_ 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 that are also being considered for use in
  86         /// the same payment) is given by `capacity_msat`. It may be determined from various sources
  87         /// such as a chain data, network gossip, or invoice hints, the latter indicating sufficient
  88         /// capacity (i.e., near [`u64::max_value`]). Thus, implementations should be overflow-safe.
  89         fn channel_penalty_msat(&self, short_channel_id: u64, send_amt_msat: u64, capacity_msat: u64, source: &NodeId, target: &NodeId) -> u64;
  90
  91         /// Handles updating channel penalties after failing to route through a channel.
  92         fn payment_path_failed(&mut self, path: &[&RouteHop], short_channel_id: u64);
  93
  94         /// Handles updating channel penalties after successfully routing along a path.
  95         fn payment_path_successful(&mut self, path: &[&RouteHop]);
  96 }
  97
  98 impl<S: Score, T: DerefMut<Target=S> $(+ $supertrait)*> Score for T {
  99         fn channel_penalty_msat(&self, short_channel_id: u64, send_amt_msat: u64, capacity_msat: u64, source: &NodeId, target: &NodeId) -> u64 {
 100                 self.deref().channel_penalty_msat(short_channel_id, send_amt_msat, capacity_msat, source, target)
 101         }
 102
 103         fn payment_path_failed(&mut self, path: &[&RouteHop], short_channel_id: u64) {
 104                 self.deref_mut().payment_path_failed(path, short_channel_id)
 105         }
 106
 107         fn payment_path_successful(&mut self, path: &[&RouteHop]) {
 108                 self.deref_mut().payment_path_successful(path)
 109         }
 110 }
 111 } }
 112
 113 #[cfg(c_bindings)]
 114 define_score!(Writeable);
 115 #[cfg(not(c_bindings))]
 116 define_score!();
 117
 118 /// A scorer that is accessed under a lock.
 119 ///
 120 /// Needed so that calls to [`Score::channel_penalty_msat`] in [`find_route`] can be made while
 121 /// having shared ownership of a scorer but without requiring internal locking in [`Score`]
 122 /// implementations. Internal locking would be detrimental to route finding performance and could
 123 /// result in [`Score::channel_penalty_msat`] returning a different value for the same channel.
 124 ///
 125 /// [`find_route`]: crate::routing::router::find_route
 126 pub trait LockableScore<'a> {
 127         /// The locked [`Score`] type.
 128         type Locked: 'a + Score;
 129
 130         /// Returns the locked scorer.
 131         fn lock(&'a self) -> Self::Locked;
 132 }
 133
 134 /// (C-not exported)
 135 impl<'a, T: 'a + Score> LockableScore<'a> for Mutex<T> {
 136         type Locked = MutexGuard<'a, T>;
 137
 138         fn lock(&'a self) -> MutexGuard<'a, T> {
 139                 Mutex::lock(self).unwrap()
 140         }
 141 }
 142
 143 impl<'a, T: 'a + Score> LockableScore<'a> for RefCell<T> {
 144         type Locked = RefMut<'a, T>;
 145
 146         fn lock(&'a self) -> RefMut<'a, T> {
 147                 self.borrow_mut()
 148         }
 149 }
 150
 151 #[cfg(c_bindings)]
 152 /// A concrete implementation of [`LockableScore`] which supports multi-threading.
 153 pub struct MultiThreadedLockableScore<S: Score> {
 154         score: Mutex<S>,
 155 }
 156 #[cfg(c_bindings)]
 157 /// (C-not exported)
 158 impl<'a, T: Score + 'a> LockableScore<'a> for MultiThreadedLockableScore<T> {
 159         type Locked = MutexGuard<'a, T>;
 160
 161         fn lock(&'a self) -> MutexGuard<'a, T> {
 162                 Mutex::lock(&self.score).unwrap()
 163         }
 164 }
 165
 166 #[cfg(c_bindings)]
 167 impl<T: Score> MultiThreadedLockableScore<T> {
 168         /// Creates a new [`MultiThreadedLockableScore`] given an underlying [`Score`].
