X-Git-Url: http://git.bitcoin.ninja/index.cgi?a=blobdiff_plain;f=lightning%2Fsrc%2Frouting%2Fscoring.rs;h=91349d845179b89a811cdec77d96512af8f0799f;hb=00d740e3cbb12d33a65a5689f9c310841f32e0a3;hp=c4f31db9471039581d028888725de76c999c7ac4;hpb=c6a1a12acaec7994694bb389aaa183719873ebee;p=rust-lightning diff --git a/lightning/src/routing/scoring.rs b/lightning/src/routing/scoring.rs index c4f31db9..91349d84 100644 --- a/lightning/src/routing/scoring.rs +++ b/lightning/src/routing/scoring.rs @@ -89,7 +89,7 @@ macro_rules! define_score { ($($supertrait: path)*) => { /// `ScoreLookUp` is used to determine the penalty for a given channel. /// /// Scoring is in terms of fees willing to be paid in order to avoid routing through a channel. -pub trait ScoreLookUp $(: $supertrait)* { +pub trait ScoreLookUp { /// A configurable type which should contain various passed-in parameters for configuring the scorer, /// on a per-routefinding-call basis through to the scorer methods, /// which are used to determine the parameters for the suitability of channels for use. @@ -108,7 +108,7 @@ pub trait ScoreLookUp $(: $supertrait)* { } /// `ScoreUpdate` is used to update the scorer's internal state after a payment attempt. -pub trait ScoreUpdate $(: $supertrait)* { +pub trait ScoreUpdate { /// Handles updating channel penalties after failing to route through a channel. fn payment_path_failed(&mut self, path: &Path, short_channel_id: u64); @@ -122,8 +122,20 @@ pub trait ScoreUpdate $(: $supertrait)* { fn probe_successful(&mut self, path: &Path); } -impl, T: Deref $(+ $supertrait)*> ScoreLookUp for T { - type ScoreParams = SP; +/// A trait which can both lookup and update routing channel penalty scores. +/// +/// This is used in places where both bounds are required and implemented for all types which +/// implement [`ScoreLookUp`] and [`ScoreUpdate`]. +/// +/// Bindings users may need to manually implement this for their custom scoring implementations. +pub trait Score : ScoreLookUp + ScoreUpdate $(+ $supertrait)* {} + +#[cfg(not(c_bindings))] +impl Score for T {} + +#[cfg(not(c_bindings))] +impl> ScoreLookUp for T { + type ScoreParams = S::ScoreParams; fn channel_penalty_msat( &self, short_channel_id: u64, source: &NodeId, target: &NodeId, usage: ChannelUsage, score_params: &Self::ScoreParams ) -> u64 { @@ -131,7 +143,8 @@ impl, T: Deref $(+ $supert } } -impl $(+ $supertrait)*> ScoreUpdate for T { +#[cfg(not(c_bindings))] +impl> ScoreUpdate for T { fn payment_path_failed(&mut self, path: &Path, short_channel_id: u64) { self.deref_mut().payment_path_failed(path, short_channel_id) } @@ -192,7 +205,7 @@ pub trait WriteableScore<'a>: LockableScore<'a> + Writeable {} #[cfg(not(c_bindings))] impl<'a, T> WriteableScore<'a> for T where T: LockableScore<'a> + Writeable {} #[cfg(not(c_bindings))] -impl<'a, T: 'a + ScoreLookUp + ScoreUpdate> LockableScore<'a> for Mutex { +impl<'a, T: Score + 'a> LockableScore<'a> for Mutex { type ScoreUpdate = T; type ScoreLookUp = T; @@ -209,7 +222,7 @@ impl<'a, T: 'a + ScoreLookUp + ScoreUpdate> LockableScore<'a> for Mutex { } #[cfg(not(c_bindings))] -impl<'a, T: 'a + ScoreUpdate + ScoreLookUp> LockableScore<'a> for RefCell { +impl<'a, T: Score + 'a> LockableScore<'a> for RefCell { type ScoreUpdate = T; type ScoreLookUp = T; @@ -226,7 +239,7 @@ impl<'a, T: 'a + ScoreUpdate + ScoreLookUp> LockableScore<'a> for RefCell { } #[cfg(not(c_bindings))] -impl<'a, SP:Sized, T: 'a + ScoreUpdate + ScoreLookUp> LockableScore<'a> for RwLock { +impl<'a, T: Score + 'a> LockableScore<'a> for RwLock { type ScoreUpdate = T; type ScoreLookUp = T; @@ -244,12 +257,12 @@ impl<'a, SP:Sized, T: 'a + ScoreUpdate + ScoreLookUp> Lockabl #[cfg(c_bindings)] /// A concrete implementation of [`LockableScore`] which supports multi-threading. -pub struct MultiThreadedLockableScore { +pub struct MultiThreadedLockableScore { score: RwLock, } #[cfg(c_bindings)] -impl<'a, SP:Sized, T: 'a + ScoreLookUp + ScoreUpdate> LockableScore<'a> for MultiThreadedLockableScore { +impl<'a, T: Score + 'a> LockableScore<'a> for MultiThreadedLockableScore { type ScoreUpdate = T; type ScoreLookUp = T; type WriteLocked = MultiThreadedScoreLockWrite<'a, Self::ScoreUpdate>; @@ -265,17 +278,17 @@ impl<'a, SP:Sized, T: 'a + ScoreLookUp + ScoreUpdate> Lockable } #[cfg(c_bindings)] -impl Writeable for MultiThreadedLockableScore { +impl Writeable for MultiThreadedLockableScore { fn write(&self, writer: &mut W) -> Result<(), io::Error> { self.score.read().unwrap().write(writer) } } #[cfg(c_bindings)] -impl<'a, T: 'a + ScoreUpdate + ScoreLookUp> WriteableScore<'a> for MultiThreadedLockableScore {} +impl<'a, T: Score + 'a> WriteableScore<'a> for MultiThreadedLockableScore {} #[cfg(c_bindings)] -impl MultiThreadedLockableScore { +impl MultiThreadedLockableScore { /// Creates a new [`MultiThreadedLockableScore`] given an underlying [`Score`]. pub fn new(score: T) -> Self { MultiThreadedLockableScore { score: RwLock::new(score) } @@ -284,14 +297,14 @@ impl MultiThreadedLockableScore { #[cfg(c_bindings)] /// A locked `MultiThreadedLockableScore`. -pub struct MultiThreadedScoreLockRead<'a, T: ScoreLookUp>(RwLockReadGuard<'a, T>); +pub struct MultiThreadedScoreLockRead<'a, T: Score>(RwLockReadGuard<'a, T>); #[cfg(c_bindings)] /// A locked `MultiThreadedLockableScore`. -pub struct MultiThreadedScoreLockWrite<'a, T: ScoreUpdate>(RwLockWriteGuard<'a, T>); +pub struct MultiThreadedScoreLockWrite<'a, T: Score>(RwLockWriteGuard<'a, T>); #[cfg(c_bindings)] -impl<'a, T: 'a + ScoreLookUp> Deref for MultiThreadedScoreLockRead<'a, T> { +impl<'a, T: 'a + Score> Deref for MultiThreadedScoreLockRead<'a, T> { type Target = T; fn deref(&self) -> &Self::Target { @@ -300,14 +313,24 @@ impl<'a, T: 'a + ScoreLookUp> Deref for MultiThreadedScoreLockRead<'a, T> { } #[cfg(c_bindings)] -impl<'a, T: 'a + ScoreUpdate> Writeable for MultiThreadedScoreLockWrite<'a, T> { +impl<'a, T: Score> ScoreLookUp for MultiThreadedScoreLockRead<'a, T> { + type ScoreParams = T::ScoreParams; + fn channel_penalty_msat(&self, short_channel_id: u64, source: &NodeId, + target: &NodeId, usage: ChannelUsage, score_params: &Self::ScoreParams + ) -> u64 { + self.0.channel_penalty_msat(short_channel_id, source, target, usage, score_params) + } +} + +#[cfg(c_bindings)] +impl<'a, T: Score> Writeable for MultiThreadedScoreLockWrite<'a, T> { fn write(&self, writer: &mut W) -> Result<(), io::Error> { self.0.write(writer) } } #[cfg(c_bindings)] -impl<'a, T: 'a + ScoreUpdate> Deref for MultiThreadedScoreLockWrite<'a, T> { +impl<'a, T: 'a + Score> Deref for MultiThreadedScoreLockWrite<'a, T> { type Target = T; fn deref(&self) -> &Self::Target { @@ -316,12 +339,31 @@ impl<'a, T: 'a + ScoreUpdate> Deref for MultiThreadedScoreLockWrite<'a, T> { } #[cfg(c_bindings)] -impl<'a, T: 'a + ScoreUpdate> DerefMut for MultiThreadedScoreLockWrite<'a, T> { +impl<'a, T: 'a + Score> DerefMut for MultiThreadedScoreLockWrite<'a, T> { fn deref_mut(&mut self) -> &mut Self::Target { self.0.deref_mut() } } +#[cfg(c_bindings)] +impl<'a, T: Score> ScoreUpdate for MultiThreadedScoreLockWrite<'a, T> { + fn payment_path_failed(&mut self, path: &Path, short_channel_id: u64) { + self.0.payment_path_failed(path, short_channel_id) + } + + fn payment_path_successful(&mut self, path: &Path) { + self.0.payment_path_successful(path) + } + + fn probe_failed(&mut self, path: &Path, short_channel_id: u64) { + self.0.probe_failed(path, short_channel_id) + } + + fn probe_successful(&mut self, path: &Path) { + self.0.probe_successful(path) + } +} + /// Proposed use of a channel passed as a parameter to [`ScoreLookUp::channel_penalty_msat`]. #[derive(Clone, Copy, Debug, PartialEq)] @@ -454,12 +496,13 @@ pub struct ProbabilisticScoringFeeParameters { /// Default value: 500 msat pub base_penalty_msat: u64, - /// A multiplier used with the payment amount to calculate a fixed penalty applied to each - /// channel, in excess of the [`base_penalty_msat`]. + /// A multiplier used with the total amount flowing over a channel to calculate a fixed penalty + /// applied to each channel, in excess of the [`base_penalty_msat`]. /// /// The purpose of the amount penalty is to avoid having fees dominate the channel cost (i.e., /// fees plus penalty) for large payments. The penalty is computed as the product of this - /// multiplier and `2^30`ths of the payment amount. + /// multiplier and `2^30`ths of the total amount flowing over a channel (i.e. the payment + /// amount plus the amount of any other HTLCs flowing we sent over the same channel). /// /// ie `base_penalty_amount_multiplier_msat * amount_msat / 2^30` /// @@ -486,14 +529,14 @@ pub struct ProbabilisticScoringFeeParameters { /// [`liquidity_offset_half_life`]: ProbabilisticScoringDecayParameters::liquidity_offset_half_life pub liquidity_penalty_multiplier_msat: u64, - /// A multiplier used in conjunction with a payment amount and the negative `log10` of the - /// channel's success probability for the payment, as determined by our latest estimates of the - /// channel's liquidity, to determine the amount penalty. + /// A multiplier used in conjunction with the total amount flowing over a channel and the + /// negative `log10` of the channel's success probability for the payment, as determined by our + /// latest estimates of the channel's liquidity, to determine the amount penalty. /// /// The purpose of the amount penalty is to avoid having fees dominate the channel cost (i.e., /// fees plus penalty) for large payments. The penalty is computed as the product of this - /// multiplier and `2^20`ths of the payment amount, weighted by the negative `log10` of the - /// success probability. + /// multiplier and `2^20`ths of the amount flowing over this channel, weighted by the negative + /// `log10` of the success probability. /// /// `-log10(success_probability) * liquidity_penalty_amount_multiplier_msat * amount_msat / 2^20` /// @@ -522,13 +565,15 @@ pub struct ProbabilisticScoringFeeParameters { /// [`liquidity_penalty_multiplier_msat`]: Self::liquidity_penalty_multiplier_msat pub historical_liquidity_penalty_multiplier_msat: u64, - /// A multiplier used in conjunction with the payment amount and the negative `log10` of the - /// channel's success probability