java.util.PriorityQueue Java Examples

/**
 * Determine the k nearest neighbors for a test instance.
 *
 * @param testInstance
 *            The time series to determine the k nearest neighbors for.
 * @return Queue of the k nearest neighbors as pairs (class, distance).
 */
protected PriorityQueue<Pair<Integer, Double>> calculateNearestNeigbors(final double[] testInstance) {
	int numberOfTrainInstances = this.values.length;
	// Priority queue of (class, distance)-pairs for nearest neigbors, sorted by
	// distance ascending.
	PriorityQueue<Pair<Integer, Double>> nearestNeighbors = new PriorityQueue<>(nearestNeighborComparator);

	// Calculate the k nearest neighbors.
	for (int i = 0; i < numberOfTrainInstances; i++) {
		double d = this.distanceMeasure.distance(testInstance, this.values[i]);

		Pair<Integer, Double> neighbor = new Pair<>(this.targets[i], d);
		nearestNeighbors.add(neighbor);
		if (nearestNeighbors.size() > this.k) {
			nearestNeighbors.poll();
		}
	}
	return nearestNeighbors;
}
 

private PriorityQueue<RocksSingleStateIterator> buildIteratorHeap(
	List<Tuple2<RocksIteratorWrapper, Integer>> kvStateIterators) {

	Comparator<RocksSingleStateIterator> iteratorComparator = COMPARATORS.get(keyGroupPrefixByteCount - 1);

	PriorityQueue<RocksSingleStateIterator> iteratorPriorityQueue =
		new PriorityQueue<>(kvStateIterators.size(), iteratorComparator);

	for (Tuple2<RocksIteratorWrapper, Integer> rocksIteratorWithKVStateId : kvStateIterators) {
		final RocksIteratorWrapper rocksIterator = rocksIteratorWithKVStateId.f0;
		rocksIterator.seekToFirst();
		if (rocksIterator.isValid()) {
			iteratorPriorityQueue.offer(
				new RocksSingleStateIterator(rocksIterator, rocksIteratorWithKVStateId.f1));
		} else {
			IOUtils.closeQuietly(rocksIterator);
		}
	}
	return iteratorPriorityQueue;
}
 

@Override
public PriorityQueue<T> add(PriorityQueue<T> aggregate, Integer n, T val) {
    if (n <= 0) {
        return aggregate;
    }
    if (aggregate.size() >= n) {
        if (val.compareTo(aggregate.peek()) > 0) {
            aggregate.remove();
            aggregate.add(val);
        }
    } else {
        aggregate.add(val);
    }
    return aggregate;

}
 

/**
 * It classifies the object/objects on the image
 *
 * @param tensorFlowOutput output from the TensorFlow, it is a 13x13x((num_class +1) * 5) tensor
 * 125 = (numClass +  Tx, Ty, Tw, Th, To) * 5 - cause we have 5 boxes per each cell
 * @param labels a string vector with the labels
 * @return a list of recognition objects
 */
private List<Recognition> classifyImage(final float[] tensorFlowOutput, final String[] labels) {
  int numClass = (int) (tensorFlowOutput.length / (Math.pow(SIZE, 2) * NUMBER_OF_BOUNDING_BOX)
      - 5);
  BoundingBox[][][] boundingBoxPerCell = new BoundingBox[SIZE][SIZE][NUMBER_OF_BOUNDING_BOX];
  PriorityQueue<Recognition> priorityQueue = new PriorityQueue<>(
      MAX_RECOGNIZED_CLASSES,
      new RecognitionComparator());

  int offset = 0;
  for (int cy = 0; cy < SIZE; cy++) {        // SIZE * SIZE cells
    for (int cx = 0; cx < SIZE; cx++) {
      for (int b = 0; b < NUMBER_OF_BOUNDING_BOX; b++) {   // 5 bounding boxes per each cell
        boundingBoxPerCell[cx][cy][b] = getModel(tensorFlowOutput, cx, cy, b, numClass, offset);
        calculateTopPredictions(boundingBoxPerCell[cx][cy][b], priorityQueue, labels);
        offset = offset + numClass + 5;
      }
    }
  }

  return getRecognition(priorityQueue);
}
 

/**
 * find the last TimeseriesMetadata in unseq files and unpack all overlapped unseq files
 */
private void UnpackOverlappedUnseqFiles(long lBoundTime) throws IOException {
  PriorityQueue<TsFileResource> unseqFileResource =
      sortUnSeqFileResourcesInDecendingOrder(dataSource.getUnseqResources());

