f docs + TODO

Author: valentinewallace

lightning/src/routing/onion_message.rs

@@ -22,7 +22,8 @@ use prelude::*;
 
 /// Finds a route from us to the given `destination` node.
 /// If we have private channels, it may be useful to fill in `first_hops` with the results from
-/// [`ChannelManager::list_usable_channels`].
+/// [`ChannelManager::list_usable_channels`]. If `first_hops` is not filled in, connected peers
+/// without public channels will not be forwarded over.
 ///
 /// [`ChannelManager::list_usable_channels`]: crate::ln::channelmanager::ChannelManager::list_usable_channels
 pub fn find_path<L: Deref, GL: Deref>(
@@ -99,6 +100,8 @@ struct PathBuildingHop {
 impl PartialOrd for PathBuildingHop {
 	fn partial_cmp(&self, other: &Self) -> Option<cmp::Ordering> {
 		// We need a min-heap, whereas `BinaryHeap`s are a max-heap, so compare the costs in reverse.
+		// TODO: randomize which node is selected if they are equal-cost. Currently there is an
+		// incentive to grind lower node ids to attract more message forwards.
 		other.cost.partial_cmp(&self.cost)
 	}
 }