cargo.js

import queue from './internal/queue.js'

/**
 * Creates a `cargo` object with the specified payload. Tasks added to the
 * cargo will be processed altogether (up to the `payload` limit). If the
 * `worker` is in progress, the task is queued until it becomes available. Once
 * the `worker` has completed some tasks, each callback of those tasks is
 * called. Check out [these](../img/queue.gif) [animations](../img/cargo.gif)
 * for how `cargo` and `queue` work.
 *
 * While [`queue`]{@link module:ControlFlow.queue} passes only one task to one of a group of workers
 * at a time, cargo passes an array of tasks to a single worker, repeating
 * when the worker is finished.
 *
 * @name cargo
 * @static
 * @memberOf module:ControlFlow
 * @method
 * @see [async.queue]{@link module:ControlFlow.queue}
 * @category Control Flow
 * @param {AsyncFunction} worker - An asynchronous function for processing an array
 * of queued tasks. Invoked with `(tasks, callback)`.
 * @param {number} [payload=Infinity] - An optional `integer` for determining
 * how many tasks should be processed per round; if omitted, the default is
 * unlimited.
 * @returns {module:ControlFlow.QueueObject} A cargo object to manage the tasks. Callbacks can
 * attached as certain properties to listen for specific events during the
 * lifecycle of the cargo and inner queue.
 * @example
 *
 * // create a cargo object with payload 2
 * var cargo = async.cargo(function(tasks, callback) {
 *     for (var i=0; i<tasks.length; i++) {
 *         console.log('hello ' + tasks[i].name);
 *     }
 *     callback();
 * }, 2);
 *
 * // add some items
 * cargo.push({name: 'foo'}, function(err) {
 *     console.log('finished processing foo');
 * });
 * cargo.push({name: 'bar'}, function(err) {
 *     console.log('finished processing bar');
 * });
 * await cargo.push({name: 'baz'});
 * console.log('finished processing baz');
 */
export default function cargo(worker, payload) {
    return queue(worker, 1, payload);
}