  while (!unseqFileResource.isEmpty()
      && (lBoundTime <= unseqFileResource.peek().getEndTime(seriesPath.getDevice()))) {
    TimeseriesMetadata timeseriesMetadata =
        FileLoaderUtils.loadTimeSeriesMetadata(
            unseqFileResource.poll(), seriesPath, context, timeFilter, deviceMeasurements);

    if (timeseriesMetadata == null || (!timeseriesMetadata.isModified()
        && timeseriesMetadata.getStatistics().getEndTime() < lBoundTime)) {
      continue;
    }
    unseqTimeseriesMetadataList.add(timeseriesMetadata);
    if (!timeseriesMetadata.isModified()) {
      if (endtimeContainedByTimeFilter(timeseriesMetadata.getStatistics())) {
        lBoundTime = Math.max(lBoundTime, timeseriesMetadata.getStatistics().getEndTime());
      } else {
        lBoundTime = Math.max(lBoundTime, timeseriesMetadata.getStatistics().getStartTime());
      }
    }
  }
}
 

public static void main(String[] args) {
	Scanner sc = new Scanner(System.in);
	PriorityQueue<Integer> highers = new PriorityQueue<Integer>();
	PriorityQueue<Integer> lowers = new PriorityQueue<Integer>(new Comparator<Integer>() {
		public int compare(Integer i1, Integer i2) {
			return i2.compareTo(i1);
		}
	});
	int N = sc.nextInt();
	double meadian = 0;
	for (int i = 1; i <= N; i++) {
		int number = sc.nextInt();
		addNumber(number, lowers, highers);
		rebalance(lowers, highers);
		meadian = getMedian(lowers, highers);
		System.out.println(meadian);
	}
	sc.close();
}
 

protected Collection<TempQueue> getMostUnderservedQueues(
    PriorityQueue<TempQueue> orderedByNeed, TQComparator tqComparator) {
  ArrayList<TempQueue> underserved = new ArrayList<TempQueue>();
  while (!orderedByNeed.isEmpty()) {
    TempQueue q1 = orderedByNeed.remove();
    underserved.add(q1);
    TempQueue q2 = orderedByNeed.peek();
    // q1's pct of guaranteed won't be larger than q2's. If it's less, then
    // return what has already been collected. Otherwise, q1's pct of
    // guaranteed == that of q2, so add q2 to underserved list during the
    // next pass.
    if (q2 == null || tqComparator.compare(q1,q2) < 0) {
      return underserved;
    }
  }
  return underserved;
}
 

public static ArrayList<Long> primeFactorization(long n) {
  ArrayList<Long> factors = new ArrayList<>();
  if (n <= 0) throw new IllegalArgumentException();
  else if (n == 1) return factors;
  PriorityQueue<Long> divisorQueue = new PriorityQueue<>();
  divisorQueue.add(n);
  while (!divisorQueue.isEmpty()) {
    long divisor = divisorQueue.remove();
    if (isPrime(divisor)) {
      factors.add(divisor);
      continue;
    }
    long next_divisor = pollardRho(divisor);
    if (next_divisor == divisor) {
      divisorQueue.add(divisor);
    } else {
      divisorQueue.add(next_divisor);
      divisorQueue.add(divisor / next_divisor);
    }
  }
  return factors;
}
 

public static List<Integer> mergekSortedArrays(List<List<Integer>> arrays) {
    ArrayList<Integer> list = new ArrayList<>();
    if (arrays == null || arrays.size() == 0 || arrays.get(0).size() == 0) {
        return list;
    }
    PriorityQueue<NewInteger> pq = new PriorityQueue<>(arrays.size(), (x, y) -> x.value > y.value ? -1 : 1);
    for (int i = 0; i < arrays.size(); i++) {
        pq.offer(new NewInteger(arrays.get(i).get(0), i, 0));
    }
    while (list.size() < 3000 && !pq.isEmpty()) {
        NewInteger min = pq.poll();
        if (min.col + 1 < arrays.get(min.row).size()) {
            pq.offer(new NewInteger(arrays.get(min.row).get(min.col + 1), min.row, min.col + 1));
        }
        list.add(min.value);
    }
    return list;
}
 

