Add cargo queue type and tests

lib/cargoQueue.js

@@ -0,0 +1,59 @@
+import queue from './internal/queue';
+
+/**
+ * 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.CargoObject} 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);
+}

lib/index.js

@@ -70,6 +70,7 @@ import asyncify from './asyncify'
 import auto from './auto'
 import autoInject from './autoInject'
 import cargo from './cargo'
+import cargoQueue from './cargoQueue'
 import compose from './compose'
 import concat from './concat'
 import concatLimit from './concatLimit'
@@ -147,6 +148,7 @@ export default {
     auto,
     autoInject,
     cargo,
+    cargoQueue,
     compose,
     concat,
     concatLimit,
@@ -251,6 +253,7 @@ export {
     auto as auto,
     autoInject as autoInject,
     cargo as cargo,
+    cargoQueue as cargoQueue,
     compose as compose,
     concat as concat,
     concatLimit as concatLimit,