_ 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 //! Persisting when built with feature `no-std` and restoring without it, or vice versa, uses
  50 //! different types and thus is undefined.
  51 //!
  52 //! [`find_route`]: crate::routing::router::find_route
  53
  54 use ln::msgs::DecodeError;
  55 use routing::network_graph::NodeId;
  56 use routing::router::RouteHop;
  57 use util::ser::{Readable, Writeable, Writer};
  58
  59 use prelude::*;
  60 use core::cell::{RefCell, RefMut};
  61 use core::ops::DerefMut;
  62 use core::time::Duration;
  63 use io::{self, Read};
  64 use sync::{Mutex, MutexGuard};
  65
  66 /// We define Score ever-so-slightly differently based on whether we are being built for C bindings
  67 /// or not. For users, `LockableScore` must somehow be writeable to disk. For Rust users, this is
  68 /// no problem - you move a `Score` that implements `Writeable` into a `Mutex`, lock it, and now
  69 /// you have the original, concrete, `Score` type, which presumably implements `Writeable`.
  70 ///
  71 /// For C users, once you've moved the `Score` into a `LockableScore` all you have after locking it
  72 /// is an opaque trait object with an opaque pointer with no type info. Users could take the unsafe
  73 /// approach of blindly casting that opaque pointer to a concrete type and calling `Writeable` from
  74 /// there, but other languages downstream of the C bindings (e.g. Java) can't even do that.
  75 /// Instead, we really want `Score` and `LockableScore` to implement `Writeable` directly, which we
  76 /// do here by defining `Score` differently for `cfg(c_bindings)`.
  77 macro_rules! define_score { ($($supertrait: path)*) => {
  78 /// An interface used to score payment channels for path finding.
  79 ///
  80 ///     Scoring is in terms of fees willing to be paid in order to avoid routing through a channel.
  81 pub trait Score $(: $supertrait)* {
  82         /// Returns the fee in msats willing to be paid to avoid routing `send_amt_msat` through the
  83         /// given channel in the direction from `source` to `target`.
  84         ///
  85         /// The channel's capacity (less any other MPP parts which are also being considered for use in
  86         /// the same payment) is given by `channel_capacity_msat`. It may be guessed from various
  87         /// sources or assumed from no data at all.
  88         ///
  89         /// For hints provided in the invoice, we assume the channel has sufficient capacity to accept
  90         /// the invoice's full amount, and provide a `channel_capacity_msat` of `None`. In all other
  91         /// cases it is set to `Some`, even if we're guessing at the channel value.
  92         ///
  93         /// Your code should be overflow-safe through a `channel_capacity_msat` of 21 million BTC.
  94         fn channel_penalty_msat(&self, short_channel_id: u64, send_amt_msat: u64, channel_capacity_msat: Option<u64>, source: &NodeId, target: &NodeId) -> u64;
  95
  96         /// Handles updating channel penalties after failing to route through a channel.
  97         fn payment_path_failed(&mut self, path: &[&RouteHop], short_channel_id: u64);
  98 }
  99
 100 impl<S: Score, T: DerefMut<Target=S> $(+ $supertrait)*> Score for T {
 101         fn channel_penalty_msat(&self, short_channel_id: u64, send_amt_msat: u64, channel_capacity_msat: Option<u64>, source: &NodeId, target: &NodeId) -> u64 {
 102                 self.deref().channel_penalty_msat(short_channel_id, send_amt_msat, channel_capacity_msat, source, target)
 103         }
 104
 105         fn payment_path_failed(&mut self, path: &[&RouteHop], short_channel_id: u64) {
 106                 self.deref_mut().payment_path_failed(path, short_channel_id)
 107         }
 108 }
 109 } }
 110
 111 #[cfg(c_bindings)]
 112 define_score!(Writeable);
 113 #[cfg(not(c_bindings))]
 114 define_score!();
 115
 116 /// A scorer that is accessed under a lock.
 117 ///
 118 /// Needed so that calls to [`Score::channel_penalty_msat`] in [`find_route`] can be made while
 119 /// having shared ownership of a scorer but without requiring internal locking in [`Score`]
 120 /// implementations. Internal locking would be detrimental to route finding performance and could
 121 /// result in [`Score::channel_penalty_msat`] returning a different value for the same channel.
 122 ///
 123 /// [`find_route`]: crate::routing::router::find_route
 124 pub trait LockableScore<'a> {
 125         /// The locked [`Score`] type.
