_ 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         /// Handles updating channel penalties after successfully routing along a path.
 100         fn payment_path_successful(&mut self, path: &[&RouteHop]);
 101 }
 102
 103 impl<S: Score, T: DerefMut<Target=S> $(+ $supertrait)*> Score for T {
 104         fn channel_penalty_msat(&self, short_channel_id: u64, send_amt_msat: u64, channel_capacity_msat: Option<u64>, source: &NodeId, target: &NodeId) -> u64 {
 105                 self.deref().channel_penalty_msat(short_channel_id, send_amt_msat, channel_capacity_msat, source, target)
 106         }
 107
 108         fn payment_path_failed(&mut self, path: &[&RouteHop], short_channel_id: u64) {
 109                 self.deref_mut().payment_path_failed(path, short_channel_id)
 110         }
 111
 112         fn payment_path_successful(&mut self, path: &[&RouteHop]) {
 113                 self.deref_mut().payment_path_successful(path)
 114         }
 115 }
 116 } }
 117
 118 #[cfg(c_bindings)]
 119 define_score!(Writeable);
 120 #[cfg(not(c_bindings))]
 121 define_score!();
 122
 123 /// A scorer that is accessed under a lock.
 124 ///
 125 /// Needed so that calls to [`Score::channel_penalty_msat`] in [`find_route`] can be made while
 126 /// having shared ownership of a scorer but without requiring internal locking in [`Score`]
 127 /// implementations. Internal locking would be detrimental to route finding performance and could
 128 /// result in [`Score::channel_penalty_msat`] returning a different value for the same channel.
 129 ///
 130 /// [`find_route`]: crate::routing::router::find_route
 131 pub trait LockableScore<'a> {
 132         /// The locked [`Score`] type.
 133         type Locked: 'a + Score;
 134
 135         /// Returns the locked scorer.
 136         fn lock(&'a self) -> Self::Locked;
 137 }
 138
 139 /// (C-not exported)
 140 impl<'a, T: 'a + Score> LockableScore<'a> for Mutex<T> {
 141         type Locked = MutexGuard<'a, T>;
 142
 143         fn lock(&'a self) -> MutexGuard<'a, T> {
 144                 Mutex::lock(self).unwrap()
 145         }
 146 }
 147
 148 impl<'a, T: 'a + Score> LockableScore<'a> for RefCell<T> {
 149         type Locked = RefMut<'a, T>;
 150
 151         fn lock(&'a self) -> RefMut<'a, T> {
 152                 self.borrow_mut()
 153         }
 154 }
 155
 156 #[cfg(c_bindings)]
 157 /// A concrete implementation of [`LockableScore`] which supports multi-threading.
 158 pub struct MultiThreadedLockableScore<S: Score> {
 159         score: Mutex<S>,
 160 }
 161 #[cfg(c_bindings)]
 162 /// (C-not exported)
 163 impl<'a, T: Score + 'a> LockableScore<'a> for MultiThreadedLockableScore<T> {
 164         type Locked = MutexGuard<'a, T>;
 165
 166         fn lock(&'a self) -> MutexGuard<'a, T> {
 167                 Mutex::lock(&self.score).unwrap()
 168         }
 169 }
 170
 171 #[cfg(c_bindings)]
 172 impl<T: Score> MultiThreadedLockableScore<T> {
 173         /// Creates a new [`MultiThreadedLockableScore`] given an underlying [`Score`].
 174         pub fn new(score: T) -> Self {
 175                 MultiThreadedLockableScore { score: Mutex::new(score) }
 176         }
 177 }
 178
 179 #[cfg(c_bindings)]
 180 /// (C-not exported)
 181 impl<'a, T: Writeable> Writeable for RefMut<'a, T> {
 182         fn write<W: Writer>(&self, writer: &mut W) -> Result<(), io::Error> {
 183                 T::write(&**self, writer)
 184         }
 185 }
 186
 187 #[cfg(c_bindings)]
 188 /// (C-not exported)
 189 impl<'a, S: Writeable> Writeable for MutexGuard<'a, S> {
 190         fn write<W: Writer>(&self, writer: &mut W) -> Result<(), io::Error> {
 191                 S::write(&**self, writer)
 192         }
 193 }
 194
 195 /// [`Score`] implementation that provides reasonable default behavior.
