Refactor channel failure penalty logic

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

diff --git a/lightning/src/routing/mod.rs b/lightning/src/routing/mod.rs
index 1cf73c2689eecc9029114d7ab6d24c4b19b66557..d6c016468ce79f696483ccafcee03e0269b6267f 100644 (file)
--- a/lightning/src/routing/mod.rs
+++ b/lightning/src/routing/mod.rs
@@ -13,10 +13,64 @@ pub mod network_graph;
 pub mod router;
 pub mod scorer;
 
+use routing::network_graph::NodeId;
+use routing::router::RouteHop;
+
+use prelude::*;
+use core::cell::{RefCell, RefMut};
+use core::ops::DerefMut;
+use sync::{Mutex, MutexGuard};
+
 /// An interface used to score payment channels for path finding.
 ///
 ///    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.
-       fn channel_penalty_msat(&self, short_channel_id: u64) -> u64;
+       /// 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;
+
+       /// Handles updating channel penalties after failing to route through a channel.
+       fn payment_path_failed(&mut self, path: &Vec<RouteHop>, short_channel_id: u64);
+}
+
+/// A scorer that is accessed under a lock.
+///
+/// Needed so that calls to [`Score::channel_penalty_msat`] in [`find_route`] can be made while
+/// having shared ownership of a scorer but without requiring internal locking in [`Score`]
+/// implementations. Internal locking would be detrimental to route finding performance and could
+/// result in [`Score::channel_penalty_msat`] returning a different value for the same channel.
+///
+/// [`find_route`]: crate::routing::router::find_route
+pub trait LockableScore<'a> {
+       /// The locked [`Score`] type.
+       type Locked: 'a + Score;
+
+       /// Returns the locked scorer.
+       fn lock(&'a self) -> Self::Locked;
+}
+
+impl<'a, T: 'a + Score> LockableScore<'a> for Mutex<T> {
+       type Locked = MutexGuard<'a, T>;
+
+       fn lock(&'a self) -> MutexGuard<'a, T> {
+               Mutex::lock(self).unwrap()
+       }
+}
+
+impl<'a, T: 'a + Score> LockableScore<'a> for RefCell<T> {
+       type Locked = RefMut<'a, T>;
+
+       fn lock(&'a self) -> RefMut<'a, T> {
+               self.borrow_mut()
+       }
+}
+
+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 payment_path_failed(&mut self, path: &Vec<RouteHop>, short_channel_id: u64) {
+               self.deref_mut().payment_path_failed(path, short_channel_id)
+       }
 }