} catch (Throwable t) { // sneaky checked exception
      return false;
    }
  }

  private static <X extends Exception> X newWithCause(Class<X> exceptionClass, Throwable cause) {
    // getConstructors() guarantees this as long as we don't modify the array.
    @SuppressWarnings({"unchecked", "rawtypes"})
    List<Constructor<X>> constructors = (List) Arrays.asList(exceptionClass.getConstructors());

   * service changes state. The listener will not have previous state changes replayed, so it is
   * suggested that listeners are added before the service starts.
   *
   * <p>{@code addListener} guarantees execution ordering across calls to a given listener but not
   * across calls to multiple listeners. Specifically, a given listener will have its callbacks

 *
 * <p>See the Guava User's Guide's <a
 * href="https://github.com/google/guava/wiki/GraphsExplained#immutable-implementations">discussion
 * of the {@code Immutable*} types</a> for more information on the properties and guarantees
 * provided by this class.
 *
 * @author James Sexton
 * @author Jens Nyman
 * @param <N> Node parameter type
 * @param <V> Value parameter type
 * @since 20.0
 */
@Beta

            // So that is why we cancel only in the case of CAS success.
            taskFuture.cancel(false);
          }
        };
    // Adding the listener to both futures guarantees that newFuture will always be set. Adding to
    // taskFuture guarantees completion if the callable is invoked, and adding to outputFuture
    // propagates cancellation if the callable has not yet been invoked.

existing object replication are not marked as `PENDING` prior to replication.

   *
   * <p>May <a
   * href="http://download.oracle.com/javase/7/docs/api/java/util/concurrent/atomic/package-summary.html#Spurious">
   * fail spuriously</a> and does not provide ordering guarantees, so is only rarely an appropriate
   * alternative to {@code compareAndSet}.
   *
   * @param i the index
   * @param expect the expected value
   * @param update the new value
   * @return true if successful

            }
        } catch (final InterruptedException ie) {
            state = 0;
            thread = null;
            throw new TransportException(ie);
        } finally {
            /* This guarantees that we leave in a valid state
             */
            if (state != 0 && state != 3 && state != 4) {
                if (LogStream.level >= 1) {
                    log.println("Invalid state: " + state);

   * compares as equal to the key.
   */
  enum KeyPresentBehavior {
    /**
     * Return the index of any list element that compares as equal to the key. No guarantees are
     * made as to which index is returned, if more than one element compares as equal to the key.
     */
    ANY_PRESENT {
      @Override
      <E extends @Nullable Object> int resultIndex(

   * compares as equal to the key.
   */
  enum KeyPresentBehavior {
    /**
     * Return the index of any list element that compares as equal to the key. No guarantees are
     * made as to which index is returned, if more than one element compares as equal to the key.
     */
    ANY_PRESENT {
      @Override
      <E extends @Nullable Object> int resultIndex(

and
<a href="/pkg/sync/#WaitGroup">wait groups</a>.
The documentation for each of these specifies the guarantees it
makes concerning synchronization.
</p>

<p>
Other packages that provide synchronization abstractions
should document the guarantees they make too.
</p>


<h2 id="badsync">Incorrect synchronization</h2>

<p>
Programs with races are incorrect and