question: public synchronized void commit ( ) { synchronized ( mutex ) { Map < Column , Set < Interval > > temp = workingIntervals ; workingIntervals = Collections . synchronizedMap ( new LinkedHashMap < > ( ) ) ; availableIntervalsRef . set ( Collections . unmodifiableMap ( new LinkedHashMap < > ( temp ) ) ) ; super . columns = new LinkedHashSet < > ( temp . keySet ( ) ) ; } }
target:  Swaps the actual cache with the built-up temporary cache and creates a fresh, empty temporary cache.