 126         type Locked: 'a + Score;
 127
 128         /// Returns the locked scorer.
 129         fn lock(&'a self) -> Self::Locked;
 130 }
 131
 132 /// (C-not exported)
 133 impl<'a, T: 'a + Score> LockableScore<'a> for Mutex<T> {
 134         type Locked = MutexGuard<'a, T>;
 135
 136         fn lock(&'a self) -> MutexGuard<'a, T> {
 137                 Mutex::lock(self).unwrap()
 138         }
 139 }
 140
 141 impl<'a, T: 'a + Score> LockableScore<'a> for RefCell<T> {
 142         type Locked = RefMut<'a, T>;
 143
 144         fn lock(&'a self) -> RefMut<'a, T> {
 145                 self.borrow_mut()
 146         }
 147 }
 148
 149 #[cfg(c_bindings)]
 150 /// A concrete implementation of [`LockableScore`] which supports multi-threading.
 151 pub struct MultiThreadedLockableScore<S: Score> {
 152         score: Mutex<S>,
 153 }
 154 #[cfg(c_bindings)]
 155 /// (C-not exported)
 156 impl<'a, T: Score + 'a> LockableScore<'a> for MultiThreadedLockableScore<T> {
 157         type Locked = MutexGuard<'a, T>;
 158
 159         fn lock(&'a self) -> MutexGuard<'a, T> {
 160                 Mutex::lock(&self.score).unwrap()
 161         }
 162 }
 163
 164 #[cfg(c_bindings)]
 165 /// (C-not exported)
 166 impl<'a, T: Writeable> Writeable for RefMut<'a, T> {
 167         fn write<W: Writer>(&self, writer: &mut W) -> Result<(), io::Error> {
 168                 T::write(&**self, writer)
 169         }
 170 }
 171
 172 #[cfg(c_bindings)]
 173 /// (C-not exported)
 174 impl<'a, S: Writeable> Writeable for MutexGuard<'a, S> {
 175         fn write<W: Writer>(&self, writer: &mut W) -> Result<(), io::Error> {
 176                 S::write(&**self, writer)
 177         }
 178 }
 179
 180 /// [`Score`] implementation that provides reasonable default behavior.
 181 ///
 182 /// Used to apply a fixed penalty to each channel, thus avoiding long paths when shorter paths with
 183 /// slightly higher fees are available. Will further penalize channels that fail to relay payments.
 184 ///
 185 /// See [module-level documentation] for usage.
 186 ///
 187 /// [module-level documentation]: crate::routing::scoring
 188 #[cfg(not(feature = "no-std"))]
 189 pub type Scorer = ScorerUsingTime::<std::time::Instant>;
 190 /// [`Score`] implementation that provides reasonable default behavior.
 191 ///
 192 /// Used to apply a fixed penalty to each channel, thus avoiding long paths when shorter paths with
 193 /// slightly higher fees are available. Will further penalize channels that fail to relay payments.
 194 ///
 195 /// See [module-level documentation] for usage.
 196 ///
 197 /// [module-level documentation]: crate::routing::scoring
 198 #[cfg(feature = "no-std")]
 199 pub type Scorer = ScorerUsingTime::<time::Eternity>;
 200
 201 // Note that ideally we'd hide ScorerUsingTime from public view by sealing it as well, but rustdoc
 202 // doesn't handle this well - instead exposing a `Scorer` which has no trait implementation(s) or
 203 // methods at all.
 204
 205 /// [`Score`] implementation.
 206 ///
 207 /// See [`Scorer`] for details.
 208 ///
 209 /// # Note
 210 ///
 211 /// Mixing the `no-std` feature between serialization and deserialization results in undefined
 212 /// behavior.
 213 ///
 214 /// (C-not exported) generally all users should use the [`Scorer`] type alias.
 215 pub struct ScorerUsingTime<T: Time> {
 216         params: ScoringParameters,
 217         // TODO: Remove entries of closed channels.
 218         channel_failures: HashMap<u64, ChannelFailure<T>>,
 219 }
 220
 221 /// Parameters for configuring [`Scorer`].
 222 pub struct ScoringParameters {
 223         /// A fixed penalty in msats to apply to each channel.
 224         ///
 225         /// Default value: 500 msat
 226         pub base_penalty_msat: u64,
 227
 228         /// A penalty in msats to apply to a channel upon failing to relay a payment.