 169         pub fn new(score: T) -> Self {
 170                 MultiThreadedLockableScore { score: Mutex::new(score) }
 171         }
 172 }
 173
 174 #[cfg(c_bindings)]
 175 /// (C-not exported)
 176 impl<'a, T: Writeable> Writeable for RefMut<'a, T> {
 177         fn write<W: Writer>(&self, writer: &mut W) -> Result<(), io::Error> {
 178                 T::write(&**self, writer)
 179         }
 180 }
 181
 182 #[cfg(c_bindings)]
 183 /// (C-not exported)
 184 impl<'a, S: Writeable> Writeable for MutexGuard<'a, S> {
 185         fn write<W: Writer>(&self, writer: &mut W) -> Result<(), io::Error> {
 186                 S::write(&**self, writer)
 187         }
 188 }
 189
 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(not(feature = "no-std"))]
 199 pub type Scorer = ScorerUsingTime::<std::time::Instant>;
 200 /// [`Score`] implementation that provides reasonable default behavior.
 201 ///
 202 /// Used to apply a fixed penalty to each channel, thus avoiding long paths when shorter paths with
 203 /// slightly higher fees are available. Will further penalize channels that fail to relay payments.
 204 ///
 205 /// See [module-level documentation] for usage and [`ScoringParameters`] for customization.
 206 ///
 207 /// [module-level documentation]: crate::routing::scoring
 208 #[cfg(feature = "no-std")]
 209 pub type Scorer = ScorerUsingTime::<time::Eternity>;
 210
 211 // Note that ideally we'd hide ScorerUsingTime from public view by sealing it as well, but rustdoc
 212 // doesn't handle this well - instead exposing a `Scorer` which has no trait implementation(s) or
 213 // methods at all.
 214
 215 /// [`Score`] implementation.
 216 ///
 217 /// See [`Scorer`] for details.
 218 ///
 219 /// # Note
 220 ///
 221 /// Mixing the `no-std` feature between serialization and deserialization results in undefined
 222 /// behavior.
 223 ///
 224 /// (C-not exported) generally all users should use the [`Scorer`] type alias.
 225 pub struct ScorerUsingTime<T: Time> {
 226         params: ScoringParameters,
 227         // TODO: Remove entries of closed channels.
 228         channel_failures: HashMap<u64, ChannelFailure<T>>,
 229 }
 230
 231 /// Parameters for configuring [`Scorer`].
 232 pub struct ScoringParameters {
 233         /// A fixed penalty in msats to apply to each channel.
 234         ///
 235         /// Default value: 500 msat
 236         pub base_penalty_msat: u64,
 237
 238         /// A penalty in msats to apply to a channel upon failing to relay a payment.
 239         ///
 240         /// This accumulates for each failure but may be reduced over time based on
 241         /// [`failure_penalty_half_life`] or when successfully routing through a channel.
 242         ///
 243         /// Default value: 1,024,000 msat
 244         ///
 245         /// [`failure_penalty_half_life`]: Self::failure_penalty_half_life
 246         pub failure_penalty_msat: u64,
 247
 248         /// When the amount being sent over a channel is this many 1024ths of the total channel
 249         /// capacity, we begin applying [`overuse_penalty_msat_per_1024th`].
 250         ///
 251         /// Default value: 128 1024ths (i.e. begin penalizing when an HTLC uses 1/8th of a channel)
 252         ///
 253         /// [`overuse_penalty_msat_per_1024th`]: Self::overuse_penalty_msat_per_1024th
 254         pub overuse_penalty_start_1024th: u16,
 255
 256         /// A penalty applied, per whole 1024ths of the channel capacity which the amount being sent
 257         /// over the channel exceeds [`overuse_penalty_start_1024th`] by.
 258         ///
 259         /// Default value: 20 msat (i.e. 2560 msat penalty to use 1/4th of a channel, 7680 msat penalty
 260         ///                to use half a channel, and 12,560 msat penalty to use 3/4ths of a channel)
 261         ///
 262         /// [`overuse_penalty_start_1024th`]: Self::overuse_penalty_start_1024th
 263         pub overuse_penalty_msat_per_1024th: u64,
 264
 265         /// The time required to elapse before any accumulated [`failure_penalty_msat`] penalties are
 266         /// cut in half.
 267         ///
 268         /// Successfully routing through a channel will immediately cut the penalty in half as well.
 269         ///
 270         /// # Note
 271         ///
 272         /// When built with the `no-std` feature, time will never elapse. Therefore, this penalty will
 273         /// never decay.
