Java Code Examples for java.util.Queue

private void initialize() {
    //perform bgs to build failure links
    final Queue<Node> queue = new LinkedList<>();
    queue.add(root);
    root.setFailureNode(null);
    while (!queue.isEmpty()) {
        final Node current = queue.poll();
        for (int i = 0; i < 256; i++) {
            final Node next = current.getNeighbor(i);
            if (next != null) {
                //traverse failure to get state
                Node fail = current.getFailureNode();
                while ((fail != null) && fail.getNeighbor(i) == null) {
                    fail = fail.getFailureNode();
                }
                if (fail != null) {
                    next.setFailureNode(fail.getNeighbor(i));
                } else {
                    next.setFailureNode(root);
                }
                queue.add(next);
            }
        }
    }
}
 

@Test
public void scanOverlapSubscriberSmallBuffered() {
 @SuppressWarnings("unchecked")
 Queue<FluxIdentityProcessor<Integer>> mockQueue = Mockito.mock(Queue.class);

    CoreSubscriber<Flux<Integer>> actual = new LambdaSubscriber<>(null, e -> {}, null, null);
    FluxWindow.WindowOverlapSubscriber<Integer> test = new FluxWindow.WindowOverlapSubscriber<Integer>(actual,
            3,3, Queues.unbounded(), mockQueue);

    when(mockQueue.size()).thenReturn(Integer.MAX_VALUE - 2);
    //size() is 1
    test.offer(Processors.unicast());

    assertThat(test.scan(Scannable.Attr.BUFFERED)).isEqualTo(Integer.MAX_VALUE - 1);
    assertThat(test.scan(Scannable.Attr.LARGE_BUFFERED)).isEqualTo(Integer.MAX_VALUE - 1L);
}
 

public static void main(final String[] args) throws Exception {
    System.out.println("capacity:" + QUEUE_CAPACITY + " reps:" + REPETITIONS);
    final Queue<Integer> queue = SPSCQueueFactory.createQueue(Integer.parseInt(args[0]), Integer.getInteger("scale", 17));

    final long[] results = new long[20];
    for (int i = 0; i < 20; i++) {
        System.gc();
        results[i] = performanceRun(i, queue);
    }
    // only average last 10 results for summary
    long sum = 0;
    for (int i = 10; i < 20; i++) {
        sum += results[i];
    }
    System.out.format("summary,QueuePerfTest3,%s,%d\n", queue.getClass().getSimpleName(), sum / 10);
}
 

/**
 * Moves all the buffered messages for the given key into the sendQueue and removes the
 * entry in the messages data structure if all the messages are moved
 *
 * @param target target for which the move needs to be done
 * @param messagesPerTarget messages for given target
 * @param key the key to be moved
 * @return true if all the messages for that key are moved successfully
 */
protected boolean moveMessageToSendQueue(int target, Map<Object, Queue<Object>> messagesPerTarget,
                                         Object key) {
  Queue<Object> targetSendQueue = sendQueue.get(target);
  Queue<Object> entryQueue = messagesPerTarget.get(key);
  Object current;

  while ((current = entryQueue.peek()) != null) {
    Tuple send = new Tuple(key, current);

    if (targetSendQueue.offer(send)) {
      entryQueue.poll();
    } else {
      return false;
    }
  }

  if (messagesPerTarget.get(key).isEmpty()) {
    messagesPerTarget.remove(key);
    return true;
  } else {
    return false;
  }
}
 

public List<PojoClass> getPojoClassesRecursively(final String packageName, final PojoClassFilter pojoClassFilter) {
  final List<PojoClass> pojoClasses = new LinkedList<PojoClass>();
  final PojoClassFilter finalFilterChain = getFinalFilterChain(pojoClassFilter);

  final PojoPackage pojoPackage = PojoPackageFactory.getPojoPackage(packageName);

  Queue<PojoPackage> pending = new ConcurrentLinkedQueue<PojoPackage>();
  pending.add(pojoPackage);

  while (!pending.isEmpty()) {
    final PojoPackage entry = pending.remove();
    pending.addAll(entry.getPojoSubPackages());
    pojoClasses.addAll(entry.getPojoClasses(finalFilterChain));
  }
  return pojoClasses;
}
 