for the payment, as determined based on the history of our - /// estimates of the channel's available liquidity, to determine a penalty. + /// A multiplier used in conjunction with the total amount flowing over a channel and the + /// negative `log10` of the channel's success probability for the payment, as determined based + /// on the history of our estimates of the channel's available liquidity, to determine a + /// penalty. /// /// The purpose of the amount penalty is to avoid having fees dominate the channel cost for - /// large payments. The penalty is computed as the product of this multiplier and the `2^20`ths - /// of the payment amount, weighted by the negative `log10` of the success probability. + /// large payments. The penalty is computed as the product of this multiplier and `2^20`ths + /// of the amount flowing over this channel, weighted by the negative `log10` of the success + /// probability. /// /// This penalty is similar to [`liquidity_penalty_amount_multiplier_msat`], however, instead /// of using only our latest estimate for the current liquidity available in the channel, it @@ -558,8 +603,9 @@ pub struct ProbabilisticScoringFeeParameters { /// Default value: 250 msat pub anti_probing_penalty_msat: u64, - /// This penalty is applied when the amount we're attempting to send over a channel exceeds our - /// current estimate of the channel's available liquidity. + /// This penalty is applied when the total amount flowing over a channel exceeds our current + /// estimate of the channel's available liquidity. The total amount is the amount of the + /// current HTLC plus any HTLCs which we've sent over the same channel. /// /// Note that in this case all other penalties, including the /// [`liquidity_penalty_multiplier_msat`] and [`liquidity_penalty_amount_multiplier_msat`]-based @@ -576,6 +622,28 @@ pub struct ProbabilisticScoringFeeParameters { /// [`base_penalty_msat`]: Self::base_penalty_msat /// [`anti_probing_penalty_msat`]: Self::anti_probing_penalty_msat pub considered_impossible_penalty_msat: u64, + + /// In order to calculate most of the scores above, we must first convert a lower and upper + /// bound on the available liquidity in a channel into the probability that we think a payment + /// will succeed. That probability is derived from a Probability Density Function for where we + /// think the liquidity in a channel likely lies, given such bounds. + /// + /// If this flag is set, that PDF is simply a constant - we assume that the actual available + /// liquidity in a channel is just as likely to be at any point between our lower and upper + /// bounds. + /// + /// If this flag is *not* set, that PDF is `(x - 0.5*capacity) ^ 2`. That is, we use an + /// exponential curve which expects the liquidity of a channel to lie "at the edges". This + /// matches experimental results - most routing nodes do not aggressively rebalance their + /// channels and flows in the network are often unbalanced, leaving liquidity usually + /// unavailable. + /// + /// Thus, for the "best" routes, leave this flag `false`. However, the flag does imply a number + /// of floating-point multiplications in the hottest routing code, which may lead to routing + /// performance degradation on some machines. + /// + /// Default value: false + pub linear_success_probability: bool, } impl Default for ProbabilisticScoringFeeParameters { @@ -590,6 +658,7 @@ impl Default for ProbabilisticScoringFeeParameters { considered_impossible_penalty_msat: 1_0000_0000_000, historical_liquidity_penalty_multiplier_msat: 10_000, historical_liquidity_penalty_amount_multiplier_msat: 64, + linear_success_probability: false, } } } @@ -643,6 +712,7 @@ impl ProbabilisticScoringFeeParameters { manual_node_penalties: HashMap::new(), anti_probing_penalty_msat: 0, considered_impossible_penalty_msat: 0, + linear_success_probability: true, } } } @@ -733,7 +803,6 @@ struct DirectedChannelLiquidity, BRT: Deref, - inflight_htlc_msat: u64, capacity_msat: u64, last_updated: U, now: T, @@ -771,23 +840,38 @@ impl>, L: Deref, T: Time> ProbabilisticScorerU let log_direction = |source, target| { if let Some((directed_info, _)) = chan_debug.as_directed_to(target) { let amt = directed_info.effective_capacity().as_msat(); - let dir_liq = liq.as_directed(source, target, 0, amt, self.decay_params); + let dir_liq = liq.as_directed(source, target, amt, self.decay_params); - let (min_buckets, max_buckets, _) = dir_liq.liquidity_history + let (min_buckets, max_buckets) = dir_liq.liquidity_history .get_decayed_buckets(now, *dir_liq.last_updated, - self.decay_params.historical_no_updates_half_life); + self.decay_params.historical_no_updates_half_life) + .unwrap_or(([0; 32], [0; 32])); log_debug!(self.logger, core::concat!( "Liquidity from {} to {} via {} is in the range ({}, {}).\n", - "\tHistorical min liquidity octile relative probabilities: {} {} {} {} {} {} {} {}\n", - "\tHistorical max liquidity octile relative probabilities: {} {} {} {} {} {} {} {}"), + "\tHistorical min liquidity bucket relative probabilities:\n", + "\t\t{} {} {} {} {} {} {} {} {} {} {} {} {} {} {} {} {} {} {} {} {} {} {} {} {} {} {} {} {} {} {} {}\n", + "\tHistorical max liquidity bucket relative probabilities:\n", + "\t\t{} {} {} {} {} {} {} {} {} {} {} {} {} {} {} {} {} {} {} {} {} {} {} {} {} {} {} {} {} {} {} {}"), source, target, scid, dir_liq.min_liquidity_msat(), dir_liq.max_liquidity_msat(), - min_buckets[0], min_buckets[1], min_buckets[2], min_buckets[3], - min_buckets[4], min_buckets[5], min_buckets[6], min_buckets[7], + min_buckets[ 0], min_buckets[ 1], min_buckets[ 2], min_buckets[ 3], + min_buckets[ 4], min_buckets[ 5], min_buckets[ 6], min_buckets[ 7], + min_buckets[ 8], min_buckets[ 9], min_buckets[10], min_buckets[11], + min_buckets[12], min_buckets[13], min_buckets[14], min_buckets[15], + min_buckets[16], min_buckets[17], min_buckets[18], min_buckets[19], + min_buckets[20], min_buckets[21], min_buckets[22], min_buckets[23], + min_buckets[24], min_buckets[25], min_buckets[26], min_buckets[27], + min_buckets[28], min_buckets[29], min_buckets[30], min_buckets[31], // Note that the liquidity buckets are an offset from the edge, so we // inverse the max order to get the probabilities from zero. - max_buckets[7], max_buckets[6], max_buckets[5], max_buckets[4], - max_buckets[3], max_buckets[2], max_buckets[1], max_buckets[0]); + max_buckets[31], max_buckets[30], max_buckets[29], max_buckets[28], + max_buckets[27], max_buckets[26], max_buckets[25], max_buckets[24], + max_buckets[23], max_buckets[22], max_buckets[21], max_buckets[20], + max_buckets[19], max_buckets[18], max_buckets[17], max_buckets[16], + max_buckets[15], max_buckets[14], max_buckets[13], max_buckets[12], + max_buckets[11], max_buckets[10], max_buckets[ 9], max_buckets[ 8], + max_buckets[ 7], max_buckets[ 6], max_buckets[ 5], max_buckets[ 4], + max_buckets[ 3], max_buckets[ 2], max_buckets[ 1], max_buckets[ 0]); } else { log_debug!(self.logger, "No amount known for SCID {} from {:?} to {:?}", scid, source, target); } @@ -810,7 +894,7 @@ impl>, L: Deref, T: Time> ProbabilisticScorerU if let Some(liq) = self.channel_liquidities.get(&scid) { if let Some((directed_info, source)) = chan.as_directed_to(target) { let amt = directed_info.effective_capacity().as_msat(); - let dir_liq = liq.as_directed(source, target, 0, amt, self.decay_params); + let dir_liq = liq.as_directed(source, target, amt, self.decay_params); return Some((dir_liq.min_liquidity_msat(), dir_liq.max_liquidity_msat())); } } @@ -821,40 +905,45 @@ impl>, L: Deref, T: Time> ProbabilisticScorerU /// Query the historical estimated minimum and maximum liquidity available for sending a /// payment over the channel with `scid` towards the given `target` node. /// - /// Returns two sets of 8 buckets. The first set describes the octiles for lower-bound - /// liquidity estimates, the second set describes the octiles for upper-bound liquidity - /// estimates. Each bucket describes the relative frequency at which we've seen a liquidity - /// bound in the octile relative to the channel's total capacity, on an arbitrary scale. - /// Because the values are slowly decayed, more recent data points are weighted more heavily - /// than older datapoints. + /// Returns two sets of 32 buckets. The first set describes the lower-bound liquidity history, + /// the second set describes the upper-bound liquidity history. Each bucket describes the + /// relative frequency at which we've seen a liquidity bound in the bucket's range relative to + /// the channel's total capacity, on an arbitrary scale. Because the values are slowly decayed, + /// more recent data points are weighted more heavily than older datapoints. + /// + /// Note that the range of each bucket varies by its location to provide more granular results + /// at the edges of a channel's capacity, where it is more likely to sit. /// - /// When scoring, the estimated probability that an upper-/lower-bound lies in a given octile - /// relative to the channel's total capacity is calculated by dividing that bucket's value with - /// the total of all buckets for the given bound. + /// When scoring, the estimated probability that an upper-/lower-bound lies in a given bucket + /// is calculated by dividing that bucket's value with the total value of all buckets. /// - /// For example, a value of `[0, 0, 0, 0, 0, 0, 32]` indicates that we believe the probability - /// of a bound being in the top octile to be 100%, and have never (recently) seen it in any - /// other octiles. A value of `[31, 0, 0, 0, 0, 0, 0, 32]` indicates we've seen the bound being - /// both in the top and bottom octile, and roughly with similar (recent) frequency. + /// For example, using a lower bucket count for illustrative purposes, a value of + /// `[0, 0, 0, ..., 0, 32]` indicates that we believe the probability of a bound being very + /// close to the channel's capacity to be 100%, and have never (recently) seen it in any other + /// bucket. A value of `[31, 0, 0, ..., 0, 0, 32]` indicates we've seen the bound being both + /// in the top and bottom bucket, and roughly with similar (recent) frequency. /// /// Because the datapoints are decayed slowly over time, values