//! # }
//! ```
//!
+//! # 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::*;
-#[cfg(not(feature = "no-std"))]
+use core::ops::Sub;
use core::time::Duration;
-#[cfg(not(feature = "no-std"))]
-use std::time::Instant;
+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. May also further penalize failed channels.
+/// 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 struct 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,
- #[cfg(not(feature = "no-std"))]
- channel_failures: HashMap<u64, (u64, Instant)>,
- #[cfg(feature = "no-std")]
- channel_failures: HashMap<u64, u64>,
+ // TODO: Remove entries of closed channels.
+ channel_failures: HashMap<u64, ChannelFailure<T>>,
}
/// Parameters for configuring [`Scorer`].
/// A fixed penalty in msats to apply to each channel.
pub base_penalty_msat: u64,
- /// A penalty in msats to apply to a channel upon failure.
+ /// A penalty in msats to apply to a channel upon failing to relay a payment.
///
- /// This may be reduced over time based on [`failure_penalty_half_life`].
+ /// This accumulates for each failure but may be reduced over time based on
+ /// [`failure_penalty_half_life`].
///
/// [`failure_penalty_half_life`]: Self::failure_penalty_half_life
pub failure_penalty_msat: u64,
- /// The time needed before any accumulated channel failure penalties are cut in half.
- #[cfg(not(feature = "no-std"))]
+ /// 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 Scorer {
+impl_writeable_tlv_based!(ScoringParameters, {
+ (0, base_penalty_msat, required),
+ (2, failure_penalty_msat, required),
+ (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 {
Self::new(ScoringParameters {
base_penalty_msat: penalty_msat,
failure_penalty_msat: 0,
- #[cfg(not(feature = "no-std"))]
failure_penalty_half_life: Duration::from_secs(0),
})
}
+}
+
+impl<T: Time> ChannelFailure<T> {
+ fn new(failure_penalty_msat: u64) -> Self {
+ Self {
+ undecayed_penalty_msat: failure_penalty_msat,
+ last_failed: T::now(),
+ }
+ }
- #[cfg(not(feature = "no-std"))]
- fn decay_from(&self, penalty_msat: u64, last_failure: &Instant) -> u64 {
- decay_from(penalty_msat, last_failure, self.params.failure_penalty_half_life)
+ 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 Default for Scorer {
+impl<T: Time> Default for ScorerUsingTime<T> {
fn default() -> Self {
- Scorer::new(ScoringParameters::default())
+ Self::new(ScoringParameters::default())
}
}
Self {
base_penalty_msat: 500,
failure_penalty_msat: 1024 * 1000,
- #[cfg(not(feature = "no-std"))]
failure_penalty_half_life: Duration::from_secs(3600),
}
}
}
-impl routing::Score for Scorer {
+impl<T: Time> routing::Score for ScorerUsingTime<T> {
fn channel_penalty_msat(
&self, short_channel_id: u64, _source: &NodeId, _target: &NodeId
) -> u64 {
- #[cfg(not(feature = "no-std"))]
- let failure_penalty_msat = match self.channel_failures.get(&short_channel_id) {
- Some((penalty_msat, last_failure)) => self.decay_from(*penalty_msat, last_failure),
- None => 0,
- };
- #[cfg(feature = "no-std")]
- let failure_penalty_msat =
- self.channel_failures.get(&short_channel_id).copied().unwrap_or(0);
+ 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));
self.params.base_penalty_msat + failure_penalty_msat
}
fn payment_path_failed(&mut self, _path: &Vec<RouteHop>, short_channel_id: u64) {
let failure_penalty_msat = self.params.failure_penalty_msat;
- #[cfg(not(feature = "no-std"))]
- {
- let half_life = self.params.failure_penalty_half_life;
- self.channel_failures
- .entry(short_channel_id)
- .and_modify(|(penalty_msat, last_failure)| {
- let decayed_penalty = decay_from(*penalty_msat, last_failure, half_life);
- *penalty_msat = decayed_penalty + failure_penalty_msat;
- *last_failure = Instant::now();
- })
- .or_insert_with(|| (failure_penalty_msat, Instant::now()));
- }
- #[cfg(feature = "no-std")]
+ let half_life = self.params.failure_penalty_half_life;
self.channel_failures
.entry(short_channel_id)
- .and_modify(|penalty_msat| *penalty_msat += failure_penalty_msat)
- .or_insert(failure_penalty_msat);
+ .and_modify(|failure| failure.add_penalty(failure_penalty_msat, half_life))
+ .or_insert_with(|| ChannelFailure::new(failure_penalty_msat));
}
}
#[cfg(not(feature = "no-std"))]
-fn decay_from(penalty_msat: u64, last_failure: &Instant, half_life: Duration) -> u64 {
- let decays = last_failure.elapsed().as_secs().checked_div(half_life.as_secs());
- match decays {
- Some(decays) => penalty_msat >> decays,
- None => 0,
+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.
+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)
+ }
+}
+
+impl<T: Time> Readable for ScorerUsingTime<T> {
+ #[inline]
+ fn read<R: Read>(r: &mut R) -> Result<Self, DecodeError> {
+ Ok(Self {
+ params: Readable::read(r)?,
+ channel_failures: Readable::read(r)?,
+ })
+ }
+}
+
+impl<T: Time> Writeable for ChannelFailure<T> {
+ #[inline]
+ fn write<W: Writer>(&self, w: &mut W) -> Result<(), io::Error> {
+ self.undecayed_penalty_msat.write(w)?;
+ (T::duration_since_epoch() - self.last_failed.elapsed()).write(w)
+ }
+}
+
+impl<T: Time> Readable for ChannelFailure<T> {
+ #[inline]
+ fn read<R: Read>(r: &mut R) -> Result<Self, DecodeError> {
+ Ok(Self {
+ undecayed_penalty_msat: Readable::read(r)?,
+ last_failed: T::now() - (T::duration_since_epoch() - Readable::read(r)?),
+ })
}
}
projects / rust-lightning / blobdiff