function = null;
    }

    /*
     * If set()/setValue() throws an Error, we let it propagate. Why? The most likely Error is a
     * StackOverflowError (from deep transform(..., directExecutor()) nesting), and calling
     * setException(stackOverflowError) would fail:
     *
     * - If the stack overflowed before set()/setValue() could even store the result in the output

      function = null;
    }

    /*
     * If set()/setValue() throws an Error, we let it propagate. Why? The most likely Error is a
     * StackOverflowError (from deep transform(..., directExecutor()) nesting), and calling
     * setException(stackOverflowError) would fail:
     *
     * - If the stack overflowed before set()/setValue() could even store the result in the output

      prev.setFuture(curr);
      prev = curr;
    }
    // prev represents the 'innermost' future
    prev.set("done");
    assertTrue(orig.isDone());
  }

  // Verify that StackOverflowError in a long chain of SetFuture doesn't cause the entire toString
  // call to fail
  @J2ktIncompatible
  @GwtIncompatible
  @AndroidIncompatible // b/391667564: crashes from stack overflows

      prev.setFuture(curr);
      prev = curr;
    }
    // prev represents the 'innermost' future
    prev.set("done");
    assertTrue(orig.isDone());
  }

  // Verify that StackOverflowError in a long chain of SetFuture doesn't cause the entire toString
  // call to fail
  @J2ktIncompatible
  @GwtIncompatible
  @AndroidIncompatible // b/391667564: crashes from stack overflows

           *
           * Also, it's nice that this approach should let us catch *only* ClassNotFoundException
           * instead of having to catch more broadly (potentially even including, say, a
           * StackOverflowError).
           */
          Class.forName("java.lang.invoke.VarHandle");
        } catch (ClassNotFoundException beforeJava9) {
          return null;
        }
        return new VarHandleAtomicHelper();

    return outputFuture;
  }

  enum RunningState {
    NOT_RUN,
    CANCELLED,
    STARTED,
  }

  /**
   * This class helps avoid a StackOverflowError when large numbers of tasks are submitted with
   * {@link MoreExecutors#directExecutor}. Normally, when the first future completes, all the other