 229         ///
 230         /// This accumulates for each failure but may be reduced over time based on
 231         /// [`failure_penalty_half_life`].
 232         ///
 233         /// Default value: 1,024,000 msat
 234         ///
 235         /// [`failure_penalty_half_life`]: Self::failure_penalty_half_life
 236         pub failure_penalty_msat: u64,
 237
 238         /// When the amount being sent over a channel is this many 1024ths of the total channel
 239         /// capacity, we begin applying [`overuse_penalty_msat_per_1024th`].
 240         ///
 241         /// Default value: 128 1024ths (i.e. begin penalizing when an HTLC uses 1/8th of a channel)
 242         ///
 243         /// [`overuse_penalty_msat_per_1024th`]: Self::overuse_penalty_msat_per_1024th
 244         pub overuse_penalty_start_1024th: u16,
 245
 246         /// A penalty applied, per whole 1024ths of the channel capacity which the amount being sent
 247         /// over the channel exceeds [`overuse_penalty_start_1024th`] by.
 248         ///
 249         /// Default value: 20 msat (i.e. 2560 msat penalty to use 1/4th of a channel, 7680 msat penalty
 250         ///                to use half a channel, and 12,560 msat penalty to use 3/4ths of a channel)
 251         ///
 252         /// [`overuse_penalty_start_1024th`]: Self::overuse_penalty_start_1024th
 253         pub overuse_penalty_msat_per_1024th: u64,
 254
 255         /// The time required to elapse before any accumulated [`failure_penalty_msat`] penalties are
 256         /// cut in half.
 257         ///
 258         /// # Note
 259         ///
 260         /// When built with the `no-std` feature, time will never elapse. Therefore, this penalty will
 261         /// never decay.
 262         ///
 263         /// [`failure_penalty_msat`]: Self::failure_penalty_msat
 264         pub failure_penalty_half_life: Duration,
 265 }
 266
 267 impl_writeable_tlv_based!(ScoringParameters, {
 268         (0, base_penalty_msat, required),
 269         (1, overuse_penalty_start_1024th, (default_value, 128)),
 270         (2, failure_penalty_msat, required),
 271         (3, overuse_penalty_msat_per_1024th, (default_value, 20)),
 272         (4, failure_penalty_half_life, required),
 273 });
 274
 275 /// Accounting for penalties against a channel for failing to relay any payments.
 276 ///
 277 /// Penalties decay over time, though accumulate as more failures occur.
 278 struct ChannelFailure<T: Time> {
 279         /// Accumulated penalty in msats for the channel as of `last_failed`.
 280         undecayed_penalty_msat: u64,
 281
 282         /// Last time the channel failed. Used to decay `undecayed_penalty_msat`.
 283         last_failed: T,
 284 }
 285
 286 impl<T: Time> ScorerUsingTime<T> {
 287         /// Creates a new scorer using the given scoring parameters.
 288         pub fn new(params: ScoringParameters) -> Self {
 289                 Self {
 290                         params,
 291                         channel_failures: HashMap::new(),
 292                 }
 293         }
 294
 295         /// Creates a new scorer using `penalty_msat` as a fixed channel penalty.
