horizon.removeFirst();
          return null;
        }
      };
    }

    final Iterator<N> breadthFirst(Iterator<? extends N> startNodes) {
      return topDown(startNodes, InsertionOrder.BACK);
    }

    final Iterator<N> preOrder(Iterator<? extends N> startNodes) {
      return topDown(startNodes, InsertionOrder.FRONT);
    }

    /**

    public <T> T[] toArray(T[] array) {
      return snapshot().toArray(array);
    }

    /*
     * We'd love to use 'new ArrayList(this)' or 'list.addAll(this)', but
     * either of these would recurse back to us again!
     */
    private List<E> snapshot() {
      List<E> list = Lists.newArrayListWithExpectedSize(size());
      for (Multiset.Entry<E> entry : entrySet()) {
        E element = entry.getElement();

@GwtCompatible(emulated = true)
@ElementTypesAreNonnullByDefault
abstract class AbstractMapBasedMultiset<E extends @Nullable Object> extends AbstractMultiset<E>
    implements Serializable {
  // TODO(lowasser): consider overhauling this back to Map<E, Integer>
  private transient Map<E, Count> backingMap;

  /*
   * Cache the size for efficiency. Using a long lets us avoid the need for
   * overflow checking and ensures that size() will function correctly even if

  public void testCreateParentDirectories_symlinkParentExists() throws IOException {
    /*
     * We use a fake filesystem to sidestep:
     *
     * - flaky problems with Windows (b/136041958)
     *
     * - the lack of support for symlinks in the default filesystem under Android's desugared
     *   java.nio.file
     */
    try (FileSystem fs = Jimfs.newFileSystem(Configuration.unix())) {
      Path symlink = fs.getPath("linkToDir");

   * entire stream. To avoid a potentially expensive operation, see {@link #lengthIfKnown}.
   *
   * <p>The default implementation calls {@link #lengthIfKnown} and returns the value if present. If
   * absent, it will fall back to a heavyweight operation that will open a stream, {@link
   * Reader#skip(long) skip} to the end of the stream, and return the total number of chars that
   * were skipped.
   *

   * input.
   */
  @VisibleForTesting(
      )
  static final double HASH_FLOODING_FPP = 0.001;

  /**
   * Maximum allowed length of a hash table bucket before falling back to a j.u.LinkedHashSet based
   * implementation. Experimentally determined.
   */
  private static final int MAX_HASH_BUCKET_LENGTH = 9;

 *
 * @author Colin Decker
 */
public class CharSourceTest extends IoTestCase {

  @AndroidIncompatible // Android doesn't understand suites whose tests lack default constructors.
  public static TestSuite suite() {
    TestSuite suite = new TestSuite();
    for (boolean asByteSource : new boolean[] {false, true}) {
      suite.addTest(
          CharSourceTester.tests(

   * Returns whether the source has zero bytes. The default implementation first checks {@link
   * #sizeIfKnown}, returning true if it's known to be zero and false if it's known to be non-zero.
   * If the size is not known, it falls back to opening a stream and checking for EOF.
   *
   * <p>Note that, in cases where {@code sizeIfKnown} returns zero, it is <i>possible</i> that bytes

      /*
       * https://github.com/google/guava/issues/6634: ProcessHandle has more accurate information,
       * but that class isn't available under all environments that we support. We use it if
       * available and fall back if not.
       */
      String fromSystemProperty = requireNonNull(USER_NAME.value());

      try {
        Class<?> processHandleClass = Class.forName("java.lang.ProcessHandle");

            cells = rs;
            init = true;
          }
        } finally {
          busy = 0;
        }
        if (init) break;
      } else if (casBase(v = base, fn(v, x))) break; // Fall back on using base
    }
  }

  /** Sets base and all cells to the given value. */
  final void internalReset(long initialValue) {
    Cell[] as = cells;
    base = initialValue;
    if (as != null) {