//!
//! # 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.
+//! 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 prelude::*;
use core::cell::{RefCell, RefMut};
-use core::ops::{DerefMut, Sub};
+use core::ops::DerefMut;
use core::time::Duration;
-use io::{self, Read}; use sync::{Mutex, MutexGuard};
+use io::{self, Read};
+use sync::{Mutex, MutexGuard};
/// We define Score ever-so-slightly differently based on whether we are being built for C bindings
/// or not. For users, `LockableScore` must somehow be writeable to disk. For Rust users, this is
/// Handles updating channel penalties after failing to route through a channel.
fn payment_path_failed(&mut self, path: &[&RouteHop], short_channel_id: u64);
+
+ /// Handles updating channel penalties after successfully routing along a path.
+ fn payment_path_successful(&mut self, path: &[&RouteHop]);
}
impl<S: Score, T: DerefMut<Target=S> $(+ $supertrait)*> Score for T {
fn payment_path_failed(&mut self, path: &[&RouteHop], short_channel_id: u64) {
self.deref_mut().payment_path_failed(path, short_channel_id)
}
+
+ fn payment_path_successful(&mut self, path: &[&RouteHop]) {
+ self.deref_mut().payment_path_successful(path)
+ }
}
} }
/// See [module-level documentation] for usage.
///
/// [module-level documentation]: crate::routing::scoring
-pub type Scorer = ScorerUsingTime::<DefaultTime>;
-
-/// Time used by [`Scorer`].
#[cfg(not(feature = "no-std"))]
-pub type DefaultTime = std::time::Instant;
-
-/// Time used by [`Scorer`].
+pub type Scorer = ScorerUsingTime::<std::time::Instant>;
+/// [`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 and [`ScoringParameters`] for customization.
+///
+/// [module-level documentation]: crate::routing::scoring
#[cfg(feature = "no-std")]
-pub type DefaultTime = Eternity;
+pub type Scorer = ScorerUsingTime::<time::Eternity>;
+
+// Note that ideally we'd hide ScorerUsingTime from public view by sealing it as well, but rustdoc
+// doesn't handle this well - instead exposing a `Scorer` which has no trait implementation(s) or
+// methods at all.
-/// [`Score`] implementation parameterized by [`Time`].
+/// [`Score`] implementation.
///
/// See [`Scorer`] for details.
///
/// # Note
///
-/// Mixing [`Time`] types between serialization and deserialization results in undefined behavior.
+/// Mixing the `no-std` feature between serialization and deserialization results in undefined
+/// behavior.
+///
+/// (C-not exported) generally all users should use the [`Scorer`] type alias.
pub struct ScorerUsingTime<T: Time> {
params: ScoringParameters,
// TODO: Remove entries of closed channels.
/// 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`].
+ /// [`failure_penalty_half_life`] or when successfully routing through a channel.
///
/// Default value: 1,024,000 msat
///
/// The time required to elapse before any accumulated [`failure_penalty_msat`] penalties are
/// cut in half.
///
+ /// Successfully routing through a channel will immediately cut the penalty in half as well.
+ ///
/// # Note
///
- /// When time is an [`Eternity`], as is default when enabling feature `no-std`, it will never
- /// elapse. Therefore, this penalty will never decay.
+ /// When built with the `no-std` feature, time will never elapse. Therefore, this penalty will
+ /// never decay.
///
/// [`failure_penalty_msat`]: Self::failure_penalty_msat
pub failure_penalty_half_life: Duration,
///
/// 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`.
+ /// Accumulated penalty in msats for the channel as of `last_updated`.
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;
+ /// Last time the channel either failed to route or successfully routed a payment. Used to decay
+ /// `undecayed_penalty_msat`.
+ last_updated: T,
}
impl<T: Time> ScorerUsingTime<T> {
fn new(failure_penalty_msat: u64) -> Self {
Self {
undecayed_penalty_msat: failure_penalty_msat,
- last_failed: T::now(),
+ last_updated: 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();
+ self.last_updated = T::now();
+ }
+
+ fn reduce_penalty(&mut self, half_life: Duration) {
+ self.undecayed_penalty_msat = self.decayed_penalty_msat(half_life) >> 1;
+ self.last_updated = 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());
+ let decays = self.last_updated.elapsed().as_secs().checked_div(half_life.as_secs());
match decays {
Some(decays) => self.undecayed_penalty_msat >> decays,
None => 0,
.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
+ fn payment_path_successful(&mut self, path: &[&RouteHop]) {
+ let half_life = self.params.failure_penalty_half_life;
+ for hop in path.iter() {
+ self.channel_failures
+ .entry(hop.short_channel_id)
+ .and_modify(|failure| failure.reduce_penalty(half_life));
+ }
}
}
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();
+ let duration_since_epoch = T::duration_since_epoch() - self.last_updated.elapsed();
write_tlv_fields!(w, {
(0, self.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),
+ last_updated: T::now() - (T::duration_since_epoch() - duration_since_epoch),
})
}
}
+pub(crate) mod time {
+ use core::ops::Sub;
+ use core::time::Duration;
+ /// 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;
+ }
+
+ /// A state in which time has no meaning.
+ #[derive(Debug, PartialEq, Eq)]
+ pub struct Eternity;
+
+ #[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)
+ }
+ }
+
+ 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
+ }
+ }
+}
+
+pub(crate) use self::time::Time;
+
#[cfg(test)]
mod tests {
- use super::{Eternity, ScoringParameters, ScorerUsingTime, Time};
+ use super::{ScoringParameters, ScorerUsingTime, Time};
+ use super::time::Eternity;
+ use ln::features::{ChannelFeatures, NodeFeatures};
use routing::scoring::Score;
use routing::network_graph::NodeId;
+ use routing::router::RouteHop;
use util::ser::{Readable, Writeable};
use bitcoin::secp256k1::PublicKey;
assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_384);
}
+ #[test]
+ fn reduces_channel_failure_penalties_after_success() {
+ 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);
+
+ let hop = RouteHop {
+ pubkey: PublicKey::from_slice(target.as_slice()).unwrap(),
+ node_features: NodeFeatures::known(),
+ short_channel_id: 42,
+ channel_features: ChannelFeatures::known(),
+ fee_msat: 1,
+ cltv_expiry_delta: 18,
+ };
+ scorer.payment_path_successful(&[&hop]);
+ assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_128);
+
+ SinceEpoch::advance(Duration::from_secs(10));
+ assert_eq!(scorer.channel_penalty_msat(42, 1, Some(1), &source, &target), 1_064);
+ }
+
#[test]
fn restores_persisted_channel_failure_penalties() {
let mut scorer = Scorer::new(ScoringParameters {
projects / rust-lightning / blobdiff