 296         #[cfg(any(test, feature = "fuzztarget", feature = "_test_utils"))]
 297         pub fn with_fixed_penalty(penalty_msat: u64) -> Self {
 298                 Self::new(ScoringParameters {
 299                         base_penalty_msat: penalty_msat,
 300                         failure_penalty_msat: 0,
 301                         failure_penalty_half_life: Duration::from_secs(0),
 302                         overuse_penalty_start_1024th: 1024,
 303                         overuse_penalty_msat_per_1024th: 0,
 304                 })
 305         }
 306 }
 307
 308 impl<T: Time> ChannelFailure<T> {
 309         fn new(failure_penalty_msat: u64) -> Self {
 310                 Self {
 311                         undecayed_penalty_msat: failure_penalty_msat,
 312                         last_failed: T::now(),
 313                 }
 314         }
 315
 316         fn add_penalty(&mut self, failure_penalty_msat: u64, half_life: Duration) {
 317                 self.undecayed_penalty_msat = self.decayed_penalty_msat(half_life) + failure_penalty_msat;
 318                 self.last_failed = T::now();
 319         }
 320
 321         fn decayed_penalty_msat(&self, half_life: Duration) -> u64 {
 322                 let decays = self.last_failed.elapsed().as_secs().checked_div(half_life.as_secs());
 323                 match decays {
 324                         Some(decays) => self.undecayed_penalty_msat >> decays,
 325                         None => 0,
 326                 }
 327         }
 328 }
 329
 330 impl<T: Time> Default for ScorerUsingTime<T> {
 331         fn default() -> Self {
 332                 Self::new(ScoringParameters::default())
 333         }
 334 }
 335
 336 impl Default for ScoringParameters {
 337         fn default() -> Self {
 338                 Self {
 339                         base_penalty_msat: 500,
 340                         failure_penalty_msat: 1024 * 1000,
 341                         failure_penalty_half_life: Duration::from_secs(3600),
 342                         overuse_penalty_start_1024th: 1024 / 8,
 343                         overuse_penalty_msat_per_1024th: 20,
 344                 }
 345         }
 346 }
 347
 348 impl<T: Time> Score for ScorerUsingTime<T> {
 349         fn channel_penalty_msat(
 350                 &self, short_channel_id: u64, send_amt_msat: u64, chan_capacity_opt: Option<u64>, _source: &NodeId, _target: &NodeId
 351         ) -> u64 {
 352                 let failure_penalty_msat = self.channel_failures
 353                         .get(&short_channel_id)
 354                         .map_or(0, |value| value.decayed_penalty_msat(self.params.failure_penalty_half_life));
 355
 356                 let mut penalty_msat = self.params.base_penalty_msat + failure_penalty_msat;
 357
 358                 if let Some(chan_capacity_msat) = chan_capacity_opt {
 359                         let send_1024ths = send_amt_msat.checked_mul(1024).unwrap_or(u64::max_value()) / chan_capacity_msat;
 360
 361                         if send_1024ths > self.params.overuse_penalty_start_1024th as u64 {
 362                                 penalty_msat = penalty_msat.checked_add(
 363                                                 (send_1024ths - self.params.overuse_penalty_start_1024th as u64)
 364                                                 .checked_mul(self.params.overuse_penalty_msat_per_1024th).unwrap_or(u64::max_value()))
 365                                         .unwrap_or(u64::max_value());
 366                         }
 367                 }
 368
 369                 penalty_msat
 370         }
 371
 372         fn payment_path_failed(&mut self, _path: &[&RouteHop], short_channel_id: u64) {
 373                 let failure_penalty_msat = self.params.failure_penalty_msat;
 374                 let half_life = self.params.failure_penalty_half_life;
 375                 self.channel_failures
 376                         .entry(short_channel_id)
 377                         .and_modify(|failure| failure.add_penalty(failure_penalty_msat, half_life))
 378                         .or_insert_with(|| ChannelFailure::new(failure_penalty_msat));
 379         }
 380 }
 381
 382 impl<T: Time> Writeable for ScorerUsingTime<T> {
 383         #[inline]
 384         fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
 385                 self.params.write(w)?;
 386                 self.channel_failures.write(w)?;
 387                 write_tlv_fields!(w, {});
 388                 Ok(())
 389         }
 390 }
 391
 392 impl<T: Time> Readable for ScorerUsingTime<T> {
 393         #[inline]
 394         fn read<R: Read>(r: &mut R) -> Result<Self, DecodeError> {
 395                 let res = Ok(Self {
 396                         params: Readable::read(r)?,
 397                         channel_failures: Readable::read(r)?,
 398                 });
 399                 read_tlv_fields!(r, {});
 400                 res
 401         }
 402 }
 403
 404 impl<T: Time> Writeable for ChannelFailure<T> {
 405         #[inline]
 406         fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
 407                 let duration_since_epoch = T::duration_since_epoch() - self.last_failed.elapsed();
 408                 write_tlv_fields!(w, {
 409                         (0, self.undecayed_penalty_msat, required),
 410                         (2, duration_since_epoch, required),
 411                 });
 412                 Ok(())
 413         }
 414 }
 415
 416 impl<T: Time> Readable for ChannelFailure<T> {
 417         #[inline]
 418         fn read<R: Read>(r: &mut R) -> Result<Self, DecodeError> {
 419                 let mut undecayed_penalty_msat = 0;
 420                 let mut duration_since_epoch = Duration::from_secs(0);
 421                 read_tlv_fields!(r, {
 422                         (0, undecayed_penalty_msat, required),
 423                         (2, duration_since_epoch, required),
 424                 });
 425                 Ok(Self {
 426                         undecayed_penalty_msat,
 427                         last_failed: T::now() - (T::duration_since_epoch() - duration_since_epoch),
 428                 })
 429         }
 430 }
 431
 432 pub(crate) mod time {
 433         use core::ops::Sub;
 434         use core::time::Duration;
 435         /// A measurement of time.
