_ Git - rust-lightning/blob - lightning/src/routing/scorer.rs

   1 // This file is Copyright its original authors, visible in version control
   2 // history.
   3 //
   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
   8 // licenses.
   9
  10 //! Utilities for scoring payment channels.
  11 //!
  12 //! [`Scorer`] may be given to [`find_route`] to score payment channels during path finding when a
  13 //! custom [`routing::Score`] implementation is not needed.
  14 //!
  15 //! # Example
  16 //!
  17 //! ```
  18 //! # extern crate secp256k1;
  19 //! #
  20 //! # use lightning::routing::network_graph::NetworkGraph;
  21 //! # use lightning::routing::router::{RouteParameters, find_route};
  22 //! # use lightning::routing::scorer::{Scorer, ScoringParameters};
  23 //! # use lightning::util::logger::{Logger, Record};
  24 //! # use secp256k1::key::PublicKey;
  25 //! #
  26 //! # struct FakeLogger {};
  27 //! # impl Logger for FakeLogger {
  28 //! #     fn log(&self, record: &Record) { unimplemented!() }
  29 //! # }
  30 //! # fn find_scored_route(payer: PublicKey, params: RouteParameters, network_graph: NetworkGraph) {
  31 //! # let logger = FakeLogger {};
  32 //! #
  33 //! // Use the default channel penalties.
  34 //! let scorer = Scorer::default();
  35 //!
  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()
  41 //! });
  42 //!
  43 //! let route = find_route(&payer, &params, &network_graph, None, &logger, &scorer);
  44 //! # }
  45 //! ```
  46 //!
  47 //! # Note
  48 //!
  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.
  52 //!
  53 //! [`find_route`]: crate::routing::router::find_route
  54
  55 use routing;
  56
  57 use ln::msgs::DecodeError;
  58 use routing::network_graph::NodeId;
  59 use routing::router::RouteHop;
  60 use util::ser::{Readable, Writeable, Writer};
  61
  62 use prelude::*;
  63 use core::ops::Sub;
  64 use core::time::Duration;
  65 use io::{self, Read};
  66
  67 /// [`routing::Score`] implementation that provides reasonable default behavior.
  68 ///
  69 /// Used to apply a fixed penalty to each channel, thus avoiding long paths when shorter paths with
  70 /// slightly higher fees are available. Will further penalize channels that fail to relay payments.
  71 ///
  72 /// See [module-level documentation] for usage.
  73 ///
  74 /// [module-level documentation]: crate::routing::scorer
  75 pub type Scorer = ScorerUsingTime::<DefaultTime>;
  76
  77 /// Time used by [`Scorer`].
  78 #[cfg(not(feature = "no-std"))]
  79 pub type DefaultTime = std::time::Instant;
  80
  81 /// Time used by [`Scorer`].
  82 #[cfg(feature = "no-std")]
  83 pub type DefaultTime = Eternity;
  84
  85 /// [`routing::Score`] implementation parameterized by [`Time`].
  86 ///
  87 /// See [`Scorer`] for details.
  88 ///
  89 /// # Note
  90 ///
  91 /// Mixing [`Time`] types between serialization and deserialization results in undefined behavior.
  92 pub struct ScorerUsingTime<T: Time> {
  93         params: ScoringParameters,
  94         // TODO: Remove entries of closed channels.
  95         channel_failures: HashMap<u64, ChannelFailure<T>>,
  96 }
  97
  98 /// Parameters for configuring [`Scorer`].
  99 pub struct ScoringParameters {
 100         /// A fixed penalty in msats to apply to each channel.
 101         ///
 102         /// Default value: 500 msat
 103         pub base_penalty_msat: u64,
 104
 105         /// A penalty in msats to apply to a channel upon failing to relay a payment.
 106         ///
 107         /// This accumulates for each failure but may be reduced over time based on
 108         /// [`failure_penalty_half_life`].
 109         ///
 110         /// Default value: 1,024,000 msat
 111         ///
 112         /// [`failure_penalty_half_life`]: Self::failure_penalty_half_life
 113         pub failure_penalty_msat: u64,
 114
 115         /// When the amount being sent over a channel is this many 1024ths of the total channel
 116         /// capacity, we begin applying [`overuse_penalty_msat_per_1024th`].
