* that this method will return a different number of chars than would be returned by reading all
   * of the chars.
   *
   * <p>Additionally, for mutable sources such as {@code StringBuilder}s, a subsequent read may
   * return a different number of chars if the contents are changed.
   *
   * @since 19.0
   */
  public Optional<Long> lengthIfKnown() {
    return Optional.absent();
  }

  /**

    }

    @Test
    void testOpenConnection_CachedHandler_ReusesExistingHandler() throws Exception {
        // This test verifies that once a handler is cached, subsequent calls reuse it.
        setupMockProtocolHandlers();
        URL url1 = new URL("http://example.com/resource1");
        URL url2 = new URL("http://example.com/resource2");

                            robotsTxt.addDirective(currentDirective);
                        }
                        // Add to current list - multiple consecutive User-agent lines
                        // form a group and subsequent rules apply to all of them
                        currentDirectiveList.add(currentDirective);
                        continue;
                    }

                    // Mark that we've seen group-member records

        @DisplayName("read after close throws 'Bad file descriptor'")
        void readAfterCloseThrows() throws Exception {
            SmbFileInputStream in = newStream();
            // closing should null tmp; subsequent readDirect should fail
            in.close();
            IOException ex = assertThrows(IOException.class, () -> in.readDirect(new byte[8], 0, 4));
            assertTrue(ex.getMessage().contains("Bad file descriptor"));

    List<Object> buf = new ArrayList<>();
    int elements = Queues.drain(q, buf, -1, MAX_VALUE, NANOSECONDS);
    assertEquals(0, elements);
    assertThat(buf).isEmpty();

    // Free the producer thread, and give subsequent tests a clean slate.
    q.take();
  }

  public void testDrain_throws() throws Exception {
    for (BlockingQueue<Object> q : blockingQueues()) {
      checkDrainThrows(q);
    }
  }

   * key {@code c}. If that row key / column key pair in not in {@code table}, the pair maps to
   * {@code null} in the generated table.
   *
   * <p>The returned table allows subsequent {@code put} calls with the row keys in {@code
   * table.rowKeySet()} and the column keys in {@code table.columnKeySet()}. Calling {@link #put}
   * with other keys leads to an {@code IllegalArgumentException}.
   *

     */
    Waiter(boolean unused) {}

    Waiter() {
      // avoid volatile write, write is made visible by subsequent CAS on waitersField field
      putThread(this, Thread.currentThread());
    }

    // non-volatile write to the next field. Should be made visible by a subsequent CAS on
    // waitersField.
    void setNext(@Nullable Waiter next) {
      putNext(this, next);
    }

            return url;
        }
    }

    /**
     * Gets the character encoding for a parent URL from cache or data service.
     * Caches encoding information to improve performance on subsequent requests.
     *
     * @param parentUrl the parent URL to get encoding for
     * @param sessionId the session ID for the crawling session
     * @return the character encoding, or null if not found
     */

    // Although 'c' successfully committed above, the journal wasn't available to issue a CLEAN op.
    // Because the last state of 'c' was DIRTY before the journal failed, it should be removed
    // entirely on a subsequent open.
    assertThat(cache.size()).isEqualTo(4)
    assertAbsent("c")
    assertAbsent("d")
    assertAbsent("e")
  }

  @Test
  fun rebuildJournalFailureAllowsRemovals() {

                                /* Store references to the map and key so that
                                 * SmbFile.resolveDfs can re-insert the dr list with
                                 * the dr that was successful so that subsequent
                                 * attempts to resolve DFS use the last successful
                                 * referral first.
                                 */
                                tmp.map = links.map;