will eventually return to - /// `Some(([0; 8], [0; 8]))`. + /// `Some(([1; 32], [1; 32]))` and then to `None` once no datapoints remain. /// /// In order to fetch a single success probability from the buckets provided here, as used in /// the scoring model, see [`Self::historical_estimated_payment_success_probability`]. pub fn historical_estimated_channel_liquidity_probabilities(&self, scid: u64, target: &NodeId) - -> Option<([u16; 8], [u16; 8])> { + -> Option<([u16; 32], [u16; 32])> { let graph = self.network_graph.read_only(); if let Some(chan) = graph.channels().get(&scid) { if let Some(liq) = self.channel_liquidities.get(&scid) { if let Some((directed_info, source)) = chan.as_directed_to(target) { let amt = directed_info.effective_capacity().as_msat(); - let dir_liq = liq.as_directed(source, target, 0, amt, self.decay_params); + let dir_liq = liq.as_directed(source, target, amt, self.decay_params); + + let (min_buckets, mut max_buckets) = + dir_liq.liquidity_history.get_decayed_buckets( + dir_liq.now, *dir_liq.last_updated, + self.decay_params.historical_no_updates_half_life + )?; - let (min_buckets, mut max_buckets, _) = dir_liq.liquidity_history - .get_decayed_buckets(dir_liq.now, *dir_liq.last_updated, - self.decay_params.historical_no_updates_half_life); // Note that the liquidity buckets are an offset from the edge, so we inverse // the max order to get the probabilities from zero. max_buckets.reverse(); @@ -873,7 +962,7 @@ impl>, L: Deref, T: Time> ProbabilisticScorerU /// [`Self::historical_estimated_channel_liquidity_probabilities`] (but not those returned by /// [`Self::estimated_channel_liquidity_range`]). pub fn historical_estimated_payment_success_probability( - &self, scid: u64, target: &NodeId, amount_msat: u64) + &self, scid: u64, target: &NodeId, amount_msat: u64, params: &ProbabilisticScoringFeeParameters) -> Option { let graph = self.network_graph.read_only(); @@ -881,11 +970,12 @@ impl>, L: Deref, T: Time> ProbabilisticScorerU if let Some(liq) = self.channel_liquidities.get(&scid) { if let Some((directed_info, source)) = chan.as_directed_to(target) { let capacity_msat = directed_info.effective_capacity().as_msat(); - let dir_liq = liq.as_directed(source, target, 0, capacity_msat, self.decay_params); + let dir_liq = liq.as_directed(source, target, capacity_msat, self.decay_params); return dir_liq.liquidity_history.calculate_success_probability_times_billion( dir_liq.now, *dir_liq.last_updated, - self.decay_params.historical_no_updates_half_life, amount_msat, capacity_msat + self.decay_params.historical_no_updates_half_life, ¶ms, amount_msat, + capacity_msat ).map(|p| p as f64 / (1024 * 1024 * 1024) as f64); } } @@ -909,7 +999,7 @@ impl ChannelLiquidity { /// Returns a view of the channel liquidity directed from `source` to `target` assuming /// `capacity_msat`. fn as_directed( - &self, source: &NodeId, target: &NodeId, inflight_htlc_msat: u64, capacity_msat: u64, decay_params: ProbabilisticScoringDecayParameters + &self, source: &NodeId, target: &NodeId, capacity_msat: u64, decay_params: ProbabilisticScoringDecayParameters ) -> DirectedChannelLiquidity<&u64, &HistoricalBucketRangeTracker, T, &T> { let (min_liquidity_offset_msat, max_liquidity_offset_msat, min_liquidity_offset_history, max_liquidity_offset_history) = if source < target { @@ -927,7 +1017,6 @@ impl ChannelLiquidity { min_liquidity_offset_history, max_liquidity_offset_history, }, - inflight_htlc_msat, capacity_msat, last_updated: &self.last_updated, now: T::now(), @@ -938,7 +1027,7 @@ impl ChannelLiquidity { /// Returns a mutable view of the channel liquidity directed from `source` to `target` assuming /// `capacity_msat`. fn as_directed_mut( - &mut self, source: &NodeId, target: &NodeId, inflight_htlc_msat: u64, capacity_msat: u64, decay_params: ProbabilisticScoringDecayParameters + &mut self, source: &NodeId, target: &NodeId, capacity_msat: u64, decay_params: ProbabilisticScoringDecayParameters ) -> DirectedChannelLiquidity<&mut u64, &mut HistoricalBucketRangeTracker, T, &mut T> { let (min_liquidity_offset_msat, max_liquidity_offset_msat, min_liquidity_offset_history, max_liquidity_offset_history) = if source < target { @@ -956,7 +1045,6 @@ impl ChannelLiquidity { min_liquidity_offset_history, max_liquidity_offset_history, }, - inflight_htlc_msat, capacity_msat, last_updated: &mut self.last_updated, now: T::now(), @@ -977,11 +1065,80 @@ const PRECISION_LOWER_BOUND_DENOMINATOR: u64 = approx::LOWER_BITS_BOUND; const AMOUNT_PENALTY_DIVISOR: u64 = 1 << 20; const BASE_AMOUNT_PENALTY_DIVISOR: u64 = 1 << 30; +/// Raises three `f64`s to the 3rd power, without `powi` because it requires `std` (dunno why). +#[inline(always)] +fn three_f64_pow_3(a: f64, b: f64, c: f64) -> (f64, f64, f64) { + (a * a * a, b * b * b, c * c * c) +} + +/// Given liquidity bounds, calculates the success probability (in the form of a numerator and +/// denominator) of an HTLC. This is a key assumption in our scoring models. +/// +/// Must not return a numerator or denominator greater than 2^31 for arguments less than 2^31. +/// +/// min_zero_implies_no_successes signals that a `min_liquidity_msat` of 0 means we've not +/// (recently) seen an HTLC successfully complete over this channel. +#[inline(always)] +fn success_probability( + amount_msat: u64, min_liquidity_msat: u64, max_liquidity_msat: u64, capacity_msat: u64, + params: &ProbabilisticScoringFeeParameters, min_zero_implies_no_successes: bool, +) -> (u64, u64) { + debug_assert!(min_liquidity_msat <= amount_msat); + debug_assert!(amount_msat < max_liquidity_msat); + debug_assert!(max_liquidity_msat <= capacity_msat); + + let (numerator, mut denominator) = + if params.linear_success_probability { + (max_liquidity_msat - amount_msat, + (max_liquidity_msat - min_liquidity_msat).saturating_add(1)) + } else { + let capacity = capacity_msat as f64; + let min = (min_liquidity_msat as f64) / capacity; + let max = (max_liquidity_msat as f64) / capacity; + let amount = (amount_msat as f64) / capacity; + + // Assume the channel has a probability density function of (x - 0.5)^2 for values from + // 0 to 1 (where 1 is the channel's full capacity). The success probability given some + // liquidity bounds is thus the integral under the curve from the amount to maximum + // estimated liquidity, divided by the same integral from the minimum to the maximum + // estimated liquidity bounds. + // + // Because the integral from x to y is simply (y - 0.5)^3 - (x - 0.5)^3, we can + // calculate the cumulative density function between the min/max bounds trivially. Note + // that we don't bother to normalize the CDF to total to 1, as it will come out in the + // division of num / den. + let (max_pow, amt_pow, min_pow) = three_f64_pow_3(max - 0.5, amount - 0.5, min - 0.5); + let num = max_pow - amt_pow; + let den = max_pow - min_pow; + + // Because our numerator and denominator max out at 0.5^3 we need to multiply them by + // quite a large factor to get something useful (ideally in the 2^30 range). + const BILLIONISH: f64 = 1024.0 * 1024.0 * 1024.0; + let numerator = (num * BILLIONISH) as u64 + 1; + let denominator = (den * BILLIONISH) as u64 + 1; + debug_assert!(numerator <= 1 << 30, "Got large numerator ({}) from float {}.", numerator, num); + debug_assert!(denominator <= 1 << 30, "Got large denominator ({}) from float {}.", denominator, den); + (numerator, denominator) + }; + + if min_zero_implies_no_successes && min_liquidity_msat == 0 && + denominator < u64::max_value() / 21 + { + // If we have no knowledge of the channel, scale probability down by ~75% + // Note that we prefer to increase the denominator rather than decrease the numerator as + // the denominator is more likely to be larger and thus provide greater precision. This is + // mostly an overoptimization but makes a large difference in tests. + denominator = denominator * 21 / 16 + } + + (numerator, denominator) +} + impl, BRT: Deref, T: Time, U: Deref> DirectedChannelLiquidity< L, BRT, T, U> { /// Returns a liquidity penalty for routing the given HTLC `amount_msat` through the channel in /// this direction. fn penalty_msat(&self, amount_msat: u64, score_params: &ProbabilisticScoringFeeParameters) -> u64 { - let available_capacity = self.available_capacity(); + let available_capacity = self.capacity_msat; let max_liquidity_msat = self.max_liquidity_msat(); let min_liquidity_msat = core::cmp::min(self.min_liquidity_msat(), max_liquidity_msat); @@ -997,9 +1154,9 @@ impl, BRT: Deref, score_params.liquidity_penalty_amount_multiplier_msat) .saturating_add(score_params.considered_impossible_penalty_msat) } else { - let numerator = (max_liquidity_msat - amount_msat).saturating_add(1); - let denominator = (max_liquidity_msat - min_liquidity_msat).saturating_add(1); - if amount_msat - min_liquidity_msat < denominator / PRECISION_LOWER_BOUND_DENOMINATOR { + let (numerator, denominator) = success_probability(amount_msat, + min_liquidity_msat, max_liquidity_msat, available_capacity, score_params, false); + if denominator - numerator < denominator / PRECISION_LOWER_BOUND_DENOMINATOR { // If the failure probability is < 1.5625% (as 1 - numerator/denominator < 1/64), // don't bother trying to use the log approximation as it gets too noisy to be // particularly helpful, instead just round down to 0. @@ -1026,7 +1183,8 @@ impl, BRT: Deref, score_params.historical_liquidity_penalty_amount_multiplier_msat != 0 { if let Some(cumulative_success_prob_times_billion) = self.liquidity_history .calculate_success_probability_times_billion(self.now, *self.last_updated, - self.decay_params.historical_no_updates_half_life, amount_msat, self.capacity_msat) + self.decay_params.historical_no_updates_half_life, score_params, amount_msat, + self.capacity_msat) { let historical_negative_log10_times_2048 = approx::negative_log10_times_2048(cumulative_success_prob_times_billion + 1, 1024 * 1024 * 1024); res = res.saturating_add(Self::combined_penalty_msat(amount_msat, @@ -1036,9 +1194,8 @@ impl, BRT: Deref, // If we don't have any valid points (or, once decayed, we have less than a full // point), redo the non-historical calculation with no liquidity bounds tracked and // the historical penalty multipliers. - let