Move network_graph.rs to gossip.rs
[rust-lightning] / lightning / src / routing / scoring.rs
index cffd2d90533b7290250b5a4886ad8c55fa5462fd..54400624dce63a30ec0e506bfc1c87800a6bac4a 100644 (file)
@@ -17,9 +17,9 @@
 //! ```
 //! # extern crate bitcoin;
 //! #
-//! # use lightning::routing::network_graph::NetworkGraph;
+//! # use lightning::routing::gossip::NetworkGraph;
 //! # use lightning::routing::router::{RouteParameters, find_route};
-//! # use lightning::routing::scoring::{ProbabilisticScorer, ProbabilisticScoringParameters, Scorer, ScoringParameters};
+//! # use lightning::routing::scoring::{ProbabilisticScorer, ProbabilisticScoringParameters};
 //! # use lightning::chain::keysinterface::{KeysManager, KeysInterface};
 //! # use lightning::util::logger::{Logger, Record};
 //! # use bitcoin::secp256k1::PublicKey;
@@ -55,7 +55,7 @@
 //! [`find_route`]: crate::routing::router::find_route
 
 use ln::msgs::DecodeError;
-use routing::network_graph::{NetworkGraph, NodeId};
+use routing::gossip::{EffectiveCapacity, NetworkGraph, NodeId};
 use routing::router::RouteHop;
 use util::ser::{Readable, ReadableArgs, Writeable, Writer};
 use util::logger::Logger;
@@ -93,7 +93,9 @@ pub trait Score $(: $supertrait)* {
        /// such as a chain data, network gossip, or invoice hints. For invoice hints, a capacity near
        /// [`u64::max_value`] is given to indicate sufficient capacity for the invoice's full amount.
        /// Thus, implementations should be overflow-safe.
-       fn channel_penalty_msat(&self, short_channel_id: u64, send_amt_msat: u64, capacity_msat: u64, source: &NodeId, target: &NodeId) -> u64;
+       fn channel_penalty_msat(
+               &self, short_channel_id: u64, source: &NodeId, target: &NodeId, usage: ChannelUsage
+       ) -> u64;
 
        /// Handles updating channel penalties after failing to route through a channel.
        fn payment_path_failed(&mut self, path: &[&RouteHop], short_channel_id: u64);
@@ -103,8 +105,10 @@ pub trait Score $(: $supertrait)* {
 }
 
 impl<S: Score, T: DerefMut<Target=S> $(+ $supertrait)*> Score for T {
-       fn channel_penalty_msat(&self, short_channel_id: u64, send_amt_msat: u64, capacity_msat: u64, source: &NodeId, target: &NodeId) -> u64 {
-               self.deref().channel_penalty_msat(short_channel_id, send_amt_msat, capacity_msat, source, target)
+       fn channel_penalty_msat(
+               &self, short_channel_id: u64, source: &NodeId, target: &NodeId, usage: ChannelUsage
+       ) -> u64 {
+               self.deref().channel_penalty_msat(short_channel_id, source, target, usage)
        }
 
        fn payment_path_failed(&mut self, path: &[&RouteHop], short_channel_id: u64) {
@@ -202,6 +206,20 @@ impl<'a, S: Writeable> Writeable for MutexGuard<'a, S> {
        }
 }
 
+/// Proposed use of a channel passed as a parameter to [`Score::channel_penalty_msat`].
+#[derive(Clone, Copy)]
+pub struct ChannelUsage {
+       /// The amount to send through the channel, denominated in millisatoshis.
+       pub amount_msat: u64,
+
+       /// Total amount, denominated in millisatoshis, already allocated to send through the channel
+       /// as part of a multi-path payment.
+       pub inflight_htlc_msat: u64,
+
+       /// The effective capacity of the channel.
+       pub effective_capacity: EffectiveCapacity,
+}
+
 #[derive(Clone)]
 /// [`Score`] implementation that uses a fixed penalty.
 pub struct FixedPenaltyScorer {
@@ -216,7 +234,7 @@ impl FixedPenaltyScorer {
 }
 
 impl Score for FixedPenaltyScorer {
-       fn channel_penalty_msat(&self, _: u64, _: u64, _: u64, _: &NodeId, _: &NodeId) -> u64 {
+       fn channel_penalty_msat(&self, _: u64, _: &NodeId, _: &NodeId, _: ChannelUsage) -> u64 {
                self.penalty_msat
        }
 
@@ -241,25 +259,6 @@ impl ReadableArgs<u64> for FixedPenaltyScorer {
        }
 }
 
-/// [`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.
-///
-/// # Note
-///
-/// Mixing the `no-std` feature between serialization and deserialization results in undefined
-/// behavior.
-///
-/// [module-level documentation]: crate::routing::scoring
-#[deprecated(
-       since = "0.0.105",
-       note = "ProbabilisticScorer should be used instead of Scorer.",
-)]
-pub type Scorer = ScorerUsingTime::<ConfiguredTime>;
-
 #[cfg(not(feature = "no-std"))]
 type ConfiguredTime = std::time::Instant;
 #[cfg(feature = "no-std")]
@@ -267,233 +266,6 @@ use util::time::Eternity;
 #[cfg(feature = "no-std")]
 type ConfiguredTime = 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.
-///
-/// (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.
-       channel_failures: HashMap<u64, ChannelFailure<T>>,
-}
-
-#[derive(Clone)]
-/// 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`] or when successfully routing through a channel.
-       ///
-       /// 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.
-       ///
-       /// Successfully routing through a channel will immediately cut the penalty in half as well.
-       ///
-       /// Default value: 1 hour
-       ///
-       /// # Note
-       ///
-       /// 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,
-}
-
-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_updated`.
-       undecayed_penalty_msat: u64,
-
-       /// 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> {
-       /// Creates a new scorer using the given scoring parameters.
-       pub fn new(params: ScoringParameters) -> Self {
-               Self {
-                       params,
-                       channel_failures: HashMap::new(),
-               }
-       }
-}
-
-impl<T: Time> ChannelFailure<T> {
-       fn new(failure_penalty_msat: u64) -> Self {
-               Self {
-                       undecayed_penalty_msat: failure_penalty_msat,
-                       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_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 {
-               self.last_updated.elapsed().as_secs()
-                       .checked_div(half_life.as_secs())
-                       .and_then(|decays| self.undecayed_penalty_msat.checked_shr(decays as u32))
-                       .unwrap_or(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> Score for ScorerUsingTime<T> {
-       fn channel_penalty_msat(
-               &self, short_channel_id: u64, send_amt_msat: u64, capacity_msat: 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;
-               let send_1024ths = send_amt_msat.checked_mul(1024).unwrap_or(u64::max_value()) / 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));
-       }
-
-       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> {
-       #[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_updated.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_updated: T::now() - (T::duration_since_epoch() - duration_since_epoch),
-               })
-       }
-}
-
 /// [`Score`] implementation using channel success probability distributions.
 ///
 /// Based on *Optimally Reliable & Cheap Payment Flows on the Lightning Network* by Rene Pickhardt
@@ -880,10 +652,20 @@ impl<L: DerefMut<Target = u64>, T: Time, U: DerefMut<Target = T>> DirectedChanne
 