public PriorityQueue<?> read(Kryo k, Input i, Class<PriorityQueue<?>> c) {
	Comparator<Object> comp = (Comparator<Object>) k.readClassAndObject(i);
	int sz = i.readInt(true);
	// can't create with size 0:
	PriorityQueue<Object> result;
	if (sz == 0) {
		result = new PriorityQueue<Object>(1, comp);
	}
	else {
		result = new PriorityQueue<Object>(sz, comp);
	}
	int idx = 0;
	while (idx < sz) {
		result.add(k.readClassAndObject(i));
		idx += 1;
	}
	return result;
}
 

public DumpMerger(List<Dump> dumps) {
    minHeap = new PriorityQueue<>(dumps.size(), new Comparator<Entry<byte[], Integer>>() {
        @Override
        public int compare(Entry<byte[], Integer> o1, Entry<byte[], Integer> o2) {
            return bytesComparator.compare(o1.getKey(), o2.getKey());
        }
    });
    dumpIterators = Lists.newArrayListWithCapacity(dumps.size());
    dumpCurrentValues = Lists.newArrayListWithCapacity(dumps.size());

    Iterator<Pair<byte[], byte[]>> it;
    for (int i = 0; i < dumps.size(); i++) {
        it = dumps.get(i).iterator();
        dumpCurrentValues.add(i, null);
        if (it.hasNext()) {
            dumpIterators.add(i, it);
            enqueueFromDump(i);
        } else {
            dumpIterators.add(i, null);
        }
    }
}
 

@Test
public void searchItemMultipleValues2() {
	Hash hash = TestResources.createHash("101010100011", 0);
	Hash hash1 = TestResources.createHash("101010100010", 0);

	binTree.addHash(hash, 1);
	binTree.addHash(hash, 2);
	binTree.addHash(hash, 3);
	binTree.addHash(hash1, 3);
	binTree.addHash(hash1, 3);
	binTree.addHash(hash1, 3);

	PriorityQueue<Result> results = binTree.getElementsWithinHammingDistance(hash, 2);

	assertEquals(6, results.size());
}
 

public boolean isPossibleDivide(int[] nums, int k) {
    int len = nums.length;
    if (len % k != 0) {
        return false;
    }

    PriorityQueue<Integer> minHeap = new PriorityQueue<>(len);
    for (int num : nums) {
        minHeap.offer(num);
    }

    while (!minHeap.isEmpty()) {
        Integer top = minHeap.poll();

        for (int i = 1; i < k; i++) {
            // 从 1 开始，正好需要移除 k - 1 个元素
            // i 正好就是相对于 top 的偏移
            if (!minHeap.remove(top + i)) {
                // 如果移除失败，说明划分不存在，直接返回 false 即可
                return false;
            }
        }
    }
    return true;
}
 

public void test_spliterator() throws Exception {
    ArrayList<Integer> testElements = new ArrayList<>(
            Arrays.asList(1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16));
    PriorityQueue<Integer> list = new PriorityQueue<>();
    list.addAll(testElements);

    SpliteratorTester.runBasicIterationTests(list.spliterator(), testElements);
    SpliteratorTester.runBasicSplitTests(list, testElements);
    SpliteratorTester.testSpliteratorNPE(list.spliterator());

    assertTrue(list.spliterator().hasCharacteristics(
            Spliterator.SIZED | Spliterator.SUBSIZED));

    SpliteratorTester.runSizedTests(list, 16 /* expected size */);
    SpliteratorTester.runSubSizedTests(list, 16 /* expected size */);
    SpliteratorTester.assertSupportsTrySplit(list);
}
 

private List<Recognition> getRecognition(final PriorityQueue<Recognition> priorityQueue) {
  ArrayList<Recognition> recognitions = new ArrayList<>();

  if (priorityQueue.size() > 0) {
    // Best recognition
    Recognition bestRecognition = priorityQueue.poll();
    recognitions.add(bestRecognition);

    for (int i = 0; i < Math.min(priorityQueue.size(), MAX_RESULTS); ++i) {
      Recognition recognition = priorityQueue.poll();
      boolean overlaps = false;
      for (Recognition previousRecognition : recognitions) {
        overlaps = overlaps || (getIntersectionProportion(previousRecognition.getLocation(),
            recognition.getLocation()) > OVERLAP_THRESHOLD);
      }

      if (!overlaps) {
        recognitions.add(recognition);
      }
    }
  }

  return recognitions;
}
 

public Object getObject(final String command) throws Exception {
	final TemplatesImpl templates = Gadgets.createTemplatesImpl(command);
	// mock method name until armed
	final BeanComparator comparator = new BeanComparator("lowestSetBit");