available_capacity = self.available_capacity(); - let numerator = available_capacity.saturating_sub(amount_msat).saturating_add(1); - let denominator = available_capacity.saturating_add(1); + let (numerator, denominator) = success_probability(amount_msat, 0, + available_capacity, available_capacity, score_params, true); let negative_log10_times_2048 = approx::negative_log10_times_2048(numerator, denominator); res = res.saturating_add(Self::combined_penalty_msat(amount_msat, negative_log10_times_2048, @@ -1077,16 +1234,10 @@ impl, BRT: Deref, /// Returns the upper bound of the channel liquidity balance in this direction. #[inline(always)] fn max_liquidity_msat(&self) -> u64 { - self.available_capacity() + self.capacity_msat .saturating_sub(self.decayed_offset_msat(*self.max_liquidity_offset_msat)) } - /// Returns the capacity minus the in-flight HTLCs in this direction. - #[inline(always)] - fn available_capacity(&self) -> u64 { - self.capacity_msat.saturating_sub(self.inflight_htlc_msat) - } - fn decayed_offset_msat(&self, offset_msat: u64) -> u64 { let half_life = self.decay_params.liquidity_offset_half_life.as_secs(); if half_life != 0 { @@ -1121,7 +1272,7 @@ impl, BRT: DerefMut, BRT: DerefMut, BRT: DerefMut, BRT: DerefMut>, L: Deref, T: Time> ScoreLookUp for Prob _ => {}, } - let amount_msat = usage.amount_msat; + let amount_msat = usage.amount_msat.saturating_add(usage.inflight_htlc_msat); let capacity_msat = usage.effective_capacity.as_msat(); - let inflight_htlc_msat = usage.inflight_htlc_msat; self.channel_liquidities .get(&short_channel_id) .unwrap_or(&ChannelLiquidity::new()) - .as_directed(source, target, inflight_htlc_msat, capacity_msat, self.decay_params) + .as_directed(source, target, capacity_msat, self.decay_params) .penalty_msat(amount_msat, score_params) .saturating_add(anti_probing_penalty_msat) .saturating_add(base_penalty_msat) @@ -1253,13 +1407,13 @@ impl>, L: Deref, T: Time> ScoreUpdate for Prob self.channel_liquidities .entry(hop.short_channel_id) .or_insert_with(ChannelLiquidity::new) - .as_directed_mut(source, &target, 0, capacity_msat, self.decay_params) + .as_directed_mut(source, &target, capacity_msat, self.decay_params) .failed_at_channel(amount_msat, format_args!("SCID {}, towards {:?}", hop.short_channel_id, target), &self.logger); } else { self.channel_liquidities .entry(hop.short_channel_id) .or_insert_with(ChannelLiquidity::new) - .as_directed_mut(source, &target, 0, capacity_msat, self.decay_params) + .as_directed_mut(source, &target, capacity_msat, self.decay_params) .failed_downstream(amount_msat, format_args!("SCID {}, towards {:?}", hop.short_channel_id, target), &self.logger); } } else { @@ -1287,7 +1441,7 @@ impl>, L: Deref, T: Time> ScoreUpdate for Prob self.channel_liquidities .entry(hop.short_channel_id) .or_insert_with(ChannelLiquidity::new) - .as_directed_mut(source, &target, 0, capacity_msat, self.decay_params) + .as_directed_mut(source, &target, capacity_msat, self.decay_params) .successful(amount_msat, format_args!("SCID {}, towards {:?}", hop.short_channel_id, target), &self.logger); } else { log_debug!(self.logger, "Not able to learn for channel with SCID {} as we do not have graph info for it (likely a route-hint last-hop).", @@ -1305,6 +1459,10 @@ impl>, L: Deref, T: Time> ScoreUpdate for Prob } } +#[cfg(c_bindings)] +impl>, L: Deref, T: Time> Score for ProbabilisticScorerUsingTime +where L::Target: Logger {} + mod approx { const BITS: u32 = 64; const HIGHEST_BIT: u32 = BITS - 1; @@ -1319,26 +1477,26 @@ mod approx { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0], - [617, 617, 617, 617, 617, 617, 617, 617, 617, 617, 617, 617, 617, 617, 617, 617, - 617, 617, 617, 617, 617, 617, 617, 617, 617, 617, 617, 617, 617, 617, 617, 617, - 977, 977, 977, 977, 977, 977, 977, 977, 977, 977, 977, 977, 977, 977, 977, 977, - 977, 977, 977, 977, 977, 977, 977, 977, 977, 977, 977, 977, 977, 977, 977, 977], - [1233, 1233, 1233, 1233, 1233, 1233, 1233, 1233, 1233, 1233, 1233, 1233, 1233, 1233, 1233, 1233, - 1431, 1431, 1431, 1431, 1431, 1431, 1431, 1431, 1431, 1431, 1431, 1431, 1431, 1431, 1431, 1431, - 1594, 1594, 1594, 1594, 1594, 1594, 1594, 1594, 1594, 1594, 1594, 1594, 1594, 1594, 1594, 1594, - 1731, 1731, 1731, 1731, 1731, 1731, 1731, 1731, 1731, 1731, 1731, 1731, 1731, 1731, 1731, 1731], - [1850, 1850, 1850, 1850, 1850, 1850, 1850, 1850, 1954, 1954, 1954, 1954, 1954, 1954, 1954, 1954, - 2048, 2048, 2048, 2048, 2048, 2048, 2048, 2048, 2133, 2133, 2133, 2133, 2133, 2133, 2133, 2133, - 2210, 2210, 2210, 2210, 2210, 2210, 2210, 2210, 2281, 2281, 2281, 2281, 2281, 2281, 2281, 2281, - 2347, 2347, 2347, 2347, 2347, 2347, 2347, 2347, 2409, 2409, 2409, 2409, 2409, 2409, 2409, 2409], - [2466, 2466, 2466, 2466, 2520, 2520, 2520, 2520, 2571, 2571, 2571, 2571, 2619, 2619, 2619, 2619, - 2665, 2665, 2665, 2665, 2708, 2708, 2708, 2708, 2749, 2749, 2749, 2749, 2789, 2789, 2789, 2789, - 2827, 2827, 2827, 2827, 2863, 2863, 2863, 2863, 2898, 2898, 2898, 2898, 2931, 2931, 2931, 2931, - 2964, 2964, 2964, 2964, 2995, 2995, 2995, 2995, 3025, 3025, 3025, 3025, 3054, 3054, 3054, 3054], - [3083, 3083, 3110, 3110, 3136, 3136, 3162, 3162, 3187, 3187, 3212, 3212, 3235, 3235, 3259, 3259, - 3281, 3281, 3303, 3303, 3324, 3324, 3345, 3345, 3366, 3366, 3386, 3386, 3405, 3405, 3424, 3424, - 3443, 3443, 3462, 3462, 3479, 3479, 3497, 3497, 3514, 3514, 3531, 3531, 3548, 3548, 3564, 3564, - 3580, 3580, 3596, 3596, 3612, 3612, 3627, 3627, 3642, 3642, 3656, 3656, 3671, 3671, 3685, 3685], + [617, 617, 617, 977, 617, 977, 617, 977, 617, 977, 617, 977, 617, 977, 617, 977, + 617, 977, 617, 977, 617, 977, 617, 977, 617, 977, 617, 977, 617, 977, 617, 977, + 617, 977, 617, 977, 617, 977, 617, 977, 617, 977, 617, 977, 617, 977, 617, 977, + 617, 977, 617, 977, 617, 977, 617, 977, 617, 977, 617, 977, 617, 977, 617, 977], + [1233, 1233, 1233, 1233, 1233, 1431, 1594, 1731, 1233, 1431, 1594, 1731, 1233, 1431, 1594, 1731, + 1233, 1431, 1594, 1731, 1233, 1431, 1594, 1731, 1233, 1431, 1594, 1731, 1233, 1431, 1594, 1731, + 1233, 1431, 1594, 1731, 1233, 1431, 1594, 1731, 1233, 1431, 1594, 1731, 1233, 1431, 1594, 1731, + 1233, 1431, 1594, 1731, 1233, 1431, 1594, 1731, 1233, 1431, 1594, 1731, 1233, 1431, 1594, 1731], + [1850, 1850, 1850, 1850, 1850, 1850, 1850, 1850, 1850, 1954, 2048, 2133, 2210, 2281, 2347, 2409, + 1850, 1954, 2048, 2133, 2210, 2281, 2347, 2409, 1850, 1954, 2048, 2133, 2210, 2281, 2347, 2409, + 1850, 1954, 2048, 2133, 2210, 2281, 2347, 2409, 1850, 1954, 2048, 2133, 2210, 2281, 2347, 2409, + 1850, 1954, 2048, 2133, 2210, 2281, 2347, 2409, 1850, 1954, 2048, 2133, 2210, 2281, 2347, 2409], + [2466, 2466, 2466, 2466, 2466, 2466, 2466, 2466, 2466, 2466, 2466, 2466, 2466, 2466, 2466, 2466, + 2466, 2520, 2571, 2619, 2665, 2708, 2749, 2789, 2827, 2863, 2898, 2931, 2964, 2995, 3025, 3054, + 2466, 2520, 2571, 2619, 2665, 2708, 2749, 2789, 2827, 2863, 2898, 2931, 2964, 2995, 3025, 3054, + 2466, 2520, 2571, 2619, 2665, 2708, 2749, 2789, 2827, 2863, 2898, 2931, 2964, 2995, 3025, 3054], + [3083, 3083, 3083, 3083, 3083, 3083, 3083, 3083, 3083, 3083, 3083, 3083, 3083, 3083, 3083, 3083, + 3083, 3083, 3083, 3083, 3083, 3083, 3083, 3083, 3083, 3083, 3083, 3083, 3083, 3083, 3083, 3083, + 3083, 3110, 3136, 3162, 3187, 3212, 3235, 3259, 3281, 3303, 3324, 3345, 3366, 3386, 3405, 3424, + 3443, 3462, 3479, 3497, 3514, 3531, 3548, 3564, 3580, 3596, 3612, 3627, 3642, 3656, 3671, 3685], [3699, 3713, 3726, 3740, 3753, 3766, 3779, 3791, 3804, 3816, 3828, 3840, 3852, 3864, 3875, 3886, 3898, 3909, 3919, 3930, 3941, 3951, 3962, 3972, 3982, 3992, 4002, 4012, 4022, 4031, 4041, 4050, 4060, 4069, 4078, 4087, 4096, 4105, 4114, 4122, 4131, 4139, 4148, 4156, 4164, 4173, 4181, 4189, @@ -1596,18 +1754,25 @@ mod approx { fn prints_negative_log10_times_2048_lookup_table() { for msb in 0..BITS { for i in 0..LOWER_BITS_BOUND { - let x = ((LOWER_BITS_BOUND + i) << (HIGHEST_BIT - LOWER_BITS)) >> (HIGHEST_BIT - msb); - let log10_times_2048 = ((x as f64).log10() * 2048.0).round() as u16; - assert_eq!(log10_times_2048, LOG10_TIMES_2048[msb as usize][i as usize]); + let mut x = 1 << msb; + if msb >= LOWER_BITS || i >= (1 << msb) { + x |= i << msb.saturating_sub(LOWER_BITS); + } + x <<= 63 - msb; + x >>= 63 - msb; + if x == 0 { x = 1; } + let calc_log10_times_2048 = ((x as f64).log10() * 2048.0).round() as u16; + assert_eq!(calc_log10_times_2048, log10_times_2048(x)); + assert_eq!(calc_log10_times_2048, LOG10_TIMES_2048[msb as usize][i as usize]); if i % LOWER_BITS_BOUND == 0 { - print!("\t\t[{}, ", log10_times_2048); + print!("\t\t[{}, ", calc_log10_times_2048); } else if i % LOWER_BITS_BOUND == LOWER_BITS_BOUND - 1 { - println!("{}],", log10_times_2048); + println!("{}],", calc_log10_times_2048); } else if i % (LOWER_BITS_BOUND/4) == LOWER_BITS_BOUND/4 - 1 { - print!("{},\n\t\t\t", log10_times_2048); + print!("{},\n\t\t\t", calc_log10_times_2048); } else { - print!("{}, ", log10_times_2048); + print!("{}, ", calc_log10_times_2048); } } } @@ -1618,17 +1783,125 @@ mod approx { mod bucketed_history { use super::*; + // Because liquidity is often skewed heavily in one direction, we store historical state + // distribution in buckets of different size. For backwards compatibility, buckets of size 1/8th + // must fit evenly into the buckets here. + // + // The smallest bucket is 2^-14th of the channel, for each of our 32 buckets here we define the + // width of the bucket in 2^14'ths of the channel. This increases exponentially until we reach + // a full 16th of the channel's capacity, which is reapeated a few times for backwards + // compatibility. The four middle buckets represent full octiles of the channel's capacity. + // + // For a 1 BTC channel, this let's us differentiate between failures in the bottom 6k sats, or + // between the 12,000th sat and 24,000th sat, while only needing to store and operate on 32 + // buckets in total. + + const BUCKET_START_POS: [u16; 33] = [ + 0, 1, 2, 4, 8, 16, 32, 64, 128, 256, 512, 1024, 2048, 3072, 4096, 6144, 8192, 10240, 12288, + 13312, 14336, 15360, 15872, 16128, 16256, 16320, 16352, 16368, 16376, 16380, 16382, 16383, 16384, + ]; + + const LEGACY_TO_BUCKET_RANGE: [(u8, u8); 8] = [ + (0, 12), (12, 14), (14, 15), (15, 16), (16, 17), (17, 18), (18, 20), (20, 32) + ]; + + const POSITION_TICKS: u16 = 1 << 14; + + fn pos_to_bucket(pos: u16) -> usize { + for bucket in 0..32 { + if pos < BUCKET_START_POS[bucket + 1] { + return bucket; + } + } + debug_assert!