@Override
  protected abstract BlockingQueue<E> delegate();

  @CanIgnoreReturnValue
  @Override
  public int drainTo(Collection<? super E> c, int maxElements) {
    return delegate().drainTo(c, maxElements);
  }

  @CanIgnoreReturnValue
  @Override
  public int drainTo(Collection<? super E> c) {
    return delegate().drainTo(c);
  }

  @Override
  protected abstract BlockingQueue<E> delegate();

  @CanIgnoreReturnValue
  @Override
  public int drainTo(Collection<? super E> c, int maxElements) {
    return delegate().drainTo(c, maxElements);
  }

  @CanIgnoreReturnValue
  @Override
  public int drainTo(Collection<? super E> c) {
    return delegate().drainTo(c);
  }

  }

  @Override
  public int drainTo(Collection<? super E> c) {
    return delegate().drainTo(c);
  }

  @Override
  public int drainTo(Collection<? super E> c, int maxElements) {
    return delegate().drainTo(c, maxElements);
  }

  public int drainTo(Collection<? super E> c, int maxElements) {
    if (c == null) throw new NullPointerException();
    if (c == this) throw new IllegalArgumentException();
    if (maxElements <= 0) return 0;
    E[] items = this.items;
    Monitor monitor = this.monitor;
    monitor.enter();
    try {
      int i = takeIndex;
      int n = 0;
      int max = (maxElements < count) ? maxElements : count;
      while (n < max) {

  @Override
  public int drainTo(Collection<? super E> c, int maxElements) {
    if (c == null) throw new NullPointerException();
    if (c == this) throw new IllegalArgumentException();
    if (maxElements <= 0) return 0;
    Monitor monitor = this.monitor;
    monitor.enter();
    try {
      int n = 0;
      E e;
      while (n < maxElements && (e = q.poll()) != null) {
        c.add(e);
        ++n;
      }

    override fun remainingCapacity() = error("unsupported")

    override fun drainTo(sink: MutableCollection<in T>) = error("unsupported")

    override fun drainTo(
      sink: MutableCollection<in T>,
      maxElements: Int,
    ) = error("unsupported")
  }

  /** Returns true if no tasks have been scheduled. This runs the coordinator for confirmation. */
  fun isIdle() = taskRunner.activeQueues().isEmpty()