 274         ///
 275         /// [`failure_penalty_msat`]: Self::failure_penalty_msat
 276         pub failure_penalty_half_life: Duration,
 277 }
 278
 279 impl_writeable_tlv_based!(ScoringParameters, {
 280         (0, base_penalty_msat, required),
 281         (1, overuse_penalty_start_1024th, (default_value, 128)),
 282         (2, failure_penalty_msat, required),
 283         (3, overuse_penalty_msat_per_1024th, (default_value, 20)),
 284         (4, failure_penalty_half_life, required),
 285 });
 286
 287 /// Accounting for penalties against a channel for failing to relay any payments.
 288 ///
 289 /// Penalties decay over time, though accumulate as more failures occur.
 290 struct ChannelFailure<T: Time> {
 291         /// Accumulated penalty in msats for the channel as of `last_updated`.
 292         undecayed_penalty_msat: u64,
 293
 294         /// Last time the channel either failed to route or successfully routed a payment. Used to decay
 295         /// `undecayed_penalty_msat`.
 296         last_updated: T,
 297 }
 298
 299 impl<T: Time> ScorerUsingTime<T> {
 300         /// Creates a new scorer using the given scoring parameters.
 301         pub fn new(params: ScoringParameters) -> Self {
 302                 Self {
 303                         params,
 304                         channel_failures: HashMap::new(),
 305                 }
 306         }
 307
 308         /// Creates a new scorer using `penalty_msat` as a fixed channel penalty.
 309         #[cfg(any(test, feature = "fuzztarget", feature = "_test_utils"))]
 310         pub fn with_fixed_penalty(penalty_msat: u64) -> Self {
 311                 Self::new(ScoringParameters {
 312                         base_penalty_msat: penalty_msat,
 313                         failure_penalty_msat: 0,
 314                         failure_penalty_half_life: Duration::from_secs(0),
 315                         overuse_penalty_start_1024th: 1024,
 316                         overuse_penalty_msat_per_1024th: 0,
 317                 })
 318         }
 319 }
 320
 321 impl<T: Time> ChannelFailure<T> {
 322         fn new(failure_penalty_msat: u64) -> Self {
 323                 Self {
 324                         undecayed_penalty_msat: failure_penalty_msat,
 325                         last_updated: T::now(),
 326                 }
 327         }
 328
 329         fn add_penalty(&mut self, failure_penalty_msat: u64, half_life: Duration) {
 330                 self.undecayed_penalty_msat = self.decayed_penalty_msat(half_life) + failure_penalty_msat;
 331                 self.last_updated = T::now();
 332         }
 333
 334         fn reduce_penalty(&mut self, half_life: Duration) {
 335                 self.undecayed_penalty_msat = self.decayed_penalty_msat(half_life) >> 1;
 336                 self.last_updated = T::now();
 337         }
 338
 339         fn decayed_penalty_msat(&self, half_life: Duration) -> u64 {
 340                 self.last_updated.elapsed().as_secs()
 341                         .checked_div(half_life.as_secs())
 342                         .and_then(|decays| self.undecayed_penalty_msat.checked_shr(decays as u32))
 343                         .unwrap_or(0)
 344         }
 345 }
 346
 347 impl<T: Time> Default for ScorerUsingTime<T> {
 348         fn default() -> Self {
 349                 Self::new(ScoringParameters::default())
 350         }
 351 }
 352
 353 impl Default for ScoringParameters {
 354         fn default() -> Self {
 355                 Self {
 356                         base_penalty_msat: 500,
 357                         failure_penalty_msat: 1024 * 1000,
 358                         failure_penalty_half_life: Duration::from_secs(3600),
 359                         overuse_penalty_start_1024th: 1024 / 8,
 360                         overuse_penalty_msat_per_1024th: 20,
 361                 }
 362         }
 363 }
 364
 365 impl<T: Time> Score for ScorerUsingTime<T> {
 366         fn channel_penalty_msat(
 367                 &self, short_channel_id: u64, send_amt_msat: u64, capacity_msat: u64, _source: &NodeId, _target: &NodeId
 368         ) -> u64 {
 369                 let failure_penalty_msat = self.channel_failures
 370                         .get(&short_channel_id)
 371                         .map_or(0, |value| value.decayed_penalty_msat(self.params.failure_penalty_half_life));
 372
 373                 let mut penalty_msat = self.params.base_penalty_msat + failure_penalty_msat;
