duration_since_epoch() - self.last_failed.elapsed();
404 write_tlv_fields!(w, {
405 (0, self.undecayed_penalty_msat, required),
406 (2, duration_since_epoch, required),
412 impl<T: Time> Readable for ChannelFailure<T> {
414 fn read<R: Read>(r: &mut R) -> Result<Self, DecodeError> {
415 let mut undecayed_penalty_msat = 0;
416 let mut duration_since_epoch = Duration::from_secs(0);
417 read_tlv_fields!(r, {
418 (0, undecayed_penalty_msat, required),
419 (2, duration_since_epoch, required),
422 undecayed_penalty_msat,
423 last_failed: T::now() - (T::duration_since_epoch() - duration_since_epoch),
430 use super::{Eternity, ScoringParameters, ScorerUsingTime, Time};
432 use routing::scoring::Score;
433 use routing::network_graph::NodeId;
434 use util::ser::{Readable, Writeable};
436 use bitcoin::secp256k1::PublicKey;
437 use core::cell::Cell;
439 use core::time::Duration;
442 /// Time that can be advanced manually in tests.
443 #[derive(Debug, PartialEq, Eq)]
444 struct SinceEpoch(Duration);
448 static ELAPSED: Cell<Duration> = core::cell::Cell::new(Duration::from_secs(0));
451 fn advance(duration: Duration) {
452 Self::ELAPSED.with(|elapsed| elapsed.set(elapsed.get() + duration))
456 impl Time for SinceEpoch {
458 Self(Self::duration_since_epoch())
461 fn duration_since_epoch() -> Duration {
462 Self::ELAPSED.with(|elapsed| elapsed.get())
465 fn elapsed(&self) -> Duration {
466 Self::duration_since_epoch() - self.0
470 impl Sub<Duration> for SinceEpoch {
473 fn sub(self, other: Duration) -> Self {
479 fn time_passes_when_advanced() {
480 let now = SinceEpoch::now();
481 assert_eq!(now.elapsed(), Duration::from_secs(0));
483 SinceEpoch::advance(Duration::from_secs(1));
484 SinceEpoch::advance(Duration::from_secs(1));
486 let elapsed = now.elapsed();
487 let later = SinceEpoch::now();
489 assert_eq!(elapsed, Duration::from_secs(2));
490 assert_eq!(later - elapsed, now);
494 fn time_never_passes_in_an_eternity() {
495 let now = Eternity::now();
496 let elapsed = now.elapsed();
497 let later = Eternity::now();
499 assert_eq!(now.elapsed(), Duration::from_secs(0));
500 assert_eq!(later - elapsed, now);
503 /// A scorer for testing with time that can be manually advanced.
504 type Scorer = ScorerUsingTime::<SinceEpoch>;
506 fn source_node_id() -> NodeId {
507 NodeId::from_pubkey(&PublicKey::from_slice(&hex::decode("02eec7245d6b7d2ccb30380bfbe2a3648cd7a942653f5aa340edcea1f283686619").unwrap()[..]).unwrap())
510 fn target_node_id() -> NodeId {
511 NodeId::from_pubkey(&PublicKey::from_slice(&hex::decode("0324653eac434488002cc06bbfb7f10fe18991e35f9fe4302dbea6d2353dc0ab1c").unwrap()[..]).unwrap())
515 fn penalizes_without_channel_failures() {
516 let scorer = Scorer::new(ScoringParameters {
517 base_penalty_msat: 1_000,
518 failure_penalty_msat: 512,
519 failure_penalty_half_life: Duration::from_secs(1),
520 overuse_penalty_start_1024th: 1024,
521 overuse_penalty_msat_per_1024th: 0,
523 let source = source_node_id();
524 let target = target_node_id();
525 assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_000);
527 SinceEpoch::advance(Duration::from_secs(1));
528 assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_000);
532 fn accumulates_channel_failure_penalties() {
533 let mut scorer = Scorer::new(ScoringParameters {
534 base_penalty_msat: 1_000,
535 failure_penalty_msat: 64,
536 failure_penalty_half_life: Duration::from_secs(10),
537 overuse_penalty_start_1024th: 1024,
538 overuse_penalty_msat_per_1024th: 0,
540 let source = source_node_id();
541 let target = target_node_id();
542 assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_000);
544 scorer.payment_path_failed(&[], 42);
545 assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_064);
547 scorer.payment_path_failed(&[], 42);
548 assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_128);
550 scorer.payment_path_failed(&[], 42);
551 assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_192);
555 fn decays_channel_failure_penalties_over_time() {
556 let mut scorer = Scorer::new(ScoringParameters {
557 base_penalty_msat: 1_000,
558 failure_penalty_msat: 512,
559 failure_penalty_half_life: Duration::from_secs(10),
560 overuse_penalty_start_1024th: 1024,
561 overuse_penalty_msat_per_1024th: 0,
563 let source = source_node_id();
564 let target = target_node_id();
565 assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_000);
567 scorer.payment_path_failed(&[], 42);
568 assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_512);