/**
 * This method add's a mix of createBucket/DeleteBucket responses to double
 * buffer. Total number of responses added is specified by bucketCount.
 */
private void doMixTransactions(String volumeName, int bucketCount,
    Queue<OMBucketDeleteResponse> deleteBucketQueue,
    Queue<OMBucketCreateResponse> bucketQueue) {
  for (int i=0; i < bucketCount; i++) {
    String bucketName = UUID.randomUUID().toString();
    long transactionID = trxId.incrementAndGet();
    OMBucketCreateResponse omBucketCreateResponse = createBucket(volumeName,
        bucketName, transactionID);
    // For every 2 transactions have a deleted bucket.
    if (i % 2 == 0) {
      OMBucketDeleteResponse omBucketDeleteResponse =
          (OMBucketDeleteResponse) deleteBucket(volumeName, bucketName,
              trxId.incrementAndGet());
      deleteBucketQueue.add(omBucketDeleteResponse);
    } else {
      bucketQueue.add(omBucketCreateResponse);
    }
  }
}
 

public int deepestLeavesSum(TreeNode root) {
    if (root == null) return 0;

    Queue<TreeNode> queue = new LinkedList<>();
    queue.add(root);
    int deepLeavesSum = root.val;

    while (!queue.isEmpty()) {
        int len = queue.size();
        deepLeavesSum = 0;
        for (int i = 0; i < len; i++) {
            TreeNode node = queue.poll();
            deepLeavesSum += node.val;
            if (node.left != null) queue.add(node.left);
            if (node.right != null) queue.add(node.right);
        }
    }

    return deepLeavesSum;
}
 

/**
 * Constructor that implements the {@link CacheTransactionManager} interface.
 * Only only one instance per {@link com.gemstone.gemfire.cache.Cache}
 */
public TXManagerImpl(CachePerfStats cachePerfStats, LogWriterI18n logWriter,
    GemFireCacheImpl cache) {
  this.cache = cache;
  this.dm = cache.getDistributedSystem().getDistributionManager();
  this.cachePerfStats = cachePerfStats;
  this.logWriter = logWriter;
  this.hostedTXStates = new CustomEntryConcurrentHashMap<TXId, TXStateProxy>(
      128, CustomEntryConcurrentHashMap.DEFAULT_LOAD_FACTOR,
      TXMAP_CONCURRENCY);
  this.suspendedTXs = new ConcurrentHashMap<TXId, TXStateInterface>();
  this.finishedTXStates = new TXFinishedMap(cache.getDistributedSystem(),
      cache.getCancelCriterion());
  this.waitMap = new ConcurrentHashMap<TransactionId, Queue<Thread>>();
  this.expiryTasks = new ConcurrentHashMap<TransactionId, SystemTimerTask>();
}
 

public List<Double> averageOfLevels(TreeNode root) {
    ArrayList<Double> result = new ArrayList<>();
    Queue<TreeNode> queue = new LinkedList<>();
    queue.add(root);
    while (!queue.isEmpty()) {
        int size = queue.size();
        double sum = 0;
        for (int i = 0; i < size; i++) {
            TreeNode tmp = queue.poll();
            sum += (double) tmp.val;
            if (tmp.left != null) queue.add(tmp.left);
            if (tmp.right != null) queue.add(tmp.right);
        }
        result.add(sum / size);
    }
    return result;
}
 

@Test
public void testAppendThrows() throws Exception {
    ReplyProcessor processor = new ReplyProcessor(); 
    Flow flow = new Flow(10, 0);
    FlowHandler flowHandler = new FlowHandler("testConnection");
    @Cleanup
    ClientConnection clientConnection = flowHandler.createFlow(flow, processor);
    EmbeddedChannel embeddedChannel = createChannelWithContext(flowHandler);
    embeddedChannel.runScheduledPendingTasks();
    embeddedChannel.runPendingTasks();
    Queue<Object> messages = embeddedChannel.outboundMessages();
    assertEquals(1, messages.size());
    clientConnection.send(new WireCommands.SetupAppend(1, new UUID(1, 2), "segment", ""));
    embeddedChannel.runPendingTasks();
    clientConnection.send(new Append("segment", new UUID(1, 2), 1, new Event(Unpooled.EMPTY_BUFFER), 2));
    embeddedChannel.disconnect();
    embeddedChannel.runPendingTasks();
    assertTrue(processor.falure.get());
}
 

private static <L> Constituent<L> getLeastCommonAncestorConstituentHelper(
		Tree<L> tree, int start, int end, int i, int j) {

	if (start == i && end == j)
		return new Constituent<L>(tree.getLabel(), start, end);