 196 ///
 197 /// Used to apply a fixed penalty to each channel, thus avoiding long paths when shorter paths with
 198 /// slightly higher fees are available. Will further penalize channels that fail to relay payments.
 199 ///
 200 /// See [module-level documentation] for usage.
 201 ///
 202 /// [module-level documentation]: crate::routing::scoring
 203 #[cfg(not(feature = "no-std"))]
 204 pub type Scorer = ScorerUsingTime::<std::time::Instant>;
 205 /// [`Score`] implementation that provides reasonable default behavior.
 206 ///
 207 /// Used to apply a fixed penalty to each channel, thus avoiding long paths when shorter paths with
 208 /// slightly higher fees are available. Will further penalize channels that fail to relay payments.
 209 ///
 210 /// See [module-level documentation] for usage and [`ScoringParameters`] for customization.
 211 ///
 212 /// [module-level documentation]: crate::routing::scoring
 213 #[cfg(feature = "no-std")]
 214 pub type Scorer = ScorerUsingTime::<time::Eternity>;
 215
 216 // Note that ideally we'd hide ScorerUsingTime from public view by sealing it as well, but rustdoc
 217 // doesn't handle this well - instead exposing a `Scorer` which has no trait implementation(s) or
 218 // methods at all.
 219
 220 /// [`Score`] implementation.
 221 ///
 222 /// See [`Scorer`] for details.
 223 ///
 224 /// # Note
 225 ///
 226 /// Mixing the `no-std` feature between serialization and deserialization results in undefined
 227 /// behavior.
 228 ///
 229 /// (C-not exported) generally all users should use the [`Scorer`] type alias.
 230 pub struct ScorerUsingTime<T: Time> {
 231         params: ScoringParameters,
 232         // TODO: Remove entries of closed channels.
 233         channel_failures: HashMap<u64, ChannelFailure<T>>,
 234 }
 235
 236 /// Parameters for configuring [`Scorer`].
 237 pub struct ScoringParameters {
 238         /// A fixed penalty in msats to apply to each channel.
 239         ///
 240         /// Default value: 500 msat
 241         pub base_penalty_msat: u64,
 242
 243         /// A penalty in msats to apply to a channel upon failing to relay a payment.
 244         ///
 245         /// This accumulates for each failure but may be reduced over time based on
 246         /// [`failure_penalty_half_life`] or when successfully routing through a channel.
 247         ///
 248         /// Default value: 1,024,000 msat
 249         ///
 250         /// [`failure_penalty_half_life`]: Self::failure_penalty_half_life
 251         pub failure_penalty_msat: u64,
 252
 253         /// When the amount being sent over a channel is this many 1024ths of the total channel
 254         /// capacity, we begin applying [`overuse_penalty_msat_per_1024th`].
 255         ///
 256         /// Default value: 128 1024ths (i.e. begin penalizing when an HTLC uses 1/8th of a channel)
 257         ///
 258         /// [`overuse_penalty_msat_per_1024th`]: Self::overuse_penalty_msat_per_1024th
 259         pub overuse_penalty_start_1024th: u16,
 260
 261         /// A penalty applied, per whole 1024ths of the channel capacity which the amount being sent
 262         /// over the channel exceeds [`overuse_penalty_start_1024th`] by.
 263         ///
 264         /// Default value: 20 msat (i.e. 2560 msat penalty to use 1/4th of a channel, 7680 msat penalty
 265         ///                to use half a channel, and 12,560 msat penalty to use 3/4ths of a channel)
 266         ///
 267         /// [`overuse_penalty_start_1024th`]: Self::overuse_penalty_start_1024th
 268         pub overuse_penalty_msat_per_1024th: u64,
 269
 270         /// The time required to elapse before any accumulated [`failure_penalty_msat`] penalties are
 271         /// cut in half.