 117         ///
 118         /// Default value: 128 1024ths (i.e. begin penalizing when an HTLC uses 1/8th of a channel)
 119         ///
 120         /// [`overuse_penalty_msat_per_1024th`]: Self::overuse_penalty_msat_per_1024th
 121         pub overuse_penalty_start_1024th: u16,
 122
 123         /// A penalty applied, per whole 1024ths of the channel capacity which the amount being sent
 124         /// over the channel exceeds [`overuse_penalty_start_1024th`] by.
 125         ///
 126         /// Default value: 20 msat (i.e. 2560 msat penalty to use 1/4th of a channel, 7680 msat penalty
 127         ///                to use half a channel, and 12,560 msat penalty to use 3/4ths of a channel)
 128         ///
 129         /// [`overuse_penalty_start_1024th`]: Self::overuse_penalty_start_1024th
 130         pub overuse_penalty_msat_per_1024th: u64,
 131
 132         /// The time required to elapse before any accumulated [`failure_penalty_msat`] penalties are
 133         /// cut in half.
 134         ///
 135         /// # Note
 136         ///
 137         /// When time is an [`Eternity`], as is default when enabling feature `no-std`, it will never
 138         /// elapse. Therefore, this penalty will never decay.
 139         ///
 140         /// [`failure_penalty_msat`]: Self::failure_penalty_msat
 141         pub failure_penalty_half_life: Duration,
 142 }
 143
 144 impl_writeable_tlv_based!(ScoringParameters, {
 145         (0, base_penalty_msat, required),
 146         (1, overuse_penalty_start_1024th, (default_value, 128)),
 147         (2, failure_penalty_msat, required),
 148         (3, overuse_penalty_msat_per_1024th, (default_value, 20)),
 149         (4, failure_penalty_half_life, required),
 150 });
 151
 152 /// Accounting for penalties against a channel for failing to relay any payments.
 153 ///
 154 /// Penalties decay over time, though accumulate as more failures occur.
 155 struct ChannelFailure<T: Time> {
 156         /// Accumulated penalty in msats for the channel as of `last_failed`.
 157         undecayed_penalty_msat: u64,
 158
 159         /// Last time the channel failed. Used to decay `undecayed_penalty_msat`.
 160         last_failed: T,
 161 }
 162
 163 /// A measurement of time.
 164 pub trait Time: Sub<Duration, Output = Self> where Self: Sized {
 165         /// Returns an instance corresponding to the current moment.
 166         fn now() -> Self;
 167
 168         /// Returns the amount of time elapsed since `self` was created.
 169         fn elapsed(&self) -> Duration;
 170
 171         /// Returns the amount of time passed since the beginning of [`Time`].
 172         ///
 173         /// Used during (de-)serialization.
 174         fn duration_since_epoch() -> Duration;
 175 }
 176
 177 impl<T: Time> ScorerUsingTime<T> {
 178         /// Creates a new scorer using the given scoring parameters.
 179         pub fn new(params: ScoringParameters) -> Self {
 180                 Self {
 181                         params,
 182                         channel_failures: HashMap::new(),
 183                 }
 184         }
 185
 186         /// Creates a new scorer using `penalty_msat` as a fixed channel penalty.
