Fix minimal contribution at 10% of final_value_msat

Author: tnull

lightning/src/routing/router.rs

@@ -847,11 +847,8 @@ where L::Target: Logger {
 	let mut used_channel_liquidities: HashMap<(u64, bool), u64> =
 		HashMap::with_capacity(network_nodes.len());
 
-	// Keeping track of how much value we already collected across other paths. Helps to decide:
-	// - how much a new path should be transferring (upper bound);
-	// - whether a channel should be disregarded because
-	//   it's available liquidity is too small comparing to how much more we need to collect;
-	// - when we want to stop looking for new paths.
+	// Keeping track of how much value we already collected across other paths. Helps to decide
+	// when we want to stop looking for new paths. 
 	let mut already_collected_value_msat = 0;
 
 	for (_, channels) in first_hop_targets.iter_mut() {
@@ -920,16 +917,12 @@ where L::Target: Logger {
 					// Taking too many smaller paths also increases the chance of payment failure.
 					// Thus to avoid this effect, we require from our collected links to provide
 					// at least a minimal contribution to the recommended value yet-to-be-fulfilled.
-					//
-					// This requirement is currently 5% of the remaining-to-be-collected value.
-					// This means as we successfully advance in our collection,
-					// the absolute liquidity contribution is lowered,
-					// thus increasing the number of potential channels to be selected.
+					// This requirement is currently 10% of the value.
 
-					// Derive the minimal liquidity contribution with a ratio of 20 (5%, rounded up)
+					// Derive the minimal liquidity contribution with a ratio of 10 (10%, rounded up)
 					// or 100% if we're not allowed to do multipath payments.
 					let minimal_value_contribution_msat: u64 = if allow_mpp {
-						(recommended_value_msat - already_collected_value_msat + 19) / 20
+						(final_value_msat + 9) / 10
 					} else {
 						final_value_msat
 					};
@@ -1504,10 +1497,8 @@ where L::Target: Logger {
 					*used_channel_liquidities.entry((victim_scid, true)).or_default() = exhausted;
 				}
 
-				// Track the total amount all our collected paths allow to send so that we:
-				// - know when to stop looking for more paths
-				// - know which of the hops are useless considering how much more sats we need
-				//   (contributes_sufficient_value)
+				// Track the total amount all our collected paths allow to send so that we know
+				// when to stop looking for more paths
 				already_collected_value_msat += value_contribution_msat;
 
 				payment_paths.push(payment_path);