 272         ///
 273         /// Successfully routing through a channel will immediately cut the penalty in half as well.
 274         ///
 275         /// # Note
 276         ///
 277         /// When built with the `no-std` feature, time will never elapse. Therefore, this penalty will
 278         /// never decay.
 279         ///
 280         /// [`failure_penalty_msat`]: Self::failure_penalty_msat
 281         pub failure_penalty_half_life: Duration,
 282 }
 283
 284 impl_writeable_tlv_based!(ScoringParameters, {
 285         (0, base_penalty_msat, required),
 286         (1, overuse_penalty_start_1024th, (default_value, 128)),
 287         (2, failure_penalty_msat, required),
 288         (3, overuse_penalty_msat_per_1024th, (default_value, 20)),
 289         (4, failure_penalty_half_life, required),
 290 });
 291
 292 /// Accounting for penalties against a channel for failing to relay any payments.
 293 ///
 294 /// Penalties decay over time, though accumulate as more failures occur.
 295 struct ChannelFailure<T: Time> {
 296         /// Accumulated penalty in msats for the channel as of `last_updated`.
 297         undecayed_penalty_msat: u64,
 298
 299         /// Last time the channel either failed to route or successfully routed a payment. Used to decay
 300         /// `undecayed_penalty_msat`.
 301         last_updated: T,
 302 }
 303
 304 impl<T: Time> ScorerUsingTime<T> {
 305         /// Creates a new scorer using the given scoring parameters.
 306         pub fn new(params: ScoringParameters) -> Self {
 307                 Self {
 308                         params,
 309                         channel_failures: HashMap::new(),
 310                 }
 311         }
 312
 313         /// Creates a new scorer using `penalty_msat` as a fixed channel penalty.
 314         #[cfg(any(test, feature = "fuzztarget", feature = "_test_utils"))]
 315         pub fn with_fixed_penalty(penalty_msat: u64) -> Self {
 316                 Self::new(ScoringParameters {
 317                         base_penalty_msat: penalty_msat,
 318                         failure_penalty_msat: 0,
 319                         failure_penalty_half_life: Duration::from_secs(0),
 320                         overuse_penalty_start_1024th: 1024,
 321                         overuse_penalty_msat_per_1024th: 0,
 322                 })
 323         }
 324 }
 325
 326 impl<T: Time> ChannelFailure<T> {
 327         fn new(failure_penalty_msat: u64) -> Self {
 328                 Self {
 329                         undecayed_penalty_msat: failure_penalty_msat,
 330                         last_updated: T::now(),
 331                 }
 332         }
 333
 334         fn add_penalty(&mut self, failure_penalty_msat: u64, half_life: Duration) {
 335                 self.undecayed_penalty_msat = self.decayed_penalty_msat(half_life) + failure_penalty_msat;
 336                 self.last_updated = T::now();
 337         }
 338
 339         fn reduce_penalty(&mut self, half_life: Duration) {
 340                 self.undecayed_penalty_msat = self.decayed_penalty_msat(half_life) >> 1;
 341                 self.last_updated = T::now();
 342         }
 343
 344         fn decayed_penalty_msat(&self, half_life: Duration) -> u64 {
 345                 self.last_updated.elapsed().as_secs()
 346                         .checked_div(half_life.as_secs())
 347                         .and_then(|decays| self.undecayed_penalty_msat.checked_shr(decays as u32))
 348                         .unwrap_or(0)
 349         }
 350 }
 351
 352 impl<T: Time> Default for ScorerUsingTime<T> {
 353         fn default() -> Self {
 354                 Self::new(ScoringParameters::default())
 355         }
 356 }
 357
 358 impl Default for ScoringParameters {
 359         fn default() -> Self {
 360                 Self {
 361                         base_penalty_msat: 500,
 362                         failure_penalty_msat: 1024 * 1000,
 363                         failure_penalty_half_life: Duration::from_secs(3600),
 364                         overuse_penalty_start_1024th: 1024 / 8,
 365                         overuse_penalty_msat_per_1024th: 20,
 366                 }
 367         }
 368 }
 369
 370 impl<T: Time> Score for ScorerUsingTime<T> {
 371         fn channel_penalty_msat(
 372                 &self, short_channel_id: u64, send_amt_msat: u64, chan_capacity_opt: Option<u64>, _source: &NodeId, _target: &NodeId