 374                 let send_1024ths = send_amt_msat.checked_mul(1024).unwrap_or(u64::max_value()) / capacity_msat;
 375                 if send_1024ths > self.params.overuse_penalty_start_1024th as u64 {
 376                         penalty_msat = penalty_msat.checked_add(
 377                                         (send_1024ths - self.params.overuse_penalty_start_1024th as u64)
 378                                         .checked_mul(self.params.overuse_penalty_msat_per_1024th).unwrap_or(u64::max_value()))
 379                                 .unwrap_or(u64::max_value());
 380                 }
 381
 382                 penalty_msat
 383         }
 384
 385         fn payment_path_failed(&mut self, _path: &[&RouteHop], short_channel_id: u64) {
 386                 let failure_penalty_msat = self.params.failure_penalty_msat;
 387                 let half_life = self.params.failure_penalty_half_life;
 388                 self.channel_failures
 389                         .entry(short_channel_id)
 390                         .and_modify(|failure| failure.add_penalty(failure_penalty_msat, half_life))
 391                         .or_insert_with(|| ChannelFailure::new(failure_penalty_msat));
 392         }
 393
 394         fn payment_path_successful(&mut self, path: &[&RouteHop]) {
 395                 let half_life = self.params.failure_penalty_half_life;
 396                 for hop in path.iter() {
 397                         self.channel_failures
 398                                 .entry(hop.short_channel_id)
 399                                 .and_modify(|failure| failure.reduce_penalty(half_life));
 400                 }
 401         }
 402 }
 403
 404 impl<T: Time> Writeable for ScorerUsingTime<T> {
 405         #[inline]
 406         fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
 407                 self.params.write(w)?;
 408                 self.channel_failures.write(w)?;
 409                 write_tlv_fields!(w, {});
 410                 Ok(())
 411         }
 412 }
 413
 414 impl<T: Time> Readable for ScorerUsingTime<T> {
 415         #[inline]
 416         fn read<R: Read>(r: &mut R) -> Result<Self, DecodeError> {
 417                 let res = Ok(Self {
 418                         params: Readable::read(r)?,
 419                         channel_failures: Readable::read(r)?,
 420                 });
 421                 read_tlv_fields!(r, {});
 422                 res
 423         }
 424 }
 425
 426 impl<T: Time> Writeable for ChannelFailure<T> {
 427         #[inline]
 428         fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
 429                 let duration_since_epoch = T::duration_since_epoch() - self.last_updated.elapsed();
 430                 write_tlv_fields!(w, {
 431                         (0, self.undecayed_penalty_msat, required),
 432                         (2, duration_since_epoch, required),
 433                 });
 434                 Ok(())
 435         }
 436 }
 437
 438 impl<T: Time> Readable for ChannelFailure<T> {
 439         #[inline]
 440         fn read<R: Read>(r: &mut R) -> Result<Self, DecodeError> {
 441                 let mut undecayed_penalty_msat = 0;
 442                 let mut duration_since_epoch = Duration::from_secs(0);
 443                 read_tlv_fields!(r, {
 444                         (0, undecayed_penalty_msat, required),
 445                         (2, duration_since_epoch, required),
 446                 });
 447                 Ok(Self {
 448                         undecayed_penalty_msat,
 449                         last_updated: T::now() - (T::duration_since_epoch() - duration_since_epoch),
 450                 })
 451         }
 452 }
 453
 454 pub(crate) mod time {
 455         use core::ops::Sub;
 456         use core::time::Duration;
 457         /// A measurement of time.
 458         pub trait Time: Sub<Duration, Output = Self> where Self: Sized {
 459                 /// Returns an instance corresponding to the current moment.
 460                 fn now() -> Self;
 461
 462                 /// Returns the amount of time elapsed since `self` was created.
 463                 fn elapsed(&self) -> Duration;
 464
 465                 /// Returns the amount of time passed since the beginning of [`Time`].
 466                 ///
 467                 /// Used during (de-)serialization.
 468                 fn duration_since_epoch() -> Duration;
 469         }
 470
 471         /// A state in which time has no meaning.