 436         pub trait Time: Sub<Duration, Output = Self> where Self: Sized {
 437                 /// Returns an instance corresponding to the current moment.
 438                 fn now() -> Self;
 439
 440                 /// Returns the amount of time elapsed since `self` was created.
 441                 fn elapsed(&self) -> Duration;
 442
 443                 /// Returns the amount of time passed since the beginning of [`Time`].
 444                 ///
 445                 /// Used during (de-)serialization.
 446                 fn duration_since_epoch() -> Duration;
 447         }
 448
 449         /// A state in which time has no meaning.
 450         #[derive(Debug, PartialEq, Eq)]
 451         pub struct Eternity;
 452
 453         #[cfg(not(feature = "no-std"))]
 454         impl Time for std::time::Instant {
 455                 fn now() -> Self {
 456                         std::time::Instant::now()
 457                 }
 458
 459                 fn duration_since_epoch() -> Duration {
 460                         use std::time::SystemTime;
 461                         SystemTime::now().duration_since(SystemTime::UNIX_EPOCH).unwrap()
 462                 }
 463
 464                 fn elapsed(&self) -> Duration {
 465                         std::time::Instant::elapsed(self)
 466                 }
 467         }
 468
 469         impl Time for Eternity {
 470                 fn now() -> Self {
 471                         Self
 472                 }
 473
 474                 fn duration_since_epoch() -> Duration {
 475                         Duration::from_secs(0)
 476                 }
 477
 478                 fn elapsed(&self) -> Duration {
 479                         Duration::from_secs(0)
 480                 }
 481         }
 482
 483         impl Sub<Duration> for Eternity {
 484                 type Output = Self;
 485
 486                 fn sub(self, _other: Duration) -> Self {
 487                         self
 488                 }
 489         }
 490 }
 491
 492 pub(crate) use self::time::Time;
 493
 494 #[cfg(test)]
 495 mod tests {
 496         use super::{ScoringParameters, ScorerUsingTime, Time};
 497         use super::time::Eternity;
 498
 499         use routing::scoring::Score;
 500         use routing::network_graph::NodeId;
 501         use util::ser::{Readable, Writeable};
 502
 503         use bitcoin::secp256k1::PublicKey;
 504         use core::cell::Cell;
 505         use core::ops::Sub;
 506         use core::time::Duration;
 507         use io;
 508
 509         /// Time that can be advanced manually in tests.
 510         #[derive(Debug, PartialEq, Eq)]
 511         struct SinceEpoch(Duration);
 512
 513         impl SinceEpoch {
 514                 thread_local! {
 515                         static ELAPSED: Cell<Duration> = core::cell::Cell::new(Duration::from_secs(0));
 516                 }
 517
 518                 fn advance(duration: Duration) {
 519                         Self::ELAPSED.with(|elapsed| elapsed.set(elapsed.get() + duration))
 520                 }
 521         }
 522
 523         impl Time for SinceEpoch {
 524                 fn now() -> Self {
 525                         Self(Self::duration_since_epoch())
 526                 }
 527
 528                 fn duration_since_epoch() -> Duration {
 529                         Self::ELAPSED.with(|elapsed| elapsed.get())
 530                 }
 531
 532                 fn elapsed(&self) -> Duration {
 533                         Self::duration_since_epoch() - self.0
 534                 }
 535         }
 536
 537         impl Sub<Duration> for SinceEpoch {
 538                 type Output = Self;
 539
 540                 fn sub(self, other: Duration) -> Self {
 541                         Self(self.0 - other)
 542                 }
 543         }
 544
 545         #[test]
 546         fn time_passes_when_advanced() {
 547                 let now = SinceEpoch::now();
 548                 assert_eq!(now.elapsed(), Duration::from_secs(0));
 549
 550                 SinceEpoch::advance(Duration::from_secs(1));
 551                 SinceEpoch::advance(Duration::from_secs(1));
 552
 553                 let elapsed = now.elapsed();
 554                 let later = SinceEpoch::now();
 555
 556                 assert_eq!(elapsed, Duration::from_secs(2));
 557                 assert_eq!(later - elapsed, now);
 558         }
 559
 560         #[test]
 561         fn time_never_passes_in_an_eternity() {
 562                 let now = Eternity::now();
 563                 let elapsed = now.elapsed();
 564                 let later = Eternity::now();
 565
 566                 assert_eq!(now.elapsed(), Duration::from_secs(0));
 567                 assert_eq!(later - elapsed, now);
 568         }
 569
 570         /// A scorer for testing with time that can be manually advanced.
