f rewrite to just check the await time

Author: TheBlueMatt

lightning-background-processor/src/lib.rs

@@ -218,24 +218,23 @@ impl BackgroundProcessor {
 			let mut last_prune_call = Instant::now();
 			let mut have_pruned = false;
 
-			// When considering how long its taken since the last timer tick, we don't want to
-			// count any time spent in user code, especially since event processing can block on
-			// disk writes. Thus, we track how long we spent in event handling here.
-			let mut ev_handle_time_since_last_ping = Duration::from_millis(0);
 			loop {
-				let ev_handle_start = Instant::now();
 				peer_manager.process_events(); // Note that this may block on ChannelManager's locking
 				channel_manager.process_pending_events(&event_handler);
 				chain_monitor.process_pending_events(&event_handler);
-				ev_handle_time_since_last_ping += ev_handle_start.elapsed();
+
+				// We wait up to 100ms, but on a mobile device without a ton of activity, if we get
+				// put in the background and paused, this is likely where it will happen, causing
+				// the wait time to be substantially longer.
+				let await_start = Instant::now();
 				let updates_available =
 					channel_manager.await_persistable_update_timeout(Duration::from_millis(100));
+				let await_time = await_start.elapsed();
+
 				if updates_available {
-					let persist_start = Instant::now();
 					log_trace!(logger, "Persisting ChannelManager...");
 					persister.persist_manager(&*channel_manager)?;
 					log_trace!(logger, "Done persisting ChannelManager.");
-					ev_handle_time_since_last_ping += persist_start.elapsed();
 				}
 				// Exit the loop if the background processor was requested to stop.
 				if stop_thread.load(Ordering::Acquire) == true {
@@ -247,7 +246,7 @@ impl BackgroundProcessor {
 					channel_manager.timer_tick_occurred();
 					last_freshness_call = Instant::now();
 				}
-				if (last_ping_call.elapsed() - ev_handle_time_since_last_ping).as_secs() > PING_TIMER * 2 {
+				if await_time > Duration::from_secs(1) {
 					// 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
@@ -263,12 +262,10 @@ impl BackgroundProcessor {
 					log_trace!(logger, "Awoke after more than double our ping timer, disconnecting peers.");
 					peer_manager.disconnect_all_peers();
 					last_ping_call = Instant::now();
-					ev_handle_time_since_last_ping = Duration::from_millis(0);
 				} 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();
-					ev_handle_time_since_last_ping = Duration::from_millis(0);
 				}
 
 				// Note that we want to run a graph prune once not long after startup before