	// create queue with numbers and basic comparator
	final PriorityQueue<Object> queue = new PriorityQueue<Object>(2, comparator);
	// stub data for replacement later
	queue.add(new BigInteger("1"));
	queue.add(new BigInteger("1"));

	// switch method called by comparator
	Reflections.setFieldValue(comparator, "property", "outputProperties");

	// switch contents of queue
	final Object[] queueArray = (Object[]) Reflections.getFieldValue(queue, "queue");
	queueArray[0] = templates;
	queueArray[1] = templates;

	return queue;
}
 

@Test
public void testGetControllerAutobalancing() throws Exception {
    ControllerHelixManager mockHelixManager = EasyMock.createMock(ControllerHelixManager.class);
    AdminHelper helper = new AdminHelper(mockHelixManager);
    Map<String, PriorityQueue<InstanceTopicPartitionHolder>> instanceMap = new HashMap<>();
    PriorityQueue<InstanceTopicPartitionHolder> sjc1aTosjc1Agg1 = new PriorityQueue<>();
    String pipeline = ControllerUtils.getPipelineName("sjc1a", "sjc1-agg1");
    InstanceTopicPartitionHolder ith = new InstanceTopicPartitionHolder("compute9527-sjc1",
        new TopicPartition(pipeline, 0));
    sjc1aTosjc1Agg1.add(ith);
    instanceMap.put(pipeline, sjc1aTosjc1Agg1);
    EasyMock.expect(mockHelixManager.getPipelineToInstanceMap()).andReturn(instanceMap).atLeastOnce();
    EasyMock.expect(mockHelixManager.getControllerAutobalancingStatus("compute9527-sjc1"))
        .andReturn(false);
    EasyMock.replay(mockHelixManager);
    JSONObject status = helper.getControllerAutobalancingStatus();
    Assert.assertEquals(status.size(), 1);
    JSONObject detail = (JSONObject) status.get("compute9527-sjc1");
    Assert.assertEquals(detail.get("autoBalance"), false);
    EasyMock.verify(mockHelixManager);
}
 

private <T extends AbstractSession<?>> void processTimeouts(final long currentTime, final String outputPortName, final PriorityQueue<T> timeoutQueue,
		final Map<String, T> openSessions) {
	while (!timeoutQueue.isEmpty()) {
		final T session = timeoutQueue.peek();
		final long currentThinkTime = (currentTime - session.getEndTimestamp());

		// The current session timed out
		if (currentThinkTime > this.maxThinkTime) {
			timeoutQueue.remove();
			openSessions.remove(session.getSessionId());
			this.dispatchCompletedSession(session, outputPortName);
		} else { // If the current session has not timed out, we are done due to the ordering of the queue
			break;
		}
	}
}
 

@Override
protected List<AbstractBlock> pruneEdges() {
    nearestEntities = new HashSet[noOfEntities];
    topKEdges = new PriorityQueue<>((int) (2 * threshold), new IncComparisonWeightComparator());
    if (weightingScheme.equals(WeightingScheme.ARCS)) {
        for (int i = 0; i < noOfEntities; i++) {
            processArcsEntity(i);
            verifyValidEntities(i);
        }
    } else {
        for (int i = 0; i < noOfEntities; i++) {
            processEntity(i);
            verifyValidEntities(i);
        }
    }

    return retainValidComparisons();
}
 

private static void createDatabaseViaCredentials() throws Exception {
	String dbName = "imageHashDB";
	String userName = "root";
	String password = "";

	// Wrap in try with block or call close at the end!
	try (H2DatabaseImageMatcher db = new H2DatabaseImageMatcher(dbName, userName, password)) {
		// Proceed as normal
		db.addHashingAlgorithm(new DifferenceHash(32, Precision.Double), .4);
		db.addHashingAlgorithm(new PerceptiveHash(32), .2);

		// Image files
		File ballon = new File("src/test/resources/ballon.jpg");
		File copyright = new File("src/test/resources/copyright.jpg");
		File highQuality = new File("src/test/resources/highQuality.jpg");

		db.addImages(ballon, copyright, highQuality);

		PriorityQueue<Result<String>> results = db.getMatchingImages(copyright);
		results.forEach(System.out::println);

		// Find all images which are similar to any image in the database
		System.out.println(db.getAllMatchingImages());
	}

