/// 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.
+/// See [module-level documentation] for usage and [`ScoringParameters`] for customization.
///
/// [module-level documentation]: crate::routing::scoring
#[cfg(feature = "no-std")]
/// 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 built with the `no-std` feature, time will never elapse. Therefore, this penalty will
///
/// 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,
+ /// 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,
.or_insert_with(|| ChannelFailure::new(failure_penalty_msat));
}
- fn payment_path_successful(&mut self, _path: &[&RouteHop]) {}
+ 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 ScorerUsingTime<T> {
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),
})
}
}
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 {
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