Move to a constant for "bucket one" in the scoring buckets

[rust-lightning] / lightning / src / routing / scoring.rs

diff --git a/lightning/src/routing/scoring.rs b/lightning/src/routing/scoring.rs
index b13f5531ec77f970e7fa4f9be330d93386af0142..5fdbf9ae3a9c8eff91ba0948ec86d8f9f3f7bdec 100644 (file)
--- a/lightning/src/routing/scoring.rs
+++ b/lightning/src/routing/scoring.rs
@@ -1684,6 +1684,10 @@ mod bucketed_history {
                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; 32] } }
                pub(super) fn track_datapoint(&mut self, liquidity_offset_msat: u64, capacity_msat: u64) {
@@ -1714,7 +1718,7 @@ mod bucketed_history {
                                        *e = ((*e as u32) * 2047 / 2048) as u16;
                                }
                                let bucket = pos_to_bucket(pos);
-                               self.buckets[bucket] = self.buckets[bucket].saturating_add(32);
+                               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
@@ -1768,7 +1772,8 @@ mod bucketed_history {
 
                        // 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 {
+                       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;
                        }
 
@@ -1806,7 +1811,7 @@ mod bucketed_history {
                                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 >= 32 {
+                                       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;