 impl<G: Deref<Target = NetworkGraph>, L: Deref, T: Time> Score for ProbabilisticScorerUsingTime<G, L, T> where L::Target: Logger {
        fn channel_penalty_msat(
-               &self, short_channel_id: u64, amount_msat: u64, capacity_msat: u64, source: &NodeId,
-               target: &NodeId
+               &self, short_channel_id: u64, source: &NodeId, target: &NodeId, usage: ChannelUsage
        ) -> u64 {
+               if let EffectiveCapacity::ExactLiquidity { liquidity_msat } = usage.effective_capacity {
+                       if usage.amount_msat > liquidity_msat {
+                               return u64::max_value();
+                       } else {
+                               return self.params.base_penalty_msat;
+                       };
+               }
+
                let liquidity_offset_half_life = self.params.liquidity_offset_half_life;
+               let amount_msat = usage.amount_msat;
+               let capacity_msat = usage.effective_capacity.as_msat()
+                       .saturating_sub(usage.inflight_htlc_msat);
                self.channel_liquidities
                        .get(&short_channel_id)
                        .unwrap_or(&ChannelLiquidity::new())
@@ -1332,16 +1114,16 @@ impl<T: Time> Readable for ChannelLiquidity<T> {
 
 #[cfg(test)]
 mod tests {
-       use super::{ChannelLiquidity, ProbabilisticScoringParameters, ProbabilisticScorerUsingTime, ScoringParameters, ScorerUsingTime};
+       use super::{ChannelLiquidity, ProbabilisticScoringParameters, ProbabilisticScorerUsingTime};
        use util::time::Time;
        use util::time::tests::SinceEpoch;
 
        use ln::features::{ChannelFeatures, NodeFeatures};
        use ln::msgs::{ChannelAnnouncement, ChannelUpdate, OptionalField, UnsignedChannelAnnouncement, UnsignedChannelUpdate};
-       use routing::scoring::Score;
-       use routing::network_graph::{NetworkGraph, NodeId};
+       use routing::gossip::{EffectiveCapacity, NetworkGraph, NodeId};
        use routing::router::RouteHop;
-       use util::ser::{Readable, ReadableArgs, Writeable};
+       use routing::scoring::{ChannelUsage, Score};
+       use util::ser::{ReadableArgs, Writeable};
        use util::test_utils::TestLogger;
 
        use bitcoin::blockdata::constants::genesis_block;
@@ -1352,9 +1134,6 @@ mod tests {
        use core::time::Duration;
        use io;
 
-       /// A scorer for testing with time that can be manually advanced.
-       type Scorer = ScorerUsingTime::<SinceEpoch>;
-
        fn source_privkey() -> SecretKey {
                SecretKey::from_slice(&[42; 32]).unwrap()
        }
@@ -1381,238 +1160,6 @@ mod tests {
                NodeId::from_pubkey(&target_pubkey())
        }
 
-       #[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, 1, &source, &target), 1_000);
-
-               SinceEpoch::advance(Duration::from_secs(1));
-               assert_eq!(scorer.channel_penalty_msat(42, 1, 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, 1, &source, &target), 1_000);
-
-               scorer.payment_path_failed(&[], 42);
-               assert_eq!(scorer.channel_penalty_msat(42, 1, 1, &source, &target), 1_064);
-
-               scorer.payment_path_failed(&[], 42);
-               assert_eq!(scorer.channel_penalty_msat(42, 1, 1, &source, &target), 1_128);
-
-               scorer.payment_path_failed(&[], 42);
-               assert_eq!(scorer.channel_penalty_msat(42, 1, 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, 1, &source, &target), 1_000);
-
-               scorer.payment_path_failed(&[], 42);
-               assert_eq!(scorer.channel_penalty_msat(42, 1, 1, &source, &target), 1_512);
-
-               SinceEpoch::advance(Duration::from_secs(9));
-               assert_eq!(scorer.channel_penalty_msat(42, 1, 1, &source, &target), 1_512);
-
-               SinceEpoch::advance(Duration::from_secs(1));
-               assert_eq!(scorer.channel_penalty_msat(42, 1, 1, &source, &target), 1_256);
-
-               SinceEpoch::advance(Duration::from_secs(10 * 8));
-               assert_eq!(scorer.channel_penalty_msat(42, 1, 1, &source, &target), 1_001);
-
-               SinceEpoch::advance(Duration::from_secs(10));
-               assert_eq!(scorer.channel_penalty_msat(42, 1, 1, &source, &target), 1_000);
-
-               SinceEpoch::advance(Duration::from_secs(10));
-               assert_eq!(scorer.channel_penalty_msat(42, 1, 1, &source, &target), 1_000);
-       }
-
-       #[test]
-       fn decays_channel_failure_penalties_without_shift_overflow() {
-               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, 1, &source, &target), 1_000);
-
-               scorer.payment_path_failed(&[], 42);
-               assert_eq!(scorer.channel_penalty_msat(42, 1, 1, &source, &target), 1_512);
-
-               // An unchecked right shift 64 bits or more in ChannelFailure::decayed_penalty_msat would
-               // cause an overflow.
-               SinceEpoch::advance(Duration::from_secs(10 * 64));
-               assert_eq!(scorer.channel_penalty_msat(42, 1, 1, &source, &target), 1_000);
-
-               SinceEpoch::advance(Duration::from_secs(10));
-               assert_eq!(scorer.channel_penalty_msat(42, 1, 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, 1, &source, &target), 1_000);
-
-               scorer.payment_path_failed(&[], 42);
-               assert_eq!(scorer.channel_penalty_msat(42, 1, 1, &source, &target), 1_512);
-
-               SinceEpoch::advance(Duration::from_secs(10));
-               assert_eq!(scorer.channel_penalty_msat(42, 1, 1, &source, &target), 1_256);
-
-               scorer.payment_path_failed(&[], 42);
-               assert_eq!(scorer.channel_penalty_msat(42, 1, 1, &source, &target), 1_768);
-
-               SinceEpoch::advance(Duration::from_secs(10));
-               assert_eq!(scorer.channel_penalty_msat(42, 1, 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, 1, &source, &target), 1_000);
-
-               scorer.payment_path_failed(&[], 42);
-               assert_eq!(scorer.channel_penalty_msat(42, 1, 1, &source, &target), 1_512);
-
-               SinceEpoch::advance(Duration::from_secs(10));
-               assert_eq!(scorer.channel_penalty_msat(42, 1, 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, 1, &source, &target), 1_128);
-
-               SinceEpoch::advance(Duration::from_secs(10));
-               assert_eq!(scorer.channel_penalty_msat(42, 1, 1, &source, &target), 1_064);
-       }
-
-       #[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, 1, &source, &target), 1_512);
-
-               SinceEpoch::advance(Duration::from_secs(10));
-               assert_eq!(scorer.channel_penalty_msat(42, 1, 1, &source, &target), 1_256);
-
-               scorer.payment_path_failed(&[], 43);
-               assert_eq!(scorer.channel_penalty_msat(43, 1, 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, 1, &source, &target), 1_256);
-               assert_eq!(deserialized_scorer.channel_penalty_msat(43, 1, 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, 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, 1, &source, &target), 1_256);
-
-               SinceEpoch::advance(Duration::from_secs(10));
-               assert_eq!(deserialized_scorer.channel_penalty_msat(42, 1, 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, 1_024_000, &source, &target), 0);
-               assert_eq!(scorer.channel_penalty_msat(42, 256_999, 1_024_000, &source, &target), 0);
-               assert_eq!(scorer.channel_penalty_msat(42, 257_000, 1_024_000, &source, &target), 100);
-               assert_eq!(scorer.channel_penalty_msat(42, 258_000, 1_024_000, &source, &target), 200);
-               assert_eq!(scorer.channel_penalty_msat(42, 512_000, 1_024_000, &source, &target), 256 * 100);
-       }
-
        // `ProbabilisticScorer` tests
 
