final Segment<K,V> segmentFor(int hash) {
        return segments[(hash >>> segmentShift) & segmentMask];
    }
Returns the segment that should be used for key with given hash
@param hash the hash code for the key
@return the segment
commons-profiler/src/main/java/com/navercorp/pinpoint/common/profiler/concurrent/jsr166/ConcurrentWeakHashMap.java