// the run latch.
    exec.execute(task);
    runLatch.await();
    assertEquals(1, listenerLatch.getCount());
    assertFalse(task.isDone());
    assertFalse(task.isCancelled());

    // Finish the task by unblocking the task latch.  Then wait for the
    // listener to be called by blocking on the listener latch.
    taskLatch.countDown();
    assertEquals(25, task.get().intValue());

      A finalAccum = scheme.result(collector, inputs);
      if (collector.characteristics().contains(Collector.Characteristics.IDENTITY_FINISH)) {
        @SuppressWarnings("unchecked") // `R` and `A` match for an `IDENTITY_FINISH`
        R result = (R) finalAccum;
        assertEquivalent(expectedResult, result);
      }
      assertEquivalent(expectedResult, collector.finisher().apply(finalAccum));

   *
   * <p>If another call to {@link #get} or {@link #getUnchecked} is currently loading the value for
   * {@code key}, simply waits for that thread to finish and returns its loaded value. Note that
   * multiple threads can concurrently load values for distinct keys.
   *
   * <p>Caches loaded by a {@link CacheLoader} will call {@link CacheLoader#load} to load new values

  }

  /**
   * Returns a future that delegates to this future but will finish early (via a {@link
   * TimeoutException} wrapped in an {@link ExecutionException}) if the specified timeout expires.
   * If the timeout expires, not only will the output future finish, but also the input future
   * ({@code this}) will be cancelled and interrupted.
   *

    // give the third get a chance to run; it is okay for this to be racy
    // as the end result should be the same either way
    fourthSignal.await();
    Thread.yield();

    // let computation finish
    computeSignal.countDown();
    doneSignal.await();

    assertTrue(callCount.get() == 1);
    assertEquals("barfoo", result.get(0));
    assertEquals("barfoo", result.get(1));

   * to calling it exactly once.
   *
   * @since 10.0 (present in 1.0 as {@code run})
   */
  public void execute() {
    // Lock while we update our state so the add method above will finish adding any listeners
    // before we start to run them.
    RunnableExecutorPair list;
    synchronized (this) {
      if (executed) {
        return;
      }
      executed = true;

  private static final class Failure {
    static final Failure FALLBACK_INSTANCE =
        new Failure(
            new Throwable("Failure occurred while trying to finish a future.") {
              @Override
              public synchronized Throwable fillInStackTrace() {
                return this; // no stack trace
              }
            });
    final Throwable exception;

    // give the third get a chance to run; it is okay for this to be racy
    // as the end result should be the same either way
    fourthSignal.await();
    Thread.yield();

    // let computation finish
    computeSignal.countDown();
    doneSignal.await();

    assertTrue(callCount.get() == 1);
    assertEquals("barfoo", result.get(0));
    assertEquals("barfoo", result.get(1));

            inputs.assertHasImmediateFailure(iFuture, jFuture, e);
          } catch (TimeoutException e) {
            inputs.assertHasDelayed(iFuture, jFuture, e);
          }

          // Finish the two futures in the currently specified order:
          inputs.allFutures.get(iBeforeJ ? i : j).finisher.run();
          inputs.allFutures.get(iBeforeJ ? j : i).finisher.run();

import javax.annotation.CheckForNull;
import org.checkerframework.checker.nullness.qual.Nullable;

/**
 * Implementation of {@code Futures#withTimeout}.
 *
 * <p>Future that delegates to another but will finish early (via a {@link TimeoutException} wrapped
 * in an {@link ExecutionException}) if the specified duration expires. The delegate future is
 * interrupted and cancelled if it times out.
 */
@J2ktIncompatible
@GwtIncompatible