 187         #[cfg(any(test, feature = "fuzztarget", feature = "_test_utils"))]
 188         pub fn with_fixed_penalty(penalty_msat: u64) -> Self {
 189                 Self::new(ScoringParameters {
 190                         base_penalty_msat: penalty_msat,
 191                         failure_penalty_msat: 0,
 192                         failure_penalty_half_life: Duration::from_secs(0),
 193                         overuse_penalty_start_1024th: 1024,
 194                         overuse_penalty_msat_per_1024th: 0,
 195                 })
 196         }
 197 }
 198
 199 impl<T: Time> ChannelFailure<T> {
 200         fn new(failure_penalty_msat: u64) -> Self {
 201                 Self {
 202                         undecayed_penalty_msat: failure_penalty_msat,
 203                         last_failed: T::now(),
 204                 }
 205         }
 206
 207         fn add_penalty(&mut self, failure_penalty_msat: u64, half_life: Duration) {
 208                 self.undecayed_penalty_msat = self.decayed_penalty_msat(half_life) + failure_penalty_msat;
 209                 self.last_failed = T::now();
 210         }
 211
 212         fn decayed_penalty_msat(&self, half_life: Duration) -> u64 {
 213                 let decays = self.last_failed.elapsed().as_secs().checked_div(half_life.as_secs());
 214                 match decays {
 215                         Some(decays) => self.undecayed_penalty_msat >> decays,
 216                         None => 0,
 217                 }
 218         }
 219 }
 220
 221 impl<T: Time> Default for ScorerUsingTime<T> {
 222         fn default() -> Self {
 223                 Self::new(ScoringParameters::default())
 224         }
 225 }
 226
 227 impl Default for ScoringParameters {
 228         fn default() -> Self {
 229                 Self {
 230                         base_penalty_msat: 500,
 231                         failure_penalty_msat: 1024 * 1000,
 232                         failure_penalty_half_life: Duration::from_secs(3600),
 233                         overuse_penalty_start_1024th: 1024 / 8,
 234                         overuse_penalty_msat_per_1024th: 20,
 235                 }
 236         }
 237 }
 238
 239 impl<T: Time> routing::Score for ScorerUsingTime<T> {
 240         fn channel_penalty_msat(
 241                 &self, short_channel_id: u64, send_amt_msat: u64, chan_capacity_opt: Option<u64>, _source: &NodeId, _target: &NodeId
 242         ) -> u64 {
 243                 let failure_penalty_msat = self.channel_failures
 244                         .get(&short_channel_id)
 245                         .map_or(0, |value| value.decayed_penalty_msat(self.params.failure_penalty_half_life));
 246
 247                 let mut penalty_msat = self.params.base_penalty_msat + failure_penalty_msat;
 248
 249                 if let Some(chan_capacity_msat) = chan_capacity_opt {
 250                         let send_1024ths = send_amt_msat.checked_mul(1024).unwrap_or(u64::max_value()) / chan_capacity_msat;
 251
 252                         if send_1024ths > self.params.overuse_penalty_start_1024th as u64 {
 253                                 penalty_msat = penalty_msat.checked_add(
 254                                                 (send_1024ths - self.params.overuse_penalty_start_1024th as u64)
 255                                                 .checked_mul(self.params.overuse_penalty_msat_per_1024th).unwrap_or(u64::max_value()))
 256                                         .unwrap_or(u64::max_value());
 257                         }
 258                 }
 259
 260                 penalty_msat
 261         }
 262
 263         fn payment_path_failed(&mut self, _path: &[&RouteHop], short_channel_id: u64) {
 264                 let failure_penalty_msat = self.params.failure_penalty_msat;
 265                 let half_life = self.params.failure_penalty_half_life;
 266                 self.channel_failures
 267                         .entry(short_channel_id)
 268                         .and_modify(|failure| failure.add_penalty(failure_penalty_msat, half_life))
 269                         .or_insert_with(|| ChannelFailure::new(failure_penalty_msat));
 270         }
 271 }
 272
 273 #[cfg(not(feature = "no-std"))]
 274 impl Time for std::time::Instant {
 275         fn now() -> Self {
 276                 std::time::Instant::now()
 277         }
 278
 279         fn duration_since_epoch() -> Duration {
 280                 use std::time::SystemTime;
 281                 SystemTime::now().duration_since(SystemTime::UNIX_EPOCH).unwrap()
 282         }
 283
 284         fn elapsed(&self) -> Duration {
 285                 std::time::Instant::elapsed(self)
 286         }
 287 }
 288
 289 /// A state in which time has no meaning.