 472         #[derive(Debug, PartialEq, Eq)]
 473         pub struct Eternity;
 474
 475         #[cfg(not(feature = "no-std"))]
 476         impl Time for std::time::Instant {
 477                 fn now() -> Self {
 478                         std::time::Instant::now()
 479                 }
 480
 481                 fn duration_since_epoch() -> Duration {
 482                         use std::time::SystemTime;
 483                         SystemTime::now().duration_since(SystemTime::UNIX_EPOCH).unwrap()
 484                 }
 485
 486                 fn elapsed(&self) -> Duration {
 487                         std::time::Instant::elapsed(self)
 488                 }
 489         }
 490
 491         impl Time for Eternity {
 492                 fn now() -> Self {
 493                         Self
 494                 }
 495
 496                 fn duration_since_epoch() -> Duration {
 497                         Duration::from_secs(0)
 498                 }
 499
 500                 fn elapsed(&self) -> Duration {
 501                         Duration::from_secs(0)
 502                 }
 503         }
 504
 505         impl Sub<Duration> for Eternity {
 506                 type Output = Self;
 507
 508                 fn sub(self, _other: Duration) -> Self {
 509                         self
 510                 }
 511         }
 512 }
 513
 514 pub(crate) use self::time::Time;
 515
 516 #[cfg(test)]
 517 mod tests {
 518         use super::{ScoringParameters, ScorerUsingTime, Time};
 519         use super::time::Eternity;
 520
 521         use ln::features::{ChannelFeatures, NodeFeatures};
 522         use routing::scoring::Score;
 523         use routing::network_graph::NodeId;
 524         use routing::router::RouteHop;
 525         use util::ser::{Readable, Writeable};
 526
 527         use bitcoin::secp256k1::PublicKey;
 528         use core::cell::Cell;
 529         use core::ops::Sub;
 530         use core::time::Duration;
 531         use io;
 532
 533         /// Time that can be advanced manually in tests.
 534         #[derive(Debug, PartialEq, Eq)]
 535         struct SinceEpoch(Duration);
 536
 537         impl SinceEpoch {
 538                 thread_local! {
 539                         static ELAPSED: Cell<Duration> = core::cell::Cell::new(Duration::from_secs(0));
 540                 }
 541
 542                 fn advance(duration: Duration) {
 543                         Self::ELAPSED.with(|elapsed| elapsed.set(elapsed.get() + duration))
 544                 }
 545         }
 546
 547         impl Time for SinceEpoch {
 548                 fn now() -> Self {
 549                         Self(Self::duration_since_epoch())
 550                 }
 551
 552                 fn duration_since_epoch() -> Duration {
 553                         Self::ELAPSED.with(|elapsed| elapsed.get())
 554                 }
 555
 556                 fn elapsed(&self) -> Duration {
 557                         Self::duration_since_epoch() - self.0
 558                 }
 559         }
 560
 561         impl Sub<Duration> for SinceEpoch {
 562                 type Output = Self;
 563
 564                 fn sub(self, other: Duration) -> Self {
 565                         Self(self.0 - other)
 566                 }
 567         }
 568
 569         #[test]
 570         fn time_passes_when_advanced() {
 571                 let now = SinceEpoch::now();
 572                 assert_eq!(now.elapsed(), Duration::from_secs(0));
 573
 574                 SinceEpoch::advance(Duration::from_secs(1));
 575                 SinceEpoch::advance(Duration::from_secs(1));
 576
 577                 let elapsed = now.elapsed();
 578                 let later = SinceEpoch::now();
 579
 580                 assert_eq!(elapsed, Duration::from_secs(2));
 581                 assert_eq!(later - elapsed, now);
 582         }
 583
 584         #[test]
 585         fn time_never_passes_in_an_eternity() {
 586                 let now = Eternity::now();
 587                 let elapsed = now.elapsed();
 588                 let later = Eternity::now();
 589
 590                 assert_eq!(now.elapsed(), Duration::from_secs(0));
 591                 assert_eq!(later - elapsed, now);
 592         }
 593
 594         /// A scorer for testing with time that can be manually advanced.
