- // First, drop some expensive low-value paths entirely if possible.
- // Sort by value so that we drop many really-low values first, since
- // fewer paths is better: the payment is less likely to fail.
- // 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.get_value_msat());
+ // First, we drop some expensive low-value paths entirely if possible, since fewer
+ // paths is better: the payment is less likely to fail. In order to do so, we sort
+ // by value and fall back to total fees paid, i.e., in case of equal values we
+ // prefer lower cost paths.
+ cur_route.sort_unstable_by(|a, b| {
+ a.get_value_msat().cmp(&b.get_value_msat())
+ // Reverse ordering for fees, so we drop higher-fee paths first
+ .then_with(|| b.get_total_fee_paid_msat().saturating_add(b.get_path_penalty_msat())
+ .cmp(&a.get_total_fee_paid_msat().saturating_add(a.get_path_penalty_msat())))
+ });
+