(false); + return 32; + } + + #[cfg(test)] + #[test] + fn check_bucket_maps() { + const BUCKET_WIDTH_IN_16384S: [u16; 32] = [ + 1, 1, 2, 4, 8, 16, 32, 64, 128, 256, 512, 1024, 1024, 1024, 2048, 2048, + 2048, 2048, 1024, 1024, 1024, 512, 256, 128, 64, 32, 16, 8, 4, 2, 1, 1]; + + let mut min_size_iter = 0; + let mut legacy_bucket_iter = 0; + for (bucket, width) in BUCKET_WIDTH_IN_16384S.iter().enumerate() { + assert_eq!(BUCKET_START_POS[bucket], min_size_iter); + for i in 0..*width { + assert_eq!(pos_to_bucket(min_size_iter + i) as usize, bucket); + } + min_size_iter += *width; + if min_size_iter % (POSITION_TICKS / 8) == 0 { + assert_eq!(LEGACY_TO_BUCKET_RANGE[legacy_bucket_iter].1 as usize, bucket + 1); + if legacy_bucket_iter + 1 < 8 { + assert_eq!(LEGACY_TO_BUCKET_RANGE[legacy_bucket_iter + 1].0 as usize, bucket + 1); + } + legacy_bucket_iter += 1; + } + } + assert_eq!(BUCKET_START_POS[32], POSITION_TICKS); + assert_eq!(min_size_iter, POSITION_TICKS); + } + + #[inline] + fn amount_to_pos(amount_msat: u64, capacity_msat: u64) -> u16 { + let pos = if amount_msat < u64::max_value() / (POSITION_TICKS as u64) { + (amount_msat * (POSITION_TICKS as u64) / capacity_msat.saturating_add(1)) + .try_into().unwrap_or(POSITION_TICKS) + } else { + // Only use 128-bit arithmetic when multiplication will overflow to avoid 128-bit + // division. This branch should only be hit in fuzz testing since the amount would + // need to be over 2.88 million BTC in practice. + ((amount_msat as u128) * (POSITION_TICKS as u128) + / (capacity_msat as u128).saturating_add(1)) + .try_into().unwrap_or(POSITION_TICKS) + }; + // If we are running in a client that doesn't validate gossip, its possible for a channel's + // capacity to change due to a `channel_update` message which, if received while a payment + // is in-flight, could cause this to fail. Thus, we only assert in test. + #[cfg(test)] + debug_assert!(pos < POSITION_TICKS); + pos + } + + /// Prior to LDK 0.0.117 we used eight buckets which were split evenly across the either + /// octiles. This was changed to use 32 buckets for accuracy reasons in 0.0.117, however we + /// support reading the legacy values here for backwards compatibility. + pub(super) struct LegacyHistoricalBucketRangeTracker { + buckets: [u16; 8], + } + + impl LegacyHistoricalBucketRangeTracker { + pub(crate) fn into_current(&self) -> HistoricalBucketRangeTracker { + let mut buckets = [0; 32]; + for (idx, legacy_bucket) in self.buckets.iter().enumerate() { + let mut new_val = *legacy_bucket; + let (start, end) = LEGACY_TO_BUCKET_RANGE[idx]; + new_val /= (end - start) as u16; + for i in start..end { + buckets[i as usize] = new_val; + } + } + HistoricalBucketRangeTracker { buckets } + } + } + /// Tracks the historical state of a distribution as a weighted average of how much time was spent - /// in each of 8 buckets. + /// in each of 32 buckets. #[derive(Clone, Copy)] pub(super) struct HistoricalBucketRangeTracker { - buckets: [u16; 8], + buckets: [u16; 32], } + /// Buckets are stored in fixed point numbers with a 5 bit fractional part. Thus, the value + /// "one" is 32, or this constant. + pub const BUCKET_FIXED_POINT_ONE: u16 = 32; + impl HistoricalBucketRangeTracker { - pub(super) fn new() -> Self { Self { buckets: [0; 8] } } + pub(super) fn new() -> Self { Self { buckets: [0; 32] } } pub(super) fn track_datapoint(&mut self, liquidity_offset_msat: u64, capacity_msat: u64) { - // We have 8 leaky buckets for min and max liquidity. Each bucket tracks the amount of time + // We have 32 leaky buckets for min and max liquidity. Each bucket tracks the amount of time // we spend in each bucket as a 16-bit fixed-point number with a 5 bit fractional part. // // Each time we update our liquidity estimate, we add 32 (1.0 in our fixed-point system) to @@ -1649,21 +1922,18 @@ mod bucketed_history { // The constants were picked experimentally, selecting a decay amount that restricts us // from overflowing buckets without having to cap them manually. - // Ensure the bucket index is in the range [0, 7], even if the liquidity offset is zero or - // the channel's capacity, though the second should generally never happen. - debug_assert!(liquidity_offset_msat <= capacity_msat); - let bucket_idx: u8 = (liquidity_offset_msat * 8 / capacity_msat.saturating_add(1)) - .try_into().unwrap_or(32); // 32 is bogus for 8 buckets, and will be ignored - debug_assert!(bucket_idx < 8); - if bucket_idx < 8 { + let pos: u16 = amount_to_pos(liquidity_offset_msat, capacity_msat); + if pos < POSITION_TICKS { for e in self.buckets.iter_mut() { *e = ((*e as u32) * 2047 / 2048) as u16; } - self.buckets[bucket_idx as usize] = self.buckets[bucket_idx as usize].saturating_add(32); + let bucket = pos_to_bucket(pos); + self.buckets[bucket] = self.buckets[bucket].saturating_add(BUCKET_FIXED_POINT_ONE); } } /// Decay all buckets by the given number of half-lives. Used to more aggressively remove old /// datapoints as we receive newer information. + #[inline] pub(super) fn time_decay_data(&mut self, half_lives: u32) { for e in self.buckets.iter_mut() { *e = e.checked_shr(half_lives).unwrap_or(0); @@ -1672,99 +1942,122 @@ mod bucketed_history { } impl_writeable_tlv_based!(HistoricalBucketRangeTracker, { (0, buckets, required) }); + impl_writeable_tlv_based!(LegacyHistoricalBucketRangeTracker, { (0, buckets, required) }); + /// A set of buckets representing the history of where we've seen the minimum- and maximum- + /// liquidity bounds for a given channel. pub(super) struct HistoricalMinMaxBuckets> { + /// Buckets tracking where and how often we've seen the minimum liquidity bound for a + /// channel. pub(super) min_liquidity_offset_history: D, + /// Buckets tracking where and how often we've seen the maximum liquidity bound for a + /// channel. pub(super) max_liquidity_offset_history: D, } impl> HistoricalMinMaxBuckets { - #[inline] pub(super) fn get_decayed_buckets(&self, now: T, last_updated: T, half_life: Duration) - -> ([u16; 8], [u16; 8], u32) { - let required_decays = now.duration_since(last_updated).as_secs() - .checked_div(half_life.as_secs()) - .map_or(u32::max_value(), |decays| cmp::min(decays, u32::max_value() as u64) as u32); + -> Option<([u16; 32], [u16; 32])> { + let (_, required_decays) = self.get_total_valid_points(now, last_updated, half_life)?; + let mut min_buckets = *self.min_liquidity_offset_history; min_buckets.time_decay_data(required_decays); let mut max_buckets = *self.max_liquidity_offset_history; max_buckets.time_decay_data(required_decays); - (min_buckets.buckets, max_buckets.buckets, required_decays) + Some((min_buckets.buckets, max_buckets.buckets)) } - #[inline] - pub(super) fn calculate_success_probability_times_billion( - &self, now: T, last_updated: T, half_life: Duration, amount_msat: u64, capacity_msat: u64) - -> Option { - // If historical penalties are enabled, calculate the penalty by walking the set of - // historical liquidity bucket (min, max) combinations (where min_idx < max_idx) and, for - // each, calculate the probability of success given our payment amount, then total the - // weighted average probability of success. - // - // We use a sliding scale to decide which point within a given bucket will be compared to - // the amount being sent - for lower-bounds, the amount being sent is compared to the lower - // edge of the first bucket (i.e. zero), but compared to the upper 7/8ths of the last - // bucket (i.e. 9 times the index, or 63), with each bucket in between increasing the - // comparison point by 1/64th. For upper-bounds, the same applies, however with an offset - // of 1/64th (i.e. starting at one and ending at 64). This avoids failing to assign - // penalties to channels at the edges. - // - // If we used the bottom edge of buckets, we'd end up never assigning any penalty at all to - // such a channel when sending less than ~0.19% of the channel's capacity (e.g. ~200k sats - // for a 1 BTC channel!). - // - // If we used the middle of each bucket we'd never assign any penalty at all when sending - // less than 1/16th of a channel's capacity, or 1/8th if we used the top of the bucket. - let mut total_valid_points_tracked = 0; - - let payment_amt_64th_bucket: u8 = if amount_msat < u64::max_value() / 64 { - (amount_msat * 64 / capacity_msat.saturating_add(1)) - .try_into().unwrap_or(65) - } else { - // Only use 128-bit arithmetic when multiplication will overflow to avoid 128-bit - // division. This branch should only be hit in fuzz testing since the amount would - // need to be over 2.88 million BTC in practice. - ((amount_msat as u128) * 64 / (capacity_msat as u128).saturating_add(1)) - .try_into().unwrap_or(65) - }; - #[cfg(not(fuzzing))] - debug_assert!