 373         ) -> u64 {
 374                 let failure_penalty_msat = self.channel_failures
 375                         .get(&short_channel_id)
 376                         .map_or(0, |value| value.decayed_penalty_msat(self.params.failure_penalty_half_life));
 377
 378                 let mut penalty_msat = self.params.base_penalty_msat + failure_penalty_msat;
 379
 380                 if let Some(chan_capacity_msat) = chan_capacity_opt {
 381                         let send_1024ths = send_amt_msat.checked_mul(1024).unwrap_or(u64::max_value()) / chan_capacity_msat;
 382
 383                         if send_1024ths > self.params.overuse_penalty_start_1024th as u64 {
 384                                 penalty_msat = penalty_msat.checked_add(
 385                                                 (send_1024ths - self.params.overuse_penalty_start_1024th as u64)
 386                                                 .checked_mul(self.params.overuse_penalty_msat_per_1024th).unwrap_or(u64::max_value()))
 387                                         .unwrap_or(u64::max_value());
 388                         }
 389                 }
 390
 391                 penalty_msat
 392         }
 393
 394         fn payment_path_failed(&mut self, _path: &[&RouteHop], short_channel_id: u64) {
 395                 let failure_penalty_msat = self.params.failure_penalty_msat;
 396                 let half_life = self.params.failure_penalty_half_life;
 397                 self.channel_failures
 398                         .entry(short_channel_id)
 399                         .and_modify(|failure| failure.add_penalty(failure_penalty_msat, half_life))
 400                         .or_insert_with(|| ChannelFailure::new(failure_penalty_msat));
 401         }
 402
 403         fn payment_path_successful(&mut self, path: &[&RouteHop]) {
 404                 let half_life = self.params.failure_penalty_half_life;
 405                 for hop in path.iter() {
 406                         self.channel_failures
 407                                 .entry(hop.short_channel_id)
 408                                 .and_modify(|failure| failure.reduce_penalty(half_life));
 409                 }
 410         }
 411 }
 412
 413 impl<T: Time> Writeable for ScorerUsingTime<T> {
 414         #[inline]
 415         fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
 416                 self.params.write(w)?;
 417                 self.channel_failures.write(w)?;
 418                 write_tlv_fields!(w, {});
 419                 Ok(())
 420         }
 421 }
 422
 423 impl<T: Time> Readable for ScorerUsingTime<T> {
 424         #[inline]
 425         fn read<R: Read>(r: &mut R) -> Result<Self, DecodeError> {
 426                 let res = Ok(Self {
 427                         params: Readable::read(r)?,
 428                         channel_failures: Readable::read(r)?,
 429                 });
 430                 read_tlv_fields!(r, {});
 431                 res
 432         }
 433 }
 434
 435 impl<T: Time> Writeable for ChannelFailure<T> {
 436         #[inline]
 437         fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
 438                 let duration_since_epoch = T::duration_since_epoch() - self.last_updated.elapsed();
 439                 write_tlv_fields!(w, {
 440                         (0, self.undecayed_penalty_msat, required),
 441                         (2, duration_since_epoch, required),
 442                 });
 443                 Ok(())
 444         }
 445 }
 446
 447 impl<T: Time> Readable for ChannelFailure<T> {
 448         #[inline]
 449         fn read<R: Read>(r: &mut R) -> Result<Self, DecodeError> {
 450                 let mut undecayed_penalty_msat = 0;
 451                 let mut duration_since_epoch = Duration::from_secs(0);
 452                 read_tlv_fields!(r, {
 453                         (0, undecayed_penalty_msat, required),
 454                         (2, duration_since_epoch, required),
 455                 });
 456                 Ok(Self {
 457                         undecayed_penalty_msat,
 458                         last_updated: T::now() - (T::duration_since_epoch() - duration_since_epoch),
 459                 })
 460         }
 461 }
 462
 463 pub(crate) mod time {
 464         use core::ops::Sub;
 465         use core::time::Duration;
 466         /// A measurement of time.
