+++ /dev/null
-// This file is Copyright its original authors, visible in version control
-// history.
-//
-// This file is licensed under the Apache License, Version 2.0 <LICENSE-APACHE
-// or http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
-// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your option.
-// You may not use this file except in accordance with one or both of these
-// licenses.
-
-//! Utilities for scoring payment channels.
-//!
-//! [`Scorer`] may be given to [`find_route`] to score payment channels during path finding when a
-//! custom [`routing::Score`] implementation is not needed.
-//!
-//! # Example
-//!
-//! ```
-//! # extern crate secp256k1;
-//! #
-//! # use lightning::routing::network_graph::NetworkGraph;
-//! # use lightning::routing::router::{RouteParameters, find_route};
-//! # use lightning::routing::scorer::{Scorer, ScoringParameters};
-//! # use lightning::util::logger::{Logger, Record};
-//! # use secp256k1::key::PublicKey;
-//! #
-//! # struct FakeLogger {};
-//! # impl Logger for FakeLogger {
-//! # fn log(&self, record: &Record) { unimplemented!() }
-//! # }
-//! # fn find_scored_route(payer: PublicKey, params: RouteParameters, network_graph: NetworkGraph) {
-//! # let logger = FakeLogger {};
-//! #
-//! // Use the default channel penalties.
-//! let scorer = Scorer::default();
-//!
-//! // Or use custom channel penalties.
-//! let scorer = Scorer::new(ScoringParameters {
-//! base_penalty_msat: 1000,
-//! failure_penalty_msat: 2 * 1024 * 1000,
-//! ..ScoringParameters::default()
-//! });
-//!
-//! let route = find_route(&payer, ¶ms, &network_graph, None, &logger, &scorer);
-//! # }
-//! ```
-//!
-//! # Note
-//!
-//! If persisting [`Scorer`], it must be restored using the same [`Time`] parameterization. Using a
-//! different type results in undefined behavior. Specifically, persisting when built with feature
-//! `no-std` and restoring without it, or vice versa, uses different types and thus is undefined.
-//!
-//! [`find_route`]: crate::routing::router::find_route
-
-use routing;
-
-use ln::msgs::DecodeError;
-use routing::network_graph::NodeId;
-use routing::router::RouteHop;
-use util::ser::{Readable, Writeable, Writer};
-
-use prelude::*;
-use core::ops::Sub;
-use core::time::Duration;
-use io::{self, Read};
-
-/// [`routing::Score`] implementation that provides reasonable default behavior.
-///
-/// Used to apply a fixed penalty to each channel, thus avoiding long paths when shorter paths with
-/// slightly higher fees are available. Will further penalize channels that fail to relay payments.
-///
-/// See [module-level documentation] for usage.
-///
-/// [module-level documentation]: crate::routing::scorer
-pub type Scorer = ScorerUsingTime::<DefaultTime>;
-
-/// Time used by [`Scorer`].
-#[cfg(not(feature = "no-std"))]
-pub type DefaultTime = std::time::Instant;
-
-/// Time used by [`Scorer`].
-#[cfg(feature = "no-std")]
-pub type DefaultTime = Eternity;
-
-/// [`routing::Score`] implementation parameterized by [`Time`].
-///
-/// See [`Scorer`] for details.
-///
-/// # Note
-///
-/// Mixing [`Time`] types between serialization and deserialization results in undefined behavior.
-pub struct ScorerUsingTime<T: Time> {
- params: ScoringParameters,
- // TODO: Remove entries of closed channels.
- channel_failures: HashMap<u64, ChannelFailure<T>>,
-}
-
-/// Parameters for configuring [`Scorer`].
-pub struct ScoringParameters {
- /// A fixed penalty in msats to apply to each channel.
- ///
- /// Default value: 500 msat
- pub base_penalty_msat: u64,
-
- /// A penalty in msats to apply to a channel upon failing to relay a payment.
- ///
- /// This accumulates for each failure but may be reduced over time based on
- /// [`failure_penalty_half_life`].
- ///
- /// Default value: 1,024,000 msat
- ///
- /// [`failure_penalty_half_life`]: Self::failure_penalty_half_life
- pub failure_penalty_msat: u64,
-
- /// When the amount being sent over a channel is this many 1024ths of the total channel
- /// capacity, we begin applying [`overuse_penalty_msat_per_1024th`].
