Use cached sort when iterating over path.

Author: tnull

lightning/src/routing/router.rs

@@ -1442,7 +1442,7 @@ where L::Target: Logger {
 	}
 
 	// Sort by total fees and take the best paths.
-	payment_paths.sort_by_key(|path| path.get_total_fee_paid_msat());
+	payment_paths.sort_by_cached_key(|path| path.get_total_fee_paid_msat());
 	if payment_paths.len() > 50 {
 		payment_paths.truncate(50);
 	}
@@ -1522,7 +1522,7 @@ where L::Target: Logger {
 				// Now, subtract the overpaid value from the most-expensive path.
 				// TODO: this could also be optimized by also sorting by feerate_per_sat_routed,
 				// so that the sender pays less fees overall. And also htlc_minimum_msat.
-				cur_route.sort_by_key(|path| { path.hops.iter().map(|hop| hop.0.candidate.fees().proportional_millionths as u64).sum::<u64>() });
+				cur_route.sort_by_cached_key(|path| { path.hops.iter().map(|hop| hop.0.candidate.fees().proportional_millionths as u64).sum::<u64>() });
 				let expensive_payment_path = cur_route.first_mut().unwrap();
 
 				// We already dropped all the small value paths above, meaning all the
@@ -1538,7 +1538,7 @@ where L::Target: Logger {
 
 	// Step (9).
 	// Select the best route by lowest total fee.
-	drawn_routes.sort_by_key(|paths| paths.iter().map(|path| path.get_total_fee_paid_msat()).sum::<u64>());
+	drawn_routes.sort_by_cached_key(|paths| paths.iter().map(|path| path.get_total_fee_paid_msat()).sum::<u64>());
 	let mut selected_paths = Vec::<Vec<Result<RouteHop, LightningError>>>::new();
 	for payment_path in drawn_routes.first().unwrap() {
 		let mut path = payment_path.hops.iter().map(|(payment_hop, node_features)| {