167 lines
7.2 KiB
JavaScript
167 lines
7.2 KiB
JavaScript
'use strict';
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Object.defineProperty(exports, "__esModule", {
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value: true
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});
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exports.default = function (worker, concurrency) {
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var _worker = (0, _wrapAsync2.default)(worker);
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return (0, _queue2.default)((items, cb) => {
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_worker(items[0], cb);
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}, concurrency, 1);
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};
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var _queue = require('./internal/queue');
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var _queue2 = _interopRequireDefault(_queue);
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var _wrapAsync = require('./internal/wrapAsync');
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var _wrapAsync2 = _interopRequireDefault(_wrapAsync);
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function _interopRequireDefault(obj) { return obj && obj.__esModule ? obj : { default: obj }; }
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module.exports = exports['default'];
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/**
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* A queue of tasks for the worker function to complete.
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* @typedef {Iterable} QueueObject
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* @memberOf module:ControlFlow
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* @property {Function} length - a function returning the number of items
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* waiting to be processed. Invoke with `queue.length()`.
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* @property {boolean} started - a boolean indicating whether or not any
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* items have been pushed and processed by the queue.
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* @property {Function} running - a function returning the number of items
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* currently being processed. Invoke with `queue.running()`.
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* @property {Function} workersList - a function returning the array of items
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* currently being processed. Invoke with `queue.workersList()`.
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* @property {Function} idle - a function returning false if there are items
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* waiting or being processed, or true if not. Invoke with `queue.idle()`.
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* @property {number} concurrency - an integer for determining how many `worker`
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* functions should be run in parallel. This property can be changed after a
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* `queue` is created to alter the concurrency on-the-fly.
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* @property {number} payload - an integer that specifies how many items are
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* passed to the worker function at a time. only applies if this is a
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* [cargo]{@link module:ControlFlow.cargo} object
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* @property {AsyncFunction} push - add a new task to the `queue`. Calls `callback`
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* once the `worker` has finished processing the task. Instead of a single task,
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* a `tasks` array can be submitted. The respective callback is used for every
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* task in the list. Invoke with `queue.push(task, [callback])`,
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* @property {AsyncFunction} unshift - add a new task to the front of the `queue`.
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* Invoke with `queue.unshift(task, [callback])`.
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* @property {AsyncFunction} pushAsync - the same as `q.push`, except this returns
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* a promise that rejects if an error occurs.
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* @property {AsyncFunction} unshiftAsync - the same as `q.unshift`, except this returns
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* a promise that rejects if an error occurs.
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* @property {Function} remove - remove items from the queue that match a test
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* function. The test function will be passed an object with a `data` property,
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* and a `priority` property, if this is a
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* [priorityQueue]{@link module:ControlFlow.priorityQueue} object.
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* Invoked with `queue.remove(testFn)`, where `testFn` is of the form
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* `function ({data, priority}) {}` and returns a Boolean.
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* @property {Function} saturated - a function that sets a callback that is
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* called when the number of running workers hits the `concurrency` limit, and
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* further tasks will be queued. If the callback is omitted, `q.saturated()`
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* returns a promise for the next occurrence.
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* @property {Function} unsaturated - a function that sets a callback that is
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* called when the number of running workers is less than the `concurrency` &
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* `buffer` limits, and further tasks will not be queued. If the callback is
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* omitted, `q.unsaturated()` returns a promise for the next occurrence.
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* @property {number} buffer - A minimum threshold buffer in order to say that
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* the `queue` is `unsaturated`.
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* @property {Function} empty - a function that sets a callback that is called
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* when the last item from the `queue` is given to a `worker`. If the callback
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* is omitted, `q.empty()` returns a promise for the next occurrence.
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* @property {Function} drain - a function that sets a callback that is called
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* when the last item from the `queue` has returned from the `worker`. If the
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* callback is omitted, `q.drain()` returns a promise for the next occurrence.
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* @property {Function} error - a function that sets a callback that is called
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* when a task errors. Has the signature `function(error, task)`. If the
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* callback is omitted, `error()` returns a promise that rejects on the next
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* error.
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* @property {boolean} paused - a boolean for determining whether the queue is
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* in a paused state.
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* @property {Function} pause - a function that pauses the processing of tasks
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* until `resume()` is called. Invoke with `queue.pause()`.
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* @property {Function} resume - a function that resumes the processing of
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* queued tasks when the queue is paused. Invoke with `queue.resume()`.
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* @property {Function} kill - a function that removes the `drain` callback and
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* empties remaining tasks from the queue forcing it to go idle. No more tasks
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* should be pushed to the queue after calling this function. Invoke with `queue.kill()`.
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*
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* @example
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* const q = async.queue(worker, 2)
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* q.push(item1)
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* q.push(item2)
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* q.push(item3)
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* // queues are iterable, spread into an array to inspect
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* const items = [...q] // [item1, item2, item3]
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* // or use for of
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* for (let item of q) {
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* console.log(item)
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* }
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*
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* q.drain(() => {
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* console.log('all done')
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* })
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* // or
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* await q.drain()
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*/
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/**
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* Creates a `queue` object with the specified `concurrency`. Tasks added to the
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* `queue` are processed in parallel (up to the `concurrency` limit). If all
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* `worker`s are in progress, the task is queued until one becomes available.
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* Once a `worker` completes a `task`, that `task`'s callback is called.
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*
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* @name queue
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* @static
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* @memberOf module:ControlFlow
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* @method
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* @category Control Flow
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* @param {AsyncFunction} worker - An async function for processing a queued task.
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* If you want to handle errors from an individual task, pass a callback to
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* `q.push()`. Invoked with (task, callback).
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* @param {number} [concurrency=1] - An `integer` for determining how many
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* `worker` functions should be run in parallel. If omitted, the concurrency
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* defaults to `1`. If the concurrency is `0`, an error is thrown.
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* @returns {module:ControlFlow.QueueObject} A queue object to manage the tasks. Callbacks can be
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* attached as certain properties to listen for specific events during the
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* lifecycle of the queue.
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* @example
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*
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* // create a queue object with concurrency 2
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* var q = async.queue(function(task, callback) {
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* console.log('hello ' + task.name);
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* callback();
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* }, 2);
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*
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* // assign a callback
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* q.drain(function() {
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* console.log('all items have been processed');
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* });
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* // or await the end
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* await q.drain()
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*
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* // assign an error callback
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* q.error(function(err, task) {
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* console.error('task experienced an error');
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* });
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*
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* // add some items to the queue
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* q.push({name: 'foo'}, function(err) {
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* console.log('finished processing foo');
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* });
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* // callback is optional
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* q.push({name: 'bar'});
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*
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* // add some items to the queue (batch-wise)
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* q.push([{name: 'baz'},{name: 'bay'},{name: 'bax'}], function(err) {
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* console.log('finished processing item');
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* });
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*
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* // add some items to the front of the queue
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* q.unshift({name: 'bar'}, function (err) {
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* console.log('finished processing bar');
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* });
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*/ |