_ Git - rust-lightning/blob - lightning/src/routing/scoring.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 [`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::scoring::{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 ln::msgs::DecodeError;
  56 use routing::network_graph::NodeId;
  57 use routing::router::RouteHop;
  58 use util::ser::{Readable, Writeable, Writer};
  59
  60 use prelude::*;
  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};
  65
  66 /// An interface used to score payment channels for path finding.
  67 ///
  68 ///     Scoring is in terms of fees willing to be paid in order to avoid routing through a channel.
  69 pub trait Score {
  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`.
  72         ///
  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.
  76         ///
  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.
  80         ///
  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;
  83
  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);
  86 }
  87
  88 /// A scorer that is accessed under a lock.
  89 ///
  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.
  94 ///
  95 /// [`find_route`]: crate::routing::router::find_route
  96 pub trait LockableScore<'a> {
  97         /// The locked [`Score`] type.
  98         type Locked: 'a + Score;
  99
 100         /// Returns the locked scorer.
 101         fn lock(&'a self) -> Self::Locked;
 102 }
 103
 104 impl<'a, T: 'a + Score> LockableScore<'a> for Mutex<T> {
 105         type Locked = MutexGuard<'a, T>;
 106
 107         fn lock(&'a self) -> MutexGuard<'a, T> {
 108                 Mutex::lock(self).unwrap()
 109         }
 110 }
 111
 112 impl<'a, T: 'a + Score> LockableScore<'a> for RefCell<T> {
 113         type Locked = RefMut<'a, T>;
 114
 115         fn lock(&'a self) -> RefMut<'a, T> {
 116                 self.borrow_mut()
 117         }
 118 }
 119
 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)
 123         }
 124
 125         fn payment_path_failed(&mut self, path: &[&RouteHop], short_channel_id: u64) {
 126                 self.deref_mut().payment_path_failed(path, short_channel_id)
 127         }
 128 }
 129
 130 /// [`Score`] implementation that provides reasonable default behavior.
 131 ///
 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.
 134 ///
 135 /// See [module-level documentation] for usage.
 136 ///
 137 /// [module-level documentation]: crate::routing::scoring
 138 pub type Scorer = ScorerUsingTime::<DefaultTime>;
 139
 140 /// Time used by [`Scorer`].
 141 #[cfg(not(feature = "no-std"))]
 142 pub type DefaultTime = std::time::Instant;
 143
 144 /// Time used by [`Scorer`].
 145 #[cfg(feature = "no-std")]
 146 pub type DefaultTime = Eternity;
 147
 148 /// [`Score`] implementation parameterized by [`Time`].
 149 ///
 150 /// See [`Scorer`] for details.
 151 ///
 152 /// # Note
 153 ///
 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>>,
 159 }
 160
 161 /// Parameters for configuring [`Scorer`].
 162 pub struct ScoringParameters {
 163         /// A fixed penalty in msats to apply to each channel.
 164         ///
 165         /// Default value: 500 msat
 166         pub base_penalty_msat: u64,
 167
 168         /// A penalty in msats to apply to a channel upon failing to relay a payment.
 169         ///
 170         /// This accumulates for each failure but may be reduced over time based on
 171         /// [`failure_penalty_half_life`].
 172         ///
 173         /// Default value: 1,024,000 msat
 174         ///
 175         /// [`failure_penalty_half_life`]: Self::failure_penalty_half_life
 176         pub failure_penalty_msat: u64,
 177
 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`].
 180         ///
 181         /// Default value: 128 1024ths (i.e. begin penalizing when an HTLC uses 1/8th of a channel)
 182         ///
 183         /// [`overuse_penalty_msat_per_1024th`]: Self::overuse_penalty_msat_per_1024th
 184         pub overuse_penalty_start_1024th: u16,
 185
 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.
 188         ///
 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)
 191         ///
 192         /// [`overuse_penalty_start_1024th`]: Self::overuse_penalty_start_1024th
 193         pub overuse_penalty_msat_per_1024th: u64,
 194
 195         /// The time required to elapse before any accumulated [`failure_penalty_msat`] penalties are
 196         /// cut in half.
 197         ///
 198         /// # Note
 199         ///
 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.
 202         ///
 203         /// [`failure_penalty_msat`]: Self::failure_penalty_msat
 204         pub failure_penalty_half_life: Duration,
 205 }
 206
 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),
 213 });
 214
 215 /// Accounting for penalties against a channel for failing to relay any payments.
 216 ///
 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,
 221
 222         /// Last time the channel failed. Used to decay `undecayed_penalty_msat`.
 223         last_failed: T,
 224 }
 225
 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.
 229         fn now() -> Self;
 230
 231         /// Returns the amount of time elapsed since `self` was created.
 232         fn elapsed(&self) -> Duration;
 233
 234         /// Returns the amount of time passed since the beginning of [`Time`].
 235         ///
 236         /// Used during (de-)serialization.
 237         fn duration_since_epoch() -> Duration;
 238 }
 239
 240 impl<T: Time> ScorerUsingTime<T> {
 241         /// Creates a new scorer using the given scoring parameters.