        /// A probabilistic scorer for testing with time that can be manually advanced.
@@ -1943,18 +1490,37 @@ mod tests {
                let source = source_node_id();
                let target = target_node_id();
 
-               assert_eq!(scorer.channel_penalty_msat(42, 1_024, 1_024_000, &source, &target), 0);
-               assert_eq!(scorer.channel_penalty_msat(42, 10_240, 1_024_000, &source, &target), 0);
-               assert_eq!(scorer.channel_penalty_msat(42, 102_400, 1_024_000, &source, &target), 47);
-               assert_eq!(scorer.channel_penalty_msat(42, 1_024_000, 1_024_000, &source, &target), 2_000);
-
-               assert_eq!(scorer.channel_penalty_msat(42, 128, 1_024, &source, &target), 58);
-               assert_eq!(scorer.channel_penalty_msat(42, 256, 1_024, &source, &target), 125);
-               assert_eq!(scorer.channel_penalty_msat(42, 374, 1_024, &source, &target), 198);
-               assert_eq!(scorer.channel_penalty_msat(42, 512, 1_024, &source, &target), 300);
-               assert_eq!(scorer.channel_penalty_msat(42, 640, 1_024, &source, &target), 425);
-               assert_eq!(scorer.channel_penalty_msat(42, 768, 1_024, &source, &target), 602);
-               assert_eq!(scorer.channel_penalty_msat(42, 896, 1_024, &source, &target), 902);
+               let usage = ChannelUsage {
+                       amount_msat: 1_024,
+                       inflight_htlc_msat: 0,
+                       effective_capacity: EffectiveCapacity::Total { capacity_msat: 1_024_000 },
+               };
+               assert_eq!(scorer.channel_penalty_msat(42, &source, &target, usage), 0);
+               let usage = ChannelUsage { amount_msat: 10_240, ..usage };
+               assert_eq!(scorer.channel_penalty_msat(42, &source, &target, usage), 0);
+               let usage = ChannelUsage { amount_msat: 102_400, ..usage };
+               assert_eq!(scorer.channel_penalty_msat(42, &source, &target, usage), 47);
+               let usage = ChannelUsage { amount_msat: 1_024_000, ..usage };
+               assert_eq!(scorer.channel_penalty_msat(42, &source, &target, usage), 2_000);
+
+               let usage = ChannelUsage {
+                       amount_msat: 128,
+                       inflight_htlc_msat: 0,
+                       effective_capacity: EffectiveCapacity::Total { capacity_msat: 1_024 },
+               };
+               assert_eq!(scorer.channel_penalty_msat(42, &source, &target, usage), 58);
+               let usage = ChannelUsage { amount_msat: 256, ..usage };
+               assert_eq!(scorer.channel_penalty_msat(42, &source, &target, usage), 125);
+               let usage = ChannelUsage { amount_msat: 374, ..usage };
+               assert_eq!(scorer.channel_penalty_msat(42, &source, &target, usage), 198);
+               let usage = ChannelUsage { amount_msat: 512, ..usage };
+               assert_eq!(scorer.channel_penalty_msat(42, &source, &target, usage), 300);
+               let usage = ChannelUsage { amount_msat: 640, ..usage };
+               assert_eq!(scorer.channel_penalty_msat(42, &source, &target, usage), 425);
+               let usage = ChannelUsage { amount_msat: 768, ..usage };
+               assert_eq!(scorer.channel_penalty_msat(42, &source, &target, usage), 602);
+               let usage = ChannelUsage { amount_msat: 896, ..usage };
+               assert_eq!(scorer.channel_penalty_msat(42, &source, &target, usage), 902);
        }
 
        #[test]
@@ -1974,10 +1540,17 @@ mod tests {
                let source = source_node_id();
                let target = target_node_id();
 
-               assert_eq!(scorer.channel_penalty_msat(42, 39, 100, &source, &target), 0);
-               assert_ne!(scorer.channel_penalty_msat(42, 50, 100, &source, &target), 0);
-               assert_ne!(scorer.channel_penalty_msat(42, 50, 100, &source, &target), u64::max_value());
-               assert_eq!(scorer.channel_penalty_msat(42, 61, 100, &source, &target), u64::max_value());
+               let usage = ChannelUsage {
+                       amount_msat: 39,
+                       inflight_htlc_msat: 0,
+                       effective_capacity: EffectiveCapacity::Total { capacity_msat: 100 },
+               };
+               assert_eq!(scorer.channel_penalty_msat(42, &source, &target, usage), 0);
+               let usage = ChannelUsage { amount_msat: 50, ..usage };
+               assert_ne!(scorer.channel_penalty_msat(42, &source, &target, usage), 0);
+               assert_ne!(scorer.channel_penalty_msat(42, &source, &target, usage), u64::max_value());
+               let usage = ChannelUsage { amount_msat: 61, ..usage };
+               assert_eq!(scorer.channel_penalty_msat(42, &source, &target, usage), u64::max_value());
        }
 