(payment_amt_64th_bucket <= 64); - if payment_amt_64th_bucket >= 64 { return None; } - - // Check if all our buckets are zero, once decayed and treat it as if we had no data. We - // don't actually use the decayed buckets, though, as that would lose precision. - let (decayed_min_buckets, decayed_max_buckets, required_decays) = - self.get_decayed_buckets(now, last_updated, half_life); - if decayed_min_buckets.iter().all(|v| *v == 0) || decayed_max_buckets.iter().all(|v| *v == 0) { - return None; - } + pub(super) fn get_total_valid_points(&self, now: T, last_updated: T, half_life: Duration) + -> Option<(u64, u32)> { + let required_decays = now.duration_since(last_updated).as_secs() + .checked_div(half_life.as_secs()) + .map_or(u32::max_value(), |decays| cmp::min(decays, u32::max_value() as u64) as u32); + let mut total_valid_points_tracked = 0; for (min_idx, min_bucket) in self.min_liquidity_offset_history.buckets.iter().enumerate() { - for max_bucket in self.max_liquidity_offset_history.buckets.iter().take(8 - min_idx) { + for max_bucket in self.max_liquidity_offset_history.buckets.iter().take(32 - min_idx) { total_valid_points_tracked += (*min_bucket as u64) * (*max_bucket as u64); } } - // If the total valid points is smaller than 1.0 (i.e. 32 in our fixed-point scheme), treat - // it as if we were fully decayed. - if total_valid_points_tracked.checked_shr(required_decays).unwrap_or(0) < 32*32 { + + // If the total valid points is smaller than 1.0 (i.e. 32 in our fixed-point scheme), + // treat it as if we were fully decayed. + const FULLY_DECAYED: u16 = BUCKET_FIXED_POINT_ONE * BUCKET_FIXED_POINT_ONE; + if total_valid_points_tracked.checked_shr(required_decays).unwrap_or(0) < FULLY_DECAYED.into() { return None; } + Some((total_valid_points_tracked, required_decays)) + } + + #[inline] + pub(super) fn calculate_success_probability_times_billion( + &self, now: T, last_updated: T, half_life: Duration, + params: &ProbabilisticScoringFeeParameters, amount_msat: u64, capacity_msat: u64 + ) -> Option { + // If historical penalties are enabled, we try to calculate a probability of success + // given our historical distribution of min- and max-liquidity bounds in a channel. + // To do so, we walk the set of historical liquidity bucket (min, max) combinations + // (where min_idx < max_idx, as having a minimum above our maximum is an invalid + // state). For each pair, we calculate the probability as if the bucket's corresponding + // min- and max- liquidity bounds were our current liquidity bounds and then multiply + // that probability by the weight of the selected buckets. + let payment_pos = amount_to_pos(amount_msat, capacity_msat); + if payment_pos >= POSITION_TICKS { return None; } + + // Check if all our buckets are zero, once decayed and treat it as if we had no data. We + // don't actually use the decayed buckets, though, as that would lose precision. + let (total_valid_points_tracked, _) + = self.get_total_valid_points(now, last_updated, half_life)?; + let mut cumulative_success_prob_times_billion = 0; - for (min_idx, min_bucket) in self.min_liquidity_offset_history.buckets.iter().enumerate() { - for (max_idx, max_bucket) in self.max_liquidity_offset_history.buckets.iter().enumerate().take(8 - min_idx) { - let bucket_prob_times_million = (*min_bucket as u64) * (*max_bucket as u64) - * 1024 * 1024 / total_valid_points_tracked; - let min_64th_bucket = min_idx as u8 * 9; - let max_64th_bucket = (7 - max_idx as u8) * 9 + 1; - if payment_amt_64th_bucket > max_64th_bucket { - // Success probability 0, the payment amount is above the max liquidity - } else if payment_amt_64th_bucket <= min_64th_bucket { - cumulative_success_prob_times_billion += bucket_prob_times_million * 1024; + // Special-case the 0th min bucket - it generally means we failed a payment, so only + // consider the highest (i.e. largest-offset-from-max-capacity) max bucket for all + // points against the 0th min bucket. This avoids the case where we fail to route + // increasingly lower values over a channel, but treat each failure as a separate + // datapoint, many of which may have relatively high maximum-available-liquidity + // values, which will result in us thinking we have some nontrivial probability of + // routing up to that amount. + if self.min_liquidity_offset_history.buckets[0] != 0 { + let mut highest_max_bucket_with_points = 0; // The highest max-bucket with any data + let mut total_max_points = 0; // Total points in max-buckets to consider + for (max_idx, max_bucket) in self.max_liquidity_offset_history.buckets.iter().enumerate() { + if *max_bucket >= BUCKET_FIXED_POINT_ONE { + highest_max_bucket_with_points = cmp::max(highest_max_bucket_with_points, max_idx); + } + total_max_points += *max_bucket as u64; + } + let max_bucket_end_pos = BUCKET_START_POS[32 - highest_max_bucket_with_points] - 1; + if payment_pos < max_bucket_end_pos { + let (numerator, denominator) = success_probability(payment_pos as u64, 0, + max_bucket_end_pos as u64, POSITION_TICKS as u64 - 1, params, true); + let bucket_prob_times_billion = + (self.min_liquidity_offset_history.buckets[0] as u64) * total_max_points + * 1024 * 1024 * 1024 / total_valid_points_tracked; + cumulative_success_prob_times_billion += bucket_prob_times_billion * + numerator / denominator; + } + } + + for (min_idx, min_bucket) in self.min_liquidity_offset_history.buckets.iter().enumerate().skip(1) { + let min_bucket_start_pos = BUCKET_START_POS[min_idx]; + for (max_idx, max_bucket) in self.max_liquidity_offset_history.buckets.iter().enumerate().take(32 - min_idx) { + let max_bucket_end_pos = BUCKET_START_POS[32 - max_idx] - 1; + // Note that this multiply can only barely not overflow - two 16 bit ints plus + // 30 bits is 62 bits. + let bucket_prob_times_billion = (*min_bucket as u64) * (*max_bucket as u64) + * 1024 * 1024 * 1024 / total_valid_points_tracked; + if payment_pos >= max_bucket_end_pos { + // Success probability 0, the payment amount may be above the max liquidity + break; + } else if payment_pos < min_bucket_start_pos { + cumulative_success_prob_times_billion += bucket_prob_times_billion; } else { - cumulative_success_prob_times_billion += bucket_prob_times_million * - ((max_64th_bucket - payment_amt_64th_bucket) as u64) * 1024 / - ((max_64th_bucket - min_64th_bucket) as u64); + let (numerator, denominator) = success_probability(payment_pos as u64, + min_bucket_start_pos as u64, max_bucket_end_pos as u64, + POSITION_TICKS as u64 - 1, params, true); + cumulative_success_prob_times_billion += bucket_prob_times_billion * + numerator / denominator; } } } @@ -1773,7 +2066,7 @@ mod bucketed_history { } } } -use bucketed_history::{HistoricalBucketRangeTracker, HistoricalMinMaxBuckets}; +use bucketed_history::{LegacyHistoricalBucketRangeTracker, HistoricalBucketRangeTracker, HistoricalMinMaxBuckets}; impl>, L: Deref, T: Time> Writeable for ProbabilisticScorerUsingTime where L::Target: Logger { #[inline] @@ -1811,10 +2104,12 @@ impl Writeable for ChannelLiquidity { let duration_since_epoch = T::duration_since_epoch() - self.last_updated.elapsed(); write_tlv_fields!(w, { (0, self.min_liquidity_offset_msat, required), - (1, Some(self.min_liquidity_offset_history), option), + // 1 was the min_liquidity_offset_history in octile form (2, self.max_liquidity_offset_msat, required), - (3, Some(self.max_liquidity_offset_history), option), + // 3 was the max_liquidity_offset_history in octile form (4, duration_since_epoch, required), + (5, Some(self.min_liquidity_offset_history), option), + (7, Some(self.max_liquidity_offset_history), option), }); Ok(()) } @@ -1825,15 +2120,19 @@ impl Readable for ChannelLiquidity { fn read(r: &mut R) -> Result { let mut min_liquidity_offset_msat = 0; let mut max_liquidity_offset_msat = 0; - let mut min_liquidity_offset_history = Some(HistoricalBucketRangeTracker::new()); - let mut max_liquidity_offset_history = Some(HistoricalBucketRangeTracker::new()); + let mut legacy_min_liq_offset_history: Option = None; + let mut legacy_max_liq_offset_history: Option = None; + let mut min_liquidity_offset_history: Option = None; + let mut max_liquidity_offset_history: Option = None; let mut duration_since_epoch = Duration::from_secs(0); read_tlv_fields!(r, { (0, min_liquidity_offset_msat, required), - (1, min_liquidity_offset_history, option), + (1, legacy_min_liq_offset_history, option), (2, max_liquidity_offset_msat, required), - (3, max_liquidity_offset_history, option), + (3, legacy_max_liq_offset_history, option), (4, duration_since_epoch, required), + (5, min_liquidity_offset_history, option), + (7, max_liquidity_offset_history, option), }); // On rust prior to 1.60 `Instant::duration_since` will panic if time goes backwards. // We write `last_updated` as wallclock time even though its ultimately an `Instant` (which @@ -1847,6 +2146,20 @@ impl Readable for ChannelLiquidity { let last_updated = if wall_clock_now > duration_since_epoch { now - (wall_clock_now - duration_since_epoch) } else { now }; + if min_liquidity_offset_history.is_none() { + if let Some(legacy_buckets) = legacy_min_liq_offset_history { + min_liquidity_offset_history = Some(legacy_buckets.into_current()); + } else { + min_liquidity_offset_history = Some(HistoricalBucketRangeTracker::new()); + } + } + if max_liquidity_offset_history.is_none() { + if let Some(legacy_buckets) = legacy_max_liq_offset_history { + max_liquidity_offset_history = Some(legacy_buckets.into_current()); + } else { + max_liquidity_offset_history = Some(HistoricalBucketRangeTracker::new()); + } + } Ok(Self { min_liquidity_offset_msat, max_liquidity_offset_msat, @@ -1873,7 +2186,7 @@ mod tests { use crate::util::ser::{ReadableArgs, Writeable}; use crate::util::test_utils::{self, TestLogger}; - use bitcoin::blockdata::constants::genesis_block; + use bitcoin::blockdata::constants::ChainHash; use bitcoin::hashes::Hash; use bitcoin::hashes::sha256d::Hash as Sha256dHash; use bitcoin::network::constants::Network; @@ -1950,7 +2263,7 @@ mod tests { network_graph: &mut NetworkGraph<&TestLogger>, short_channel_id: u64, node_1_key: SecretKey, node_2_key: SecretKey ) { - let genesis_hash = genesis_block(Network::Testnet).header.block_hash(); + let genesis_hash = ChainHash::using_genesis_block(Network::Testnet); let node_1_secret = &SecretKey::from_slice(&[39; 32]).unwrap(); let node_2_secret = &SecretKey::from_slice(&[40; 32]).unwrap(); let secp_ctx = Secp256k1::new(); @@ -1975,20 +2288,20 @@ mod tests { let chain_source: Option<&crate::util::test_utils::TestChainSource> = None; network_graph.update_channel_from_announcement( &signed_announcement, &chain_source).unwrap(); - update_channel(network_graph, short_channel_id, node_1_key, 0, 1_000); - update_channel(network_graph, short_channel_id, node_2_key, 1, 0); + update_channel(network_graph, short_channel_id, node_1_key, 0, 1_000, 100); + update_channel(network_graph, short_channel_id, node_2_key, 1, 0, 100); } fn update_channel( network_graph: &mut NetworkGraph<&TestLogger>, short_channel_id: u64, node_key: SecretKey, - flags: u8, htlc_maximum_msat: u64 + flags: u8, htlc_maximum_msat: u64, timestamp: u32, ) { - let genesis_hash = genesis_block(Network::Testnet).header.block_hash(); + let genesis_hash = ChainHash::using_genesis_block(Network::Testnet); let secp_ctx = Secp256k1::new(); let unsigned_update = UnsignedChannelUpdate { chain_hash: genesis_hash, short_channel_id, - timestamp: 100, + timestamp, flags, cltv_expiry_delta: 18, htlc_minimum_msat: 0, @@ -2056,52 +2369,52 @@ mod tests { // Update minimum liquidity. let liquidity = scorer.channel_liquidities.get(&42).unwrap() - .as_directed(&source, &target, 0, 1_000, decay_params); + .as_directed(&source, &target, 1_000, decay_params); assert_eq!