/*!
 * Copyright 2016 Google LLC
 *
 * 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 { Response } from 'teeny-request';
/**
 * @type {module:commonGrpc/service}
 * @private
 */
import { GrpcService } from './service';
/**
 * @type {module:commonGrpc/serviceObject}
 * @private
 */
import { GrpcServiceObject } from './service-object';
export declare class GrpcOperation extends GrpcServiceObject {
    completeListeners: number;
    hasActiveListeners: boolean;
    /**
     * An Operation object allows you to interact with APIs that take longer to
     * process things.
     *
     * @constructor
     * @alias module:common/grpcOperation
     *
     * @param {module:commonGrpc/service|module:commonGrpc/serviceObject} parent - The
     *     parent object. This should be configured to use the
     * longrunning.operation service.
     * @param {string} name - The operation name.
     */
    constructor(parent: GrpcService | GrpcServiceObject, name: string);
    /**
     * Cancel the operation.
     *
     * @param {function=} callback - The callback function.
     * @param {?error} callback.err - An error returned while making this
     *     request.
     * @param {object} callback.apiResponse - The full API response.
     */
    cancel(callback: (err: Error | null, apiResponse?: Response) => void): void;
    /**
     * Poll for a status update. Execute the callback:
     *
     *   - callback(err): Operation failed
     *   - callback(): Operation incomplete
     *   - callback(null, metadata): Operation complete
     *
     * @private
     *
     * @param {function} callback
     */
    private poll_;
    /**
     * Begin listening for events on the operation. This method keeps track of how
     * many "complete" listeners are registered and removed, making sure polling
     * is handled automatically.
     *
     * As long as there is one active "complete" listener, the connection is open.
     * When there are no more listeners, the polling stops.
     *
     * @private
     */
    protected listenForEvents_(): void;
    /**
     * Poll `getMetadata` to check the operation's status. This runs a loop to
     * ping the API on an interval.
     *
     * Note: This method is automatically called once a "complete" event handler
     * is registered on the operation.
     *
     * @private
     */
    protected startPolling_(): Promise<void>;
}