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cargoQueue.js
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cargoQueue.js
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import queue from './internal/queue';
/**
* A cargoQueue of tasks for the worker function to complete. CargoQueue inherits all of
* the same methods and event callbacks as [`queue`]{@link module:ControlFlow.queue}.
* @typedef {Object} CargoObject
* @memberOf module:ControlFlow
* @property {Function} length - A function returning the number of items
* waiting to be processed. Invoke like `cargoQueue.length()`.
* @property {number} payload - An `integer` for determining how many tasks
* should be process per round. This property can be changed after a `cargoQueue` is
* created to alter the payload on-the-fly.
* @property {number} concurrency - an integer for determining how many `worker`
* functions should be run in parallel. This property can be changed after a
* `cargoQueue` is created to alter the concurrency on-the-fly.
* @property {Function} push - Adds `task` to the `cargoQueue`. The callback is
* called once the `worker` has finished processing the task. Instead of a
* single task, an array of `tasks` can be submitted. The respective callback is
* used for every task in the list. Invoke like `cargoQueue.push(task, [callback])`.
* @property {Function} unshift - add a new task to the front of the `cargoQueue`.
* Invoke with `cargoQueue.unshift(task, [callback])`.
* @property {Function} remove - remove items from the `cargoQueue` that match a test
* function. The test function will be passed an object with a `data` property,
* and a `priority` property, if this is a
* [priorityQueue]{@link module:ControlFlow.priorityQueue} object.
* Invoked with `cargoQueue.remove(testFn)`, where `testFn` is of the form
* `function ({data, priority}) {}` and returns a Boolean.
* @property {Function} saturated - A callback that is called when the
* `cargoQueue.length()` hits the concurrency and further tasks will be queued.
* @property {Function} unsaturated - a callback that is called when the number
* of running workers is less than the `concurrency` & `buffer` limits, and
* further tasks will not be queued.
* @property {number} buffer - A minimum threshold buffer in order to say that
* the `cargoQueue` is `unsaturated`.
* @property {Function} empty - A callback that is called when the last item
* from the `cargoQueue` is given to a `worker`.
* @property {Function} drain - A callback that is called when the last item
* from the `cargoQueue` has returned from the `worker`.
* @property {Function} error - a callback that is called when a task errors.
* Has the signature `function(error, task)`.
* @property {Function} idle - a function returning false if there are items
* waiting or being processed, or true if not. Invoke like `cargoQueue.idle()`.
* @property {boolean} paused - a boolean for determining whether the `cargoQueue` is
* in a paused state.
* @property {Function} pause - a function that pauses the processing of tasks
* until `resume()` is called. Invoke like `cargoQueue.pause()`.
* @property {Function} resume - a function that resumes the processing of
* queued tasks when the queue is paused. Invoke like `cargoQueue.resume()`.
* @property {Function} kill - a function that removes the `drain` callback and
* empties remaining tasks from the queue forcing it to go idle. Invoke like `cargoQueue.kill()`.
*/
/**
* Creates a `cargoQueue` object with the specified payload. Tasks added to the
* cargoQueue will be processed together (up to the `payload` limit) in `concurrency` parallel workers.
* If the all `workers` are in progress, the task is queued until one becomes available. Once
* a `worker` has completed some tasks, each callback of those tasks is
* called. Check out [these](https://camo.githubusercontent.com/6bbd36f4cf5b35a0f11a96dcd2e97711ffc2fb37/68747470733a2f2f662e636c6f75642e6769746875622e636f6d2f6173736574732f313637363837312f36383130382f62626330636662302d356632392d313165322d393734662d3333393763363464633835382e676966) [animations](https://camo.githubusercontent.com/f4810e00e1c5f5f8addbe3e9f49064fd5d102699/68747470733a2f2f662e636c6f75642e6769746875622e636f6d2f6173736574732f313637363837312f36383130312f38346339323036362d356632392d313165322d383134662d3964336430323431336266642e676966)
* 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, and [`cargo`]{@link module:ControlFlow.cargo} passes an array of tasks to a single worker,
* the cargoQueue passes an array of tasks to multiple parallel workers.
*
* @name cargoQueue
* @static
* @memberOf module:ControlFlow
* @method
* @see [async.queue]{@link module:ControlFlow.queue}
* @see [async.cargo]{@link module:ControlFLow.cargo}
* @category Control Flow
* @param {AsyncFunction} worker - An asynchronous function for processing an array
* of queued tasks. Invoked with `(tasks, callback)`.
* @param {number} [concurrency=1] - An `integer` for determining how many
* `worker` functions should be run in parallel. If omitted, the concurrency
* defaults to `1`. If the concurrency is `0`, an error is thrown.
* @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.CargoQueueObject} A cargoQueue object to manage the tasks. Callbacks can
* attached as certain properties to listen for specific events during the
* lifecycle of the cargoQueue and inner queue.
* @example
*
* // create a cargoQueue object with payload 2 and concurrency 2
* var cargoQueue = async.cargoQueue(function(tasks, callback) {
* for (var i=0; i<tasks.length; i++) {
* console.log('hello ' + tasks[i].name);
* }
* callback();
* }, 2, 2);
*
* // add some items
* cargoQueue.push({name: 'foo'}, function(err) {
* console.log('finished processing foo');
* });
* cargoQueue.push({name: 'bar'}, function(err) {
* console.log('finished processing bar');
* });
* cargoQueue.push({name: 'baz'}, function(err) {
* console.log('finished processing baz');
* });
* cargoQueue.push({name: 'boo'}, function(err) {
* console.log('finished processing boo');
* });
*/
export default function cargo(worker, concurrency, payload) {
return queue(worker, concurrency, payload);
}