 595         type Scorer = ScorerUsingTime::<SinceEpoch>;
 596
 597         fn source_node_id() -> NodeId {
 598                 NodeId::from_pubkey(&PublicKey::from_slice(&hex::decode("02eec7245d6b7d2ccb30380bfbe2a3648cd7a942653f5aa340edcea1f283686619").unwrap()[..]).unwrap())
 599         }
 600
 601         fn target_node_id() -> NodeId {
 602                 NodeId::from_pubkey(&PublicKey::from_slice(&hex::decode("0324653eac434488002cc06bbfb7f10fe18991e35f9fe4302dbea6d2353dc0ab1c").unwrap()[..]).unwrap())
 603         }
 604
 605         #[test]
 606         fn penalizes_without_channel_failures() {
 607                 let scorer = Scorer::new(ScoringParameters {
 608                         base_penalty_msat: 1_000,
 609                         failure_penalty_msat: 512,
 610                         failure_penalty_half_life: Duration::from_secs(1),
 611                         overuse_penalty_start_1024th: 1024,
 612                         overuse_penalty_msat_per_1024th: 0,
 613                 });
 614                 let source = source_node_id();
 615                 let target = target_node_id();
 616                 assert_eq!(scorer.channel_penalty_msat(42, 1, 1, &source, &target), 1_000);
 617
 618                 SinceEpoch::advance(Duration::from_secs(1));
 619                 assert_eq!(scorer.channel_penalty_msat(42, 1, 1, &source, &target), 1_000);
 620         }
 621
 622         #[test]
 623         fn accumulates_channel_failure_penalties() {
 624                 let mut scorer = Scorer::new(ScoringParameters {
 625                         base_penalty_msat: 1_000,
 626                         failure_penalty_msat: 64,
 627                         failure_penalty_half_life: Duration::from_secs(10),
 628                         overuse_penalty_start_1024th: 1024,
 629                         overuse_penalty_msat_per_1024th: 0,
 630                 });
 631                 let source = source_node_id();
 632                 let target = target_node_id();
 633                 assert_eq!(scorer.channel_penalty_msat(42, 1, 1, &source, &target), 1_000);
 634
 635                 scorer.payment_path_failed(&[], 42);
 636                 assert_eq!(scorer.channel_penalty_msat(42, 1, 1, &source, &target), 1_064);
 637
 638                 scorer.payment_path_failed(&[], 42);
 639                 assert_eq!(scorer.channel_penalty_msat(42, 1, 1, &source, &target), 1_128);
 640
 641                 scorer.payment_path_failed(&[], 42);
 642                 assert_eq!(scorer.channel_penalty_msat(42, 1, 1, &source, &target), 1_192);
 643         }
 644
 645         #[test]
 646         fn decays_channel_failure_penalties_over_time() {
 647                 let mut scorer = Scorer::new(ScoringParameters {
 648                         base_penalty_msat: 1_000,
 649                         failure_penalty_msat: 512,
 650                         failure_penalty_half_life: Duration::from_secs(10),
 651                         overuse_penalty_start_1024th: 1024,
 652                         overuse_penalty_msat_per_1024th: 0,
 653                 });
 654                 let source = source_node_id();
 655                 let target = target_node_id();
 656                 assert_eq!(scorer.channel_penalty_msat(42, 1, 1, &source, &target), 1_000);
 657
 658                 scorer.payment_path_failed(&[], 42);
 659                 assert_eq!(scorer.channel_penalty_msat(42, 1, 1, &source, &target), 1_512);
 660
 661                 SinceEpoch::advance(Duration::from_secs(9));
 662                 assert_eq!(scorer.channel_penalty_msat(42, 1, 1, &source, &target), 1_512);
 663
 664                 SinceEpoch::advance(Duration::from_secs(1));
 665                 assert_eq!(scorer.channel_penalty_msat(42, 1, 1, &source, &target), 1_256);
 666
 667                 SinceEpoch::advance(Duration::from_secs(10 * 8));
 668                 assert_eq!(scorer.channel_penalty_msat(42, 1, 1, &source, &target), 1_001);
 669
 670                 SinceEpoch::advance(Duration::from_secs(10));
 671                 assert_eq!(scorer.channel_penalty_msat(42, 1, 1, &source, &target), 1_000);
 672
 673                 SinceEpoch::advance(Duration::from_secs(10));
 674                 assert_eq!(scorer.channel_penalty_msat(42, 1, 1, &source, &target), 1_000);
 675         }
 676
 677         #[test]
 678         fn decays_channel_failure_penalties_without_shift_overflow() {
 679                 let mut scorer = Scorer::new(ScoringParameters {
 680                         base_penalty_msat: 1_000,
 681                         failure_penalty_msat: 512,
 682                         failure_penalty_half_life: Duration::from_secs(10),
 683                         overuse_penalty_start_1024th: 1024,
 684                         overuse_penalty_msat_per_1024th: 0,
 685                 });
 686                 let source = source_node_id();
 687                 let target = target_node_id();
 688                 assert_eq!(scorer.channel_penalty_msat(42, 1, 1, &source, &target), 1_000);
 689
 690                 scorer.payment_path_failed(&[], 42);
 691                 assert_eq!(scorer.channel_penalty_msat(42, 1, 1, &source, &target), 1_512);
 692
 693                 // An unchecked right shift 64 bits or more in ChannelFailure::decayed_penalty_msat would
 694                 // cause an overflow.