 571         type Scorer = ScorerUsingTime::<SinceEpoch>;
 572
 573         fn source_node_id() -> NodeId {
 574                 NodeId::from_pubkey(&PublicKey::from_slice(&hex::decode("02eec7245d6b7d2ccb30380bfbe2a3648cd7a942653f5aa340edcea1f283686619").unwrap()[..]).unwrap())
 575         }
 576
 577         fn target_node_id() -> NodeId {
 578                 NodeId::from_pubkey(&PublicKey::from_slice(&hex::decode("0324653eac434488002cc06bbfb7f10fe18991e35f9fe4302dbea6d2353dc0ab1c").unwrap()[..]).unwrap())
 579         }
 580
 581         #[test]
 582         fn penalizes_without_channel_failures() {
 583                 let scorer = Scorer::new(ScoringParameters {
 584                         base_penalty_msat: 1_000,
 585                         failure_penalty_msat: 512,
 586                         failure_penalty_half_life: Duration::from_secs(1),
 587                         overuse_penalty_start_1024th: 1024,
 588                         overuse_penalty_msat_per_1024th: 0,
 589                 });
 590                 let source = source_node_id();
 591                 let target = target_node_id();
 592                 assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_000);
 593
 594                 SinceEpoch::advance(Duration::from_secs(1));
 595                 assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_000);
 596         }
 597
 598         #[test]
 599         fn accumulates_channel_failure_penalties() {
 600                 let mut scorer = Scorer::new(ScoringParameters {
 601                         base_penalty_msat: 1_000,
 602                         failure_penalty_msat: 64,
 603                         failure_penalty_half_life: Duration::from_secs(10),
 604                         overuse_penalty_start_1024th: 1024,
 605                         overuse_penalty_msat_per_1024th: 0,
 606                 });
 607                 let source = source_node_id();
 608                 let target = target_node_id();
 609                 assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_000);
 610
 611                 scorer.payment_path_failed(&[], 42);
 612                 assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_064);
 613
 614                 scorer.payment_path_failed(&[], 42);
 615                 assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_128);
 616
 617                 scorer.payment_path_failed(&[], 42);
 618                 assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_192);
 619         }
 620
 621         #[test]
 622         fn decays_channel_failure_penalties_over_time() {
 623                 let mut scorer = Scorer::new(ScoringParameters {
 624                         base_penalty_msat: 1_000,
 625                         failure_penalty_msat: 512,
 626                         failure_penalty_half_life: Duration::from_secs(10),
 627                         overuse_penalty_start_1024th: 1024,
 628                         overuse_penalty_msat_per_1024th: 0,
 629                 });
 630                 let source = source_node_id();
 631                 let target = target_node_id();
 632                 assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_000);
 633
 634                 scorer.payment_path_failed(&[], 42);
 635                 assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_512);
 636
 637                 SinceEpoch::advance(Duration::from_secs(9));
 638                 assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_512);
 639
 640                 SinceEpoch::advance(Duration::from_secs(1));
 641                 assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_256);
 642
 643                 SinceEpoch::advance(Duration::from_secs(10 * 8));
 644                 assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_001);
 645
 646                 SinceEpoch::advance(Duration::from_secs(10));
 647                 assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_000);
 648
 649                 SinceEpoch::advance(Duration::from_secs(10));
 650                 assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_000);
 651         }
 652
 653         #[test]
 654         fn accumulates_channel_failure_penalties_after_decay() {
 655                 let mut scorer = Scorer::new(ScoringParameters {
 656                         base_penalty_msat: 1_000,
 657                         failure_penalty_msat: 512,
 658                         failure_penalty_half_life: Duration::from_secs(10),
 659                         overuse_penalty_start_1024th: 1024,
 660                         overuse_penalty_msat_per_1024th: 0,
 661                 });
 662                 let source = source_node_id();
 663                 let target = target_node_id();
 664                 assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_000);