 290 #[derive(Debug, PartialEq, Eq)]
 291 pub struct Eternity;
 292
 293 impl Time for Eternity {
 294         fn now() -> Self {
 295                 Self
 296         }
 297
 298         fn duration_since_epoch() -> Duration {
 299                 Duration::from_secs(0)
 300         }
 301
 302         fn elapsed(&self) -> Duration {
 303                 Duration::from_secs(0)
 304         }
 305 }
 306
 307 impl Sub<Duration> for Eternity {
 308         type Output = Self;
 309
 310         fn sub(self, _other: Duration) -> Self {
 311                 self
 312         }
 313 }
 314
 315 impl<T: Time> Writeable for ScorerUsingTime<T> {
 316         #[inline]
 317         fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
 318                 self.params.write(w)?;
 319                 self.channel_failures.write(w)?;
 320                 write_tlv_fields!(w, {});
 321                 Ok(())
 322         }
 323 }
 324
 325 impl<T: Time> Readable for ScorerUsingTime<T> {
 326         #[inline]
 327         fn read<R: Read>(r: &mut R) -> Result<Self, DecodeError> {
 328                 let res = Ok(Self {
 329                         params: Readable::read(r)?,
 330                         channel_failures: Readable::read(r)?,
 331                 });
 332                 read_tlv_fields!(r, {});
 333                 res
 334         }
 335 }
 336
 337 impl<T: Time> Writeable for ChannelFailure<T> {
 338         #[inline]
 339         fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
 340                 let duration_since_epoch = T::duration_since_epoch() - self.last_failed.elapsed();
 341                 write_tlv_fields!(w, {
 342                         (0, self.undecayed_penalty_msat, required),
 343                         (2, duration_since_epoch, required),
 344                 });
 345                 Ok(())
 346         }
 347 }
 348
 349 impl<T: Time> Readable for ChannelFailure<T> {
 350         #[inline]
 351         fn read<R: Read>(r: &mut R) -> Result<Self, DecodeError> {
 352                 let mut undecayed_penalty_msat = 0;
 353                 let mut duration_since_epoch = Duration::from_secs(0);
 354                 read_tlv_fields!(r, {
 355                         (0, undecayed_penalty_msat, required),
 356                         (2, duration_since_epoch, required),
 357                 });
 358                 Ok(Self {
 359                         undecayed_penalty_msat,
 360                         last_failed: T::now() - (T::duration_since_epoch() - duration_since_epoch),
 361                 })
 362         }
 363 }
 364
 365 #[cfg(test)]
 366 mod tests {
 367         use super::{Eternity, ScoringParameters, ScorerUsingTime, Time};
 368
 369         use routing::Score;
 370         use routing::network_graph::NodeId;
 371         use util::ser::{Readable, Writeable};
 372
 373         use bitcoin::secp256k1::PublicKey;
 374         use core::cell::Cell;
 375         use core::ops::Sub;
 376         use core::time::Duration;
 377         use io;
 378
 379         /// Time that can be advanced manually in tests.
 380         #[derive(Debug, PartialEq, Eq)]
 381         struct SinceEpoch(Duration);
 382
 383         impl SinceEpoch {
 384                 thread_local! {
 385                         static ELAPSED: Cell<Duration> = core::cell::Cell::new(Duration::from_secs(0));
 386                 }
 387
 388                 fn advance(duration: Duration) {
 389                         Self::ELAPSED.with(|elapsed| elapsed.set(elapsed.get() + duration))
 390                 }
 391         }
 392
 393         impl Time for SinceEpoch {
 394                 fn now() -> Self {
 395                         Self(Self::duration_since_epoch())
 396                 }
 397
 398                 fn duration_since_epoch() -> Duration {
 399                         Self::ELAPSED.with(|elapsed| elapsed.get())
 400                 }
 401
 402                 fn elapsed(&self) -> Duration {
 403                         Self::duration_since_epoch() - self.0
 404                 }
 405         }
 406
 407         impl Sub<Duration> for SinceEpoch {
 408                 type Output = Self;
 409
 410                 fn sub(self, other: Duration) -> Self {
 411                         Self(self.0 - other)
 412                 }
 413         }
 414
 415         #[test]
 416         fn time_passes_when_advanced() {
 417                 let now = SinceEpoch::now();
 418                 assert_eq!(now.elapsed(), Duration::from_secs(0));
 419
 420                 SinceEpoch::advance(Duration::from_secs(1));
 421                 SinceEpoch::advance(Duration::from_secs(1));
 422
 423                 let elapsed = now.elapsed();
 424                 let later = SinceEpoch::now();
 425
 426                 assert_eq!(elapsed, Duration::from_secs(2));
 427                 assert_eq!(later - elapsed, now);
 428         }
 429
 430         #[test]
 431         fn time_never_passes_in_an_eternity() {
 432                 let now = Eternity::now();
 433                 let elapsed = now.elapsed();
 434                 let later = Eternity::now();
 435
 436                 assert_eq!(now.elapsed(), Duration::from_secs(0));
 437                 assert_eq!(later - elapsed, now);
 438         }
 439
 440         /// A scorer for testing with time that can be manually advanced.
