}

  /**
   * Gets the value from an entry. Returns null if the entry is invalid, partially-collected,
   * loading, or expired. Unlike {@link Segment#getLiveValue} this method does not attempt to clean
   * up stale entries. As such it should only be called outside a segment context, such as during
   * iteration.
   */
  @CheckForNull
  V getLiveValue(ReferenceEntry<K, V> entry, long now) {
    if (entry.getKey() == null) {

        makeLocalCache(createCacheBuilder().concurrencyLevel(concurrencyLevel));
    assertThat(map.segments).hasLength(segmentCount);
  }

  public void testSetInitialCapacity() {
    // share capacity over each segment, then round up to the nearest power of two

    checkInitialCapacity(1, 0, 1);
    checkInitialCapacity(1, 1, 1);
    checkInitialCapacity(1, 2, 2);
    checkInitialCapacity(1, 3, 4);

        makeLocalCache(createCacheBuilder().concurrencyLevel(concurrencyLevel));
    assertThat(map.segments).hasLength(segmentCount);
  }

  public void testSetInitialCapacity() {
    // share capacity over each segment, then round up to the nearest power of two

    checkInitialCapacity(1, 0, 1);
    checkInitialCapacity(1, 1, 1);
    checkInitialCapacity(1, 2, 2);
    checkInitialCapacity(1, 3, 4);

        else if (a.cas(v = a.value, fn(v, x))) break;
        else if (n >= NCPU || cells != as) collide = false; // At max size or stale
        else if (!collide) collide = true;
        else if (busy == 0 && casBusy()) {
          try {
            if (cells == as) { // Expand table unless stale
              Cell[] rs = new Cell[n << 1];
              for (int i = 0; i < n; ++i) rs[i] = as[i];
              cells = rs;

       * regardless of whether some failed. This lets us avoid calling expensive methods like
       * Future.get() when we don't need to (specifically, for whenAllComplete().call*()), and it
       * lets all futures share the same listener.
       *
       * We store `localFutures` inside the listener because `this.futures` might be nulled out by
       * the time the listener runs for the final future -- at which point we need to check all

        V value = getLiveValue(entry);
        if (value != null) {
          nextExternal = new WriteThroughEntry(key, value);
          return true;
        } else {
          // Skip stale entry.
          return false;
        }
      } finally {
        currentSegment.postReadCleanup();
      }
    }

    @Override
    public boolean hasNext() {

   * implementation; otherwise refreshes will be performed during unrelated cache read and write
   * operations.
   *
   * <p>Currently automatic refreshes are performed when the first stale request for an entry
   * occurs. The request triggering refresh will make a synchronous call to {@link
   * CacheLoader#reload}
   * to obtain a future of the new value. If the returned future is already complete, it is returned

public final class GcFinalization {
  private GcFinalization() {}

  /**
   * 10 seconds ought to be long enough for any object to be GC'ed and finalized. Unless we have a
   * gigantic heap, in which case we scale by heap size.
   */
  private static long timeoutSeconds() {
    // This class can make no hard guarantees.  The methods in this class are inherently flaky, but

        else if (a.cas(v = a.value, fn(v, x))) break;
        else if (n >= NCPU || cells != as) collide = false; // At max size or stale
        else if (!collide) collide = true;
        else if (busy == 0 && casBusy()) {
          try {
            if (cells == as) { // Expand table unless stale
              Cell[] rs = new Cell[n << 1];
              for (int i = 0; i < n; ++i) rs[i] = as[i];
              cells = rs;

 * object.
 *
 * <p><b>Comparison to {@code java.util.Optional} (JDK 8 and higher):</b> A new {@code Optional}
 * class was added for Java 8. The two classes are extremely similar, but incompatible (they cannot
 * share a common supertype). <i>All</i> known differences are listed either here or with the
 * relevant methods below.
 *
 * <ul>
 *   <li>This class is serializable; {@code java.util.Optional} is not.