Handle being asleep for more than double our ping time gracefully

If we've been asleep for double our ping time, for whatever reason,
disconnect all open sockets.

diff --git a/lightning-background-processor/src/lib.rs b/lightning-background-processor/src/lib.rs
index 5573b101ef7139bdb53ac6201d4b01c8b9cb07f5..c75c47262e51d2873a335acc37518bccd6ed2984 100644 (file)
--- a/lightning-background-processor/src/lib.rs
+++ b/lightning-background-processor/src/lib.rs
@@ -160,7 +160,19 @@ impl BackgroundProcessor {
                                        channel_manager.timer_tick_occurred();
                                        last_freshness_call = Instant::now();
                                }
-                               if last_ping_call.elapsed().as_secs() > PING_TIMER {
+                               if last_ping_call.elapsed().as_secs() > PING_TIMER * 2 {
+                                       // On various platforms, we may be starved of CPU cycles for several reasons.
+                                       // E.g. on iOS, if we've been in the background, we will be entirely paused.
+                                       // Similarly, if we're on a desktop platform and the device has been asleep, we
+                                       // may not get any cycles.
+                                       // In any case, if we've been entirely paused for more than double our ping
+                                       // timer, we should have disconnected all sockets by now (and they're probably
+                                       // dead anyway), so disconnect them by calling `timer_tick_occurred()` twice.
+                                       log_trace!(logger, "Awoke after more than double our ping timer, disconnecting peers.");
+                                       peer_manager.timer_tick_occurred();
+                                       peer_manager.timer_tick_occurred();
+                                       last_ping_call = Instant::now();
+                               } else if last_ping_call.elapsed().as_secs() > PING_TIMER {
                                        log_trace!(logger, "Calling PeerManager's timer_tick_occurred");
                                        peer_manager.timer_tick_occurred();
                                        last_ping_call = Instant::now();