 467         pub trait Time: Sub<Duration, Output = Self> where Self: Sized {
 468                 /// Returns an instance corresponding to the current moment.
 469                 fn now() -> Self;
 470
 471                 /// Returns the amount of time elapsed since `self` was created.
 472                 fn elapsed(&self) -> Duration;
 473
 474                 /// Returns the amount of time passed since the beginning of [`Time`].
 475                 ///
 476                 /// Used during (de-)serialization.
 477                 fn duration_since_epoch() -> Duration;
 478         }
 479
 480         /// A state in which time has no meaning.
 481         #[derive(Debug, PartialEq, Eq)]
 482         pub struct Eternity;
 483
 484         #[cfg(not(feature = "no-std"))]
 485         impl Time for std::time::Instant {
 486                 fn now() -> Self {
 487                         std::time::Instant::now()
 488                 }
 489
 490                 fn duration_since_epoch() -> Duration {
 491                         use std::time::SystemTime;
 492                         SystemTime::now().duration_since(SystemTime::UNIX_EPOCH).unwrap()
 493                 }
 494
 495                 fn elapsed(&self) -> Duration {
 496                         std::time::Instant::elapsed(self)
 497                 }
 498         }
 499
 500         impl Time for Eternity {
 501                 fn now() -> Self {
 502                         Self
 503                 }
 504
 505                 fn duration_since_epoch() -> Duration {
 506                         Duration::from_secs(0)
 507                 }
 508
 509                 fn elapsed(&self) -> Duration {
 510                         Duration::from_secs(0)
 511                 }
 512         }
 513
 514         impl Sub<Duration> for Eternity {
 515                 type Output = Self;
 516
 517                 fn sub(self, _other: Duration) -> Self {
 518                         self
 519                 }
 520         }
 521 }
 522
 523 pub(crate) use self::time::Time;
 524
 525 #[cfg(test)]
 526 mod tests {
 527         use super::{ScoringParameters, ScorerUsingTime, Time};
 528         use super::time::Eternity;
 529
 530         use ln::features::{ChannelFeatures, NodeFeatures};
 531         use routing::scoring::Score;
 532         use routing::network_graph::NodeId;
 533         use routing::router::RouteHop;
 534         use util::ser::{Readable, Writeable};
 535
 536         use bitcoin::secp256k1::PublicKey;
 537         use core::cell::Cell;
 538         use core::ops::Sub;
 539         use core::time::Duration;
 540         use io;
 541
 542         /// Time that can be advanced manually in tests.
