* to reduce cache contention on most processors. Padding is
   * overkill for most Atomics because they are usually irregularly
   * scattered in memory and thus don't interfere much with each
   * other. But Atomic objects residing in arrays will tend to be
   * placed adjacent to each other, and so will most often share
   * cache lines (with a huge negative performance impact) without
   * this precaution.

 *
 * <p>Unlike {@code java.util.HashMap}, iteration is only proportional to the actual {@code size()},
 * which is optimal, and <i>not</i> the size of the internal hashtable, which could be much larger
 * than {@code size()}. Furthermore, this structure places significantly reduced load on the garbage
 * collector by only using a constant number of internal objects.
 *

      fail();
    } catch (IndexOutOfBoundsException expected) {
    }
  }

  /*
   * Whenever an implementation uses `instanceof` on a parameter instance, the test has to know that
   * (so much for "black box") and try instances that both do and don't pass the check. The "don't"
   * half of that is more awkward to arrange...
   */
  private static <T> Iterable<T> iterable(final Collection<T> collection) {

  }

  /**
   * Returns {@code n} choose {@code k}, also known as the binomial coefficient of {@code n} and
   * {@code k}, that is, {@code n! / (k! (n - k)!)}.
   *
   * <p><b>Warning:</b> the result can take as much as <i>O(k log n)</i> space.
   *
   * @throws IllegalArgumentException if {@code n < 0}, {@code k < 0}, or {@code k > n}
   */
  public static BigInteger binomial(int n, int k) {
    checkNonNegative("n", n);

      this.expectedCompletionWaitMillis = expectedCompletionWaitMillis;
      stopwatch = Stopwatch.createStarted();
    }

    /**
     * Asserts that the expected completion time has passed (and not "too much" time beyond that).
     */
    void assertCompletionExpected() {
      assertAtLeastTimePassed(stopwatch, expectedCompletionWaitMillis);
      assertTimeNotPassed(stopwatch, expectedCompletionWaitMillis + LONG_DELAY_MS);

   * higher value than you need can waste space and time, and a significantly lower value can lead
   * to thread contention. But overestimates and underestimates within an order of magnitude do not
   * usually have much noticeable impact. A value of one permits only one thread to modify the cache
   * at a time, but since read operations and cache loading computations can proceed concurrently,

    public Builder<E> addAll(Iterator<? extends E> elements) {
      super.addAll(elements);
      return this;
    }

    /**
     * If the specified collection is backed by an ObjectCountHashMap, it will be much more
     * efficient to iterate over it by index rather than an entry iterator, which will need to
     * allocate an object for each entry, so we check for that.
     */
    @CheckForNull

      expectedInsertions = 1;
    }
    /*
     * TODO(user): Put a warning in the javadoc about tiny fpp values, since the resulting size
     * is proportional to -log(p), but there is not much of a point after all, e.g.
     * optimalM(1000, 0.0000000000000001) = 76680 which is less than 10kb. Who cares!
     */
    long numBits = optimalNumOfBits(expectedInsertions, fpp);

   * This test attempts to cause a future to wait for longer than it was requested to from a timed
   * get() call. As measurements of time are prone to flakiness, it tries to assert based on ranges
   * derived from observing how much time actually passed for various operations.
   */
  @SuppressWarnings({"DeprecatedThreadMethods", "ThreadPriorityCheck"})
  @AndroidIncompatible // Thread.suspend
  public void testToString_delayedTimeout() throws Exception {

 * @author Bob Lee ({@code com.google.common.collect.MapMaker})
 * @author Doug Lea ({@code ConcurrentHashMap})
 */
@SuppressWarnings({
  "GoodTime", // lots of violations (nanosecond math)
  "nullness", // too much trouble for the payoff
})
@GwtCompatible(emulated = true)
// TODO(cpovirk): Annotate for nullness.
class LocalCache<K, V> extends AbstractMap<K, V> implements ConcurrentMap<K, V> {

  /*