Drop half-life-based bucket decay in `update_history_buckets`
[rust-lightning] / lightning / src / routing / scoring.rs
index 0dd0c2ea38899612d22a273c14196711344ed4c0..0bea2223cabbcf26cde7bf52ffab6173a6841874 100644 (file)
@@ -789,7 +789,7 @@ struct ChannelLiquidity {
        min_liquidity_offset_history: HistoricalBucketRangeTracker,
        max_liquidity_offset_history: HistoricalBucketRangeTracker,
 
-       /// Time when the liquidity bounds were last modified as an offset since the unix epoch.
+       /// Time when either liquidity bound was last modified as an offset since the unix epoch.
        last_updated: Duration,
 
        /// Time when the historical liquidity bounds were last modified as an offset against the unix
@@ -805,7 +805,6 @@ struct DirectedChannelLiquidity<L: Deref<Target = u64>, BRT: Deref<Target = Hist
        capacity_msat: u64,
        last_updated: T,
        offset_history_last_updated: T,
-       decay_params: ProbabilisticScoringDecayParameters,
 }
 
 impl<G: Deref<Target = NetworkGraph<L>>, L: Deref> ProbabilisticScorer<G, L> where L::Target: Logger {
@@ -837,7 +836,7 @@ impl<G: Deref<Target = NetworkGraph<L>>, L: Deref> ProbabilisticScorer<G, L> whe
                                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, amt, self.decay_params);
+                                               let dir_liq = liq.as_directed(source, target, amt);
 
                                                let min_buckets = &dir_liq.liquidity_history.min_liquidity_offset_history.buckets;
                                                let max_buckets = &dir_liq.liquidity_history.max_liquidity_offset_history.buckets;
@@ -889,7 +888,7 @@ impl<G: Deref<Target = NetworkGraph<L>>, L: Deref> ProbabilisticScorer<G, L> whe
                        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, amt, self.decay_params);
+                                       let dir_liq = liq.as_directed(source, target, amt);
                                        return Some((dir_liq.min_liquidity_msat(), dir_liq.max_liquidity_msat()));
                                }
                        }
@@ -931,7 +930,7 @@ impl<G: Deref<Target = NetworkGraph<L>>, L: Deref> ProbabilisticScorer<G, L> whe
                        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, amt, self.decay_params);
+                                       let dir_liq = liq.as_directed(source, target, amt);
 
                                        let min_buckets = dir_liq.liquidity_history.min_liquidity_offset_history.buckets;
                                        let mut max_buckets = dir_liq.liquidity_history.max_liquidity_offset_history.buckets;
@@ -962,7 +961,7 @@ impl<G: Deref<Target = NetworkGraph<L>>, L: Deref> ProbabilisticScorer<G, L> whe
                        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, capacity_msat, self.decay_params);
+                                       let dir_liq = liq.as_directed(source, target, capacity_msat);
 
                                        return dir_liq.liquidity_history.calculate_success_probability_times_billion(
                                                &params, amount_msat, capacity_msat
@@ -989,7 +988,7 @@ 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, capacity_msat: u64, decay_params: ProbabilisticScoringDecayParameters
+               &self, source: &NodeId, target: &NodeId, capacity_msat: u64,
        ) -> DirectedChannelLiquidity<&u64, &HistoricalBucketRangeTracker, &Duration> {
                let (min_liquidity_offset_msat, max_liquidity_offset_msat, min_liquidity_offset_history, max_liquidity_offset_history) =
                        if source < target {
@@ -1010,14 +1009,13 @@ impl ChannelLiquidity {
                        capacity_msat,
                        last_updated: &self.last_updated,
                        offset_history_last_updated: &self.offset_history_last_updated,
-                       decay_params: decay_params,
                }
        }
 
        /// 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, capacity_msat: u64, decay_params: ProbabilisticScoringDecayParameters
+               &mut self, source: &NodeId, target: &NodeId, capacity_msat: u64,
        ) -> DirectedChannelLiquidity<&mut u64, &mut HistoricalBucketRangeTracker, &mut Duration> {
                let (min_liquidity_offset_msat, max_liquidity_offset_msat, min_liquidity_offset_history, max_liquidity_offset_history) =
                        if source < target {
@@ -1038,7 +1036,6 @@ impl ChannelLiquidity {
                        capacity_msat,
                        last_updated: &mut self.last_updated,
                        offset_history_last_updated: &mut self.offset_history_last_updated,
-                       decay_params: decay_params,
                }
        }
 