- ///
- /// Default value: 128 1024ths (i.e. begin penalizing when an HTLC uses 1/8th of a channel)
- ///
- /// [`overuse_penalty_msat_per_1024th`]: Self::overuse_penalty_msat_per_1024th
- pub overuse_penalty_start_1024th: u16,
-
- /// A penalty applied, per whole 1024ths of the channel capacity which the amount being sent
- /// over the channel exceeds [`overuse_penalty_start_1024th`] by.
- ///
- /// Default value: 20 msat (i.e. 2560 msat penalty to use 1/4th of a channel, 7680 msat penalty
- /// to use half a channel, and 12,560 msat penalty to use 3/4ths of a channel)
- ///
- /// [`overuse_penalty_start_1024th`]: Self::overuse_penalty_start_1024th
- pub overuse_penalty_msat_per_1024th: u64,
-
- /// The time required to elapse before any accumulated [`failure_penalty_msat`] penalties are
- /// cut in half.
- ///
- /// # Note
- ///
- /// When time is an [`Eternity`], as is default when enabling feature `no-std`, it will never
- /// elapse. Therefore, this penalty will never decay.
- ///
- /// [`failure_penalty_msat`]: Self::failure_penalty_msat
- pub failure_penalty_half_life: Duration,
-}
-
-impl_writeable_tlv_based!(ScoringParameters, {
- (0, base_penalty_msat, required),
- (1, overuse_penalty_start_1024th, (default_value, 128)),
- (2, failure_penalty_msat, required),
- (3, overuse_penalty_msat_per_1024th, (default_value, 20)),
- (4, failure_penalty_half_life, required),
-});
-
-/// Accounting for penalties against a channel for failing to relay any payments.
-///
-/// Penalties decay over time, though accumulate as more failures occur.
-struct ChannelFailure<T: Time> {
- /// Accumulated penalty in msats for the channel as of `last_failed`.
- undecayed_penalty_msat: u64,
-
- /// Last time the channel failed. Used to decay `undecayed_penalty_msat`.
- last_failed: T,
-}
-
-/// A measurement of time.
-pub trait Time: Sub<Duration, Output = Self> where Self: Sized {
- /// Returns an instance corresponding to the current moment.
- fn now() -> Self;
-
- /// Returns the amount of time elapsed since `self` was created.
- fn elapsed(&self) -> Duration;
-
- /// Returns the amount of time passed since the beginning of [`Time`].
- ///
- /// Used during (de-)serialization.
- fn duration_since_epoch() -> Duration;
-}
-
-impl<T: Time> ScorerUsingTime<T> {
- /// Creates a new scorer using the given scoring parameters.
- pub fn new(params: ScoringParameters) -> Self {
- Self {
- params,
- channel_failures: HashMap::new(),
- }
- }
-
- /// Creates a new scorer using `penalty_msat` as a fixed channel penalty.
- #[cfg(any(test, feature = "fuzztarget", feature = "_test_utils"))]
- pub fn with_fixed_penalty(penalty_msat: u64) -> Self {
- Self::new(ScoringParameters {
- base_penalty_msat: penalty_msat,
- failure_penalty_msat: 0,
- failure_penalty_half_life: Duration::from_secs(0),
- overuse_penalty_start_1024th: 1024,
- overuse_penalty_msat_per_1024th: 0,
- })
- }
-}
-
-impl<T: Time> ChannelFailure<T> {
- fn new(failure_penalty_msat: u64) -> Self {
- Self {
- undecayed_penalty_msat: failure_penalty_msat,
- last_failed: T::now(),
- }
- }
-
- fn add_penalty(&mut self, failure_penalty_msat: u64, half_life: Duration) {
- self.undecayed_penalty_msat = self.decayed_penalty_msat(half_life) + failure_penalty_msat;
- self.last_failed = T::now();
- }
-
- fn decayed_penalty_msat(&self, half_life: Duration) -> u64 {
- let decays = self.last_failed.elapsed().as_secs().checked_div(half_life.as_secs());
- match decays {
- Some(decays) => self.undecayed_penalty_msat >> decays,
- None => 0,
- }
- }
-}
-
-impl<T: Time> Default for ScorerUsingTime<T> {
- fn default() -> Self {
- Self::new(ScoringParameters::default())
- }
-}
-
-impl Default for ScoringParameters {
- fn default() -> Self {
- Self {
- base_penalty_msat: 500,
- failure_penalty_msat: 1024 * 1000,
- failure_penalty_half_life: Duration::from_secs(3600),
