Update the stats using SNMP.

def update(self):
        """Update the stats using SNMP."""
        # For each plugins, call the update method
        for p in self._plugins:
            if self._plugins[p].is_disable():
                # If current plugin is disable
                # then continue to next plugin
                continue

            # Set the input method to SNMP
            self._plugins[p].input_method = 'snmp'
            self._plugins[p].short_system_name = self.system_name

            # Update the stats...
            try:
                self._plugins[p].update()
            except Exception as e:
                logger.error("Update {} failed: {}".format(p, e))
            else:
                # ... the history
                self._plugins[p].update_stats_history()
                # ... and the views
                self._plugins[p].update_views()