        #[test]
@@ -1991,16 +1564,21 @@ mod tests {
                let mut scorer = ProbabilisticScorer::new(params, &network_graph, &logger);
                let sender = sender_node_id();
                let source = source_node_id();
+               let usage = ChannelUsage {
+                       amount_msat: 500,
+                       inflight_htlc_msat: 0,
+                       effective_capacity: EffectiveCapacity::Total { capacity_msat: 1_000 },
+               };
                let failed_path = payment_path_for_amount(500);
                let successful_path = payment_path_for_amount(200);
 
-               assert_eq!(scorer.channel_penalty_msat(41, 500, 1_000, &sender, &source), 301);
+               assert_eq!(scorer.channel_penalty_msat(41, &sender, &source, usage), 301);
 
                scorer.payment_path_failed(&failed_path.iter().collect::<Vec<_>>(), 41);
-               assert_eq!(scorer.channel_penalty_msat(41, 500, 1_000, &sender, &source), 301);
+               assert_eq!(scorer.channel_penalty_msat(41, &sender, &source, usage), 301);
 
                scorer.payment_path_successful(&successful_path.iter().collect::<Vec<_>>());
-               assert_eq!(scorer.channel_penalty_msat(41, 500, 1_000, &sender, &source), 301);
+               assert_eq!(scorer.channel_penalty_msat(41, &sender, &source, usage), 301);
        }
 
        #[test]
@@ -2016,15 +1594,25 @@ mod tests {
                let target = target_node_id();
                let path = payment_path_for_amount(500);
 
-               assert_eq!(scorer.channel_penalty_msat(42, 250, 1_000, &source, &target), 128);
-               assert_eq!(scorer.channel_penalty_msat(42, 500, 1_000, &source, &target), 301);
-               assert_eq!(scorer.channel_penalty_msat(42, 750, 1_000, &source, &target), 602);
+               let usage = ChannelUsage {
+                       amount_msat: 250,
+                       inflight_htlc_msat: 0,
+                       effective_capacity: EffectiveCapacity::Total { capacity_msat: 1_000 },
+               };
+               assert_eq!(scorer.channel_penalty_msat(42, &source, &target, usage), 128);
+               let usage = ChannelUsage { amount_msat: 500, ..usage };
+               assert_eq!(scorer.channel_penalty_msat(42, &source, &target, usage), 301);
+               let usage = ChannelUsage { amount_msat: 750, ..usage };
+               assert_eq!(scorer.channel_penalty_msat(42, &source, &target, usage), 602);
 
                scorer.payment_path_failed(&path.iter().collect::<Vec<_>>(), 43);
 
-               assert_eq!(scorer.channel_penalty_msat(42, 250, 1_000, &source, &target), 0);
-               assert_eq!(scorer.channel_penalty_msat(42, 500, 1_000, &source, &target), 0);
-               assert_eq!(scorer.channel_penalty_msat(42, 750, 1_000, &source, &target), 300);
+               let usage = ChannelUsage { amount_msat: 250, ..usage };
+               assert_eq!(scorer.channel_penalty_msat(42, &source, &target, usage), 0);
+               let usage = ChannelUsage { amount_msat: 500, ..usage };
+               assert_eq!(scorer.channel_penalty_msat(42, &source, &target, usage), 0);
+               let usage = ChannelUsage { amount_msat: 750, ..usage };
+               assert_eq!(scorer.channel_penalty_msat(42, &source, &target, usage), 300);
        }
 
        #[test]
@@ -2040,15 +1628,25 @@ mod tests {
                let target = target_node_id();
                let path = payment_path_for_amount(500);
 
-               assert_eq!(scorer.channel_penalty_msat(42, 250, 1_000, &source, &target), 128);
-               assert_eq!(scorer.channel_penalty_msat(42, 500, 1_000, &source, &target), 301);
-               assert_eq!(scorer.channel_penalty_msat(42, 750, 1_000, &source, &target), 602);
+               let usage = ChannelUsage {
+                       amount_msat: 250,
+                       inflight_htlc_msat: 0,
+                       effective_capacity: EffectiveCapacity::Total { capacity_msat: 1_000 },
+               };
+               assert_eq!(scorer.channel_penalty_msat(42, &source, &target, usage), 128);
+               let usage = ChannelUsage { amount_msat: 500, ..usage };
+               assert_eq!(scorer.channel_penalty_msat(42, &source, &target, usage), 301);
+               let usage = ChannelUsage { amount_msat: 750, ..usage };
+               assert_eq!(scorer.channel_penalty_msat(42, &source, &target, usage), 602);
 
                scorer.payment_path_failed(&path.iter().collect::<Vec<_>>(), 42);
 
-               assert_eq!(scorer.channel_penalty_msat(42, 250, 1_000, &source, &target), 300);
-               assert_eq!(scorer.channel_penalty_msat(42, 500, 1_000, &source, &target), u64::max_value());
-               assert_eq!(scorer.channel_penalty_msat(42, 750, 1_000, &source, &target), u64::max_value());
+               let usage = ChannelUsage { amount_msat: 250, ..usage };
+               assert_eq!(scorer.channel_penalty_msat(42, &source, &target, usage), 300);
+               let usage = ChannelUsage { amount_msat: 500, ..usage };
+               assert_eq!(scorer.channel_penalty_msat(42, &source, &target, usage), u64::max_value());
+               let usage = ChannelUsage { amount_msat: 750, ..usage };
+               assert_eq!(scorer.channel_penalty_msat(42, &source, &target, usage), u64::max_value());
        }
 
        #[test]
@@ -2064,17 +1662,22 @@ mod tests {
                let source = source_node_id();
                let target = target_node_id();
                let recipient = recipient_node_id();
+               let usage = ChannelUsage {
+                       amount_msat: 250,
+                       inflight_htlc_msat: 0,
+                       effective_capacity: EffectiveCapacity::Total { capacity_msat: 1_000 },
+               };
                let path = payment_path_for_amount(500);
 
-               assert_eq!(scorer.channel_penalty_msat(41, 250, 1_000, &sender, &source), 128);
-               assert_eq!(scorer.channel_penalty_msat(42, 250, 1_000, &source, &target), 128);
-               assert_eq!(scorer.channel_penalty_msat(43, 250, 1_000, &target, &recipient), 128);
+               assert_eq!(scorer.channel_penalty_msat(41, &sender, &source, usage), 128);
+               assert_eq!(scorer.channel_penalty_msat(42, &source, &target, usage), 128);
+               assert_eq!(scorer.channel_penalty_msat(43, &target, &recipient, usage), 128);
 
                scorer.payment_path_successful(&path.iter().collect::<Vec<_>>());
 