- overuse_penalty_start_1024th: 1024 / 8,
- overuse_penalty_msat_per_1024th: 20,
- }
- }
-}
-
-impl<T: Time> routing::Score for ScorerUsingTime<T> {
- fn channel_penalty_msat(
- &self, short_channel_id: u64, send_amt_msat: u64, chan_capacity_opt: Option<u64>, _source: &NodeId, _target: &NodeId
- ) -> u64 {
- let failure_penalty_msat = self.channel_failures
- .get(&short_channel_id)
- .map_or(0, |value| value.decayed_penalty_msat(self.params.failure_penalty_half_life));
-
- let mut penalty_msat = self.params.base_penalty_msat + failure_penalty_msat;
-
- if let Some(chan_capacity_msat) = chan_capacity_opt {
- let send_1024ths = send_amt_msat.checked_mul(1024).unwrap_or(u64::max_value()) / chan_capacity_msat;
-
- if send_1024ths > self.params.overuse_penalty_start_1024th as u64 {
- penalty_msat = penalty_msat.checked_add(
- (send_1024ths - self.params.overuse_penalty_start_1024th as u64)
- .checked_mul(self.params.overuse_penalty_msat_per_1024th).unwrap_or(u64::max_value()))
- .unwrap_or(u64::max_value());
- }
- }
-
- penalty_msat
- }
-
- fn payment_path_failed(&mut self, _path: &[&RouteHop], short_channel_id: u64) {
- let failure_penalty_msat = self.params.failure_penalty_msat;
- let half_life = self.params.failure_penalty_half_life;
- self.channel_failures
- .entry(short_channel_id)
- .and_modify(|failure| failure.add_penalty(failure_penalty_msat, half_life))
- .or_insert_with(|| ChannelFailure::new(failure_penalty_msat));
- }
-}
-
-#[cfg(not(feature = "no-std"))]
-impl Time for std::time::Instant {
- fn now() -> Self {
- std::time::Instant::now()
- }
-
- fn duration_since_epoch() -> Duration {
- use std::time::SystemTime;
- SystemTime::now().duration_since(SystemTime::UNIX_EPOCH).unwrap()
- }
-
- fn elapsed(&self) -> Duration {
- std::time::Instant::elapsed(self)
- }
-}
-
-/// A state in which time has no meaning.
-#[derive(Debug, PartialEq, Eq)]
-pub struct Eternity;
-
-impl Time for Eternity {
- fn now() -> Self {
- Self
- }
-
- fn duration_since_epoch() -> Duration {
- Duration::from_secs(0)
- }
-
- fn elapsed(&self) -> Duration {
- Duration::from_secs(0)
- }
-}
-
-impl Sub<Duration> for Eternity {
- type Output = Self;
-
- fn sub(self, _other: Duration) -> Self {
- self
- }
-}
-
-impl<T: Time> Writeable for ScorerUsingTime<T> {
- #[inline]
- fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
- self.params.write(w)?;
- self.channel_failures.write(w)?;
- write_tlv_fields!(w, {});
- Ok(())
- }
-}
-
-impl<T: Time> Readable for ScorerUsingTime<T> {
- #[inline]
- fn read<R: Read>(r: &mut R) -> Result<Self, DecodeError> {
- let res = Ok(Self {
- params: Readable::read(r)?,
- channel_failures: Readable::read(r)?,
- });
- read_tlv_fields!(r, {});
- res
- }
-}
-
-impl<T: Time> Writeable for ChannelFailure<T> {
- #[inline]
- fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
- let duration_since_epoch = T::duration_since_epoch() - self.last_failed.elapsed();
- write_tlv_fields!(w, {
- (0, self.undecayed_penalty_msat, required),
- (2, duration_since_epoch, required),
- });
- Ok(())
- }
-}
-
-impl<T: Time> Readable for ChannelFailure<T> {
- #[inline]
- fn read<R: Read>(r: &mut R) -> Result<Self, DecodeError> {
- let mut undecayed_penalty_msat = 0;
- let mut duration_since_epoch = Duration::from_secs(0);
- read_tlv_fields!(r, {
- (0, undecayed_penalty_msat, required),
- (2, duration_since_epoch, required),
- });
- Ok(Self {
- undecayed_penalty_msat,
- last_failed: T::now() - (T::duration_since_epoch() - duration_since_epoch),
- })
- }
-}
-
-#[cfg(test)]
-mod tests {
- use super::{Eternity, ScoringParameters, ScorerUsingTime, Time};
-
- use routing::Score;
- use routing::network_graph::NodeId;
- use util::ser::{Readable, Writeable};
-
- use bitcoin::secp256k1::PublicKey;
- use core::cell::Cell;
- use core::ops::Sub;
- use core::time::Duration;
- use io;
-
- /// Time that can be advanced manually in tests.
