rhdg de-dedupe segments

dedupe.java

    private int lastTopologyId = -1;
    private Collection<Set<Integer>> lastListOfSegmentsPerServer = null;

    /** Get a duplicate free list of segments per server.
     * getSegmentPerServer contains primary and secondary segments. For a cache with numOwners>1, this means
     * a single segment is located at multiple severs. If you want to access distinct segments (e.g. for dumping the
     * whole cache), these duplicates need to be removed. That is done by this method.
     * @param cacheTopologyInfo topology of cache as returned by RemoteCache.getCacheTopologyInfo()
     * @return Collection of sets - for each server, a set of duplicate free  segment numbers.
     */
    public Collection<Set<Integer>> getSegmentsPerServerWithoutDuplicates(CacheTopologyInfo cacheTopologyInfo) {
        if (cacheTopologyInfo.getTopologyId() == lastTopologyId && lastListOfSegmentsPerServer!=null) {
            return lastListOfSegmentsPerServer;
        }
        
        int numSegments = cacheTopologyInfo.getNumSegments();
        int numServers = cacheTopologyInfo.getSegmentsPerServer().size();
        int currentServer = 0;

        Set<Integer>[] newListOfSegmentsPerServer = (Set<Integer>[])(new Set[numServers]);
        for (int i=0; i<numServers; i++)  {
            newListOfSegmentsPerServer[i] = new TreeSet<>();
        }

        Set<Integer>[] currentListOfSegmentsPerServer = (Set<Integer>[])(new Set[numServers]);
        currentListOfSegmentsPerServer = cacheTopologyInfo.getSegmentsPerServer().values().toArray(currentListOfSegmentsPerServer);

        for (int currentSegment=0; currentSegment<numSegments; currentSegment++) {
            log.fine("Find a server for segment"+currentSegment);
            
            while (! currentListOfSegmentsPerServer[currentServer].contains(currentSegment)) {
                log.fine("Current server "+currentServer+"does not does contain segment, trying next one");
                currentServer = (currentServer + 1) % numServers;
            }
            newListOfSegmentsPerServer[currentServer].add(currentSegment);

            // To ensure equal distribution of segments across servers, we progress to next server on every segment:
            currentServer = (currentServer + 1) % numServers;
        }


        lastListOfSegmentsPerServer = Arrays.asList(newListOfSegmentsPerServer);
        lastTopologyId = cacheTopologyInfo.getTopologyId();

        return lastListOfSegmentsPerServer;
    }