	Queue<Tree<L>> queue = new LinkedList<Tree<L>>();
	queue.addAll(tree.getChildren());
	int currStart = start;
	while (!queue.isEmpty()) {
		Tree<L> remove = queue.remove();
		List<L> currYield = remove.getYield();
		final int currEnd = currStart + currYield.size();
		if (currStart <= i && currEnd >= j) {
			final Constituent<L> leastCommonAncestorConstituentHelper = getLeastCommonAncestorConstituentHelper(
					remove, currStart, currEnd, i, j);
			if (leastCommonAncestorConstituentHelper != null)
				return leastCommonAncestorConstituentHelper;
			else
				break;
		}
		currStart += currYield.size();
	}
	return new Constituent<L>(tree.getLabel(), start, end);
}
 

void test(Queue<Boolean> q) {
    long t0 = System.nanoTime();
    for (int i = 0; i < count; i++)
        check(q.add(Boolean.TRUE));
    System.gc();
    System.gc();
    Boolean x;
    while ((x = q.poll()) != null)
        equal(x, Boolean.TRUE);
    check(q.isEmpty());

    for (int i = 0; i < 10 * count; i++) {
        for (int k = 0; k < 3; k++)
            check(q.add(Boolean.TRUE));
        for (int k = 0; k < 3; k++)
            if (q.poll() != Boolean.TRUE)
                fail();
    }
    check(q.isEmpty());

    String className = q.getClass().getSimpleName();
    long elapsed = System.nanoTime() - t0;
    int nanos = (int) ((double) elapsed / (10 * 3 * count));
    results.put(className, String.valueOf(nanos));
}
 

/** Obtain an instance of a Component nested inside the given inspectable Component. */
@Nullable
public InspectableComponent getNestedInstance(Component component) {
  final Queue<DebugComponent> queue = new LinkedList<>(mComponent.getChildComponents());

  while (!queue.isEmpty()) {
    final DebugComponent childComponent = queue.remove();

    if (childComponent.getComponent() == component) {
      return new InspectableComponent(childComponent);
    }

    queue.addAll(childComponent.getChildComponents());
  }

  return null;
}
 

@Override
public E waitPoll(Queue<E> q) throws InterruptedException
{
    E e = q.poll();
    if (e != null)
    {
        return e;
    }

    WAITERS_UPDATER.incrementAndGet(this);
    synchronized (obj)
    {
        while ((e = q.poll()) == null)
        {
            obj.wait();
        }
        WAITERS_UPDATER.decrementAndGet(this);
    }

    return e;
}
 

private View findScrollableViewInternal(View content, boolean selfable) {
    View scrollableView = null;
    Queue<View> views = new LinkedBlockingQueue<>(Collections.singletonList(content));
    while (!views.isEmpty() && scrollableView == null) {
        View view = views.poll();
        if (view != null) {
            if ((selfable || view != content) && (view instanceof AbsListView
                    || view instanceof ScrollView
                    || view instanceof ScrollingView
                    || view instanceof NestedScrollingChild
                    || view instanceof NestedScrollingParent
                    || view instanceof WebView
                    || view instanceof ViewPager)) {
                scrollableView = view;
            } else if (view instanceof ViewGroup) {
                ViewGroup group = (ViewGroup) view;
                for (int j = 0; j < group.getChildCount(); j++) {
                    views.add(group.getChildAt(j));
                }
            }
        }
    }
    return scrollableView;
}
 

/**
 * Similar to {@link #fullDuplexCall}, except that it waits for all streaming requests to be
 * received before starting the streaming responses.
 */
@Override
public StreamObserver<Messages.StreamingOutputCallRequest> halfDuplexCall(
    final StreamObserver<Messages.StreamingOutputCallResponse> responseObserver) {
  final ResponseDispatcher dispatcher = new ResponseDispatcher(responseObserver);
  final Queue<Chunk> chunks = new ArrayDeque<>();
  return new StreamObserver<StreamingOutputCallRequest>() {
    @Override
    public void onNext(StreamingOutputCallRequest request) {
      chunks.addAll(toChunkQueue(request));
    }

    @Override
    public void onCompleted() {
      // Dispatch all of the chunks in one shot.
      dispatcher.enqueue(chunks).completeInput();
    }

    @Override
    public void onError(Throwable cause) {
      dispatcher.onError(cause);
    }
  };
}
 