- #[derive(Debug, PartialEq, Eq)]
- struct SinceEpoch(Duration);
-
- impl SinceEpoch {
- thread_local! {
- static ELAPSED: Cell<Duration> = core::cell::Cell::new(Duration::from_secs(0));
- }
-
- fn advance(duration: Duration) {
- Self::ELAPSED.with(|elapsed| elapsed.set(elapsed.get() + duration))
- }
- }
-
- impl Time for SinceEpoch {
- fn now() -> Self {
- Self(Self::duration_since_epoch())
- }
-
- fn duration_since_epoch() -> Duration {
- Self::ELAPSED.with(|elapsed| elapsed.get())
- }
-
- fn elapsed(&self) -> Duration {
- Self::duration_since_epoch() - self.0
- }
- }
-
- impl Sub<Duration> for SinceEpoch {
- type Output = Self;
-
- fn sub(self, other: Duration) -> Self {
- Self(self.0 - other)
- }
- }
-
- #[test]
- fn time_passes_when_advanced() {
- let now = SinceEpoch::now();
- assert_eq!(now.elapsed(), Duration::from_secs(0));
-
- SinceEpoch::advance(Duration::from_secs(1));
- SinceEpoch::advance(Duration::from_secs(1));
-
- let elapsed = now.elapsed();
- let later = SinceEpoch::now();
-
- assert_eq!(elapsed, Duration::from_secs(2));
- assert_eq!(later - elapsed, now);
- }
-
- #[test]
- fn time_never_passes_in_an_eternity() {
- let now = Eternity::now();
- let elapsed = now.elapsed();
- let later = Eternity::now();
-
- assert_eq!(now.elapsed(), Duration::from_secs(0));
- assert_eq!(later - elapsed, now);
- }
-
- /// A scorer for testing with time that can be manually advanced.
- type Scorer = ScorerUsingTime::<SinceEpoch>;
-
- fn source_node_id() -> NodeId {
- NodeId::from_pubkey(&PublicKey::from_slice(&hex::decode("02eec7245d6b7d2ccb30380bfbe2a3648cd7a942653f5aa340edcea1f283686619").unwrap()[..]).unwrap())
- }
-
- fn target_node_id() -> NodeId {
- NodeId::from_pubkey(&PublicKey::from_slice(&hex::decode("0324653eac434488002cc06bbfb7f10fe18991e35f9fe4302dbea6d2353dc0ab1c").unwrap()[..]).unwrap())
- }
-
- #[test]
- fn penalizes_without_channel_failures() {
- let scorer = Scorer::new(ScoringParameters {
- base_penalty_msat: 1_000,
- failure_penalty_msat: 512,
- failure_penalty_half_life: Duration::from_secs(1),
- overuse_penalty_start_1024th: 1024,
- overuse_penalty_msat_per_1024th: 0,
- });
- let source = source_node_id();
- let target = target_node_id();
- assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_000);
-
- SinceEpoch::advance(Duration::from_secs(1));
- assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_000);
- }
-
- #[test]
- fn accumulates_channel_failure_penalties() {
- let mut scorer = Scorer::new(ScoringParameters {
- base_penalty_msat: 1_000,
- failure_penalty_msat: 64,
- failure_penalty_half_life: Duration::from_secs(10),
- overuse_penalty_start_1024th: 1024,
- overuse_penalty_msat_per_1024th: 0,
- });
- let source = source_node_id();
- let target = target_node_id();
- assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_000);
-
- scorer.payment_path_failed(&[], 42);
- assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_064);
-
- scorer.payment_path_failed(&[], 42);
- assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_128);
-
- scorer.payment_path_failed(&[], 42);
- assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_192);
- }
-
- #[test]
- fn decays_channel_failure_penalties_over_time() {
- let mut scorer = Scorer::new(ScoringParameters {
- base_penalty_msat: 1_000,
- failure_penalty_msat: 512,
- failure_penalty_half_life: Duration::from_secs(10),
- overuse_penalty_start_1024th: 1024,
- overuse_penalty_msat_per_1024th: 0,
- });
- let source = source_node_id();
- let target = target_node_id();
- assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_000);
-
- scorer.payment_path_failed(&[], 42);
- assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_512);
-
- SinceEpoch::advance(Duration::from_secs(9));
- assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_512);
-
- SinceEpoch::advance(Duration::from_secs(1));
- assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_256);
-
- SinceEpoch::advance(Duration::from_secs(10 * 8));
- assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_001);
-
- SinceEpoch::advance(Duration::from_secs(10));
- assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_000);
-
- SinceEpoch::advance(Duration::from_secs(10));
- assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_000);
- }
-
- #[test]
- fn accumulates_channel_failure_penalties_after_decay() {
- let mut scorer = Scorer::new(ScoringParameters {
- base_penalty_msat: 1_000,
- failure_penalty_msat: 512,
- failure_penalty_half_life: Duration::from_secs(10),
- overuse_penalty_start_1024th: 1024,
- overuse_penalty_msat_per_1024th: 0,
- });
- let source = source_node_id();
- let target = target_node_id();
- assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_000);
-
- scorer.payment_path_failed(&[], 42);
- assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_512);
-
- SinceEpoch::advance(Duration::from_secs(10));
- assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_256);
-
- scorer.payment_path_failed(&[], 42);
- assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_768);
-
- SinceEpoch::advance(Duration::from_secs(10));
- assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_384);
- }
-
- #[test]
- fn restores_persisted_channel_failure_penalties() {
- let mut scorer = Scorer::new(ScoringParameters {
- base_penalty_msat: 1_000,
- failure_penalty_msat: 512,
- failure_penalty_half_life: Duration::from_secs(10),
- overuse_penalty_start_1024th: 1024,
- overuse_penalty_msat_per_1024th: 0,
- });
- let source = source_node_id();
- let target = target_node_id();
-
- scorer.payment_path_failed(&[], 42);
- assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_512);
-
- SinceEpoch::advance(Duration::from_secs(10));
- assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_256);
-
- scorer.payment_path_failed(&[], 43);
- assert_eq!(scorer.channel_penalty_msat(43, 1, Some(1), &source, &target), 1_512);
-
- let mut serialized_scorer = Vec::new();
- scorer.write(&mut serialized_scorer).unwrap();
-
- let deserialized_scorer = <Scorer>::read(&mut io::Cursor::new(&serialized_scorer)).unwrap();
- assert_eq!(deserialized_scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_256);
- assert_eq!(deserialized_scorer.channel_penalty_msat(43, 1, Some(1), &source, &target), 1_512);
- }
-
- #[test]
- fn decays_persisted_channel_failure_penalties() {
- let mut scorer = Scorer::new(ScoringParameters {
- base_penalty_msat: 1_000,
- failure_penalty_msat: 512,
- failure_penalty_half_life: Duration::from_secs(10),
- overuse_penalty_start_1024th: 1024,
- overuse_penalty_msat_per_1024th: 0,
- });
- let source = source_node_id();
- let target = target_node_id();
-
- scorer.payment_path_failed(&[], 42);
- assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_512);
-
- let mut serialized_scorer = Vec::new();
- scorer.write(&mut serialized_scorer).unwrap();
-
- SinceEpoch::advance(Duration::from_secs(10));
-
- let deserialized_scorer = <Scorer>::read(&mut io::Cursor::new(&serialized_scorer)).unwrap();
- assert_eq!(deserialized_scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_256);
-
- SinceEpoch::advance(Duration::from_secs(10));
- assert_eq!(deserialized_scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_128);
- }
-
- #[test]
- fn charges_per_1024th_penalty() {
- let scorer = Scorer::new(ScoringParameters {
- base_penalty_msat: 0,
- failure_penalty_msat: 0,
- failure_penalty_half_life: Duration::from_secs(0),
- overuse_penalty_start_1024th: 256,
- overuse_penalty_msat_per_1024th: 100,
- });
- let source = source_node_id();
- let target = target_node_id();
-
- assert_eq!(scorer.channel_penalty_msat(42, 1_000, None, &source, &target), 0);
- assert_eq!(scorer.channel_penalty_msat(42, 1_000, Some(1_024_000), &source, &target), 0);
- assert_eq!(scorer.channel_penalty_msat(42, 256_999, Some(1_024_000), &source, &target), 0);
- assert_eq!(scorer.channel_penalty_msat(42, 257_000, Some(1_024_000), &source, &target), 100);
- assert_eq!(scorer.channel_penalty_msat(42, 258_000, Some(1_024_000), &source, &target), 200);
- assert_eq!(scorer.channel_penalty_msat(42, 512_000, Some(1_024_000), &source, &target), 256 * 100);
- }
-}
projects / rust-lightning / blobdiff