*       verified or created.
 *   <li>If a new edge needs to be created, the outgoing edges of the acquired locks are traversed
 *       to check for a cycle that reaches the lock to be acquired. If no cycle is detected, a new
 *       "safe" edge is created.
 *   <li>If a cycle is detected, an "unsafe" (cyclic) edge is created to represent a potential
 *       deadlock situation, and the appropriate Policy is executed.
 * </ul>
 *

  // Graph query methods

  /**
   * Returns true if {@code graph} has at least one cycle. A cycle is defined as a non-empty subset
   * of edges in a graph arranged to form a path (a sequence of adjacent outgoing edges) starting
   * and ending with the same node.
   *
   * <p>This method will detect any non-empty cycle, including self-loops (a cycle of length 1).
   */
  public static <N> boolean hasCycle(Graph<N> graph) {

  // Graph query methods

  /**
   * Returns true if {@code graph} has at least one cycle. A cycle is defined as a non-empty subset
   * of edges in a graph arranged to form a path (a sequence of adjacent outgoing edges) starting
   * and ending with the same node.
   *
   * <p>This method will detect any non-empty cycle, including self-loops (a cycle of length 1).
   */
  public static <N> boolean hasCycle(Graph<N> graph) {

       *
       * Maybe there is a way to avoid this cycle. But we think the cycle is safe enough to ignore:
       * Each task is retained for only as long as it is running -- so it's retained only as long as
       * it would already be retained by the underlying executor.
       *
       * If the cycle test starts reporting this cycle in the future, we should add an entry to
       * cycle_suppress_list.txt.
       */

       *
       * Maybe there is a way to avoid this cycle. But we think the cycle is safe enough to ignore:
       * Each task is retained for only as long as it is running -- so it's retained only as long as
       * it would already be retained by the underlying executor.
       *
       * If the cycle test starts reporting this cycle in the future, we should add an entry to
       * cycle_suppress_list.txt.
       */

  }

  public void testConcat_infiniteIterable() throws IOException {
    CharSource source = CharSource.wrap("abcd");
    Iterable<CharSource> cycle = Iterables.cycle(ImmutableList.of(source));
    CharSource concatenated = CharSource.concat(cycle);

    String expected = "abcdabcd";

    // read the first 8 chars manually, since there's no equivalent to ByteSource.slice

	minSleep time.Duration

	// cycle will be closed
	cycle chan struct{}

	// isScanner should be set when this is used by the scanner
	// to record metrics.
	isScanner bool
}

// newDynamicSleeper
func newDynamicSleeper(factor float64, maxWait time.Duration, isScanner bool) *dynamicSleeper {
	return &dynamicSleeper{
		factor:    factor,
		cycle:     make(chan struct{}),
		maxSleep:  maxWait,

   * elements.
   *
   * <p>To cycle over the iterable {@code n} times, use the following: {@code
   * Iterables.concat(Collections.nCopies(n, iterable))}
   *
   * <p><b>Java 8+ users:</b> The {@code Stream} equivalent of this method is {@code
   * Stream.generate(() -> iterable).flatMap(Streams::stream)}.
   */
  public static <T extends @Nullable Object> Iterable<T> cycle(Iterable<T> iterable) {
    checkNotNull(iterable);

   * elements.
   *
   * <p>To cycle over the iterable {@code n} times, use the following: {@code
   * Iterables.concat(Collections.nCopies(n, iterable))}
   *
   * <p><b>Java 8+ users:</b> The {@code Stream} equivalent of this method is {@code
   * Stream.generate(() -> iterable).flatMap(Streams::stream)}.
   */
  public static <T extends @Nullable Object> Iterable<T> cycle(Iterable<T> iterable) {
    checkNotNull(iterable);

  }

  public void testConcat_infiniteIterable() throws IOException {
    CharSource source = CharSource.wrap("abcd");
    Iterable<CharSource> cycle = Iterables.cycle(ImmutableList.of(source));
    CharSource concatenated = CharSource.concat(cycle);

    String expected = "abcdabcd";

    // read the first 8 chars manually, since there's no equivalent to ByteSource.slice