retry all backfiller requests once on error

backfiller/backfiller/main.py

@@ -267,7 +267,7 @@ class BackfillerManager(object):
 			hours.sort()
 
 			for hour in hours:
-				# deleting segments can take a bit time but is less important
+				# deleting segments can take a bit of time but is less important
 				# than the actually backfilling so we yield
 				gevent.idle()
 				path = os.path.join(self.base_dir, channel, quality, hour)
@@ -428,6 +428,19 @@ class BackfillerWorker(object):
 		self.logger.info('Stopping')
 		self.stopping.set()
 
+	# retries a failed function call once after TIMEOUT
+	def retry_handler(self, function, *args):
+		try:
+			return function(*args)
+		except Exception:
+			delay = common.jitter(TIMEOUT)
+			self.logger.exception('Backfill opperation failed. Retrying in {:.0f} s'.format(delay))
+			backfill_errors.labels(remote=self.node).inc()
+			self.stopping.wait(delay)
+
+			return function(*args)
+
+
 	def backfill(self):
 		"""Backfill from remote node.
 	
@@ -435,7 +448,7 @@ class BackfillerWorker(object):
 		each hour in hours.
 		"""
 		for channel, quality in itertools.product(self.channels, self.qualities):
-			for hour in list_hours(self.node, channel, quality, self.start):
+			for hour in self.retry_handler(list_hours, self.node, channel, quality, self.start):
 				# since backfilling can take a long time, recheck whether this
 				# hour is after the start
 				if self.start is not None:
@@ -448,7 +461,7 @@ class BackfillerWorker(object):
 
 				self.logger.info('Backfilling {}/{}'.format(quality, hour))
 	
-				local_segments = set(list_local_segments(self.base_dir, channel, quality, hour))
+				local_segments = set(self.retry_handler(list_local_segments, self.base_dir, channel, quality, hour))
 				remote_segments = set(list_remote_segments(self.node, channel, quality, hour))
 				missing_segments = list(remote_segments - local_segments)
 	
@@ -486,8 +499,8 @@ class BackfillerWorker(object):
 	
 					# start segment as soon as a pool slot opens up, then track it in workers
 					workers.append(pool.spawn(
-						get_remote_segment,
-						self.base_dir, self.node, channel, quality, hour, missing_segment, self.logger
+						self.retry_handler,
+						get_remote_segment, self.base_dir, self.node, channel, quality, hour, missing_segment, self.logger
 					))
 
 				# verify that all the workers succeeded. if any failed, raise the exception from