(liquidity.min_liquidity_msat(), 100); assert_eq!(liquidity.max_liquidity_msat(), 300); let liquidity = scorer.channel_liquidities.get(&42).unwrap() - .as_directed(&target, &source, 0, 1_000, decay_params); + .as_directed(&target, &source, 1_000, decay_params); assert_eq!(liquidity.min_liquidity_msat(), 700); assert_eq!(liquidity.max_liquidity_msat(), 900); scorer.channel_liquidities.get_mut(&42).unwrap() - .as_directed_mut(&source, &target, 0, 1_000, decay_params) + .as_directed_mut(&source, &target, 1_000, decay_params) .set_min_liquidity_msat(200); let liquidity = scorer.channel_liquidities.get(&42).unwrap() - .as_directed(&source, &target, 0, 1_000, decay_params); + .as_directed(&source, &target, 1_000, decay_params); assert_eq!(liquidity.min_liquidity_msat(), 200); assert_eq!(liquidity.max_liquidity_msat(), 300); let liquidity = scorer.channel_liquidities.get(&42).unwrap() - .as_directed(&target, &source, 0, 1_000, decay_params); + .as_directed(&target, &source, 1_000, decay_params); assert_eq!(liquidity.min_liquidity_msat(), 700); assert_eq!(liquidity.max_liquidity_msat(), 800); // Update maximum liquidity. let liquidity = scorer.channel_liquidities.get(&43).unwrap() - .as_directed(&target, &recipient, 0, 1_000, decay_params); + .as_directed(&target, &recipient, 1_000, decay_params); assert_eq!(liquidity.min_liquidity_msat(), 700); assert_eq!(liquidity.max_liquidity_msat(), 900); let liquidity = scorer.channel_liquidities.get(&43).unwrap() - .as_directed(&recipient, &target, 0, 1_000, decay_params); + .as_directed(&recipient, &target, 1_000, decay_params); assert_eq!(liquidity.min_liquidity_msat(), 100); assert_eq!(liquidity.max_liquidity_msat(), 300); scorer.channel_liquidities.get_mut(&43).unwrap() - .as_directed_mut(&target, &recipient, 0, 1_000, decay_params) + .as_directed_mut(&target, &recipient, 1_000, decay_params) .set_max_liquidity_msat(200); let liquidity = scorer.channel_liquidities.get(&43).unwrap() - .as_directed(&target, &recipient, 0, 1_000, decay_params); + .as_directed(&target, &recipient, 1_000, decay_params); assert_eq!(liquidity.min_liquidity_msat(), 0); assert_eq!(liquidity.max_liquidity_msat(), 200); let liquidity = scorer.channel_liquidities.get(&43).unwrap() - .as_directed(&recipient, &target, 0, 1_000, decay_params); + .as_directed(&recipient, &target, 1_000, decay_params); assert_eq!(liquidity.min_liquidity_msat(), 800); assert_eq!(liquidity.max_liquidity_msat(), 1000); } @@ -2125,42 +2438,42 @@ mod tests { // Check initial bounds. let liquidity = scorer.channel_liquidities.get(&42).unwrap() - .as_directed(&source, &target, 0, 1_000, decay_params); + .as_directed(&source, &target, 1_000, decay_params); assert_eq!(liquidity.min_liquidity_msat(), 400); assert_eq!(liquidity.max_liquidity_msat(), 800); let liquidity = scorer.channel_liquidities.get(&42).unwrap() - .as_directed(&target, &source, 0, 1_000, decay_params); + .as_directed(&target, &source, 1_000, decay_params); assert_eq!(liquidity.min_liquidity_msat(), 200); assert_eq!(liquidity.max_liquidity_msat(), 600); // Reset from source to target. scorer.channel_liquidities.get_mut(&42).unwrap() - .as_directed_mut(&source, &target, 0, 1_000, decay_params) + .as_directed_mut(&source, &target, 1_000, decay_params) .set_min_liquidity_msat(900); let liquidity = scorer.channel_liquidities.get(&42).unwrap() - .as_directed(&source, &target, 0, 1_000, decay_params); + .as_directed(&source, &target, 1_000, decay_params); assert_eq!(liquidity.min_liquidity_msat(), 900); assert_eq!(liquidity.max_liquidity_msat(), 1_000); let liquidity = scorer.channel_liquidities.get(&42).unwrap() - .as_directed(&target, &source, 0, 1_000, decay_params); + .as_directed(&target, &source, 1_000, decay_params); assert_eq!(liquidity.min_liquidity_msat(), 0); assert_eq!(liquidity.max_liquidity_msat(), 100); // Reset from target to source. scorer.channel_liquidities.get_mut(&42).unwrap() - .as_directed_mut(&target, &source, 0, 1_000, decay_params) + .as_directed_mut(&target, &source, 1_000, decay_params) .set_min_liquidity_msat(400); let liquidity = scorer.channel_liquidities.get(&42).unwrap() - .as_directed(&source, &target, 0, 1_000, decay_params); + .as_directed(&source, &target, 1_000, decay_params); assert_eq!(liquidity.min_liquidity_msat(), 0); assert_eq!(liquidity.max_liquidity_msat(), 600); let liquidity = scorer.channel_liquidities.get(&42).unwrap() - .as_directed(&target, &source, 0, 1_000, decay_params); + .as_directed(&target, &source, 1_000, decay_params); assert_eq!(liquidity.min_liquidity_msat(), 400); assert_eq!(liquidity.max_liquidity_msat(), 1_000); } @@ -2184,42 +2497,42 @@ mod tests { // Check initial bounds. let liquidity = scorer.channel_liquidities.get(&42).unwrap() - .as_directed(&source, &target, 0, 1_000, decay_params); + .as_directed(&source, &target, 1_000, decay_params); assert_eq!(liquidity.min_liquidity_msat(), 400); assert_eq!(liquidity.max_liquidity_msat(), 800); let liquidity = scorer.channel_liquidities.get(&42).unwrap() - .as_directed(&target, &source, 0, 1_000, decay_params); + .as_directed(&target, &source, 1_000, decay_params); assert_eq!(liquidity.min_liquidity_msat(), 200); assert_eq!(liquidity.max_liquidity_msat(), 600); // Reset from source to target. scorer.channel_liquidities.get_mut(&42).unwrap() - .as_directed_mut(&source, &target, 0, 1_000, decay_params) + .as_directed_mut(&source, &target, 1_000, decay_params) .set_max_liquidity_msat(300); let liquidity = scorer.channel_liquidities.get(&42).unwrap() - .as_directed(&source, &target, 0, 1_000, decay_params); + .as_directed(&source, &target, 1_000, decay_params); assert_eq!(liquidity.min_liquidity_msat(), 0); assert_eq!(liquidity.max_liquidity_msat(), 300); let liquidity = scorer.channel_liquidities.get(&42).unwrap() - .as_directed(&target, &source, 0, 1_000, decay_params); + .as_directed(&target, &source, 1_000, decay_params); assert_eq!(liquidity.min_liquidity_msat(), 700); assert_eq!(liquidity.max_liquidity_msat(), 1_000); // Reset from target to source. scorer.channel_liquidities.get_mut(&42).unwrap() - .as_directed_mut(&target, &source, 0, 1_000, decay_params) + .as_directed_mut(&target, &source, 1_000, decay_params) .set_max_liquidity_msat(600); let liquidity = scorer.channel_liquidities.get(&42).unwrap() - .as_directed(&source, &target, 0, 1_000, decay_params); + .as_directed(&source, &target, 1_000, decay_params); assert_eq!(liquidity.min_liquidity_msat(), 400); assert_eq!(liquidity.max_liquidity_msat(), 1_000); let liquidity = scorer.channel_liquidities.get(&42).unwrap() - .as_directed(&target, &source, 0, 1_000, decay_params); + .as_directed(&target, &source, 1_000, decay_params); assert_eq!(liquidity.min_liquidity_msat(), 0); assert_eq!(liquidity.max_liquidity_msat(), 600); } @@ -2548,7 +2861,7 @@ mod tests { let usage = ChannelUsage { amount_msat: 256, ..usage }; assert_eq!(scorer.channel_penalty_msat(42, &source, &target, usage, ¶ms), 106); let usage = ChannelUsage { amount_msat: 768, ..usage }; - assert_eq!(scorer.channel_penalty_msat(42, &source, &target, usage, ¶ms), 916); + assert_eq!(scorer.channel_penalty_msat(42, &source, &target, usage, ¶ms), 921); let usage = ChannelUsage { amount_msat: 896, ..usage }; assert_eq!(scorer.channel_penalty_msat(42, &source, &target, usage, ¶ms), u64::max_value()); @@ -2748,7 +3061,7 @@ mod tests { assert_eq!(scorer.channel_penalty_msat(42, &source, &target, usage, ¶ms), 300); SinceEpoch::advance(Duration::from_secs(10)); - assert_eq!(deserialized_scorer.channel_penalty_msat(42, &source, &target, usage, ¶ms), 365); + assert_eq!(deserialized_scorer.channel_penalty_msat(42, &source, &target, usage, ¶ms), 370); } #[test] @@ -2767,47 +3080,47 @@ mod tests { inflight_htlc_msat: 0, effective_capacity: EffectiveCapacity::Total { capacity_msat: 950_000_000, htlc_maximum_msat: 1_000 }, }; - assert_eq!(scorer.channel_penalty_msat(42, &source, &target, usage, ¶ms), 4375); + assert_eq!(scorer.channel_penalty_msat(42, &source, &target, usage, ¶ms), 11497); let usage = ChannelUsage { effective_capacity: EffectiveCapacity::Total { capacity_msat: 1_950_000_000, htlc_maximum_msat: 1_000 }, ..usage }; - assert_eq!(scorer.channel_penalty_msat(42, &source, &target, usage, ¶ms), 2739); + assert_eq!(scorer.channel_penalty_msat(42, &source, &target, usage, ¶ms), 7408); let usage = ChannelUsage { effective_capacity: EffectiveCapacity::Total { capacity_msat: 2_950_000_000, htlc_maximum_msat: 1_000 }, ..usage }; - assert_eq!(scorer.channel_penalty_msat(42, &source, &target, usage, ¶ms), 2236); + assert_eq!(scorer.channel_penalty_msat(42, &source, &target, usage, ¶ms), 6151); let usage = ChannelUsage { effective_capacity: EffectiveCapacity::Total { capacity_msat: 3_950_000_000, htlc_maximum_msat: 1_000 }, ..usage }; - assert_eq!(scorer.channel_penalty_msat(42, &source, &target, usage, ¶ms), 1983); + assert_eq!(scorer.channel_penalty_msat(42, &source, &target, usage, ¶ms), 5427); let usage = ChannelUsage { effective_capacity: EffectiveCapacity::Total { capacity_msat: 4_950_000_000, htlc_maximum_msat: 1_000 }, ..usage }; - assert_eq!(scorer.channel_penalty_msat(42, &source, &target, usage, ¶ms), 1637); + assert_eq!(scorer.channel_penalty_msat(42, &source, &target, usage, ¶ms), 4955); let usage = ChannelUsage { effective_capacity: EffectiveCapacity::Total { capacity_msat: 5_950_000_000, htlc_maximum_msat: 1_000 }, ..usage }; - assert_eq!(scorer.channel_penalty_msat(42, &source, &target, usage, ¶ms), 1606); + assert_eq!(scorer.channel_penalty_msat(42, &source, &target, usage, ¶ms), 4736); let usage = ChannelUsage { effective_capacity: EffectiveCapacity::Total { capacity_msat: 6_950_000_000, htlc_maximum_msat: 1_000 }, ..usage }; - assert_eq!(scorer.channel_penalty_msat(42, &source, &target, usage, ¶ms), 1331); + assert_eq!(scorer.channel_penalty_msat(42, &source, &target, usage, ¶ms), 4484); let usage = ChannelUsage { effective_capacity: EffectiveCapacity::Total { capacity_msat: 7_450_000_000, htlc_maximum_msat: 1_000 }, ..usage }; - assert_eq!