Handle new event processing logic when enqueuing forward event

[rust-lightning] / lightning / src / ln / channelmanager.rs

diff --git a/lightning/src/ln/channelmanager.rs b/lightning/src/ln/channelmanager.rs
index 65f442f1c097ea80018e33f9c56d06f1f61cc072..2cbda06684915a882ee74475368bbd51c20d59bd 100644 (file)
--- a/lightning/src/ln/channelmanager.rs
+++ b/lightning/src/ln/channelmanager.rs
@@ -1978,6 +1978,8 @@ macro_rules! process_events_body {
                                let mut pending_events = $self.pending_events.lock().unwrap();
                                pending_events.drain(..num_events);
                                processed_all_events = pending_events.is_empty();
+                               // Note that `push_pending_forwards_ev` relies on `pending_events_processor` being
+                               // updated here with the `pending_events` lock acquired.
                                $self.pending_events_processor.store(false, Ordering::Release);
                        }
 
@@ -5686,16 +5688,21 @@ where
                }
        }
 
-       // We only want to push a PendingHTLCsForwardable event if no others are queued.
        fn push_pending_forwards_ev(&self) {
                let mut pending_events = self.pending_events.lock().unwrap();
-               let forward_ev_exists = pending_events.iter()
-                       .find(|(ev, _)| if let events::Event::PendingHTLCsForwardable { .. } = ev { true } else { false })
-                       .is_some();
-               if !forward_ev_exists {
-                       pending_events.push_back((events::Event::PendingHTLCsForwardable {
-                               time_forwardable:
-                                       Duration::from_millis(MIN_HTLC_RELAY_HOLDING_CELL_MILLIS),
+               let is_processing_events = self.pending_events_processor.load(Ordering::Acquire);
+               let num_forward_events = pending_events.iter().filter(|(ev, _)|
+                       if let events::Event::PendingHTLCsForwardable { .. } = ev { true } else { false }
+               ).count();
+               // We only want to push a PendingHTLCsForwardable event if no others are queued. Processing
+               // events is done in batches and they are not removed until we're done processing each
+               // batch. Since handling a `PendingHTLCsForwardable` event will call back into the
+               // `ChannelManager`, we'll still see the original forwarding event not removed. Phantom
+               // payments will need an additional forwarding event before being claimed to make them look
+               // real by taking more time.
+               if (is_processing_events && num_forward_events <= 1) || num_forward_events < 1 {
+                       pending_events.push_back((Event::PendingHTLCsForwardable {
+                               time_forwardable: Duration::from_millis(MIN_HTLC_RELAY_HOLDING_CELL_MILLIS),
                        }, None));
                }
        }