@@ -1289,14 +1286,6 @@ DirectedChannelLiquidity<L, BRT, T> {
        /// state"), we allow the caller to set an offset applied to our liquidity bounds which
        /// represents the amount of the successful payment we just made.
        fn update_history_buckets(&mut self, bucket_offset_msat: u64, duration_since_epoch: Duration) {
-               let half_lives =
-                       duration_since_epoch.checked_sub(*self.offset_history_last_updated)
-                       .unwrap_or(Duration::ZERO).as_secs()
-                       .checked_div(self.decay_params.historical_no_updates_half_life.as_secs())
-                       .map(|v| v.try_into().unwrap_or(u32::max_value())).unwrap_or(u32::max_value());
-               self.liquidity_history.min_liquidity_offset_history.time_decay_data(half_lives);
-               self.liquidity_history.max_liquidity_offset_history.time_decay_data(half_lives);
-
                self.liquidity_history.min_liquidity_offset_history.track_datapoint(
                        *self.min_liquidity_offset_msat + bucket_offset_msat, self.capacity_msat
                );
@@ -1369,7 +1358,7 @@ impl<G: Deref<Target = NetworkGraph<L>>, L: Deref> ScoreLookUp for Probabilistic
                self.channel_liquidities
                        .get(&scid)
                        .unwrap_or(&ChannelLiquidity::new(Duration::ZERO))
-                       .as_directed(&source, &target, capacity_msat, self.decay_params)
+                       .as_directed(&source, &target, capacity_msat)
                        .penalty_msat(amount_msat, score_params)
                        .saturating_add(anti_probing_penalty_msat)
                        .saturating_add(base_penalty_msat)
@@ -1399,14 +1388,14 @@ impl<G: Deref<Target = NetworkGraph<L>>, L: Deref> ScoreUpdate for Probabilistic
                                        self.channel_liquidities
                                                .entry(hop.short_channel_id)
                                                .or_insert_with(|| ChannelLiquidity::new(duration_since_epoch))
-                                               .as_directed_mut(source, &target, capacity_msat, self.decay_params)
+                                               .as_directed_mut(source, &target, capacity_msat)
                                                .failed_at_channel(amount_msat, duration_since_epoch,
                                                        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(duration_since_epoch))
-                                               .as_directed_mut(source, &target, capacity_msat, self.decay_params)
+                                               .as_directed_mut(source, &target, capacity_msat)
                                                .failed_downstream(amount_msat, duration_since_epoch,
                                                        format_args!("SCID {}, towards {:?}", hop.short_channel_id, target), &self.logger);
                                }
@@ -1435,7 +1424,7 @@ impl<G: Deref<Target = NetworkGraph<L>>, L: Deref> ScoreUpdate for Probabilistic
                                self.channel_liquidities
                                        .entry(hop.short_channel_id)
                                        .or_insert_with(|| ChannelLiquidity::new(duration_since_epoch))
-                                       .as_directed_mut(source, &target, capacity_msat, self.decay_params)
+                                       .as_directed_mut(source, &target, capacity_msat)
                                        .successful(amount_msat, duration_since_epoch,
                                                format_args!("SCID {}, towards {:?}", hop.short_channel_id, target), &self.logger);
                        } else {
@@ -1959,14 +1948,6 @@ mod bucketed_history {
                                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);
-                       }
-               }
        }
 
        impl_writeable_tlv_based!(HistoricalBucketRangeTracker, { (0, buckets, required) });
@@ -2359,52 +2340,52 @@ mod tests {
                // Update minimum liquidity.
 
                let liquidity = scorer.channel_liquidities.get(&42).unwrap()
-                       .as_directed(&source, &target, 1_000, decay_params);
+                       .as_directed(&source, &target, 1_000);
                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, 1_000, decay_params);
+                       .as_directed(&target, &source, 1_000);
                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, 1_000, decay_params)
+                       .as_directed_mut(&source, &target, 1_000)
                        .set_min_liquidity_msat(200, Duration::ZERO);
 
                let liquidity = scorer.channel_liquidities.get(&42).unwrap()
-                       .as_directed(&source, &target, 1_000, decay_params);
+                       .as_directed(&source, &target, 1_000);
                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, 1_000, decay_params);
+                       .as_directed(&target, &source, 1_000);
                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, 1_000, decay_params);
+                       .as_directed(&target, &recipient, 1_000);
                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, 1_000, decay_params);
+                       .as_directed(&recipient, &target, 1_000);
                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, 1_000, decay_params)
+                       .as_directed_mut(&target, &recipient, 1_000)
                        .set_max_liquidity_msat(200, Duration::ZERO);
 
                let liquidity = scorer.channel_liquidities.get(&43).unwrap()
-                       .as_directed(&target, &recipient, 1_000, decay_params);
+                       .as_directed(&target, &recipient, 1_000);
                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, 1_000, decay_params);
+                       .as_directed(&recipient, &target, 1_000);
                assert_eq!(liquidity.min_liquidity_msat(), 800);
                assert_eq!(liquidity.max_liquidity_msat(), 1000);
        }
@@ -2430,42 +2411,42 @@ mod tests {
 
