resourceCollector.js 2.42 KB
"use strict";
/**
 * Copyright 2020 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.
 */
Object.defineProperty(exports, "__esModule", { value: true });
exports.ResourceCollector = void 0;
/**
 * ResourceCollector class implements asynchronous logic of calling the API call that supports pagination,
 * page by page, collecting all resources (up to `maxResults`) in the array.
 *
 * Usage:
 *   const resourceCollector = new ResourceCollector(apiCall, maxResults); // -1 for unlimited
 *   resourceCollector.processAllPages(request).then(resources => ...);
 */
class ResourceCollector {
    constructor(apiCall, maxResults = -1) {
        this.apiCall = apiCall;
        this.resources = [];
        this.maxResults = maxResults;
    }
    callback(err, resources, nextPageRequest) {
        if (err) {
            // Something went wrong with this request - failing everything
            this.rejectCallback(err);
            return;
        }
        // Process one page
        for (const resource of resources) {
            this.resources.push(resource);
            if (this.resources.length === this.maxResults) {
                nextPageRequest = null;
                break;
            }
        }
        // All done?
        if (!nextPageRequest) {
            this.resolveCallback(this.resources);
            return;
        }
        // Schedule the next call
        const callback = (...args) => this.callback(...args);
        setImmediate(this.apiCall, nextPageRequest, callback);
    }
    processAllPages(firstRequest) {
        return new Promise((resolve, reject) => {
            this.resolveCallback = resolve;
            this.rejectCallback = reject;
            // Schedule the first call
            const callback = (...args) => this.callback(...args);
            setImmediate(this.apiCall, firstRequest, callback);
        });
    }
}
exports.ResourceCollector = ResourceCollector;
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