 665
 666                 scorer.payment_path_failed(&[], 42);
 667                 assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_512);
 668
 669                 SinceEpoch::advance(Duration::from_secs(10));
 670                 assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_256);
 671
 672                 scorer.payment_path_failed(&[], 42);
 673                 assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_768);
 674
 675                 SinceEpoch::advance(Duration::from_secs(10));
 676                 assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_384);
 677         }
 678
 679         #[test]
 680         fn restores_persisted_channel_failure_penalties() {
 681                 let mut scorer = Scorer::new(ScoringParameters {
 682                         base_penalty_msat: 1_000,
 683                         failure_penalty_msat: 512,
 684                         failure_penalty_half_life: Duration::from_secs(10),
 685                         overuse_penalty_start_1024th: 1024,
 686                         overuse_penalty_msat_per_1024th: 0,
 687                 });
 688                 let source = source_node_id();
 689                 let target = target_node_id();
 690
 691                 scorer.payment_path_failed(&[], 42);
 692                 assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_512);
 693
 694                 SinceEpoch::advance(Duration::from_secs(10));
 695                 assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_256);
 696
 697                 scorer.payment_path_failed(&[], 43);
 698                 assert_eq!(scorer.channel_penalty_msat(43, 1, Some(1), &source, &target), 1_512);
 699
 700                 let mut serialized_scorer = Vec::new();
 701                 scorer.write(&mut serialized_scorer).unwrap();
 702
 703                 let deserialized_scorer = <Scorer>::read(&mut io::Cursor::new(&serialized_scorer)).unwrap();
 704                 assert_eq!(deserialized_scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_256);
 705                 assert_eq!(deserialized_scorer.channel_penalty_msat(43, 1, Some(1), &source, &target), 1_512);
 706         }
 707
 708         #[test]
 709         fn decays_persisted_channel_failure_penalties() {
 710                 let mut scorer = Scorer::new(ScoringParameters {
 711                         base_penalty_msat: 1_000,
 712                         failure_penalty_msat: 512,
 713                         failure_penalty_half_life: Duration::from_secs(10),
 714                         overuse_penalty_start_1024th: 1024,
 715                         overuse_penalty_msat_per_1024th: 0,
 716                 });
 717                 let source = source_node_id();
 718                 let target = target_node_id();
 719
 720                 scorer.payment_path_failed(&[], 42);
 721                 assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_512);
 722
 723                 let mut serialized_scorer = Vec::new();
 724                 scorer.write(&mut serialized_scorer).unwrap();
 725
 726                 SinceEpoch::advance(Duration::from_secs(10));
 727
 728                 let deserialized_scorer = <Scorer>::read(&mut io::Cursor::new(&serialized_scorer)).unwrap();
 729                 assert_eq!(deserialized_scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_256);
 730
 731                 SinceEpoch::advance(Duration::from_secs(10));
 732                 assert_eq!(deserialized_scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_128);
 733         }
 734
 735         #[test]
 736         fn charges_per_1024th_penalty() {
 737                 let scorer = Scorer::new(ScoringParameters {
 738                         base_penalty_msat: 0,
 739                         failure_penalty_msat: 0,
 740                         failure_penalty_half_life: Duration::from_secs(0),
 741                         overuse_penalty_start_1024th: 256,
 742                         overuse_penalty_msat_per_1024th: 100,
 743                 });
 744                 let source = source_node_id();
 745                 let target = target_node_id();
 746
 747                 assert_eq!(scorer.channel_penalty_msat(42, 1_000, None, &source, &target), 0);
 748                 assert_eq!(scorer.channel_penalty_msat(42, 1_000, Some(1_024_000), &source, &target), 0);
 749                 assert_eq!(scorer.channel_penalty_msat(42, 256_999, Some(1_024_000), &source, &target), 0);
 750                 assert_eq!(scorer.channel_penalty_msat(42, 257_000, Some(1_024_000), &source, &target), 100);
 751                 assert_eq!(scorer.channel_penalty_msat(42, 258_000, Some(1_024_000), &source, &target), 200);
 752                 assert_eq!(scorer.channel_penalty_msat(42, 512_000, Some(1_024_000), &source, &target), 256 * 100);
 753         }
 754 }