Provide `Score` the HTLC amount and channel capacity

[rust-lightning] / lightning / src / routing / mod.rs

diff --git a/lightning/src/routing/mod.rs b/lightning/src/routing/mod.rs
index 3a48ffe93ddf42c77fb3b3c9b17d727dba14c8f0..91478bafc0468254a4fa13e8882258b549923bed 100644 (file)
--- a/lightning/src/routing/mod.rs
+++ b/lightning/src/routing/mod.rs
@@ -24,9 +24,19 @@ use sync::{Mutex, MutexGuard};
 ///
 ///    Scoring is in terms of fees willing to be paid in order to avoid routing through a channel.
 pub trait Score {
-       /// Returns the fee in msats willing to be paid to avoid routing through the given channel
-       /// in the direction from `source` to `target`.
-       fn channel_penalty_msat(&self, short_channel_id: u64, source: &NodeId, target: &NodeId) -> u64;
+       /// Returns the fee in msats willing to be paid to avoid routing `send_amt_msat` through the
+       /// given channel in the direction from `source` to `target`.
+       ///
+       /// The channel's capacity (less any other MPP parts which are also being considered for use in
+       /// the same payment) is given by `channel_capacity_msat`. It may be guessed from various
+       /// sources or assumed from no data at all.
+       ///
+       /// For hints provided in the invoice, we assume the channel has sufficient capacity to accept
+       /// the invoice's full amount, and provide a `channel_capacity_msat` of `None`. In all other
+       /// cases it is set to `Some`, even if we're guessing at the channel value.
+       ///
+       /// Your code should be overflow-safe through a `channel_capacity_msat` of 21 million BTC.
+       fn channel_penalty_msat(&self, short_channel_id: u64, send_amt_msat: u64, channel_capacity_msat: Option<u64>, source: &NodeId, target: &NodeId) -> u64;
 
        /// Handles updating channel penalties after failing to route through a channel.
        fn payment_path_failed(&mut self, path: &[&RouteHop], short_channel_id: u64);
@@ -65,8 +75,8 @@ impl<'a, T: 'a + Score> LockableScore<'a> for RefCell<T> {
 }
 
 impl<S: Score, T: DerefMut<Target=S>> Score for T {
-       fn channel_penalty_msat(&self, short_channel_id: u64, source: &NodeId, target: &NodeId) -> u64 {
-               self.deref().channel_penalty_msat(short_channel_id, source, target)
+       fn channel_penalty_msat(&self, short_channel_id: u64, send_amt_msat: u64, channel_capacity_msat: Option<u64>, source: &NodeId, target: &NodeId) -> u64 {
+               self.deref().channel_penalty_msat(short_channel_id, send_amt_msat, channel_capacity_msat, source, target)
        }
 
        fn payment_path_failed(&mut self, path: &[&RouteHop], short_channel_id: u64) {