/**
* 
*/
 private void init() {
    feederQueue = new ArrayList<Queue<Species>>(6);
    for (int i = 1; i <= Board.NUM_COLS; i++) {
       feederQueue.add(new LinkedList<Species>());
       sizes[i - 1] = 0;
    }
 }
 

public static Object[] makeMpq(int producers, int consumers, int capacity, Ordering ordering, Queue<Integer> q)
{
    ConcurrentQueueSpec spec = new ConcurrentQueueSpec(producers, consumers, capacity, ordering,
        Preference.NONE);
    if (q == null)
    {
        q = QueueFactory.newQueue(spec);
    }
    return new Object[] {spec, q};
}
 

@Nullable
public Invocation dequeue(Object identifier) {
    synchronized (queues) {
        Queue<Invocation> queue = queues.get(identifier);
        if (queue != null) {
            return queue.poll();
        }
    }
    return null;
}
 

/**
 * A deserialized serialized queue has same elements in same order
 */
public void testSerialization() throws Exception {
    Queue x = populatedQueue(SIZE);
    Queue y = serialClone(x);

    assertNotSame(x, y);
    assertEquals(x.size(), y.size());
    assertEquals(x.toString(), y.toString());
    assertTrue(Arrays.equals(x.toArray(), y.toArray()));
    while (!x.isEmpty()) {
        assertFalse(y.isEmpty());
        assertEquals(x.remove(), y.remove());
    }
    assertTrue(y.isEmpty());
}
 

@GenerateMicroBenchmark
@OperationsPerInvocation(CAPACITY)
public void offer()
{
    final Queue<Integer> lq = q;
    for (int i = 0; i < CAPACITY; i++)
    {
        lq.offer(TOKEN);
    }
}
 

private QueueBasedObjectPool(Queue<T> queue, boolean preAllocate, Allocator<T> allocator, Resetter<T> resetter) {
    super(allocator, resetter);
    this.queue = queue;
    if (preAllocate) {
        boolean addMore;
        do {
            addMore = queue.offer(allocator.createInstance());
        } while (addMore);
    }
}
 

private void prepareTable(final JavaCodeGenContext ctx, final Progress progress,
                          final Queue<JavaTableHost> _tableHosts, final TaskTableView tableViewSp, final String[] tableNames,
                          final DatabaseCategory dbCategory) {
    for (final String tableName : tableNames) {
        ExecuteResult result = new ExecuteResult(
                "Build Table[" + tableViewSp.getAlldbs_id() + "." + tableName + "] Host");
        progress.setOtherMessage(result.getTaskName());
        JavaTableHost tableHost = buildTableHost(ctx, tableViewSp, tableName, dbCategory);
        result.setSuccessal(true);
        if (null != tableHost) {
            _tableHosts.add(tableHost);
        }
    }
}
 

public PublisherWindow(Publisher<? extends T> source, int size, int skip, 
        Supplier<? extends Queue<T>> processorQueueSupplier,
        Supplier<? extends Queue<UnicastProcessor<T>>> overflowQueueSupplier) {
    super(source);
    if (size <= 0) {
        throw new IllegalArgumentException("size > 0 required but it was " + size);
    }
    if (skip <= 0) {
        throw new IllegalArgumentException("skip > 0 required but it was " + skip);
    }
    this.size = size;
    this.skip = skip;
    this.processorQueueSupplier = Objects.requireNonNull(processorQueueSupplier, "processorQueueSupplier");
    this.overflowQueueSupplier = Objects.requireNonNull(overflowQueueSupplier, "overflowQueueSupplier");
}
 

static <T> Queue<T> newMpscQueue(final int initialCapacity, final int maxCapacity) {
    // Calculate the max capacity which can not be bigger then MAX_ALLOWED_MPSC_CAPACITY.
    // This is forced by the MpscChunkedArrayQueue implementation as will try to round it
    // up to the next power of two and so will overflow otherwise.
    final int initialCap = max(MIN_ALLOWED_MPSC_CHUNK_SIZE, initialCapacity);
    final int capacity = max(min(maxCapacity, MAX_ALLOWED_QUEUE_CAPACITY), MIN_MAX_MPSC_CAPACITY);
    return USE_UNSAFE_QUEUES ? new MpscChunkedArrayQueue<>(initialCap, capacity)
                             : new MpscGrowableAtomicArrayQueue<>(initialCap, capacity);
}
 

@Test
public void failedInitialization() {
	final Queue<String> messages = new LinkedList<>();
	SimonManager.callback().removeAllCallbacks();
	SimonManager.callback().addCallback(new CallbackSkeleton() {
		public void onManagerWarning(String warning, Exception cause) {
			messages.add(warning);
		}
	});

