* That is, each node's subtrees are traversed after the node itself is returned.
   *
   * <p>No guarantees are made about the behavior of the traversal when nodes change while iteration
   * is in progress or when the iterators generated by {@link #children} are advanced.
   *
   * @deprecated Use {@link com.google.common.graph.Traverser#depthFirstPreOrder} instead, which has
   *     the same behavior.
   */

   * |      |
   * |      |
   * e ---- c ---- f
   * }</pre>
   *
   * <p>The behavior of this method is undefined if the nodes, or the topology of the graph, change
   * while iteration is in progress.
   *
   * <p>The returned {@code Iterable} can be iterated over multiple times. Every iterator will
   * compute its next element on the fly. It is thus possible to limit the traversal to a certain

 * #entries()}, and {@link #asMap} return collections that are views of the multimap. If the
 * multimap is modified while an iteration over any of those collections is in progress, except
 * through the iterator's methods, the results of the iteration are undefined.
 *
 * <p>Keys and values may be null. All optional multimap methods are supported, and all returned
 * views are modifiable.
 *

    int nSeededEntries = 100;
    Set<String> expectedKeys = Sets.newHashSetWithExpectedSize(nTasks + nSeededEntries);
    // seed the map, so its segments have a count>0; otherwise, clear() won't visit the in-progress
    // entries
    for (int i = 0; i < nSeededEntries; i++) {
      String s = "b" + i;
      cache.getUnchecked(s);
      expectedKeys.add(s);
    }
    computationShouldWait.set(true);

          }
        }
      }
    }
  }

  /**
   * Using this as the blocker object allows introspection and debugging tools to see that the
   * currentRunner thread is blocked on the progress of the interruptor thread, which can help
   * identify deadlocks.
   */
  @VisibleForTesting
  static final class Blocker extends AbstractOwnableSynchronizer implements Runnable {

 * then Lock B, while another thread acquires Lock B, and then Lock A:
 *
 * <pre>
 * Thread1: acquire(LockA) --X acquire(LockB)
 * Thread2: acquire(LockB) --X acquire(LockA)
 * </pre>
 *
 * <p>Neither thread will progress because each is waiting for the other. In more complex
 * applications, cycles can arise from interactions among more than 2 locks:
 *
 * <pre>
 * Thread1: acquire(LockA) --X acquire(LockB)

      public void run() {
        cache.refresh(refreshKey);
        getFinishedSignal.countDown();
      }
    }.start();

    getStartedSignal.await();

    // computation is in progress; asMap shouldn't have changed
    assertEquals(1, map.size());
    assertFalse(map.containsKey(getKey));
    assertSame(refreshKey, map.get(refreshKey));

    // let computation complete

              "DelayedShutdownHook-for-" + service,
              new Runnable() {
                @Override
                public void run() {
                  try {
                    // We'd like to log progress and failures that may arise in the
                    // following code, but unfortunately the behavior of logging
                    // is undefined in shutdown hooks.

      public void run() {
        cache.refresh(refreshKey);
        getFinishedSignal.countDown();
      }
    }.start();

    getStartedSignal.await();

    // computation is in progress; asMap shouldn't have changed
    assertEquals(1, map.size());
    assertFalse(map.containsKey(getKey));
    assertSame(refreshKey, map.get(refreshKey));

    // let computation complete

   * {@code k} to value {@code v} in the specified map. The behavior of this operation is undefined
   * if the specified map is modified while the operation is in progress.
   */
  public void putAll(Map<? extends K, ? extends Long> m) {
    for (Entry<? extends K, ? extends Long> entry : m.entrySet()) {
      put(entry.getKey(), entry.getValue());
    }
  }

  /**