dbl-utils/dist/cjs/fetch-queue.js

Utilities for dbl, adba and others projects

"use strict";
var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, P, generator) {
    function adopt(value) { return value instanceof P ? value : new P(function (resolve) { resolve(value); }); }
    return new (P || (P = Promise))(function (resolve, reject) {
        function fulfilled(value) { try { step(generator.next(value)); } catch (e) { reject(e); } }
        function rejected(value) { try { step(generator["throw"](value)); } catch (e) { reject(e); } }
        function step(result) { result.done ? resolve(result.value) : adopt(result.value).then(fulfilled, rejected); }
        step((generator = generator.apply(thisArg, _arguments || [])).next());
    });
};
Object.defineProperty(exports, "__esModule", { value: true });
const js_md5_1 = require("js-md5");
/**
 * A queue to manage fetch requests with unique identification.
 *
 * Useful to deduplicate concurrent network calls to the same URL.
 *
 * @example
 * ```ts
 * const queue = new FetchQueue(fetch);
 * const [a, b] = await Promise.all([
 *   queue.addRequest('https://example.com/data'),
 *   queue.addRequest('https://example.com/data')
 * ]);
 * // only one HTTP request is performed
 * ```
 */
class FetchQueue {
    /**
     *
     * @param {Function} fetchFn - A fetch function (e.g., node-fetch or window.fetch).
     */
    constructor(fetchFn) {
        this.queue = {};
        this.isRunning = false;
        this.fetchFn = fetchFn;
    }
    /**
     * Adds a fetch request to the queue.
     * @param {string} url - The URL to fetch.
     * @param {RequestInit} [options] - Optional fetch options.
     * @returns {Promise<any>} - A promise that resolves with the fetch response.
     */
    addRequest(url, options) {
        const hash = this.createHash(url, options);
        if (this.queue[hash]) {
            return new Promise((resolve, reject) => {
                this.queue[hash].resolve.push(resolve);
                this.queue[hash].reject.push(reject);
            });
        }
        return new Promise((resolve, reject) => {
            this.queue[hash] = { url, options, resolve: [resolve], reject: [reject] };
            this.runQueue();
        });
    }
    /**
     * Runs the queue of fetch requests.
     */
    runQueue() {
        return __awaiter(this, void 0, void 0, function* () {
            if (this.isRunning)
                return;
            this.isRunning = true;
            while (Object.keys(this.queue).length > 0) {
                const hash = Object.keys(this.queue)[0];
                const { url, options, resolve, reject } = this.queue[hash];
                try {
                    const response = yield this.fetchFn(url, options);
                    resolve.forEach(r => r(response));
                    delete this.queue[hash];
                }
                catch (error) {
                    reject.forEach(r => r(error));
                    delete this.queue[hash];
                }
            }
            this.isRunning = false;
        });
    }
    /**
     * Creates a hash to uniquely identify a request.
     * @param {string} url - The URL to fetch.
     * @param {RequestInit} [options] - Optional fetch options.
     * @returns {string} - A hash representing the unique request.
     */
    createHash(url, options) {
        const optionsString = JSON.stringify(options || {});
        return (0, js_md5_1.md5)(url + optionsString);
    }
}
exports.default = FetchQueue;