3 Object.defineProperty(exports, "__esModule", {
7 exports.default = function (worker, concurrency) {
8 return (0, _queue2.default)(function (items, cb) {
13 var _queue = require('./internal/queue');
15 var _queue2 = _interopRequireDefault(_queue);
17 function _interopRequireDefault(obj) { return obj && obj.__esModule ? obj : { default: obj }; }
19 module.exports = exports['default'];
22 * A queue of tasks for the worker function to complete.
23 * @typedef {Object} QueueObject
24 * @memberOf module:ControlFlow
25 * @property {Function} length - a function returning the number of items
26 * waiting to be processed. Invoke with `queue.length()`.
27 * @property {boolean} started - a boolean indicating whether or not any
28 * items have been pushed and processed by the queue.
29 * @property {Function} running - a function returning the number of items
30 * currently being processed. Invoke with `queue.running()`.
31 * @property {Function} workersList - a function returning the array of items
32 * currently being processed. Invoke with `queue.workersList()`.
33 * @property {Function} idle - a function returning false if there are items
34 * waiting or being processed, or true if not. Invoke with `queue.idle()`.
35 * @property {number} concurrency - an integer for determining how many `worker`
36 * functions should be run in parallel. This property can be changed after a
37 * `queue` is created to alter the concurrency on-the-fly.
38 * @property {Function} push - add a new task to the `queue`. Calls `callback`
39 * once the `worker` has finished processing the task. Instead of a single task,
40 * a `tasks` array can be submitted. The respective callback is used for every
41 * task in the list. Invoke with `queue.push(task, [callback])`,
42 * @property {Function} unshift - add a new task to the front of the `queue`.
43 * Invoke with `queue.unshift(task, [callback])`.
44 * @property {Function} saturated - a callback that is called when the number of
45 * running workers hits the `concurrency` limit, and further tasks will be
47 * @property {Function} unsaturated - a callback that is called when the number
48 * of running workers is less than the `concurrency` & `buffer` limits, and
49 * further tasks will not be queued.
50 * @property {number} buffer - A minimum threshold buffer in order to say that
51 * the `queue` is `unsaturated`.
52 * @property {Function} empty - a callback that is called when the last item
53 * from the `queue` is given to a `worker`.
54 * @property {Function} drain - a callback that is called when the last item
55 * from the `queue` has returned from the `worker`.
56 * @property {Function} error - a callback that is called when a task errors.
57 * Has the signature `function(error, task)`.
58 * @property {boolean} paused - a boolean for determining whether the queue is
60 * @property {Function} pause - a function that pauses the processing of tasks
61 * until `resume()` is called. Invoke with `queue.pause()`.
62 * @property {Function} resume - a function that resumes the processing of
63 * queued tasks when the queue is paused. Invoke with `queue.resume()`.
64 * @property {Function} kill - a function that removes the `drain` callback and
65 * empties remaining tasks from the queue forcing it to go idle. Invoke with `queue.kill()`.
69 * Creates a `queue` object with the specified `concurrency`. Tasks added to the
70 * `queue` are processed in parallel (up to the `concurrency` limit). If all
71 * `worker`s are in progress, the task is queued until one becomes available.
72 * Once a `worker` completes a `task`, that `task`'s callback is called.
76 * @memberOf module:ControlFlow
78 * @category Control Flow
79 * @param {Function} worker - An asynchronous function for processing a queued
80 * task, which must call its `callback(err)` argument when finished, with an
81 * optional `error` as an argument. If you want to handle errors from an
82 * individual task, pass a callback to `q.push()`. Invoked with
84 * @param {number} [concurrency=1] - An `integer` for determining how many
85 * `worker` functions should be run in parallel. If omitted, the concurrency
86 * defaults to `1`. If the concurrency is `0`, an error is thrown.
87 * @returns {module:ControlFlow.QueueObject} A queue object to manage the tasks. Callbacks can
88 * attached as certain properties to listen for specific events during the
89 * lifecycle of the queue.
92 * // create a queue object with concurrency 2
93 * var q = async.queue(function(task, callback) {
94 * console.log('hello ' + task.name);
98 * // assign a callback
99 * q.drain = function() {
100 * console.log('all items have been processed');
103 * // add some items to the queue
104 * q.push({name: 'foo'}, function(err) {
105 * console.log('finished processing foo');
107 * q.push({name: 'bar'}, function (err) {
108 * console.log('finished processing bar');
111 * // add some items to the queue (batch-wise)
112 * q.push([{name: 'baz'},{name: 'bay'},{name: 'bax'}], function(err) {
113 * console.log('finished processing item');
116 * // add some items to the front of the queue
117 * q.unshift({name: 'bar'}, function (err) {
118 * console.log('finished processing bar');