	/*
	 * finally { //Not necessary since we use a try with otherwise db.close(); }
	 */

}
 

/**
 * Saves this queue to a stream (that is, serializes it).
 *
 * For compatibility with previous version of this class, elements
 * are first copied to a java.util.PriorityQueue, which is then
 * serialized.
 *
 * @param s the stream
 * @throws java.io.IOException if an I/O error occurs
 */
private void writeObject(java.io.ObjectOutputStream s)
    throws java.io.IOException {
    lock.lock();
    try {
        // avoid zero capacity argument
        q = new PriorityQueue<E>(Math.max(size, 1), comparator);
        q.addAll(this);
        s.defaultWriteObject();
    } finally {
        q = null;
        lock.unlock();
    }
}
 

/**
 * Saves this queue to a stream (that is, serializes it).
 *
 * For compatibility with previous version of this class, elements
 * are first copied to a java.util.PriorityQueue, which is then
 * serialized.
 *
 * @param s the stream
 * @throws java.io.IOException if an I/O error occurs
 */
private void writeObject(java.io.ObjectOutputStream s)
    throws java.io.IOException {
    lock.lock();
    try {
        // avoid zero capacity argument
        q = new PriorityQueue<E>(Math.max(size, 1), comparator);
        q.addAll(this);
        s.defaultWriteObject();
    } finally {
        q = null;
        lock.unlock();
    }
}
 

public static void main(String[] args) {
    // solution
    int[] arr = {10, 20, 30};
    System.out.println("形成 10，20,30 最少需要成本为：" + lessMoney(arr));

    int[] arrForHeap = {1, 2, 6, 4, 3, 7, 1, 8};

    System.out.println("{1,2,6,4,3,7,1,8}形成的最小堆为：");
    // min heap
    PriorityQueue<Integer> minQ1 = new PriorityQueue<>();
    for (int i = 0; i < arrForHeap.length; i++) {
        minQ1.add(arrForHeap[i]);
    }
    while (!minQ1.isEmpty()) {
        System.out.print(minQ1.poll() + " ");
    }
    System.out.println();

    // min heap use Comparator
    PriorityQueue<Integer> minQ2 = new PriorityQueue<>(new MinheapComparator());
    for (int i = 0; i < arrForHeap.length; i++) {
        minQ2.add(arrForHeap[i]);
    }
    while (!minQ2.isEmpty()) {
        System.out.print(minQ2.poll() + " ");
    }
    System.out.println();

    System.out.println("{1,2,6,4,3,7,1,8}形成的最大堆为：");
    // max heap use Comparator
    PriorityQueue<Integer> maxQ = new PriorityQueue<>(new MaxheapComparator());
    for (int i = 0; i < arrForHeap.length; i++) {
        maxQ.add(arrForHeap[i]);
    }
    while (!maxQ.isEmpty()) {
        System.out.print(maxQ.poll() + " ");
    }
}
 

@Override
public int[] verticesNearest(int vertexIdx, int top) {

    INDArray vec = lookupTable.getVector(vertexIdx).dup();
    double norm2 = vec.norm2Number().doubleValue();


    PriorityQueue<Pair<Double, Integer>> pq =
                    new PriorityQueue<>(lookupTable.getNumVertices(), new PairComparator());

    Level1 l1 = Nd4j.getBlasWrapper().level1();
    for (int i = 0; i < numVertices(); i++) {
        if (i == vertexIdx)
            continue;

        INDArray other = lookupTable.getVector(i);
        double cosineSim = l1.dot(vec.length(), 1.0, vec, other) / (norm2 * other.norm2Number().doubleValue());

        pq.add(new Pair<>(cosineSim, i));
    }

    int[] out = new int[top];
    for (int i = 0; i < top; i++) {
        out[i] = pq.remove().getSecond();
    }

    return out;
}
 

/**
 * Generate a list of recommendations based on given list of candidate nodes and the original request.
 * @param request         original request message, contains filtering criteria
 * @param candidateNodes  list of candidate nodes
 * @return                list of {@link MomentRecommendationInfo}
 */
public static List<RecommendationInfo> generateMomentRecs(
  TopSecondDegreeByCountRequestForMoment request,
  List<NodeInfo> candidateNodes) {

  int maxNumResults = Math.min(request.getMaxNumResults(), RecommendationRequest.MAX_RECOMMENDATION_RESULTS);