(scorer.channel_penalty_msat(42, &source, &target, usage, ¶ms), 1387); + assert_eq!(scorer.channel_penalty_msat(42, &source, &target, usage, ¶ms), 4484); let usage = ChannelUsage { effective_capacity: EffectiveCapacity::Total { capacity_msat: 7_950_000_000, htlc_maximum_msat: 1_000 }, ..usage }; - assert_eq!(scorer.channel_penalty_msat(42, &source, &target, usage, ¶ms), 1379); + assert_eq!(scorer.channel_penalty_msat(42, &source, &target, usage, ¶ms), 4263); let usage = ChannelUsage { effective_capacity: EffectiveCapacity::Total { capacity_msat: 8_950_000_000, htlc_maximum_msat: 1_000 }, ..usage }; - assert_eq!(scorer.channel_penalty_msat(42, &source, &target, usage, ¶ms), 1363); + assert_eq!(scorer.channel_penalty_msat(42, &source, &target, usage, ¶ms), 4263); let usage = ChannelUsage { effective_capacity: EffectiveCapacity::Total { capacity_msat: 9_950_000_000, htlc_maximum_msat: 1_000 }, ..usage }; - assert_eq!(scorer.channel_penalty_msat(42, &source, &target, usage, ¶ms), 1355); + assert_eq!(scorer.channel_penalty_msat(42, &source, &target, usage, ¶ms), 4044); } #[test] @@ -2965,52 +3278,61 @@ mod tests { inflight_htlc_msat: 0, effective_capacity: EffectiveCapacity::Total { capacity_msat: 1_024, htlc_maximum_msat: 1_024 }, }; + let usage_1 = ChannelUsage { + amount_msat: 1, + inflight_htlc_msat: 0, + effective_capacity: EffectiveCapacity::Total { capacity_msat: 1_024, htlc_maximum_msat: 1_024 }, + }; + // With no historical data the normal liquidity penalty calculation is used. - assert_eq!(scorer.channel_penalty_msat(42, &source, &target, usage, ¶ms), 47); + assert_eq!(scorer.channel_penalty_msat(42, &source, &target, usage, ¶ms), 168); assert_eq!(scorer.historical_estimated_channel_liquidity_probabilities(42, &target), None); - assert_eq!(scorer.historical_estimated_payment_success_probability(42, &target, 42), + assert_eq!(scorer.historical_estimated_payment_success_probability(42, &target, 42, ¶ms), None); scorer.payment_path_failed(&payment_path_for_amount(1), 42); assert_eq!(scorer.channel_penalty_msat(42, &source, &target, usage, ¶ms), 2048); - // The "it failed" increment is 32, where the probability should lie fully in the first - // octile. + assert_eq!(scorer.channel_penalty_msat(42, &source, &target, usage_1, ¶ms), 249); + // The "it failed" increment is 32, where the probability should lie several buckets into + // the first octile. assert_eq!(scorer.historical_estimated_channel_liquidity_probabilities(42, &target), - Some(([32, 0, 0, 0, 0, 0, 0, 0], [32, 0, 0, 0, 0, 0, 0, 0]))); - assert_eq!(scorer.historical_estimated_payment_success_probability(42, &target, 1), - Some(1.0)); - assert_eq!(scorer.historical_estimated_payment_success_probability(42, &target, 500), + Some(([32, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0], + [0, 0, 0, 0, 0, 0, 32, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]))); + assert!(scorer.historical_estimated_payment_success_probability(42, &target, 1, ¶ms) + .unwrap() > 0.35); + assert_eq!(scorer.historical_estimated_payment_success_probability(42, &target, 500, ¶ms), Some(0.0)); // Even after we tell the scorer we definitely have enough available liquidity, it will // still remember that there was some failure in the past, and assign a non-0 penalty. scorer.payment_path_failed(&payment_path_for_amount(1000), 43); - assert_eq!(scorer.channel_penalty_msat(42, &source, &target, usage, ¶ms), 198); - // The first octile should be decayed just slightly and the last octile has a new point. + assert_eq!(scorer.channel_penalty_msat(42, &source, &target, usage, ¶ms), 105); + // The first points should be decayed just slightly and the last bucket has a new point. assert_eq!(scorer.historical_estimated_channel_liquidity_probabilities(42, &target), - Some(([31, 0, 0, 0, 0, 0, 0, 32], [31, 0, 0, 0, 0, 0, 0, 32]))); + Some(([31, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 32, 0, 0, 0, 0, 0], + [0, 0, 0, 0, 0, 0, 31, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 32]))); // The exact success probability is a bit complicated and involves integer rounding, so we // simply check bounds here. let five_hundred_prob = - scorer.historical_estimated_payment_success_probability(42, &target, 500).unwrap(); - assert!(five_hundred_prob > 0.5); - assert!(five_hundred_prob < 0.52); + scorer.historical_estimated_payment_success_probability(42, &target, 500, ¶ms).unwrap(); + assert!(five_hundred_prob > 0.59); + assert!(five_hundred_prob < 0.60); let one_prob = - scorer.historical_estimated_payment_success_probability(42, &target, 1).unwrap(); - assert!(one_prob < 1.0); - assert!(one_prob > 0.99); + scorer.historical_estimated_payment_success_probability(42, &target, 1, ¶ms).unwrap(); + assert!(one_prob < 0.85); + assert!(one_prob > 0.84); // Advance the time forward 16 half-lives (which the docs claim will ensure all data is // gone), and check that we're back to where we started. SinceEpoch::advance(Duration::from_secs(10 * 16)); - assert_eq!(scorer.channel_penalty_msat(42, &source, &target, usage, ¶ms), 47); + assert_eq!(scorer.channel_penalty_msat(42, &source, &target, usage, ¶ms), 168); // Once fully decayed we still have data, but its all-0s. In the future we may remove the // data entirely instead. assert_eq!(scorer.historical_estimated_channel_liquidity_probabilities(42, &target), - Some(([0; 8], [0; 8]))); - assert_eq!(scorer.historical_estimated_payment_success_probability(42, &target, 1), None); + None); + assert_eq!(scorer.historical_estimated_payment_success_probability(42, &target, 1, ¶ms), None); let mut usage = ChannelUsage { amount_msat: 100, @@ -3018,9 +3340,9 @@ mod tests { effective_capacity: EffectiveCapacity::Total { capacity_msat: 1_024, htlc_maximum_msat: 1_024 }, }; scorer.payment_path_failed(&payment_path_for_amount(1), 42); - assert_eq!(scorer.channel_penalty_msat(42, &source, &target, usage, ¶ms), 2048); + assert_eq!(scorer.channel_penalty_msat(42, &source, &target, usage, ¶ms), 2050); usage.inflight_htlc_msat = 0; - assert_eq!(scorer.channel_penalty_msat(42, &source, &target, usage, ¶ms), 409); + assert_eq!(scorer.channel_penalty_msat(42, &source, &target, usage, ¶ms), 866); let usage = ChannelUsage { amount_msat: 1, @@ -3132,8 +3454,81 @@ mod tests { scorer.payment_path_failed(&path, 43); let liquidity = scorer.channel_liquidities.get(&42).unwrap() - .as_directed(&source, &target, 0, 1_000, decay_params); + .as_directed(&source, &target, 1_000, decay_params); assert_eq!(liquidity.min_liquidity_msat(), 256); assert_eq!(liquidity.max_liquidity_msat(), 768); } + + #[test] + fn realistic_historical_failures() { + // The motivation for the unequal sized buckets came largely from attempting to pay 10k + // sats over a one bitcoin channel. This tests that case explicitly, ensuring that we score + // properly. + let logger = TestLogger::new(); + let mut network_graph = network_graph(&logger); + let params = ProbabilisticScoringFeeParameters { + historical_liquidity_penalty_multiplier_msat: 1024, + historical_liquidity_penalty_amount_multiplier_msat: 1024, + ..ProbabilisticScoringFeeParameters::zero_penalty() + }; + let decay_params = ProbabilisticScoringDecayParameters { + liquidity_offset_half_life: Duration::from_secs(60 * 60), + historical_no_updates_half_life: Duration::from_secs(10), + ..ProbabilisticScoringDecayParameters::default() + }; + + let capacity_msat = 100_000_000_000; + update_channel(&mut network_graph, 42, source_privkey(), 0, capacity_msat, 200); + update_channel(&mut network_graph, 42, target_privkey(), 1, capacity_msat, 200); + + let mut scorer = ProbabilisticScorer::new(decay_params, &network_graph, &logger); + let source = source_node_id(); + let target = target_node_id(); + + let mut amount_msat = 10_000_000; + let usage = ChannelUsage { + amount_msat, + inflight_htlc_msat: 0, + effective_capacity: EffectiveCapacity::Total { capacity_msat, htlc_maximum_msat: capacity_msat }, + }; + // With no historical data the normal liquidity penalty calculation is used, which results + // in a success probability of ~75%. + assert_eq!(scorer.channel_penalty_msat(42, &source, &target, usage, ¶ms), 1269); + assert_eq!(scorer.historical_estimated_channel_liquidity_probabilities(42, &target), + None); + assert_eq!(scorer.historical_estimated_payment_success_probability(42, &target, 42, ¶ms), + None); + + // Fail to pay once, and then check the buckets and penalty. + scorer.payment_path_failed(&payment_path_for_amount(amount_msat), 42); + // The penalty should be the maximum penalty, as the payment we're scoring is now in the + // same bucket which is the only maximum datapoint. + assert_eq!(scorer.channel_penalty_msat(42, &source, &target, usage, ¶ms), + 2048 + 2048 * amount_msat / super::AMOUNT_PENALTY_DIVISOR); + // The "it failed" increment is 32, which we should apply to the first upper-bound (between + // 6k sats and 12k sats). + assert_eq!(scorer.historical_estimated_channel_liquidity_probabilities(42, &target), + Some(([32, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0], + [0, 32, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]))); + // The success probability estimate itself should be zero. + assert_eq!(scorer.historical_estimated_payment_success_probability(42, &target, amount_msat, ¶ms), + Some(0.0)); + + // Now test again with the amount in the bottom bucket. + amount_msat /= 2; + // The new amount is entirely within the only minimum bucket with score, so the probability + // we assign is 1/2. + assert_eq!(scorer.historical_estimated_payment_success_probability(42, &target, amount_msat, ¶ms), + Some(0.5)); + + // ...but once we see a failure, we consider the payment to be substantially less likely, + // even though not a probability of zero as we still look at the second max bucket which + // now shows 31. + scorer.payment_path_failed(&payment_path_for_amount(amount_msat), 42); + assert_eq!(scorer.historical_estimated_channel_liquidity_probabilities(42, &target), + Some(([63, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0], + [32, 31, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]))); + assert_eq!(scorer.historical_estimated_payment_success_probability(42, &target, amount_msat, ¶ms), + Some(0.0)); + } }