                // Check initial bounds.
                let liquidity = scorer.channel_liquidities.get(&42).unwrap()
-                       .as_directed(&source, &target, 1_000, decay_params);
+                       .as_directed(&source, &target, 1_000);
                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, 1_000, decay_params);
+                       .as_directed(&target, &source, 1_000);
                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, 1_000, decay_params)
+                       .as_directed_mut(&source, &target, 1_000)
                        .set_min_liquidity_msat(900, Duration::ZERO);
 
                let liquidity = scorer.channel_liquidities.get(&42).unwrap()
-                       .as_directed(&source, &target, 1_000, decay_params);
+                       .as_directed(&source, &target, 1_000);
                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, 1_000, decay_params);
+                       .as_directed(&target, &source, 1_000);
                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, 1_000, decay_params)
+                       .as_directed_mut(&target, &source, 1_000)
                        .set_min_liquidity_msat(400, Duration::ZERO);
 
                let liquidity = scorer.channel_liquidities.get(&42).unwrap()
-                       .as_directed(&source, &target, 1_000, decay_params);
+                       .as_directed(&source, &target, 1_000);
                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, 1_000, decay_params);
+                       .as_directed(&target, &source, 1_000);
                assert_eq!(liquidity.min_liquidity_msat(), 400);
                assert_eq!(liquidity.max_liquidity_msat(), 1_000);
        }
@@ -2491,42 +2472,42 @@ mod tests {
 
                // Check initial bounds.
                let liquidity = scorer.channel_liquidities.get(&42).unwrap()
-                       .as_directed(&source, &target, 1_000, decay_params);
+                       .as_directed(&source, &target, 1_000);
                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, 1_000, decay_params);
+                       .as_directed(&target, &source, 1_000);
                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, 1_000, decay_params)
+                       .as_directed_mut(&source, &target, 1_000)
                        .set_max_liquidity_msat(300, Duration::ZERO);
 
                let liquidity = scorer.channel_liquidities.get(&42).unwrap()
-                       .as_directed(&source, &target, 1_000, decay_params);
+                       .as_directed(&source, &target, 1_000);
                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, 1_000, decay_params);
+                       .as_directed(&target, &source, 1_000);
                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, 1_000, decay_params)
+                       .as_directed_mut(&target, &source, 1_000)
                        .set_max_liquidity_msat(600, Duration::ZERO);
 
                let liquidity = scorer.channel_liquidities.get(&42).unwrap()
-                       .as_directed(&source, &target, 1_000, decay_params);
+                       .as_directed(&source, &target, 1_000);
                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, 1_000, decay_params);
+                       .as_directed(&target, &source, 1_000);
                assert_eq!(liquidity.min_liquidity_msat(), 0);
                assert_eq!(liquidity.max_liquidity_msat(), 600);
        }
@@ -2971,47 +2952,6 @@ mod tests {
                assert_eq!(scorer.channel_penalty_msat(&candidate, usage, &params), u64::max_value());
        }
 
-       #[test]
-       fn decays_liquidity_bounds_without_shift_overflow() {
-               let logger = TestLogger::new();
-               let network_graph = network_graph(&logger);
-               let params = ProbabilisticScoringFeeParameters {
-                       liquidity_penalty_multiplier_msat: 1_000,
-                       ..ProbabilisticScoringFeeParameters::zero_penalty()
-               };
-               let decay_params = ProbabilisticScoringDecayParameters {
-                       liquidity_offset_half_life: Duration::from_secs(10),
-                       ..ProbabilisticScoringDecayParameters::default()
-               };
-               let mut scorer = ProbabilisticScorer::new(decay_params, &network_graph, &logger);
-               let source = source_node_id();
-               let usage = ChannelUsage {
-                       amount_msat: 256,
-                       inflight_htlc_msat: 0,
-                       effective_capacity: EffectiveCapacity::Total { capacity_msat: 1_024, htlc_maximum_msat: 1_000 },
-               };
-               let channel = network_graph.read_only().channel(42).unwrap().to_owned();
-               let (info, _) = channel.as_directed_from(&source).unwrap();
-               let candidate = CandidateRouteHop::PublicHop {
-                       info,
-                       short_channel_id: 42,
-               };
-               assert_eq!(scorer.channel_penalty_msat(&candidate, usage, &params), 125);
-
-               scorer.payment_path_failed(&payment_path_for_amount(512), 42, Duration::ZERO);
-               assert_eq!(scorer.channel_penalty_msat(&candidate, usage, &params), 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));
-               scorer.time_passed(Duration::from_secs(10 * 64));
-               assert_eq!(scorer.channel_penalty_msat(&candidate, usage, &params), 125);
-
-               SinceEpoch::advance(Duration::from_secs(10));
-               scorer.time_passed(Duration::from_secs(10 * 65));
-               assert_eq!(scorer.channel_penalty_msat(&candidate, usage, &params), 125);
-       }
-
        #[test]
        fn restricts_liquidity_bounds_after_decay() {
                let logger = TestLogger::new();
@@ -3660,7 +3600,7 @@ mod tests {
                scorer.payment_path_failed(&path, 43, Duration::ZERO);
 
                let liquidity = scorer.channel_liquidities.get(&42).unwrap()
-                       .as_directed(&source, &target, 1_000, decay_params);
+                       .as_directed(&source, &target, 1_000);
                assert_eq!(liquidity.min_liquidity_msat(), 256);
                assert_eq!(liquidity.max_liquidity_msat(), 768);
        }