 242         pub fn new(params: ScoringParameters) -> Self {
 243                 Self {
 244                         params,
 245                         channel_failures: HashMap::new(),
 246                 }
 247         }
 248
 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,
 258                 })
 259         }
 260 }
 261
 262 impl<T: Time> ChannelFailure<T> {
 263         fn new(failure_penalty_msat: u64) -> Self {
 264                 Self {
 265                         undecayed_penalty_msat: failure_penalty_msat,
 266                         last_failed: T::now(),
 267                 }
 268         }
 269
 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();
 273         }
 274
 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());
 277                 match decays {
 278                         Some(decays) => self.undecayed_penalty_msat >> decays,
 279                         None => 0,
 280                 }
 281         }
 282 }
 283
 284 impl<T: Time> Default for ScorerUsingTime<T> {
 285         fn default() -> Self {
 286                 Self::new(ScoringParameters::default())
 287         }
 288 }
 289
 290 impl Default for ScoringParameters {
 291         fn default() -> Self {
 292                 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,
 298                 }
 299         }
 300 }
 301
 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
 305         ) -> u64 {
 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));
 309
 310                 let mut penalty_msat = self.params.base_penalty_msat + failure_penalty_msat;
 311
 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;
 314
 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());
 320                         }
 321                 }
 322
 323                 penalty_msat
 324         }
 325
 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));
 333         }
 334 }
 335
 336 #[cfg(not(feature = "no-std"))]
 337 impl Time for std::time::Instant {
 338         fn now() -> Self {
 339                 std::time::Instant::now()
 340         }
 341
 342         fn duration_since_epoch() -> Duration {
 343                 use std::time::SystemTime;
 344                 SystemTime::now().duration_since(SystemTime::UNIX_EPOCH).unwrap()
 345         }
 346
 347         fn elapsed(&self) -> Duration {
 348                 std::time::Instant::elapsed(self)
 349         }
 350 }
 351
 352 /// A state in which time has no meaning.
 353 #[derive(Debug, PartialEq, Eq)]
 354 pub struct Eternity;
 355
 356 impl Time for Eternity {
 357         fn now() -> Self {
 358                 Self
 359         }
 360
 361         fn duration_since_epoch() -> Duration {
 362                 Duration::from_secs(0)
 363         }
 364
 365         fn elapsed(&self) -> Duration {
 366                 Duration::from_secs(0)
 367         }
 368 }
 369
 370 impl Sub<Duration> for Eternity {
 371         type Output = Self;
 372
 373         fn sub(self, _other: Duration) -> Self {
 374                 self
 375         }
 376 }
 377
 378 impl<T: Time> Writeable for ScorerUsingTime<T> {
 379         #[inline]
 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, {});
 384                 Ok(())
 385         }
 386 }
 387
 388 impl<T: Time> Readable for ScorerUsingTime<T> {
 389         #[inline]
 390         fn read<R: Read>(r: &mut R) -> Result<Self, DecodeError> {
 391                 let res = Ok(Self {
 392                         params: Readable::read(r)?,
 393                         channel_failures: Readable::read(r)?,
 394                 });
 395                 read_tlv_fields!(r, {});
 396                 res
 397         }
 398 }
 399
 400 impl<T: Time> Writeable for ChannelFailure<T> {
 401         #[inline]
 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),
 407                 });
 408                 Ok(())
 409         }
 410 }
 411
 412 impl<T: Time> Readable for ChannelFailure<T> {
 413         #[inline]
 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),
 420                 });
 421                 Ok(Self {
 422                         undecayed_penalty_msat,
 423                         last_failed: T::now() - (T::duration_since_epoch() - duration_since_epoch),
 424                 })
 425         }
 426 }
 427
 428 #[cfg(test)]
 429 mod tests {
 430         use super::{Eternity, ScoringParameters, ScorerUsingTime, Time};
 431
 432         use routing::scoring::Score;
 433         use routing::network_graph::NodeId;
 434         use util::ser::{Readable, Writeable};
 435
 436         use bitcoin::secp256k1::PublicKey;
 437         use core::cell::Cell;
 438         use core::ops::Sub;
 439         use core::time::Duration;
 440         use io;
 441
 442         /// Time that can be advanced manually in tests.
