Stop decaying liquidity information during bounds-based scoring

Because scoring is an incredibly performance-sensitive operation,
doing liquidity information decay (and especially fetching the
current time!) during scoring isn't really a great idea. Now that
we decay liquidity information in the background, we don't have any
reason to decay during scoring, and we ultimately remove it
entirely here.

diff --git a/lightning/src/routing/scoring.rs b/lightning/src/routing/scoring.rs
index 4391da8e93eda36581a7dd769fcce8106891b3a1..d0766b6a78a54b297d70460a7d96be875814815f 100644 (file)
--- a/lightning/src/routing/scoring.rs
+++ b/lightning/src/routing/scoring.rs
@@ -1260,25 +1260,7 @@ impl<L: Deref<Target = u64>, BRT: Deref<Target = HistoricalBucketRangeTracker>,
        }
 
        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 {
-                       // Decay the offset by the appropriate number of half lives. If half of the next half
-                       // life has passed, approximate an additional three-quarter life to help smooth out the
-                       // decay.
-                       let elapsed_time = self.now.duration_since(*self.last_updated).as_secs();
-                       let half_decays = elapsed_time / (half_life / 2);
-                       let decays = half_decays / 2;
-                       let decayed_offset_msat = offset_msat.checked_shr(decays as u32).unwrap_or(0);
-                       if half_decays % 2 == 0 {
-                               decayed_offset_msat
-                       } else {
-                               // 11_585 / 16_384 ~= core::f64::consts::FRAC_1_SQRT_2
-                               // 16_384 == 2^14
-                               (decayed_offset_msat as u128 * 11_585 / 16_384) as u64
-                       }
-               } else {
-                       0
-               }
+               offset_msat
        }
 }