* {@link MoreExecutors#directExecutor}. Normally, when the first future completes, all the other
   * tasks would be called recursively. Here, we detect that the delegate executor is executing
   * inline, and maintain a queue to dispatch tasks iteratively. There is one instance of this class
   * per call to submit() or submitAsync(), and each instance supports only one call to execute().
   *

    ListenableFuture<Boolean> future2 =
        serializer.submit(
            new Callable<Boolean>() {
              @Override
              public Boolean call() {
                return blockingCallable.isRunning();
              }
            },
            directExecutor());

 * Prefer to alternate IP addresses from different address families, (IPv6 / IPv4), starting with IPv6.
 * Don't start a new attempt until 250 ms after the most recent attempt was started.
 * Keep whichever TCP connection succeeds first and cancel all the others.
 * Race TCP only. Only attempt a TLS handshake on the winning TCP connection.

     * >60% faster than the Euclidean algorithm in benchmarks.
     */
    int aTwos = Long.numberOfTrailingZeros(a);
    a >>= aTwos; // divide out all 2s
    int bTwos = Long.numberOfTrailingZeros(b);
    b >>= bTwos; // divide out all 2s
    while (a != b) { // both a, b are odd
      // The key to the binary GCD algorithm is as follows:
      // Both a and b are odd. Assume a > b; then gcd(a - b, b) = gcd(a, b).

    public int[] batchInsert(List<ClickLog> list, RequestOptionCall<BulkRequestBuilder> call) {
        return batchInsert(list, call, null);
    }

    public int[] batchInsert(List<ClickLog> list, RequestOptionCall<BulkRequestBuilder> call,
            RequestOptionCall<IndexRequestBuilder> entityCall) {
        return doBatchInsert(new BulkList<>(list, call, entityCall), null);
    }

    public int[] batchUpdate(List<ClickLog> list) {

    public int[] batchInsert(List<Role> list, RequestOptionCall<BulkRequestBuilder> call) {
        return batchInsert(list, call, null);
    }

    public int[] batchInsert(List<Role> list, RequestOptionCall<BulkRequestBuilder> call,
            RequestOptionCall<IndexRequestBuilder> entityCall) {
        return doBatchInsert(new BulkList<>(list, call, entityCall), null);
    }

    public int[] batchUpdate(List<Role> list) {

    public int[] batchInsert(List<FailureUrl> list, RequestOptionCall<BulkRequestBuilder> call) {
        return batchInsert(list, call, null);
    }

    public int[] batchInsert(List<FailureUrl> list, RequestOptionCall<BulkRequestBuilder> call,
            RequestOptionCall<IndexRequestBuilder> entityCall) {
        return doBatchInsert(new BulkList<>(list, call, entityCall), null);
    }

    public int[] batchInsert(List<RequestHeader> list, RequestOptionCall<BulkRequestBuilder> call) {
        return batchInsert(list, call, null);
    }

    public int[] batchInsert(List<RequestHeader> list, RequestOptionCall<BulkRequestBuilder> call,
            RequestOptionCall<IndexRequestBuilder> entityCall) {
        return doBatchInsert(new BulkList<>(list, call, entityCall), null);
    }

    public int[] batchInsert(List<ThumbnailQueue> list, RequestOptionCall<BulkRequestBuilder> call) {
        return batchInsert(list, call, null);
    }

    public int[] batchInsert(List<ThumbnailQueue> list, RequestOptionCall<BulkRequestBuilder> call,
            RequestOptionCall<IndexRequestBuilder> entityCall) {
        return doBatchInsert(new BulkList<>(list, call, entityCall), null);
    }

  }

  /**
   * Cancel all calls currently enqueued or executing. Includes calls executed both
   * [synchronously][Call.execute] and [asynchronously][Call.enqueue].
   */
  @Synchronized
  fun cancelAll() {
    for (call in readyAsyncCalls) {
      call.call.cancel()
    }
    for (call in runningAsyncCalls) {
      call.call.cancel()
    }
    for (call in runningSyncCalls) {
      call.cancel()