/*!
 * Copyright 2019 Google Inc. All Rights Reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
import { grpc } from 'google-gax';
/*!
 * retryable grpc.status codes
 */
export declare const RETRY_CODES: grpc.status[];
/**
 * Used to track pull requests and determine if additional requests should be
 * made, etc.
 *
 * @class
 * @private
 */
export declare class PullRetry {
    private failures;
    /**
     * Generates a timeout that can be used for applying a backoff based on the
     * current number of failed requests.
     *
     * @see {@link https://cloud.google.com/iot/docs/how-tos/exponential-backoff}
     * @private
     * @returns {number}
     */
    createTimeout(): number;
    /**
     * Determines if a request grpc.status should be retried.
     *
     * Deadlines behave kind of unexpectedly on streams, rather than using it as
     * an indicator of when to give up trying to connect, it actually dictates
     * how long the stream should stay open. Because of this, it is virtually
     * impossible to determine whether or not a deadline error is the result of
     * the server closing the stream or if we timed out waiting for a connection.
     *
     * @private
     * @param {object} grpc.status The request grpc.status.
     * @returns {boolean}
     */
    retry(err: grpc.StatusObject): boolean;
}