// it. To preserve FIFO order and failure atomicity of rejected execution when the same
      // Runnable is executed more than once, allocate a wrapper that we know is safe to remove by
      // object identity.
      // A data structure that returned a removal handle from add() would allow eliminating this
      // allocation.
      submittedTask =
          new Runnable() {

/**
 * Manager for persistent and durable SMB handles.
 *
 * This class provides:
 * - Handle lifecycle management
 * - Persistent storage for persistent handles
 * - Expiration tracking for durable handles
 * - Thread-safe access to handle information
 */
public class PersistentHandleManager {

    private static final Logger log = LoggerFactory.getLogger(PersistentHandleManager.class);

      /*
       * uncheckedCastNullableTToT is safe: The first call to this method always enters the !hasNext() case and
       * populates key, after which it's never cleared.
       */
      return output(uncheckedCastNullableTToT(key), valueIterator.next());
    }

    @Override
    public void remove() {
      valueIterator.remove();
      /*

    assertEquals(
        "Shouldn't catch any more events when unregistered.", expectedEvents, catcher2.getEvents());
  }

  // NOTE: This test will always pass if register() is thread-safe but may also
  // pass if it isn't, though this is unlikely.
  public void testRegisterThreadSafety() throws Exception {
    List<StringCatcher> catchers = new CopyOnWriteArrayList<>();

 * are stored in the cache until either evicted or manually invalidated. The common way to build
 * instances is using {@link CacheBuilder}.
 *
 * <p>Implementations of this interface are expected to be thread-safe, and can be safely accessed
 * by multiple concurrent threads.
 *
 * <p>When evaluated as a {@link Function}, a cache yields the same result as invoking {@link
 * #getUnchecked}.
 *

    assertEquals(
        "Shouldn't catch any more events when unregistered.", expectedEvents, catcher2.getEvents());
  }

  // NOTE: This test will always pass if register() is thread-safe but may also
  // pass if it isn't, though this is unlikely.
  public void testRegisterThreadSafety() throws Exception {
    List<StringCatcher> catchers = new CopyOnWriteArrayList<>();

        return new SmbFileInputStream(mockFile, mockTree, mockHandle);
    }

    @BeforeEach
    void setUp() throws Exception {
        // Common, safe defaults for collaborators
        when(mockHandle.isValid()).thenReturn(true);
        when(mockHandle.acquire()).thenReturn(mockHandle);
        when(mockHandle.getTree()).thenReturn(mockTree);

    }

    @Test
    public void test_createIndexIfNothing_multipleCallsAreSafe() throws Exception {
        Suggester suggester = createSuggester();

        // Multiple consecutive calls should be safe
        suggester.createIndexIfNothing();
        suggester.createIndexIfNothing();
        suggester.createIndexIfNothing();

        // Should still be able to use the index
        suggester.refresh();

        }
      }
    } finally {
      if (interrupted) {
        Thread.currentThread().interrupt();
      }
    }
    return added;
  }

  /**
   * Returns a synchronized (thread-safe) queue backed by the specified queue. In order to guarantee
   * serial access, it is critical that <b>all</b> access to the backing queue is accomplished
   * through the returned queue.
   *

      subgraph.addNode(node);
    }
    for (N node : subgraph.nodes()) {
      for (N successorNode : graph.successors(node)) {
        if (subgraph.nodes().contains(successorNode)) {
          // requireNonNull is safe because the endpoint pair comes from the graph.
          subgraph.putEdgeValue(
              node,
              successorNode,
              requireNonNull(graph.edgeValueOrDefault(node, successorNode, null)));