 695                 SinceEpoch::advance(Duration::from_secs(10 * 64));
 696                 assert_eq!(scorer.channel_penalty_msat(42, 1, 1, &source, &target), 1_000);
 697
 698                 SinceEpoch::advance(Duration::from_secs(10));
 699                 assert_eq!(scorer.channel_penalty_msat(42, 1, 1, &source, &target), 1_000);
 700         }
 701
 702         #[test]
 703         fn accumulates_channel_failure_penalties_after_decay() {
 704                 let mut scorer = Scorer::new(ScoringParameters {
 705                         base_penalty_msat: 1_000,
 706                         failure_penalty_msat: 512,
 707                         failure_penalty_half_life: Duration::from_secs(10),
 708                         overuse_penalty_start_1024th: 1024,
 709                         overuse_penalty_msat_per_1024th: 0,
 710                 });
 711                 let source = source_node_id();
 712                 let target = target_node_id();
 713                 assert_eq!(scorer.channel_penalty_msat(42, 1, 1, &source, &target), 1_000);
 714
 715                 scorer.payment_path_failed(&[], 42);
 716                 assert_eq!(scorer.channel_penalty_msat(42, 1, 1, &source, &target), 1_512);
 717
 718                 SinceEpoch::advance(Duration::from_secs(10));
 719                 assert_eq!(scorer.channel_penalty_msat(42, 1, 1, &source, &target), 1_256);
 720
 721                 scorer.payment_path_failed(&[], 42);
 722                 assert_eq!(scorer.channel_penalty_msat(42, 1, 1, &source, &target), 1_768);
 723
 724                 SinceEpoch::advance(Duration::from_secs(10));
 725                 assert_eq!(scorer.channel_penalty_msat(42, 1, 1, &source, &target), 1_384);
 726         }
 727
 728         #[test]
 729         fn reduces_channel_failure_penalties_after_success() {
 730                 let mut scorer = Scorer::new(ScoringParameters {
 731                         base_penalty_msat: 1_000,
 732                         failure_penalty_msat: 512,
 733                         failure_penalty_half_life: Duration::from_secs(10),
 734                         overuse_penalty_start_1024th: 1024,
 735                         overuse_penalty_msat_per_1024th: 0,
 736                 });
 737                 let source = source_node_id();
 738                 let target = target_node_id();
 739                 assert_eq!(scorer.channel_penalty_msat(42, 1, 1, &source, &target), 1_000);
 740
 741                 scorer.payment_path_failed(&[], 42);
 742                 assert_eq!(scorer.channel_penalty_msat(42, 1, 1, &source, &target), 1_512);
 743
 744                 SinceEpoch::advance(Duration::from_secs(10));
 745                 assert_eq!(scorer.channel_penalty_msat(42, 1, 1, &source, &target), 1_256);
 746
 747                 let hop = RouteHop {
 748                         pubkey: PublicKey::from_slice(target.as_slice()).unwrap(),
 749                         node_features: NodeFeatures::known(),
 750                         short_channel_id: 42,
 751                         channel_features: ChannelFeatures::known(),
 752                         fee_msat: 1,
 753                         cltv_expiry_delta: 18,
 754                 };
 755                 scorer.payment_path_successful(&[&hop]);
 756                 assert_eq!(scorer.channel_penalty_msat(42, 1, 1, &source, &target), 1_128);
 757
 758                 SinceEpoch::advance(Duration::from_secs(10));
 759                 assert_eq!(scorer.channel_penalty_msat(42, 1, 1, &source, &target), 1_064);
 760         }
 761
 762         #[test]
 763         fn restores_persisted_channel_failure_penalties() {
 764                 let mut scorer = Scorer::new(ScoringParameters {
 765                         base_penalty_msat: 1_000,
 766                         failure_penalty_msat: 512,
