private static boolean addCallback ( String applicationId , DelayedCallback callback ) { boolean isFirst = false ; List < DelayedCallback > list = BACKLOG . get ( applicationId ) ; if ( null == list ) { list = new ArrayList < DelayedCallback > ( ) ; BACKLOG . put ( applicationId , list ) ; isFirst = true ; } list . add ( callback ) ; return isFirst ; }
Add a delayed callback for the given application id . Returns whether this is the first request for the application id .