 441         type Scorer = ScorerUsingTime::<SinceEpoch>;
 442
 443         fn source_node_id() -> NodeId {
 444                 NodeId::from_pubkey(&PublicKey::from_slice(&hex::decode("02eec7245d6b7d2ccb30380bfbe2a3648cd7a942653f5aa340edcea1f283686619").unwrap()[..]).unwrap())
 445         }
 446
 447         fn target_node_id() -> NodeId {
 448                 NodeId::from_pubkey(&PublicKey::from_slice(&hex::decode("0324653eac434488002cc06bbfb7f10fe18991e35f9fe4302dbea6d2353dc0ab1c").unwrap()[..]).unwrap())
 449         }
 450
 451         #[test]
 452         fn penalizes_without_channel_failures() {
 453                 let scorer = Scorer::new(ScoringParameters {
 454                         base_penalty_msat: 1_000,
 455                         failure_penalty_msat: 512,
 456                         failure_penalty_half_life: Duration::from_secs(1),
 457                         overuse_penalty_start_1024th: 1024,
 458                         overuse_penalty_msat_per_1024th: 0,
 459                 });
 460                 let source = source_node_id();
 461                 let target = target_node_id();
 462                 assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_000);
 463
 464                 SinceEpoch::advance(Duration::from_secs(1));
 465                 assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_000);
 466         }
 467
 468         #[test]
 469         fn accumulates_channel_failure_penalties() {
 470                 let mut scorer = Scorer::new(ScoringParameters {
 471                         base_penalty_msat: 1_000,
 472                         failure_penalty_msat: 64,
 473                         failure_penalty_half_life: Duration::from_secs(10),
 474                         overuse_penalty_start_1024th: 1024,
 475                         overuse_penalty_msat_per_1024th: 0,
 476                 });
 477                 let source = source_node_id();
 478                 let target = target_node_id();
 479                 assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_000);
 480
 481                 scorer.payment_path_failed(&[], 42);
 482                 assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_064);
 483
 484                 scorer.payment_path_failed(&[], 42);
 485                 assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_128);
 486
 487                 scorer.payment_path_failed(&[], 42);
 488                 assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_192);
 489         }
 490
 491         #[test]
 492         fn decays_channel_failure_penalties_over_time() {
 493                 let mut scorer = Scorer::new(ScoringParameters {
 494                         base_penalty_msat: 1_000,
 495                         failure_penalty_msat: 512,
 496                         failure_penalty_half_life: Duration::from_secs(10),
 497                         overuse_penalty_start_1024th: 1024,
 498                         overuse_penalty_msat_per_1024th: 0,
 499                 });
 500                 let source = source_node_id();
 501                 let target = target_node_id();
 502                 assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_000);
 503
 504                 scorer.payment_path_failed(&[], 42);
 505                 assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_512);
 506
 507                 SinceEpoch::advance(Duration::from_secs(9));
 508                 assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_512);
 509
 510                 SinceEpoch::advance(Duration::from_secs(1));
 511                 assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_256);
 512
 513                 SinceEpoch::advance(Duration::from_secs(10 * 8));
 514                 assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_001);
 515
 516                 SinceEpoch::advance(Duration::from_secs(10));
 517                 assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_000);
 518
 519                 SinceEpoch::advance(Duration::from_secs(10));
 520                 assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_000);
 521         }
 522
 523         #[test]
 524         fn accumulates_channel_failure_penalties_after_decay() {
 525                 let mut scorer = Scorer::new(ScoringParameters {
 526                         base_penalty_msat: 1_000,
 527                         failure_penalty_msat: 512,
 528                         failure_penalty_half_life: Duration::from_secs(10),
 529                         overuse_penalty_start_1024th: 1024,
 530                         overuse_penalty_msat_per_1024th: 0,
 531                 });
 532                 let source = source_node_id();
 533                 let target = target_node_id();
 534                 assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_000);