  PriorityQueue<NodeInfo> validNodes =
    GeneratorHelper.getValidNodes(candidateNodes, request.getMinUserPerSocialProof(), maxNumResults);

  return getRecommendationsFromNodes(request, validNodes);
}
 

/**
 * 创建<code>PriorityQueue</code>实例
 * 
 * @param <E>
 * @param collection 集合 @see Collection
 * @return <code>PriorityQueue</code>实例
 */
public static <E> PriorityQueue<E> createPriorityQueue(Collection<? extends E> collection) {
    if (collection == null) {
        return null;
    }

    return new PriorityQueue<E>(collection);
}
 

/**
 * Gets the sorted timestamps of any buffered events.
 *
 * @return a sorted list of timestamps that have at least one buffered event.
 */
private PriorityQueue<Long> getSortedTimestamps() throws Exception {
    PriorityQueue<Long> sortedTimestamps = new PriorityQueue<>();
    for (Long timestamp : elementQueueState.keys()) {
        sortedTimestamps.offer(timestamp);
    }
    return sortedTimestamps;
}
 

/**
 * From all possible limb candidates for a given Limb Type, select those that maximize the total PAF score.
 * The algorithm starts from the limb candidates with higher PAF score. Also the algorithm tracks the parts
 * already assigned t a final limbs and rejects limb candidates with already assigned parts.
 *
 * @param limbType Limb Type for which final limbs a selected.
 * @param limbCandidatesQueue possible Limb candidates, sorted by total PAF score in a descending order.
 * @return Returns the final list of Limbs for a given {@link org.springframework.cloud.stream.app.pose.estimation.model.Model.LimbType}
 */
private List<Limb> selectFinalLimbs(Model.LimbType limbType, PriorityQueue<Limb> limbCandidatesQueue) {

	List<Limb> finalLimbs = new ArrayList<>();

	// Parts assigned to final limbs.
	Set<Part> assignedParts = new HashSet<>();

	// Start from the candidates with higher PAF score and progress in descending order
	while (!limbCandidatesQueue.isEmpty()) {

		Limb limbCandidate = limbCandidatesQueue.poll();

		Assert.isTrue(limbType == limbCandidate.getLimbType(), "Incorrect Limb Type!");

		// Ignore candidate limbs with parts already assigned a final Limb from earlier iteration.
		if (!assignedParts.contains(limbCandidate.getFromPart())
				&& !assignedParts.contains(limbCandidate.getToPart())) {

			// Make the candidate final.
			finalLimbs.add(limbCandidate);

			// Mark limb's parts as assigned.
			assignedParts.add(limbCandidate.getFromPart());
			assignedParts.add(limbCandidate.getToPart());
		}
	}

	return finalLimbs;
}
 

/**
 * Get the broker Id that has the resource. Here we need to apply the proper placement policy.
 *
 * @param brokerQueue  the list of brokers that are sorted in resource usage
 * @param oosReplica  out of sync replicas
 * @param inBoundReq  inbound traffic
 * @param outBoundReq outbound traffc
 * @param preferredBroker preferred broker id
 * @return a BrokerId to KafkaBroker mapping
 */
public Map<Integer, KafkaBroker> getAlternativeBrokers(
    PriorityQueue<KafkaBroker> brokerQueue,
    OutOfSyncReplica oosReplica,
    double inBoundReq,
    double outBoundReq,
    int preferredBroker
) {

  boolean success = true;
  Map<Integer, KafkaBroker> result = new HashMap<>();
  Set<KafkaBroker> unusableBrokers = new HashSet<>();

  for (int oosBrokerId : oosReplica.outOfSyncBrokers) {
    // we will get the broker with the least network usage
    success = findNextBrokerForOosReplica(
        brokerQueue,
        unusableBrokers,
        oosReplica.replicaBrokers,
        result,
        oosBrokerId,
        oosReplica.topicPartition,
        inBoundReq,
        outBoundReq,
        preferredBroker
    );

    // short circuit if failed to find available broker
    if (!success) {
      break;
    }
  }
  // push the brokers back to brokerQueue to keep invariant true
  brokerQueue.addAll(unusableBrokers);
  return success ? result : null;
}
 

/**
 * toArray contains all elements
 */
public void testToArray() {
    PriorityQueue q = populatedQueue(SIZE);
    Object[] o = q.toArray();
    Arrays.sort(o);
    for (int i = 0; i < o.length; i++)
        assertSame(o[i], q.poll());
}