From: Matt Corallo <git@bluematt.me>
Date: Mon, 9 Oct 2023 01:11:10 +0000 (+0000)
Subject: Stop decaying liquidity information during bounds-based scoring
X-Git-Tag: v0.0.119~4^2~10
X-Git-Url: http://git.bitcoin.ninja/index.cgi?a=commitdiff_plain;h=6f8838fe7033b8ab6733baface32bdb183abefc7;p=rust-lightning

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 4391da8e..d0766b6a 100644
--- 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
 	}
 }