-               assert_eq!(scorer.channel_penalty_msat(41, 250, 1_000, &sender, &source), 128);
-               assert_eq!(scorer.channel_penalty_msat(42, 250, 1_000, &source, &target), 300);
-               assert_eq!(scorer.channel_penalty_msat(43, 250, 1_000, &target, &recipient), 300);
+               assert_eq!(scorer.channel_penalty_msat(41, &sender, &source, usage), 128);
+               assert_eq!(scorer.channel_penalty_msat(42, &source, &target, usage), 300);
+               assert_eq!(scorer.channel_penalty_msat(43, &target, &recipient, usage), 300);
        }
 
        #[test]
@@ -2090,44 +1693,70 @@ mod tests {
                let source = source_node_id();
                let target = target_node_id();
 
-               assert_eq!(scorer.channel_penalty_msat(42, 0, 1_024, &source, &target), 0);
-               assert_eq!(scorer.channel_penalty_msat(42, 1_024, 1_024, &source, &target), 2_000);
+               let usage = ChannelUsage {
+                       amount_msat: 0,
+                       inflight_htlc_msat: 0,
+                       effective_capacity: EffectiveCapacity::Total { capacity_msat: 1_024 },
+               };
+               assert_eq!(scorer.channel_penalty_msat(42, &source, &target, usage), 0);
+               let usage = ChannelUsage { amount_msat: 1_024, ..usage };
+               assert_eq!(scorer.channel_penalty_msat(42, &source, &target, usage), 2_000);
 
                scorer.payment_path_failed(&payment_path_for_amount(768).iter().collect::<Vec<_>>(), 42);
                scorer.payment_path_failed(&payment_path_for_amount(128).iter().collect::<Vec<_>>(), 43);
 
-               assert_eq!(scorer.channel_penalty_msat(42, 128, 1_024, &source, &target), 0);
-               assert_eq!(scorer.channel_penalty_msat(42, 256, 1_024, &source, &target), 93);
-               assert_eq!(scorer.channel_penalty_msat(42, 768, 1_024, &source, &target), 1_479);
-               assert_eq!(scorer.channel_penalty_msat(42, 896, 1_024, &source, &target), u64::max_value());
+               let usage = ChannelUsage { amount_msat: 128, ..usage };
+               assert_eq!(scorer.channel_penalty_msat(42, &source, &target, usage), 0);
+               let usage = ChannelUsage { amount_msat: 256, ..usage };
+               assert_eq!(scorer.channel_penalty_msat(42, &source, &target, usage), 93);
+               let usage = ChannelUsage { amount_msat: 768, ..usage };
+               assert_eq!(scorer.channel_penalty_msat(42, &source, &target, usage), 1_479);
+               let usage = ChannelUsage { amount_msat: 896, ..usage };
+               assert_eq!(scorer.channel_penalty_msat(42, &source, &target, usage), u64::max_value());
 
                SinceEpoch::advance(Duration::from_secs(9));
-               assert_eq!(scorer.channel_penalty_msat(42, 128, 1_024, &source, &target), 0);
-               assert_eq!(scorer.channel_penalty_msat(42, 256, 1_024, &source, &target), 93);
-               assert_eq!(scorer.channel_penalty_msat(42, 768, 1_024, &source, &target), 1_479);
-               assert_eq!(scorer.channel_penalty_msat(42, 896, 1_024, &source, &target), u64::max_value());
+               let usage = ChannelUsage { amount_msat: 128, ..usage };
+               assert_eq!(scorer.channel_penalty_msat(42, &source, &target, usage), 0);
+               let usage = ChannelUsage { amount_msat: 256, ..usage };
+               assert_eq!(scorer.channel_penalty_msat(42, &source, &target, usage), 93);
+               let usage = ChannelUsage { amount_msat: 768, ..usage };
+               assert_eq!(scorer.channel_penalty_msat(42, &source, &target, usage), 1_479);
+               let usage = ChannelUsage { amount_msat: 896, ..usage };
+               assert_eq!(scorer.channel_penalty_msat(42, &source, &target, usage), u64::max_value());
 
                SinceEpoch::advance(Duration::from_secs(1));
-               assert_eq!(scorer.channel_penalty_msat(42, 64, 1_024, &source, &target), 0);
-               assert_eq!(scorer.channel_penalty_msat(42, 128, 1_024, &source, &target), 34);
-               assert_eq!(scorer.channel_penalty_msat(42, 896, 1_024, &source, &target), 1_970);
-               assert_eq!(scorer.channel_penalty_msat(42, 960, 1_024, &source, &target), u64::max_value());
+               let usage = ChannelUsage { amount_msat: 64, ..usage };
+               assert_eq!(scorer.channel_penalty_msat(42, &source, &target, usage), 0);
+               let usage = ChannelUsage { amount_msat: 128, ..usage };
+               assert_eq!(scorer.channel_penalty_msat(42, &source, &target, usage), 34);
+               let usage = ChannelUsage { amount_msat: 896, ..usage };
+               assert_eq!(scorer.channel_penalty_msat(42, &source, &target, usage), 1_970);
+               let usage = ChannelUsage { amount_msat: 960, ..usage };
+               assert_eq!(scorer.channel_penalty_msat(42, &source, &target, usage), u64::max_value());
 
                // Fully decay liquidity lower bound.
                SinceEpoch::advance(Duration::from_secs(10 * 7));
-               assert_eq!(scorer.channel_penalty_msat(42, 0, 1_024, &source, &target), 0);
-               assert_eq!(scorer.channel_penalty_msat(42, 1, 1_024, &source, &target), 0);
-               assert_eq!(scorer.channel_penalty_msat(42, 1_023, 1_024, &source, &target), 2_000);
-               assert_eq!(scorer.channel_penalty_msat(42, 1_024, 1_024, &source, &target), 2_000);
+               let usage = ChannelUsage { amount_msat: 0, ..usage };
+               assert_eq!(scorer.channel_penalty_msat(42, &source, &target, usage), 0);
+               let usage = ChannelUsage { amount_msat: 1, ..usage };
+               assert_eq!(scorer.channel_penalty_msat(42, &source, &target, usage), 0);
+               let usage = ChannelUsage { amount_msat: 1_023, ..usage };
+               assert_eq!(scorer.channel_penalty_msat(42, &source, &target, usage), 2_000);
+               let usage = ChannelUsage { amount_msat: 1_024, ..usage };
+               assert_eq!(scorer.channel_penalty_msat(42, &source, &target, usage), 2_000);
 
