* Async method that registers tag updates for later submission, in case
* last.fm is down.
*/
public void updateTag(Artist artist, String lastFmUsername, String tagName,
int tagCount, boolean increase) {
LastFmUser lastFmUser = lastFmDao.getLastFmUser(lastFmUsername);
register(new ArtistUserTag(artist, lastFmUser, tagName, tagCount, increase));
if (!started.getAndSet(true)) {
startTagUpdateService();
}