 543         #[derive(Debug, PartialEq, Eq)]
 544         struct SinceEpoch(Duration);
 545
 546         impl SinceEpoch {
 547                 thread_local! {
 548                         static ELAPSED: Cell<Duration> = core::cell::Cell::new(Duration::from_secs(0));
 549                 }
 550
 551                 fn advance(duration: Duration) {
 552                         Self::ELAPSED.with(|elapsed| elapsed.set(elapsed.get() + duration))
 553                 }
 554         }
 555
 556         impl Time for SinceEpoch {
 557                 fn now() -> Self {
 558                         Self(Self::duration_since_epoch())
 559                 }
 560
 561                 fn duration_since_epoch() -> Duration {
 562                         Self::ELAPSED.with(|elapsed| elapsed.get())
 563                 }
 564
 565                 fn elapsed(&self) -> Duration {
 566                         Self::duration_since_epoch() - self.0
 567                 }
 568         }
 569
 570         impl Sub<Duration> for SinceEpoch {
 571                 type Output = Self;
 572
 573                 fn sub(self, other: Duration) -> Self {
 574                         Self(self.0 - other)
 575                 }
 576         }
 577
 578         #[test]
 579         fn time_passes_when_advanced() {
 580                 let now = SinceEpoch::now();
 581                 assert_eq!(now.elapsed(), Duration::from_secs(0));
 582
 583                 SinceEpoch::advance(Duration::from_secs(1));
 584                 SinceEpoch::advance(Duration::from_secs(1));
 585
 586                 let elapsed = now.elapsed();
 587                 let later = SinceEpoch::now();
 588
 589                 assert_eq!(elapsed, Duration::from_secs(2));
 590                 assert_eq!(later - elapsed, now);
 591         }
 592
 593         #[test]
 594         fn time_never_passes_in_an_eternity() {
 595                 let now = Eternity::now();
 596                 let elapsed = now.elapsed();
 597                 let later = Eternity::now();
 598
 599                 assert_eq!(now.elapsed(), Duration::from_secs(0));
 600                 assert_eq!(later - elapsed, now);
 601         }
 602
 603         /// A scorer for testing with time that can be manually advanced.
 604         type Scorer = ScorerUsingTime::<SinceEpoch>;
 605
 606         fn source_node_id() -> NodeId {
 607                 NodeId::from_pubkey(&PublicKey::from_slice(&hex::decode("02eec7245d6b7d2ccb30380bfbe2a3648cd7a942653f5aa340edcea1f283686619").unwrap()[..]).unwrap())
 608         }
 609
 610         fn target_node_id() -> NodeId {
 611                 NodeId::from_pubkey(&PublicKey::from_slice(&hex::decode("0324653eac434488002cc06bbfb7f10fe18991e35f9fe4302dbea6d2353dc0ab1c").unwrap()[..]).unwrap())
 612         }
 613
 614         #[test]
 615         fn penalizes_without_channel_failures() {
 616                 let scorer = Scorer::new(ScoringParameters {
 617                         base_penalty_msat: 1_000,
 618                         failure_penalty_msat: 512,
 619                         failure_penalty_half_life: Duration::from_secs(1),
 620                         overuse_penalty_start_1024th: 1024,
 621                         overuse_penalty_msat_per_1024th: 0,
 622                 });
 623                 let source = source_node_id();
 624                 let target = target_node_id();
 625                 assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_000);
 626
 627                 SinceEpoch::advance(Duration::from_secs(1));
 628                 assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_000);
 629         }
 630
 631         #[test]
 632         fn accumulates_channel_failure_penalties() {
 633                 let mut scorer = Scorer::new(ScoringParameters {
 634                         base_penalty_msat: 1_000,
 635                         failure_penalty_msat: 64,
 636                         failure_penalty_half_life: Duration::from_secs(10),
 637                         overuse_penalty_start_1024th: 1024,
 638                         overuse_penalty_msat_per_1024th: 0,
 639                 });
 640                 let source = source_node_id();
 641                 let target = target_node_id();
 642                 assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_000);
 643
 644                 scorer.payment_path_failed(&[], 42);
 645                 assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_064);
 646
 647                 scorer.payment_path_failed(&[], 42);
 648                 assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_128);
 649
 650                 scorer.payment_path_failed(&[], 42);
 651                 assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_192);
 652         }
 653
 654         #[test]
 655         fn decays_channel_failure_penalties_over_time() {
 656                 let mut scorer = Scorer::new(ScoringParameters {
 657                         base_penalty_msat: 1_000,