 767                         failure_penalty_half_life: Duration::from_secs(10),
 768                         overuse_penalty_start_1024th: 1024,
 769                         overuse_penalty_msat_per_1024th: 0,
 770                 });
 771                 let source = source_node_id();
 772                 let target = target_node_id();
 773
 774                 scorer.payment_path_failed(&[], 42);
 775                 assert_eq!(scorer.channel_penalty_msat(42, 1, 1, &source, &target), 1_512);
 776
 777                 SinceEpoch::advance(Duration::from_secs(10));
 778                 assert_eq!(scorer.channel_penalty_msat(42, 1, 1, &source, &target), 1_256);
 779
 780                 scorer.payment_path_failed(&[], 43);
 781                 assert_eq!(scorer.channel_penalty_msat(43, 1, 1, &source, &target), 1_512);
 782
 783                 let mut serialized_scorer = Vec::new();
 784                 scorer.write(&mut serialized_scorer).unwrap();
 785
 786                 let deserialized_scorer = <Scorer>::read(&mut io::Cursor::new(&serialized_scorer)).unwrap();
 787                 assert_eq!(deserialized_scorer.channel_penalty_msat(42, 1, 1, &source, &target), 1_256);
 788                 assert_eq!(deserialized_scorer.channel_penalty_msat(43, 1, 1, &source, &target), 1_512);
 789         }
 790
 791         #[test]
 792         fn decays_persisted_channel_failure_penalties() {
 793                 let mut scorer = Scorer::new(ScoringParameters {
 794                         base_penalty_msat: 1_000,
 795                         failure_penalty_msat: 512,
 796                         failure_penalty_half_life: Duration::from_secs(10),
 797                         overuse_penalty_start_1024th: 1024,
 798                         overuse_penalty_msat_per_1024th: 0,
 799                 });
 800                 let source = source_node_id();
 801                 let target = target_node_id();
 802
 803                 scorer.payment_path_failed(&[], 42);
 804                 assert_eq!(scorer.channel_penalty_msat(42, 1, 1, &source, &target), 1_512);
 805
 806                 let mut serialized_scorer = Vec::new();
 807                 scorer.write(&mut serialized_scorer).unwrap();
 808
 809                 SinceEpoch::advance(Duration::from_secs(10));
 810
 811                 let deserialized_scorer = <Scorer>::read(&mut io::Cursor::new(&serialized_scorer)).unwrap();
 812                 assert_eq!(deserialized_scorer.channel_penalty_msat(42, 1, 1, &source, &target), 1_256);
 813
 814                 SinceEpoch::advance(Duration::from_secs(10));
 815                 assert_eq!(deserialized_scorer.channel_penalty_msat(42, 1, 1, &source, &target), 1_128);
 816         }
 817
 818         #[test]
 819         fn charges_per_1024th_penalty() {
 820                 let scorer = Scorer::new(ScoringParameters {
 821                         base_penalty_msat: 0,
 822                         failure_penalty_msat: 0,
 823                         failure_penalty_half_life: Duration::from_secs(0),
 824                         overuse_penalty_start_1024th: 256,
 825                         overuse_penalty_msat_per_1024th: 100,
 826                 });
 827                 let source = source_node_id();
 828                 let target = target_node_id();
 829
 830                 assert_eq!(scorer.channel_penalty_msat(42, 1_000, 1_024_000, &source, &target), 0);
 831                 assert_eq!(scorer.channel_penalty_msat(42, 256_999, 1_024_000, &source, &target), 0);
 832                 assert_eq!(scorer.channel_penalty_msat(42, 257_000, 1_024_000, &source, &target), 100);
 833                 assert_eq!(scorer.channel_penalty_msat(42, 258_000, 1_024_000, &source, &target), 200);
 834                 assert_eq!(scorer.channel_penalty_msat(42, 512_000, 1_024_000, &source, &target), 256 * 100);
 835         }
 836 }