                // Fully decay liquidity upper bound.
                SinceEpoch::advance(Duration::from_secs(10));
-               assert_eq!(scorer.channel_penalty_msat(42, 0, 1_024, &source, &target), 0);
-               assert_eq!(scorer.channel_penalty_msat(42, 1_024, 1_024, &source, &target), 2_000);
+               let usage = ChannelUsage { amount_msat: 0, ..usage };
+               assert_eq!(scorer.channel_penalty_msat(42, &source, &target, usage), 0);
+               let usage = ChannelUsage { amount_msat: 1_024, ..usage };
+               assert_eq!(scorer.channel_penalty_msat(42, &source, &target, usage), 2_000);
 
                SinceEpoch::advance(Duration::from_secs(10));
-               assert_eq!(scorer.channel_penalty_msat(42, 0, 1_024, &source, &target), 0);
-               assert_eq!(scorer.channel_penalty_msat(42, 1_024, 1_024, &source, &target), 2_000);
+               let usage = ChannelUsage { amount_msat: 0, ..usage };
+               assert_eq!(scorer.channel_penalty_msat(42, &source, &target, usage), 0);
+               let usage = ChannelUsage { amount_msat: 1_024, ..usage };
+               assert_eq!(scorer.channel_penalty_msat(42, &source, &target, usage), 2_000);
        }
 
        #[test]
@@ -2142,18 +1771,23 @@ mod tests {
                let mut scorer = ProbabilisticScorer::new(params, &network_graph, &logger);
                let source = source_node_id();
                let target = target_node_id();
-               assert_eq!(scorer.channel_penalty_msat(42, 256, 1_024, &source, &target), 125);
+               let usage = ChannelUsage {
+                       amount_msat: 256,
+                       inflight_htlc_msat: 0,
+                       effective_capacity: EffectiveCapacity::Total { capacity_msat: 1_024 },
+               };
+               assert_eq!(scorer.channel_penalty_msat(42, &source, &target, usage), 125);
 
                scorer.payment_path_failed(&payment_path_for_amount(512).iter().collect::<Vec<_>>(), 42);
-               assert_eq!(scorer.channel_penalty_msat(42, 256, 1_024, &source, &target), 281);
+               assert_eq!(scorer.channel_penalty_msat(42, &source, &target, usage), 281);
 
                // An unchecked right shift 64 bits or more in DirectedChannelLiquidity::decayed_offset_msat
                // would cause an overflow.
                SinceEpoch::advance(Duration::from_secs(10 * 64));
-               assert_eq!(scorer.channel_penalty_msat(42, 256, 1_024, &source, &target), 125);
+               assert_eq!(scorer.channel_penalty_msat(42, &source, &target, usage), 125);
 
                SinceEpoch::advance(Duration::from_secs(10));
-               assert_eq!(scorer.channel_penalty_msat(42, 256, 1_024, &source, &target), 125);
+               assert_eq!(scorer.channel_penalty_msat(42, &source, &target, usage), 125);
        }
 
        #[test]
@@ -2168,31 +1802,36 @@ mod tests {
                let mut scorer = ProbabilisticScorer::new(params, &network_graph, &logger);
                let source = source_node_id();
                let target = target_node_id();
+               let usage = ChannelUsage {
+                       amount_msat: 512,
+                       inflight_htlc_msat: 0,
+                       effective_capacity: EffectiveCapacity::Total { capacity_msat: 1_024 },
+               };
 
-               assert_eq!(scorer.channel_penalty_msat(42, 512, 1_024, &source, &target), 300);
+               assert_eq!(scorer.channel_penalty_msat(42, &source, &target, usage), 300);
 
                // More knowledge gives higher confidence (256, 768), meaning a lower penalty.
                scorer.payment_path_failed(&payment_path_for_amount(768).iter().collect::<Vec<_>>(), 42);
                scorer.payment_path_failed(&payment_path_for_amount(256).iter().collect::<Vec<_>>(), 43);
-               assert_eq!(scorer.channel_penalty_msat(42, 512, 1_024, &source, &target), 281);
+               assert_eq!(scorer.channel_penalty_msat(42, &source, &target, usage), 281);
 
                // Decaying knowledge gives less confidence (128, 896), meaning a higher penalty.
                SinceEpoch::advance(Duration::from_secs(10));
-               assert_eq!(scorer.channel_penalty_msat(42, 512, 1_024, &source, &target), 291);
+               assert_eq!(scorer.channel_penalty_msat(42, &source, &target, usage), 291);
 
                // Reducing the upper bound gives more confidence (128, 832) that the payment amount (512)
                // is closer to the upper bound, meaning a higher penalty.
                scorer.payment_path_successful(&payment_path_for_amount(64).iter().collect::<Vec<_>>());
-               assert_eq!(scorer.channel_penalty_msat(42, 512, 1_024, &source, &target), 331);
+               assert_eq!(scorer.channel_penalty_msat(42, &source, &target, usage), 331);
 
                // Increasing the lower bound gives more confidence (256, 832) that the payment amount (512)
                // is closer to the lower bound, meaning a lower penalty.
                scorer.payment_path_failed(&payment_path_for_amount(256).iter().collect::<Vec<_>>(), 43);
-               assert_eq!(scorer.channel_penalty_msat(42, 512, 1_024, &source, &target), 245);
+               assert_eq!(scorer.channel_penalty_msat(42, &source, &target, usage), 245);
 
                // Further decaying affects the lower bound more than the upper bound (128, 928).
                SinceEpoch::advance(Duration::from_secs(10));
-               assert_eq!(scorer.channel_penalty_msat(42, 512, 1_024, &source, &target), 280);
+               assert_eq!(scorer.channel_penalty_msat(42, &source, &target, usage), 280);
        }
 
        #[test]
@@ -2207,15 +1846,20 @@ mod tests {
                let mut scorer = ProbabilisticScorer::new(params, &network_graph, &logger);
                let source = source_node_id();
                let target = target_node_id();
+               let usage = ChannelUsage {
+                       amount_msat: 500,
+                       inflight_htlc_msat: 0,
+                       effective_capacity: EffectiveCapacity::Total { capacity_msat: 1_000 },
+               };
 
                scorer.payment_path_failed(&payment_path_for_amount(500).iter().collect::<Vec<_>>(), 42);
-               assert_eq!(scorer.channel_penalty_msat(42, 500, 1_000, &source, &target), u64::max_value());
+               assert_eq!(scorer.channel_penalty_msat(42, &source, &target, usage), u64::max_value());
 