 658                         failure_penalty_msat: 512,
 659                         failure_penalty_half_life: Duration::from_secs(10),
 660                         overuse_penalty_start_1024th: 1024,
 661                         overuse_penalty_msat_per_1024th: 0,
 662                 });
 663                 let source = source_node_id();
 664                 let target = target_node_id();
 665                 assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_000);
 666
 667                 scorer.payment_path_failed(&[], 42);
 668                 assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_512);
 669
 670                 SinceEpoch::advance(Duration::from_secs(9));
 671                 assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_512);
 672
 673                 SinceEpoch::advance(Duration::from_secs(1));
 674                 assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_256);
 675
 676                 SinceEpoch::advance(Duration::from_secs(10 * 8));
 677                 assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_001);
 678
 679                 SinceEpoch::advance(Duration::from_secs(10));
 680                 assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_000);
 681
 682                 SinceEpoch::advance(Duration::from_secs(10));
 683                 assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_000);
 684         }
 685
 686         #[test]
 687         fn decays_channel_failure_penalties_without_shift_overflow() {
 688                 let mut scorer = Scorer::new(ScoringParameters {
 689                         base_penalty_msat: 1_000,
 690                         failure_penalty_msat: 512,
 691                         failure_penalty_half_life: Duration::from_secs(10),
 692                         overuse_penalty_start_1024th: 1024,
 693                         overuse_penalty_msat_per_1024th: 0,
 694                 });
 695                 let source = source_node_id();
 696                 let target = target_node_id();
 697                 assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_000);
 698
 699                 scorer.payment_path_failed(&[], 42);
 700                 assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_512);
 701
 702                 // An unchecked right shift 64 bits or more in ChannelFailure::decayed_penalty_msat would
 703                 // cause an overflow.
 704                 SinceEpoch::advance(Duration::from_secs(10 * 64));
 705                 assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_000);
 706
 707                 SinceEpoch::advance(Duration::from_secs(10));
 708                 assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_000);
 709         }
 710
 711         #[test]
 712         fn accumulates_channel_failure_penalties_after_decay() {
 713                 let mut scorer = Scorer::new(ScoringParameters {
 714                         base_penalty_msat: 1_000,
 715                         failure_penalty_msat: 512,
 716                         failure_penalty_half_life: Duration::from_secs(10),
 717                         overuse_penalty_start_1024th: 1024,
 718                         overuse_penalty_msat_per_1024th: 0,
 719                 });
 720                 let source = source_node_id();
 721                 let target = target_node_id();
 722                 assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_000);
 723
 724                 scorer.payment_path_failed(&[], 42);
 725                 assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_512);
 726
 727                 SinceEpoch::advance(Duration::from_secs(10));
 728                 assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_256);
 729
 730                 scorer.payment_path_failed(&[], 42);
 731                 assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_768);
 732
 733                 SinceEpoch::advance(Duration::from_secs(10));
 734                 assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_384);
 735         }
 736
 737         #[test]
 738         fn reduces_channel_failure_penalties_after_success() {
 739                 let mut scorer = Scorer::new(ScoringParameters {
 740                         base_penalty_msat: 1_000,
 741                         failure_penalty_msat: 512,
 742                         failure_penalty_half_life: Duration::from_secs(10),
 743                         overuse_penalty_start_1024th: 1024,
 744                         overuse_penalty_msat_per_1024th: 0,
 745                 });
 746                 let source = source_node_id();
 747                 let target = target_node_id();
 748                 assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_000);
 749
 750                 scorer.payment_path_failed(&[], 42);
 751                 assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_512);
 752
 753                 SinceEpoch::advance(Duration::from_secs(10));
 754                 assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_256);
