*/
  fun cancel()

  /**
   * Carries an exchange. This is usually a connection, but it could also be a connect plan for
   * CONNECT tunnels. Note that CONNECT tunnels are significantly less capable than connections.
   */
  interface Carrier {
    val route: Route

    fun trackFailure(
      call: RealCall,
      e: IOException?,
    )

    fun noNewExchanges()

 * control. Under low update contention, the two classes have similar characteristics. But under
 * high contention, expected throughput of this class is significantly higher, at the expense of
 * higher space consumption.
 *
 * <p>This class extends {@link Number}, but does not define methods such as {@code

   * strategy.
   *
   * <p>Stashing this in a static field avoids loading it over and over again and speeds up test
   * execution significantly.
   */
  private static final ClassLoader NO_ATOMIC_FIELD_UPDATER =
      getClassLoader(
          ImmutableSet.of(
              AtomicIntegerFieldUpdater.class.getName(),

 * control. Under low update contention, the two classes have similar characteristics. But under
 * high contention, expected throughput of this class is significantly higher, at the expense of
 * higher space consumption.
 *
 * <p>This class extends {@link Number}, but does not define methods such as {@code

 */

@NullUnmarked
public class AbstractFutureFallbackAtomicHelperTest extends TestCase {

  // stash these in static fields to avoid loading them over and over again (speeds up test
  // execution significantly)

  /**
   * This classloader disallows {@link java.lang.invoke.VarHandle}, which will prevent us from
   * selecting the {@code VarHandleAtomicHelper} strategy.
   */
  private static final ClassLoader NO_VAR_HANDLE =

 * from uniform), and amortized since some operations can trigger a hash table resize.
 *
 * <p>As compared with {@link java.util.LinkedHashMap}, this structure places significantly reduced
 * load on the garbage collector by only using a constant number of internal objects.
 *
 * <p>This class should not be assumed to be universally superior to {@code

   * only the entries for {@code keys} will be returned from {@code getAll}.
   *
   * <p>This method should be overridden when bulk retrieval is significantly more efficient than
   * many individual lookups. Note that {@link LoadingCache#getAll} will defer to individual calls
   * to {@link LoadingCache#get} if this method is not overridden.
   *

 * good job of distributing the elements to the buckets to a distribution not far from uniform), and
 * amortized since some operations can trigger a hash table resize.
 *
 * <p>This implementation consumes significantly less memory than {@code java.util.LinkedHashSet} or
 * even {@code java.util.HashSet}, and places considerably less load on the garbage collector. Like

 * good job of distributing the elements to the buckets to a distribution not far from uniform), and
 * amortized since some operations can trigger a hash table resize.
 *
 * <p>This implementation consumes significantly less memory than {@code java.util.LinkedHashSet} or
 * even {@code java.util.HashSet}, and places considerably less load on the garbage collector. Like

     * @return the request trace, or {@code null} if no trace information is available
     */
    @Nullable
    RequestTrace getTrace();

    /**
     * Returns a hashcode value for this request, based on all significant fields.
     * Implementations must ensure that if two requests are equal according to
     * {@link #equals(Object)}, they have the same hashcode.
     *
     * @return a hash code value for this request
     */