                SinceEpoch::advance(Duration::from_secs(10));
-               assert_eq!(scorer.channel_penalty_msat(42, 500, 1_000, &source, &target), 473);
+               assert_eq!(scorer.channel_penalty_msat(42, &source, &target, usage), 473);
 
                scorer.payment_path_failed(&payment_path_for_amount(250).iter().collect::<Vec<_>>(), 43);
-               assert_eq!(scorer.channel_penalty_msat(42, 500, 1_000, &source, &target), 300);
+               assert_eq!(scorer.channel_penalty_msat(42, &source, &target, usage), 300);
 
                let mut serialized_scorer = Vec::new();
                scorer.write(&mut serialized_scorer).unwrap();
@@ -2223,7 +1867,7 @@ mod tests {
                let mut serialized_scorer = io::Cursor::new(&serialized_scorer);
                let deserialized_scorer =
                        <ProbabilisticScorer>::read(&mut serialized_scorer, (params, &network_graph, &logger)).unwrap();
-               assert_eq!(deserialized_scorer.channel_penalty_msat(42, 500, 1_000, &source, &target), 300);
+               assert_eq!(deserialized_scorer.channel_penalty_msat(42, &source, &target, usage), 300);
        }
 
        #[test]
@@ -2238,9 +1882,14 @@ mod tests {
                let mut scorer = ProbabilisticScorer::new(params, &network_graph, &logger);
                let source = source_node_id();
                let target = target_node_id();
+               let usage = ChannelUsage {
+                       amount_msat: 500,
+                       inflight_htlc_msat: 0,
+                       effective_capacity: EffectiveCapacity::Total { capacity_msat: 1_000 },
+               };
 
                scorer.payment_path_failed(&payment_path_for_amount(500).iter().collect::<Vec<_>>(), 42);
-               assert_eq!(scorer.channel_penalty_msat(42, 500, 1_000, &source, &target), u64::max_value());
+               assert_eq!(scorer.channel_penalty_msat(42, &source, &target, usage), u64::max_value());
 
                let mut serialized_scorer = Vec::new();
                scorer.write(&mut serialized_scorer).unwrap();
@@ -2250,13 +1899,13 @@ mod tests {
                let mut serialized_scorer = io::Cursor::new(&serialized_scorer);
                let deserialized_scorer =
                        <ProbabilisticScorer>::read(&mut serialized_scorer, (params, &network_graph, &logger)).unwrap();
-               assert_eq!(deserialized_scorer.channel_penalty_msat(42, 500, 1_000, &source, &target), 473);
+               assert_eq!(deserialized_scorer.channel_penalty_msat(42, &source, &target, usage), 473);
 
                scorer.payment_path_failed(&payment_path_for_amount(250).iter().collect::<Vec<_>>(), 43);
-               assert_eq!(scorer.channel_penalty_msat(42, 500, 1_000, &source, &target), 300);
+               assert_eq!(scorer.channel_penalty_msat(42, &source, &target, usage), 300);
 
                SinceEpoch::advance(Duration::from_secs(10));
-               assert_eq!(deserialized_scorer.channel_penalty_msat(42, 500, 1_000, &source, &target), 365);
+               assert_eq!(deserialized_scorer.channel_penalty_msat(42, &source, &target, usage), 365);
        }
 
        #[test]
@@ -2270,17 +1919,52 @@ mod tests {
                let source = source_node_id();
                let target = target_node_id();
 
-               assert_eq!(scorer.channel_penalty_msat(42, 100_000_000, 950_000_000, &source, &target), 3613);
-               assert_eq!(scorer.channel_penalty_msat(42, 100_000_000, 1_950_000_000, &source, &target), 1977);
-               assert_eq!(scorer.channel_penalty_msat(42, 100_000_000, 2_950_000_000, &source, &target), 1474);
-               assert_eq!(scorer.channel_penalty_msat(42, 100_000_000, 3_950_000_000, &source, &target), 1223);
-               assert_eq!(scorer.channel_penalty_msat(42, 100_000_000, 4_950_000_000, &source, &target), 877);
-               assert_eq!(scorer.channel_penalty_msat(42, 100_000_000, 5_950_000_000, &source, &target), 845);
-               assert_eq!(scorer.channel_penalty_msat(42, 100_000_000, 6_950_000_000, &source, &target), 500);
-               assert_eq!(scorer.channel_penalty_msat(42, 100_000_000, 7_450_000_000, &source, &target), 500);
-               assert_eq!(scorer.channel_penalty_msat(42, 100_000_000, 7_950_000_000, &source, &target), 500);
-               assert_eq!(scorer.channel_penalty_msat(42, 100_000_000, 8_950_000_000, &source, &target), 500);
-               assert_eq!(scorer.channel_penalty_msat(42, 100_000_000, 9_950_000_000, &source, &target), 500);
+               let usage = ChannelUsage {
+                       amount_msat: 100_000_000,
+                       inflight_htlc_msat: 0,
+                       effective_capacity: EffectiveCapacity::Total { capacity_msat: 950_000_000 },
+               };
+               assert_eq!(scorer.channel_penalty_msat(42, &source, &target, usage), 3613);
+               let usage = ChannelUsage {
+                       effective_capacity: EffectiveCapacity::Total { capacity_msat: 1_950_000_000 }, ..usage
+               };
+               assert_eq!(scorer.channel_penalty_msat(42, &source, &target, usage), 1977);
+               let usage = ChannelUsage {
+                       effective_capacity: EffectiveCapacity::Total { capacity_msat: 2_950_000_000 }, ..usage
+               };
+               assert_eq!(scorer.channel_penalty_msat(42, &source, &target, usage), 1474);
+               let usage = ChannelUsage {
+                       effective_capacity: EffectiveCapacity::Total { capacity_msat: 3_950_000_000 }, ..usage
+               };
+               assert_eq!(scorer.channel_penalty_msat(42, &source, &target, usage), 1223);
+               let usage = ChannelUsage {
+                       effective_capacity: EffectiveCapacity::Total { capacity_msat: 4_950_000_000 }, ..usage
+               };
+               assert_eq!(scorer.channel_penalty_msat(42, &source, &target, usage), 877);
+               let usage = ChannelUsage {
+                       effective_capacity: EffectiveCapacity::Total { capacity_msat: 5_950_000_000 }, ..usage
+               };
+               assert_eq!(scorer.channel_penalty_msat(42, &source, &target, usage), 845);
+               let usage = ChannelUsage {
+                       effective_capacity: EffectiveCapacity::Total { capacity_msat: 6_950_000_000 }, ..usage
+               };
+               assert_eq!(scorer.channel_penalty_msat(42, &source, &target, usage), 500);
+               let usage = ChannelUsage {
+                       effective_capacity: EffectiveCapacity::Total { capacity_msat: 7_450_000_000 }, ..usage
+               };
+               assert_eq!(scorer.channel_penalty_msat(42, &source, &target, usage), 500);
+               let usage = ChannelUsage {
+                       effective_capacity: EffectiveCapacity::Total { capacity_msat: 7_950_000_000 }, ..usage
+               };
+               assert_eq!(scorer.channel_penalty_msat(42, &source, &target, usage), 500);
+               let usage = ChannelUsage {
+                       effective_capacity: EffectiveCapacity::Total { capacity_msat: 8_950_000_000 }, ..usage
+               };
+               assert_eq!(scorer.channel_penalty_msat(42, &source, &target, usage), 500);
+               let usage = ChannelUsage {
+                       effective_capacity: EffectiveCapacity::Total { capacity_msat: 9_950_000_000 }, ..usage
+               };
+               assert_eq!(scorer.channel_penalty_msat(42, &source, &target, usage), 500);
        }
 
