list.add(closeable, closingExecutor);
      }
      return closeable;
    }
  }

  /**
   * An operation that computes a result.
   *
   * @param <V> the type of the result
   */
  public interface ClosingCallable<V extends @Nullable Object> {
    /**
     * Computes a result, or throws an exception if unable to do so.
     *

    // Ensure that referenceMap, which doesn't use WithExpectedSize, ends up with the same table
    // size as the other two maps. If it ended up with a smaller size that would imply that we
    // computed the wrong initial capacity.
    for (int i = 0; i < size; i++) {
      referenceMap.put(i, null);
    }
    assertWithMessage("table size after adding %s elements", size)
        .that(initialBuckets)

        // so we rely on the JDK services to eventually look up a custom RootLocator.
        // This is used to compute {@code session.rootDirectory} but all {@code project.rootDirectory}
        // properties will be computed through the RootLocator found in the container.
        RootLocator rootLocator =
                ServiceLoader.load(RootLocator.class).iterator().next();

  }

  public void testInvalidateDuringLoading() throws InterruptedException, ExecutionException {
    // computation starts; invalidate() is called on the key being computed, computation finishes
    CountDownLatch computationStarted = new CountDownLatch(2);
    CountDownLatch letGetFinishSignal = new CountDownLatch(1);
    CountDownLatch getFinishedSignal = new CountDownLatch(2);

  }

  public void testInvalidateDuringLoading() throws InterruptedException, ExecutionException {
    // computation starts; invalidate() is called on the key being computed, computation finishes
    CountDownLatch computationStarted = new CountDownLatch(2);
    CountDownLatch letGetFinishSignal = new CountDownLatch(1);
    CountDownLatch getFinishedSignal = new CountDownLatch(2);

        // the value for the key is already being computed.
        computingValueReference = new ComputingValueReference<>(valueReference);

        // Compute the value now, so if it throws an exception we don't change anything.
        newValue = computingValueReference.compute(key, function);

        if (e == null) {
          createNewEntry = true;

   * computes) correspond to minimum intervals between subsequent requests, for the specified number
   * of requested permits.
   *
   * Here is an example of storedPermitsToWaitTime: If storedPermits == 10.0, and we want 3 permits,
   * we take them from storedPermits, reducing them to 7.0, and compute the throttling for these as

  private double sumOfProductsOfDeltas = 0.0;

  /** Adds the given pair of values to the dataset. */
  public void add(double x, double y) {
    // We extend the recursive expression for the one-variable case at Art of Computer Programming
    // vol. 2, Knuth, 4.2.2, (16) to the two-variable case. We have two value series x_i and y_i.
    // We define the arithmetic means X_n = 1/n \sum_{i=1}^n x_i, and Y_n = 1/n \sum_{i=1}^n y_i.

   * - median with compute taking a double-collection and with computeInPlace;
   * - quartiles with index and with indexes taking int-varargs, and with compute taking a
   *   double-collection and with computeInPlace;
   * - scale with index and with indexes taking int-varargs, and with all overloads of compute
   *   taking a double-collection and with computeInPlace;

   * - median with compute taking a double-collection and with computeInPlace;
   * - quartiles with index and with indexes taking int-varargs, and with compute taking a
   *   double-collection and with computeInPlace;
   * - scale with index and with indexes taking int-varargs, and with all overloads of compute
   *   taking a double-collection and with computeInPlace;