 535
 536                 scorer.payment_path_failed(&[], 42);
 537                 assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_512);
 538
 539                 SinceEpoch::advance(Duration::from_secs(10));
 540                 assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_256);
 541
 542                 scorer.payment_path_failed(&[], 42);
 543                 assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_768);
 544
 545                 SinceEpoch::advance(Duration::from_secs(10));
 546                 assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_384);
 547         }
 548
 549         #[test]
 550         fn restores_persisted_channel_failure_penalties() {
 551                 let mut scorer = Scorer::new(ScoringParameters {
 552                         base_penalty_msat: 1_000,
 553                         failure_penalty_msat: 512,
 554                         failure_penalty_half_life: Duration::from_secs(10),
 555                         overuse_penalty_start_1024th: 1024,
 556                         overuse_penalty_msat_per_1024th: 0,
 557                 });
 558                 let source = source_node_id();
 559                 let target = target_node_id();
 560
 561                 scorer.payment_path_failed(&[], 42);
 562                 assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_512);
 563
 564                 SinceEpoch::advance(Duration::from_secs(10));
 565                 assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_256);
 566
 567                 scorer.payment_path_failed(&[], 43);
 568                 assert_eq!(scorer.channel_penalty_msat(43, 1, Some(1), &source, &target), 1_512);
 569
 570                 let mut serialized_scorer = Vec::new();
 571                 scorer.write(&mut serialized_scorer).unwrap();
 572
 573                 let deserialized_scorer = <Scorer>::read(&mut io::Cursor::new(&serialized_scorer)).unwrap();
 574                 assert_eq!(deserialized_scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_256);
 575                 assert_eq!(deserialized_scorer.channel_penalty_msat(43, 1, Some(1), &source, &target), 1_512);
 576         }
 577
 578         #[test]
 579         fn decays_persisted_channel_failure_penalties() {
 580                 let mut scorer = Scorer::new(ScoringParameters {
 581                         base_penalty_msat: 1_000,
 582                         failure_penalty_msat: 512,
 583                         failure_penalty_half_life: Duration::from_secs(10),
 584                         overuse_penalty_start_1024th: 1024,
 585                         overuse_penalty_msat_per_1024th: 0,
 586                 });
 587                 let source = source_node_id();
 588                 let target = target_node_id();
 589
 590                 scorer.payment_path_failed(&[], 42);
 591                 assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_512);
 592
 593                 let mut serialized_scorer = Vec::new();
 594                 scorer.write(&mut serialized_scorer).unwrap();
 595
 596                 SinceEpoch::advance(Duration::from_secs(10));
 597
 598                 let deserialized_scorer = <Scorer>::read(&mut io::Cursor::new(&serialized_scorer)).unwrap();
 599                 assert_eq!(deserialized_scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_256);
 600
 601                 SinceEpoch::advance(Duration::from_secs(10));
 602                 assert_eq!(deserialized_scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_128);
 603         }
 604
 605         #[test]
 606         fn charges_per_1024th_penalty() {
 607                 let scorer = Scorer::new(ScoringParameters {
 608                         base_penalty_msat: 0,
 609                         failure_penalty_msat: 0,
 610                         failure_penalty_half_life: Duration::from_secs(0),
 611                         overuse_penalty_start_1024th: 256,
 612                         overuse_penalty_msat_per_1024th: 100,
 613                 });
 614                 let source = source_node_id();
 615                 let target = target_node_id();
 616
 617                 assert_eq!(scorer.channel_penalty_msat(42, 1_000, None, &source, &target), 0);
 618                 assert_eq!(scorer.channel_penalty_msat(42, 1_000, Some(1_024_000), &source, &target), 0);
 619                 assert_eq!(scorer.channel_penalty_msat(42, 256_999, Some(1_024_000), &source, &target), 0);
 620                 assert_eq!(scorer.channel_penalty_msat(42, 257_000, Some(1_024_000), &source, &target), 100);
 621                 assert_eq!(scorer.channel_penalty_msat(42, 258_000, Some(1_024_000), &source, &target), 200);
 622                 assert_eq!(scorer.channel_penalty_msat(42, 512_000, Some(1_024_000), &source, &target), 256 * 100);
 623         }
 624 }