}
    assertTrue(millisElapsedSince(startTime) >= timeoutMillis);
  }

  /** Fails with message "should throw exception". */
  public void shouldThrow() {
    fail("Should throw exception");
  }

  /** Fails with message "should throw " + exceptionName. */
  public void shouldThrow(String exceptionName) {
    fail("Should throw " + exceptionName);
  }

  }

  /**
   * Returns a new {@code Future} whose result is asynchronously derived from the result of the
   * given {@code Future}. If the given {@code Future} fails, the returned {@code Future} fails with
   * the same exception (and the function is not invoked).
   *
   * <p>More precisely, the returned {@code Future} takes its result from a {@code Future} produced

      if (oldValue == 0L || atomic.compareAndSet(oldValue, 0L)) {
        // only remove after setting to zero, to avoid concurrent updates
        map.remove(key, atomic);
        // succeed even if the remove fails, since the value was already adjusted
        return oldValue;
      }
    }
  }

  /**
   * If {@code (key, value)} is currently in the map, this method removes it and returns true;

    assertBitEquals(1.0, at.get());
    for (double x : VALUES) {
      at.lazySet(x);
      assertBitEquals(x, at.get());
    }
  }

  /** compareAndSet succeeds in changing value if equal to expected else fails */
  public void testCompareAndSet() {
    double prev = Math.E;
    double unused = Math.E + Math.PI;
    AtomicDouble at = new AtomicDouble(prev);
    for (double x : VALUES) {
      assertBitEquals(prev, at.get());

     * approach would be for each caller CAS it from null to a Set populated with its exception. But
     * there's another race: If the first thread fails with an exception and a second thread
     * immediately fails with the same exception:
     *
     * Thread1: calls setException(), which returns true, context switch before it can CAS
     * seenExceptions to its exception
     *

   *       {@code cls}:
   *       <ul>
   *         <li>Test will fail if default value for a parameter cannot be determined.
   *         <li>Test will fail if the factory method returns null so testing instance methods is
   *             impossible.
   *         <li>Test will fail if the constructor or factory method throws exception.
   *       </ul>

  }

  /**
   * Returns a new {@code Future} whose result is asynchronously derived from the result of the
   * given {@code Future}. If the given {@code Future} fails, the returned {@code Future} fails with
   * the same exception (and the function is not invoked).
   *
   * <p>More precisely, the returned {@code Future} takes its result from a {@code Future} produced

   * pipeline is done (other than those captured by the returned {@link ClosingFuture}).
   *
   * <p>If this {@code ClosingFuture} fails with an exception of the given type, the derived {@code
   * ClosingFuture} will be equivalent to the one returned by the function.
   *
   * <p>If this {@code ClosingFuture} succeeds or fails with a different exception type, the
   * function will not be called, and the derived {@code ClosingFuture} will be equivalent to this

      assertBitEquals(VALUES[i], aa.get(i));
      aa.lazySet(i, -3.0);
      assertBitEquals(-3.0, aa.get(i));
    }
  }

  /** compareAndSet succeeds in changing value if equal to expected else fails */
  public void testCompareAndSet() {
    AtomicDoubleArray aa = new AtomicDoubleArray(SIZE);
    for (int i : new int[] {0, SIZE - 1}) {
      double prev = 0.0;
      double unused = Math.E + Math.PI;

  }

  /**
   * The only reference to Unsafe is in this nested class. We set things up so that if
   * Unsafe.theUnsafe is inaccessible, the attempt to load the nested class fails, and the outer
   * class's static initializer can fall back on a non-Unsafe version.
   */
  @SuppressWarnings({"SunApi", "removal"}) // b/345822163
  private enum UnsafeByteArray implements LittleEndianBytes {