        #[test]
@@ -2289,19 +1973,24 @@ mod tests {
                let network_graph = network_graph();
                let source = source_node_id();
                let target = target_node_id();
+               let usage = ChannelUsage {
+                       amount_msat: 128,
+                       inflight_htlc_msat: 0,
+                       effective_capacity: EffectiveCapacity::Total { capacity_msat: 1_024 },
+               };
 
                let params = ProbabilisticScoringParameters {
                        liquidity_penalty_multiplier_msat: 1_000,
                        ..ProbabilisticScoringParameters::zero_penalty()
                };
                let scorer = ProbabilisticScorer::new(params, &network_graph, &logger);
-               assert_eq!(scorer.channel_penalty_msat(42, 128, 1_024, &source, &target), 58);
+               assert_eq!(scorer.channel_penalty_msat(42, &source, &target, usage), 58);
 
                let params = ProbabilisticScoringParameters {
                        base_penalty_msat: 500, liquidity_penalty_multiplier_msat: 1_000, ..Default::default()
                };
                let scorer = ProbabilisticScorer::new(params, &network_graph, &logger);
-               assert_eq!(scorer.channel_penalty_msat(42, 128, 1_024, &source, &target), 558);
+               assert_eq!(scorer.channel_penalty_msat(42, &source, &target, usage), 558);
        }
 
        #[test]
@@ -2310,6 +1999,11 @@ mod tests {
                let network_graph = network_graph();
                let source = source_node_id();
                let target = target_node_id();
+               let usage = ChannelUsage {
+                       amount_msat: 512_000,
+                       inflight_htlc_msat: 0,
+                       effective_capacity: EffectiveCapacity::Total { capacity_msat: 1_024_000 },
+               };
 
                let params = ProbabilisticScoringParameters {
                        liquidity_penalty_multiplier_msat: 1_000,
@@ -2317,7 +2011,7 @@ mod tests {
                        ..ProbabilisticScoringParameters::zero_penalty()
                };
                let scorer = ProbabilisticScorer::new(params, &network_graph, &logger);
-               assert_eq!(scorer.channel_penalty_msat(42, 512_000, 1_024_000, &source, &target), 300);
+               assert_eq!(scorer.channel_penalty_msat(42, &source, &target, usage), 300);
 
                let params = ProbabilisticScoringParameters {
                        liquidity_penalty_multiplier_msat: 1_000,
@@ -2325,7 +2019,7 @@ mod tests {
                        ..ProbabilisticScoringParameters::zero_penalty()
                };
                let scorer = ProbabilisticScorer::new(params, &network_graph, &logger);
-               assert_eq!(scorer.channel_penalty_msat(42, 512_000, 1_024_000, &source, &target), 337);
+               assert_eq!(scorer.channel_penalty_msat(42, &source, &target, usage), 337);
        }
 
        #[test]
@@ -2334,15 +2028,61 @@ mod tests {
                let network_graph = network_graph();
                let source = source_node_id();
                let target = target_node_id();
+               let usage = ChannelUsage {
+                       amount_msat: u64::max_value(),
+                       inflight_htlc_msat: 0,
+                       effective_capacity: EffectiveCapacity::Infinite,
+               };
 
                let params = ProbabilisticScoringParameters {
                        liquidity_penalty_multiplier_msat: 40_000,
                        ..ProbabilisticScoringParameters::zero_penalty()
                };
                let scorer = ProbabilisticScorer::new(params, &network_graph, &logger);
-               assert_eq!(
-                       scorer.channel_penalty_msat(42, u64::max_value(), u64::max_value(), &source, &target),
-                       80_000,
-               );
+               assert_eq!(scorer.channel_penalty_msat(42, &source, &target, usage), 80_000);
+       }
+
+       #[test]
+       fn accounts_for_inflight_htlc_usage() {
+               let network_graph = network_graph();
+               let logger = TestLogger::new();
+               let params = ProbabilisticScoringParameters::default();
+               let scorer = ProbabilisticScorer::new(params, &network_graph, &logger);
+               let source = source_node_id();
+               let target = target_node_id();
+
+               let usage = ChannelUsage {
+                       amount_msat: 750,
+                       inflight_htlc_msat: 0,
+                       effective_capacity: EffectiveCapacity::Total { capacity_msat: 1_000 },
+               };
+               assert_ne!(scorer.channel_penalty_msat(42, &source, &target, usage), u64::max_value());
+
+               let usage = ChannelUsage { inflight_htlc_msat: 251, ..usage };
+               assert_eq!(scorer.channel_penalty_msat(42, &source, &target, usage), u64::max_value());
+       }
+
+       #[test]
+       fn removes_uncertainity_when_exact_liquidity_known() {
+               let network_graph = network_graph();
+               let logger = TestLogger::new();
+               let params = ProbabilisticScoringParameters::default();
+               let scorer = ProbabilisticScorer::new(params, &network_graph, &logger);
+               let source = source_node_id();
+               let target = target_node_id();
+
+               let base_penalty_msat = params.base_penalty_msat;
+               let usage = ChannelUsage {
+                       amount_msat: 750,
+                       inflight_htlc_msat: 0,
+                       effective_capacity: EffectiveCapacity::ExactLiquidity { liquidity_msat: 1_000 },
+               };
+               assert_eq!(scorer.channel_penalty_msat(42, &source, &target, usage), base_penalty_msat);
+
+               let usage = ChannelUsage { amount_msat: 1_000, ..usage };
+               assert_eq!(scorer.channel_penalty_msat(42, &source, &target, usage), base_penalty_msat);
+
+               let usage = ChannelUsage { amount_msat: 1_001, ..usage };
+               assert_eq!(scorer.channel_penalty_msat(42, &source, &target, usage), u64::max_value());
        }
 }