Fix unexpected exception in snmp-subagent

Signed-off-by: Zhaohui Sun <[email protected]>

src/lldp_syncd/daemon.py

@@ -349,6 +349,26 @@ def cache_diff(self, cache, update):
 
         return new_keys, changed_keys, deleted_keys
 
+    def is_only_time_mark_modified(self, cached_interface, updated_interface):
+        """
+        Check if only lldp_rem_time_mark is modified in the update
+        :param cached_interface: Local cached interface dict
+        :param updated_interface: Updated interface dict
+        :return: True if only lldp_rem_time_mark is modified, False otherwise
+        """
+        if len(cached_interface) != len(updated_interface):
+            return False
+
+        changed_keys = 0
+
+        for key in cached_interface.keys():
+            if 'lldp_rem_time_mark' == key and cached_interface[key] != updated_interface[key]:
+                changed_keys += 1
+            elif key not in updated_interface or cached_interface[key] != updated_interface[key]:
+                return False
+
+        return True if changed_keys == 1 else False
+
     def sync(self, parsed_update):
         """
         Sync LLDP information to redis DB.
@@ -367,18 +387,32 @@ def sync(self, parsed_update):
                 logger.debug("sync'd: {}".format(json.dumps(chassis_update, indent=3)))
 
         new, changed, deleted = self.cache_diff(self.interfaces_cache, parsed_update)
+
+        # For changed elements, if only lldp_rem_time_mark changed, update its value, otherwise delete and repopulate
+        for interface in changed:
+            if re.match(SONIC_ETHERNET_RE_PATTERN, interface) is None:
+                logger.warning("Ignoring interface '{}'".format(interface))
+                continue
+            table_key = ':'.join([LldpSyncDaemon.LLDP_ENTRY_TABLE, interface])
+            if self.is_only_time_mark_modified(self.interfaces_cache[interface], parsed_update[interface]):
+                self.db_connector.set(self.db_connector.APPL_DB, table_key, 'lldp_rem_time_mark', parsed_update[interface]['lldp_rem_time_mark'], blocking=True)
+                logger.debug("Only sync'd interface {} lldp_rem_time_mark: {}".format(interface, parsed_update[interface]['lldp_rem_time_mark']))
+            else:
+                self.db_connector.delete(self.db_connector.APPL_DB, table_key)
+                self.db_connector.hmset(self.db_connector.APPL_DB, table_key, parsed_update[interface])
+                logger.debug("Sync'd changed interface {} : {}".format(interface, parsed_update[interface]))
         self.interfaces_cache = parsed_update
-        # Delete LLDP_ENTRIES which were modified or are missing
-        for interface in changed + deleted:
+        # Delete LLDP_ENTRIES which are missing
+        for interface in deleted:
             table_key = ':'.join([LldpSyncDaemon.LLDP_ENTRY_TABLE, interface])
             self.db_connector.delete(self.db_connector.APPL_DB, table_key)
-        # Repopulate LLDP_ENTRY_TABLE by adding all changed elements
-        for interface in changed + new:
+            logger.debug("Delete table_key: {}".format(table_key))
+        # Repopulate LLDP_ENTRY_TABLE by adding new elements
+        for interface in new:
             if re.match(SONIC_ETHERNET_RE_PATTERN, interface) is None:
                 logger.warning("Ignoring interface '{}'".format(interface))
                 continue
             # port_table_key = LLDP_ENTRY_TABLE:INTERFACE_NAME;
             table_key = ':'.join([LldpSyncDaemon.LLDP_ENTRY_TABLE, interface])
-            for k, v in parsed_update[interface].items():
-                self.db_connector.set(self.db_connector.APPL_DB, table_key, k, v, blocking=True)
-            logger.debug("sync'd: \n{}".format(json.dumps(parsed_update[interface], indent=3)))
+            self.db_connector.hmset(self.db_connector.APPL_DB, table_key, parsed_update[interface])
+            logger.debug("Add new interface {} : {}".format(interface, parsed_update[interface]))