abstract class AggregateFutureState<OutputT extends @Nullable Object>
    extends AbstractFuture.TrustedFuture<OutputT> {
  // Lazily initialized the first time we see an exception; not released until all the input futures
  // & this future completes. Released when the future releases the reference to the running state
  private @Nullable Set<Throwable> seenExceptions = null;
  private int remaining;

  AggregateFutureState(int remainingFutures) {

    InterruptibleFuture future = new InterruptibleFuture();
    assertTrue(future.cancel(false));
    assertTrue(future.isCancelled());
    assertTrue(future.isDone());
    assertFalse(future.wasInterrupted());
    assertFalse(future.interruptTaskWasCalled);
    CancellationException e = assertThrows(CancellationException.class, () -> future.get());
    assertThat(e).hasCauseThat().isNull();
  }

          }

          @Override
          public void onFailure(Throwable t) {
            failureCalls[0]++;
          }
        };
    addCallback(future, callback, directExecutor());
    future.set(result);
    assertEquals(result, future.get());
    assertThat(successCalls[0]).isEqualTo(1);
    assertThat(failureCalls[0]).isEqualTo(0);
  }

  public void testOnSuccessThrowsError() throws Exception {

  static final Future<String> FAILED_FUTURE_OTHER_THROWABLE =
      immediateFailedFuture(OTHER_THROWABLE);
  static final Error ERROR = new Error("mymessage");
  static final Future<String> FAILED_FUTURE_ERROR = immediateFailedFuture(ERROR);
  static final Future<String> RUNTIME_EXCEPTION_FUTURE =
      UncheckedThrowingFuture.throwingRuntimeException(RUNTIME_EXCEPTION);

import java.util.logging.Level;
import javax.annotation.CheckForNull;
import org.checkerframework.checker.nullness.qual.Nullable;

/**
 * A helper which does some thread-safe operations for aggregate futures, which must be implemented
 * differently in GWT. Namely:
 *
 * <ul>
 *   <li>Lazily initializes a set of seen exceptions
 *   <li>Decrements a counter atomically
 * </ul>
 */
@GwtCompatible(emulated = true)

    List<Future<?>> futures = Lists.newArrayList();
    ExecutorService executor = Executors.newFixedThreadPool(10);
    int numberOfCatchers = 10000;
    for (int i = 0; i < numberOfCatchers; i++) {
      futures.add(executor.submit(new Registrator(bus, catchers)));
    }
    for (int i = 0; i < numberOfCatchers; i++) {
      futures.get(i).get();
    }

@ElementTypesAreNonnullByDefault
public interface FutureCallback<V extends @Nullable Object> {
  /** Invoked with the result of the {@code Future} computation when it is successful. */
  void onSuccess(@ParametricNullness V result);

  /**
   * Invoked when a {@code Future} computation fails or is canceled.
   *
   * <p>If the future's {@link Future#get() get} method throws an {@link ExecutionException}, then

  /**
   * Do interruptible work here - do not complete Futures here, as their listeners could be
   * interrupted.
   */
  @ParametricNullness
  abstract T runInterruptibly() throws Exception;

  /**
   * Any interruption that happens as a result of calling interruptTask will arrive before this
   * method is called. Complete Futures here.
   */

import java.util.logging.Level;
import javax.annotation.CheckForNull;
import org.checkerframework.checker.nullness.qual.Nullable;

/**
 * A helper which does some thread-safe operations for aggregate futures, which must be implemented
 * differently in GWT. Namely:
 *
 * <ul>
 *   <li>Lazily initializes a set of seen exceptions
 *   <li>Decrements a counter atomically
 * </ul>
 */
@GwtCompatible(emulated = true)

                  return null;
                }
              }));
    }

    // For more about this test, see the equivalent in AbstractNetworkTest.
    for (Future<?> future : futures.build()) {
      future.get();
    }
    executor.shutdown();
  }