fixed sporadically (multi-threading) errors by reload/stop/start of polling filter inside getModified (so prevents to stop running main cycle)

fail2ban/server/filterpoll.py

@@ -97,6 +97,7 @@ class FilterPoll(FileFilter):
 
 	def run(self):
 		while self.active:
+			try:
 				if logSys.getEffectiveLevel() <= 6:
 					logSys.log(6, "Woke up idle=%s with %d files monitored",
 							   self.idle, self.getLogCount())
@@ -123,6 +124,13 @@ class FilterPoll(FileFilter):
 					except FailManagerEmpty:
 						self.failManager.cleanup(MyTime.time())
 					self.__modified = False
+			except Exception as e: # pragma: no cover
+				if not self.active: # if not active - error by stop...
+					break
+				logSys.error("Caught unhandled exception in main cycle: %r", e,
+					exc_info=logSys.getEffectiveLevel()<=logging.DEBUG)
+				# incr common error counter:
+				self.commonError()
 		logSys.debug("[%s] filter terminated", self.jailName)
 		return True
 
@@ -151,9 +159,9 @@ class FilterPoll(FileFilter):
 			return True
 		except Exception as e:
 			# stil alive (may be deleted because multi-threaded):
-			if not self.getLog(filename):
+			if not self.getLog(filename) or self.__prevStats.get(filename) is None:
 				logSys.warning("Log %r seems to be down: %s", filename, e)
-				return
+				return False
 			# log error:
 			if self.__file404Cnt[filename] < 2:
 				logSys.error("Unable to get stat on %s because of: %s",