 443         #[derive(Debug, PartialEq, Eq)]
 444         struct SinceEpoch(Duration);
 445
 446         impl SinceEpoch {
 447                 thread_local! {
 448                         static ELAPSED: Cell<Duration> = core::cell::Cell::new(Duration::from_secs(0));
 449                 }
 450
 451                 fn advance(duration: Duration) {
 452                         Self::ELAPSED.with(|elapsed| elapsed.set(elapsed.get() + duration))
 453                 }
 454         }
 455
 456         impl Time for SinceEpoch {
 457                 fn now() -> Self {
 458                         Self(Self::duration_since_epoch())
 459                 }
 460
 461                 fn duration_since_epoch() -> Duration {
 462                         Self::ELAPSED.with(|elapsed| elapsed.get())
 463                 }
 464
 465                 fn elapsed(&self) -> Duration {
 466                         Self::duration_since_epoch() - self.0
 467                 }
 468         }
 469
 470         impl Sub<Duration> for SinceEpoch {
 471                 type Output = Self;
 472
 473                 fn sub(self, other: Duration) -> Self {
 474                         Self(self.0 - other)
 475                 }
 476         }
 477
 478         #[test]
 479         fn time_passes_when_advanced() {
 480                 let now = SinceEpoch::now();
 481                 assert_eq!(now.elapsed(), Duration::from_secs(0));
 482
 483                 SinceEpoch::advance(Duration::from_secs(1));
 484                 SinceEpoch::advance(Duration::from_secs(1));
 485
 486                 let elapsed = now.elapsed();
 487                 let later = SinceEpoch::now();
 488
 489                 assert_eq!(elapsed, Duration::from_secs(2));
 490                 assert_eq!(later - elapsed, now);
 491         }
 492
 493         #[test]
 494         fn time_never_passes_in_an_eternity() {
 495                 let now = Eternity::now();
 496                 let elapsed = now.elapsed();
 497                 let later = Eternity::now();
 498
 499                 assert_eq!(now.elapsed(), Duration::from_secs(0));
 500                 assert_eq!(later - elapsed, now);
 501         }
 502
 503         /// A scorer for testing with time that can be manually advanced.
 504         type Scorer = ScorerUsingTime::<SinceEpoch>;
 505
 506         fn source_node_id() -> NodeId {
 507                 NodeId::from_pubkey(&PublicKey::from_slice(&hex::decode("02eec7245d6b7d2ccb30380bfbe2a3648cd7a942653f5aa340edcea1f283686619").unwrap()[..]).unwrap())
 508         }
 509
 510         fn target_node_id() -> NodeId {
 511                 NodeId::from_pubkey(&PublicKey::from_slice(&hex::decode("0324653eac434488002cc06bbfb7f10fe18991e35f9fe4302dbea6d2353dc0ab1c").unwrap()[..]).unwrap())
 512         }
 513
 514         #[test]
 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,
 522                 });
 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);
 526
 527                 SinceEpoch::advance(Duration::from_secs(1));
 528                 assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_000);
 529         }
 530
 531         #[test]
 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,
 539                 });
 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);
 543
 544                 scorer.payment_path_failed(&[], 42);
 545                 assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_064);
 546
 547                 scorer.payment_path_failed(&[], 42);
 548                 assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_128);
 549
 550                 scorer.payment_path_failed(&[], 42);
 551                 assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_192);
 552         }
 553
 554         #[test]
 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,
 562                 });
 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);
 566
 567                 scorer.payment_path_failed(&[], 42);
 568                 assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_512);
 569
 570                 SinceEpoch::advance(Duration::from_secs(9));
 571                 assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_512);
 572
 573                 SinceEpoch::advance(Duration::from_secs(1));
 574                 assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_256);
 575
 576                 SinceEpoch::advance(Duration::from_secs(10 * 8));
 577                 assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_001);
 578
 579                 SinceEpoch::advance(Duration::from_secs(10));
 580                 assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_000);
 581
 582                 SinceEpoch::advance(Duration::from_secs(10));
 583                 assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_000);
 584         }
 585
 586         #[test]
 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,
 594                 });
 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);
 598
 599                 scorer.payment_path_failed(&[], 42);
 600                 assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_512);
 601
 602                 SinceEpoch::advance(Duration::from_secs(10));
 603                 assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_256);
 604
 605                 scorer.payment_path_failed(&[], 42);
 606                 assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_768);
 607
 608                 SinceEpoch::advance(Duration::from_secs(10));
 609                 assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_384);
 610         }
 611
 612         #[test]
 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,
 620                 });
 621                 let source = source_node_id();
 622                 let target = target_node_id();
 623
 624                 scorer.payment_path_failed(&[], 42);
 625                 assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_512);
 626
 627                 SinceEpoch::advance(Duration::from_secs(10));
 628                 assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_256);
 629
 630                 scorer.payment_path_failed(&[], 43);
 631                 assert_eq!(scorer.channel_penalty_msat(43, 1, Some(1), &source, &target), 1_512);
 632
 633                 let mut serialized_scorer = Vec::new();
 634                 scorer.write(&mut serialized_scorer).unwrap();
 635
 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);
 639         }
 640
 641         #[test]
 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,
 649                 });
 650                 let source = source_node_id();
 651                 let target = target_node_id();
 652
 653                 scorer.payment_path_failed(&[], 42);
 654                 assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_512);
 655
 656                 let mut serialized_scorer = Vec::new();
 657                 scorer.write(&mut serialized_scorer).unwrap();
 658
 659                 SinceEpoch::advance(Duration::from_secs(10));
 660
 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);
 663
 664                 SinceEpoch::advance(Duration::from_secs(10));
 665                 assert_eq!(deserialized_scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_128);
 666         }
 667
 668         #[test]
 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,
 676                 });
 677                 let source = source_node_id();
 678                 let target = target_node_id();
 679
 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);
 686         }
 687 }