	System.setProperty(SimonManager.PROPERTY_CONFIG_RESOURCE_NAME, "whateverNonexistent");
	SimonManager.init();
	Assert.assertEquals(messages.poll(), "SimonManager initialization error");
	System.getProperties().remove(SimonManager.PROPERTY_CONFIG_RESOURCE_NAME);
}
 

@Benchmark
public void mpscSingleThreadExecutorWithConcurrentLinkedQueue() throws InterruptedException {
    execute(new MpscSingleThreadExecutor(TIMES, new NamedThreadFactory("mpsc_clq", true)) {

        @Override
        protected Queue<Runnable> newTaskQueue(final int maxPendingTasks) {
            return new ConcurrentLinkedQueue<>();
        }
    });
}
 

/**
 * Method creates policy alternatives according to provided model. The model structure is modified in the process.
 *
 * @return created policy alternatives resulting from policy source model.
 */
private Collection<AssertionSet> createPolicyAlternatives(final PolicySourceModel model) throws PolicyException {
    // creating global method variables
    final ContentDecomposition decomposition = new ContentDecomposition();

    // creating processing queue and starting the processing iterations
    final Queue<RawPolicy> policyQueue = new LinkedList<RawPolicy>();
    final Queue<Collection<ModelNode>> contentQueue = new LinkedList<Collection<ModelNode>>();

    final RawPolicy rootPolicy = new RawPolicy(model.getRootNode(), new LinkedList<RawAlternative>());
    RawPolicy processedPolicy = rootPolicy;
    do {
        Collection<ModelNode> processedContent = processedPolicy.originalContent;
        do {
            decompose(processedContent, decomposition);
            if (decomposition.exactlyOneContents.isEmpty()) {
                final RawAlternative alternative = new RawAlternative(decomposition.assertions);
                processedPolicy.alternatives.add(alternative);
                if (!alternative.allNestedPolicies.isEmpty()) {
                    policyQueue.addAll(alternative.allNestedPolicies);
                }
            } else { // we have a non-empty collection of exactly ones
                final Collection<Collection<ModelNode>> combinations = PolicyUtils.Collections.combine(decomposition.assertions, decomposition.exactlyOneContents, false);
                if (combinations != null && !combinations.isEmpty()) {
                    // processed alternative was split into some new alternatives, which we need to process
                    contentQueue.addAll(combinations);
                }
            }
        } while ((processedContent = contentQueue.poll()) != null);
    } while ((processedPolicy = policyQueue.poll()) != null);

    // normalize nested policies to contain single alternative only
    final Collection<AssertionSet> assertionSets = new LinkedList<AssertionSet>();
    for (RawAlternative rootAlternative : rootPolicy.alternatives) {
        final Collection<AssertionSet> normalizedAlternatives = normalizeRawAlternative(rootAlternative);
        assertionSets.addAll(normalizedAlternatives);
    }

    return assertionSets;
}
 

private static void processColumnNames(Queue<String> tokens,
                                       Queue<String> processedTokens) throws SQLException {
    if (!ParserUtil.isStringLiteral(tokens.peek())) {
        throw new SQLException("Syntax Error : String literal is expected");
    }
    processedTokens.add(Constants.COLUMN);
    processedTokens.add(tokens.poll());
    if (Constants.COMMA.equals(tokens.peek())) {
        tokens.poll();
        processColumnNames(tokens, processedTokens);
    }
}
 

public List<List<Integer>> zigzagLevelOrder(TreeNode root) {
    List<List<Integer>> res = new ArrayList<>();
    if (root == null) {
        return res;
    }
    
    Queue<TreeNode> queue = new LinkedList<>();
    queue.add(root);
    boolean direction = true;
    while (!queue.isEmpty()) {
        // 当前这一层遍历的节点集合
        List<Integer> curList = new ArrayList<>();

        // 特别注意：每一次只能处理上一轮入队列的的元素，
        // 所以要将上一轮入队列的元素个数先存一下
        int size = queue.size();
        for (int i = 0; i < size; i++) {
            TreeNode curNode = queue.poll();
            if (direction) {
                curList.add(curNode.val);
            } else {
                curList.add(0, curNode.val);
            }
            // 处理每一个元素都一样，都要考虑一下左右子树
            if (curNode.left != null) {
                queue.add(curNode.left);
            }
            if (curNode.right != null) {
                queue.add(curNode.right);
            }
        }
        // 改换方向
        direction = !direction;
        res.add(curList);
    }
    return res;
}