f Headers: use _subscribe over _pop, clear queue regularly

Author: tnull

lightning-transaction-sync/src/electrum.rs

@@ -88,6 +88,9 @@ where
 		let mut num_confirmed = 0;
 		let mut num_unconfirmed = 0;
 
+		// Clear any header notifications we might have gotten to keep the queue count low.
+		while let Some(_) = self.client.block_headers_pop()? {}
+
 		let tip_notification = self.client.block_headers_subscribe()?;
 		let mut tip_header = tip_notification.header;
 		let mut tip_height = tip_notification.height as u32;
@@ -109,11 +112,12 @@ where
 						Ok(unconfirmed_txs) => {
 							// Double-check the tip hash. If it changed, a reorg happened since
 							// we started syncing and we need to restart last-minute.
-							if let Some(notification) = self.client.block_headers_pop()? {
-								let check_tip_hash = notification.header.block_hash();
+							{
+								let check_notification = self.client.block_headers_subscribe()?;
+								let check_tip_hash = check_notification.header.block_hash();
 								if check_tip_hash != tip_header.block_hash() {
-									tip_header = notification.header;
-									tip_height = notification.height as u32;
+									tip_header = check_notification.header;
+									tip_height = check_notification.height as u32;
 
 									log_debug!(self.logger,
 										"Encountered inconsistency during transaction sync, restarting.");
@@ -148,11 +152,16 @@ where
 					Ok(confirmed_txs) => {
 						// Double-check the tip hash. If it changed, a reorg happened since
 						// we started syncing and we need to restart last-minute.
-						if let Some(notification) = self.client.block_headers_pop()? {
-							let check_tip_hash = notification.header.block_hash();
+						{
+							let check_notification = self.client.block_headers_subscribe()?;
+							let check_tip_hash = check_notification.header.block_hash();
 							if check_tip_hash != tip_header.block_hash() {
-								tip_header = notification.header;
-								tip_height = notification.height as u32;
+								tip_header = check_notification.header;
+								tip_height = check_notification.height as u32;
+
+								log_debug!(self.logger,
+									"Encountered inconsistency during transaction sync, restarting.");
+								sync_state.pending_sync = true;
 								continue;
 							}
 						}