question: public synchronized void saveCommitPoint ( Long indexCommitGen ) { AtomicInteger reserveCount = savedCommits . get ( indexCommitGen ) ; if ( reserveCount == null ) reserveCount = new AtomicInteger ( ) ; reserveCount . incrementAndGet ( ) ; savedCommits . put ( indexCommitGen , reserveCount ) ; }
target:  Permanently prevent this commit point from being deleted. A counter is used to allow a commit point to be correctly saved and released multiple times. 