570 SinceEpoch::advance(Duration::from_secs(9));
571 assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_512);
573 SinceEpoch::advance(Duration::from_secs(1));
574 assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_256);
576 SinceEpoch::advance(Duration::from_secs(10 * 8));
577 assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_001);
579 SinceEpoch::advance(Duration::from_secs(10));
580 assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_000);
582 SinceEpoch::advance(Duration::from_secs(10));
583 assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_000);
587 fn accumulates_channel_failure_penalties_after_decay() {
588 let mut scorer = Scorer::new(ScoringParameters {
589 base_penalty_msat: 1_000,
590 failure_penalty_msat: 512,
591 failure_penalty_half_life: Duration::from_secs(10),
592 overuse_penalty_start_1024th: 1024,
593 overuse_penalty_msat_per_1024th: 0,
595 let source = source_node_id();
596 let target = target_node_id();
597 assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_000);
599 scorer.payment_path_failed(&[], 42);
600 assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_512);
602 SinceEpoch::advance(Duration::from_secs(10));
603 assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_256);
605 scorer.payment_path_failed(&[], 42);
606 assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_768);
608 SinceEpoch::advance(Duration::from_secs(10));
609 assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_384);
613 fn restores_persisted_channel_failure_penalties() {
614 let mut scorer = Scorer::new(ScoringParameters {
615 base_penalty_msat: 1_000,
616 failure_penalty_msat: 512,
617 failure_penalty_half_life: Duration::from_secs(10),
618 overuse_penalty_start_1024th: 1024,
619 overuse_penalty_msat_per_1024th: 0,
621 let source = source_node_id();
622 let target = target_node_id();
624 scorer.payment_path_failed(&[], 42);
625 assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_512);
627 SinceEpoch::advance(Duration::from_secs(10));
628 assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_256);
630 scorer.payment_path_failed(&[], 43);
631 assert_eq!(scorer.channel_penalty_msat(43, 1, Some(1), &source, &target), 1_512);
633 let mut serialized_scorer = Vec::new();
634 scorer.write(&mut serialized_scorer).unwrap();
636 let deserialized_scorer = <Scorer>::read(&mut io::Cursor::new(&serialized_scorer)).unwrap();
637 assert_eq!(deserialized_scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_256);
638 assert_eq!(deserialized_scorer.channel_penalty_msat(43, 1, Some(1), &source, &target), 1_512);
642 fn decays_persisted_channel_failure_penalties() {
643 let mut scorer = Scorer::new(ScoringParameters {
644 base_penalty_msat: 1_000,
645 failure_penalty_msat: 512,
646 failure_penalty_half_life: Duration::from_secs(10),
647 overuse_penalty_start_1024th: 1024,
648 overuse_penalty_msat_per_1024th: 0,
650 let source = source_node_id();
651 let target = target_node_id();
653 scorer.payment_path_failed(&[], 42);
654 assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_512);
656 let mut serialized_scorer = Vec::new();
657 scorer.write(&mut serialized_scorer).unwrap();
659 SinceEpoch::advance(Duration::from_secs(10));
661 let deserialized_scorer = <Scorer>::read(&mut io::Cursor::new(&serialized_scorer)).unwrap();
662 assert_eq!(deserialized_scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_256);
664 SinceEpoch::advance(Duration::from_secs(10));
665 assert_eq!(deserialized_scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_128);
669 fn charges_per_1024th_penalty() {
670 let scorer = Scorer::new(ScoringParameters {
671 base_penalty_msat: 0,
672 failure_penalty_msat: 0,
673 failure_penalty_half_life: Duration::from_secs(0),
674 overuse_penalty_start_1024th: 256,
675 overuse_penalty_msat_per_1024th: 100,
677 let source = source_node_id();
678 let target = target_node_id();
680 assert_eq!(scorer.channel_penalty_msat(42, 1_000, None, &source, &target), 0);
681 assert_eq!(scorer.channel_penalty_msat(42, 1_000, Some(1_024_000), &source, &target), 0);
682 assert_eq!(scorer.channel_penalty_msat(42, 256_999, Some(1_024_000), &source, &target), 0);
683 assert_eq!(scorer.channel_penalty_msat(42, 257_000, Some(1_024_000), &source, &target), 100);
684 assert_eq!(scorer.channel_penalty_msat(42, 258_000, Some(1_024_000), &source, &target), 200);
685 assert_eq!(scorer.channel_penalty_msat(42, 512_000, Some(1_024_000), &source, &target), 256 * 100);