Get widget ID in update() function

Hey there,

is it possible to receive the ID of the widget in the update function?
I need to delete a transient option when saving the widget.

At this time i’m clearing all transients with a sql query.

DELETE FROM wp_options WHERE option_name LIKE ('_transient_tweets%')

but i want to do it like this

delete_transient( 'tweets_' . $widget_id );

thanks for help!