 755
 756                 let hop = RouteHop {
 757                         pubkey: PublicKey::from_slice(target.as_slice()).unwrap(),
 758                         node_features: NodeFeatures::known(),
 759                         short_channel_id: 42,
 760                         channel_features: ChannelFeatures::known(),
 761                         fee_msat: 1,
 762                         cltv_expiry_delta: 18,
 763                 };
 764                 scorer.payment_path_successful(&[&hop]);
 765                 assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_128);
 766
 767                 SinceEpoch::advance(Duration::from_secs(10));
 768                 assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_064);
 769         }
 770
 771         #[test]
 772         fn restores_persisted_channel_failure_penalties() {
 773                 let mut scorer = Scorer::new(ScoringParameters {
 774                         base_penalty_msat: 1_000,
 775                         failure_penalty_msat: 512,
 776                         failure_penalty_half_life: Duration::from_secs(10),
 777                         overuse_penalty_start_1024th: 1024,
 778                         overuse_penalty_msat_per_1024th: 0,
 779                 });
 780                 let source = source_node_id();
 781                 let target = target_node_id();
 782
 783                 scorer.payment_path_failed(&[], 42);
 784                 assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_512);
 785
 786                 SinceEpoch::advance(Duration::from_secs(10));
 787                 assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_256);
 788
 789                 scorer.payment_path_failed(&[], 43);
 790                 assert_eq!(scorer.channel_penalty_msat(43, 1, Some(1), &source, &target), 1_512);
 791
 792                 let mut serialized_scorer = Vec::new();
 793                 scorer.write(&mut serialized_scorer).unwrap();
 794
 795                 let deserialized_scorer = <Scorer>::read(&mut io::Cursor::new(&serialized_scorer)).unwrap();
 796                 assert_eq!(deserialized_scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_256);
 797                 assert_eq!(deserialized_scorer.channel_penalty_msat(43, 1, Some(1), &source, &target), 1_512);
 798         }
 799
 800         #[test]
 801         fn decays_persisted_channel_failure_penalties() {
 802                 let mut scorer = Scorer::new(ScoringParameters {
 803                         base_penalty_msat: 1_000,
 804                         failure_penalty_msat: 512,
 805                         failure_penalty_half_life: Duration::from_secs(10),
 806                         overuse_penalty_start_1024th: 1024,
 807                         overuse_penalty_msat_per_1024th: 0,
 808                 });
 809                 let source = source_node_id();
 810                 let target = target_node_id();
 811
 812                 scorer.payment_path_failed(&[], 42);
 813                 assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_512);
 814
 815                 let mut serialized_scorer = Vec::new();
 816                 scorer.write(&mut serialized_scorer).unwrap();
 817
 818                 SinceEpoch::advance(Duration::from_secs(10));
 819
 820                 let deserialized_scorer = <Scorer>::read(&mut io::Cursor::new(&serialized_scorer)).unwrap();
 821                 assert_eq!(deserialized_scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_256);
 822
 823                 SinceEpoch::advance(Duration::from_secs(10));
 824                 assert_eq!(deserialized_scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_128);
 825         }
 826
 827         #[test]
 828         fn charges_per_1024th_penalty() {
 829                 let scorer = Scorer::new(ScoringParameters {
 830                         base_penalty_msat: 0,
 831                         failure_penalty_msat: 0,
 832                         failure_penalty_half_life: Duration::from_secs(0),
 833                         overuse_penalty_start_1024th: 256,
 834                         overuse_penalty_msat_per_1024th: 100,
 835                 });
 836                 let source = source_node_id();
 837                 let target = target_node_id();
 838
 839                 assert_eq!(scorer.channel_penalty_msat(42, 1_000, None, &source, &target), 0);
 840                 assert_eq!(scorer.channel_penalty_msat(42, 1_000, Some(1_024_000), &source, &target), 0);
 841                 assert_eq!(scorer.channel_penalty_msat(42, 256_999, Some(1_024_000), &source, &target), 0);
 842                 assert_eq!(scorer.channel_penalty_msat(42, 257_000, Some(1_024_000), &source, &target), 100);
 843                 assert_eq!(scorer.channel_penalty_msat(42, 258_000, Some(1_024_000), &source, &target), 200);
 844                 assert_eq!(scorer.channel_penalty_msat(42, 512_000, Some(1_024_000), &source, &target), 256 * 100);
 845         }
 846 }