queue.js
1 'use strict'; 2 3 Object.defineProperty(exports, "__esModule", { 4 value: true 5 }); 6 7 exports.default = function (worker, concurrency) { 8 var _worker = (0, _wrapAsync2.default)(worker); 9 return (0, _queue2.default)((items, cb) => { 10 _worker(items[0], cb); 11 }, concurrency, 1); 12 }; 13 14 var _queue = require('./internal/queue'); 15 16 var _queue2 = _interopRequireDefault(_queue); 17 18 var _wrapAsync = require('./internal/wrapAsync'); 19 20 var _wrapAsync2 = _interopRequireDefault(_wrapAsync); 21 22 function _interopRequireDefault(obj) { return obj && obj.__esModule ? obj : { default: obj }; } 23 24 module.exports = exports['default']; 25 26 /** 27 * A queue of tasks for the worker function to complete. 28 * @typedef {Iterable} QueueObject 29 * @memberOf module:ControlFlow 30 * @property {Function} length - a function returning the number of items 31 * waiting to be processed. Invoke with `queue.length()`. 32 * @property {boolean} started - a boolean indicating whether or not any 33 * items have been pushed and processed by the queue. 34 * @property {Function} running - a function returning the number of items 35 * currently being processed. Invoke with `queue.running()`. 36 * @property {Function} workersList - a function returning the array of items 37 * currently being processed. Invoke with `queue.workersList()`. 38 * @property {Function} idle - a function returning false if there are items 39 * waiting or being processed, or true if not. Invoke with `queue.idle()`. 40 * @property {number} concurrency - an integer for determining how many `worker` 41 * functions should be run in parallel. This property can be changed after a 42 * `queue` is created to alter the concurrency on-the-fly. 43 * @property {number} payload - an integer that specifies how many items are 44 * passed to the worker function at a time. only applies if this is a 45 * [cargo]{@link module:ControlFlow.cargo} object 46 * @property {AsyncFunction} push - add a new task to the `queue`. Calls `callback` 47 * once the `worker` has finished processing the task. Instead of a single task, 48 * a `tasks` array can be submitted. The respective callback is used for every 49 * task in the list. Invoke with `queue.push(task, [callback])`, 50 * @property {AsyncFunction} unshift - add a new task to the front of the `queue`. 51 * Invoke with `queue.unshift(task, [callback])`. 52 * @property {AsyncFunction} pushAsync - the same as `q.push`, except this returns 53 * a promise that rejects if an error occurs. 54 * @property {AsyncFunction} unshirtAsync - the same as `q.unshift`, except this returns 55 * a promise that rejects if an error occurs. 56 * @property {Function} remove - remove items from the queue that match a test 57 * function. The test function will be passed an object with a `data` property, 58 * and a `priority` property, if this is a 59 * [priorityQueue]{@link module:ControlFlow.priorityQueue} object. 60 * Invoked with `queue.remove(testFn)`, where `testFn` is of the form 61 * `function ({data, priority}) {}` and returns a Boolean. 62 * @property {Function} saturated - a function that sets a callback that is 63 * called when the number of running workers hits the `concurrency` limit, and 64 * further tasks will be queued. If the callback is omitted, `q.saturated()` 65 * returns a promise for the next occurrence. 66 * @property {Function} unsaturated - a function that sets a callback that is 67 * called when the number of running workers is less than the `concurrency` & 68 * `buffer` limits, and further tasks will not be queued. If the callback is 69 * omitted, `q.unsaturated()` returns a promise for the next occurrence. 70 * @property {number} buffer - A minimum threshold buffer in order to say that 71 * the `queue` is `unsaturated`. 72 * @property {Function} empty - a function that sets a callback that is called 73 * when the last item from the `queue` is given to a `worker`. If the callback 74 * is omitted, `q.empty()` returns a promise for the next occurrence. 75 * @property {Function} drain - a function that sets a callback that is called 76 * when the last item from the `queue` has returned from the `worker`. If the 77 * callback is omitted, `q.drain()` returns a promise for the next occurrence. 78 * @property {Function} error - a function that sets a callback that is called 79 * when a task errors. Has the signature `function(error, task)`. If the 80 * callback is omitted, `error()` returns a promise that rejects on the next 81 * error. 82 * @property {boolean} paused - a boolean for determining whether the queue is 83 * in a paused state. 84 * @property {Function} pause - a function that pauses the processing of tasks 85 * until `resume()` is called. Invoke with `queue.pause()`. 86 * @property {Function} resume - a function that resumes the processing of 87 * queued tasks when the queue is paused. Invoke with `queue.resume()`. 88 * @property {Function} kill - a function that removes the `drain` callback and 89 * empties remaining tasks from the queue forcing it to go idle. No more tasks 90 * should be pushed to the queue after calling this function. Invoke with `queue.kill()`. 91 * 92 * @example 93 * const q = aync.queue(worker, 2) 94 * q.push(item1) 95 * q.push(item2) 96 * q.push(item3) 97 * // queues are iterable, spread into an array to inspect 98 * const items = [...q] // [item1, item2, item3] 99 * // or use for of 100 * for (let item of q) { 101 * console.log(item) 102 * } 103 * 104 * q.drain(() => { 105 * console.log('all done') 106 * }) 107 * // or 108 * await q.drain() 109 */ 110 111 /** 112 * Creates a `queue` object with the specified `concurrency`. Tasks added to the 113 * `queue` are processed in parallel (up to the `concurrency` limit). If all 114 * `worker`s are in progress, the task is queued until one becomes available. 115 * Once a `worker` completes a `task`, that `task`'s callback is called. 116 * 117 * @name queue 118 * @static 119 * @memberOf module:ControlFlow 120 * @method 121 * @category Control Flow 122 * @param {AsyncFunction} worker - An async function for processing a queued task. 123 * If you want to handle errors from an individual task, pass a callback to 124 * `q.push()`. Invoked with (task, callback). 125 * @param {number} [concurrency=1] - An `integer` for determining how many 126 * `worker` functions should be run in parallel. If omitted, the concurrency 127 * defaults to `1`. If the concurrency is `0`, an error is thrown. 128 * @returns {module:ControlFlow.QueueObject} A queue object to manage the tasks. Callbacks can be 129 * attached as certain properties to listen for specific events during the 130 * lifecycle of the queue. 131 * @example 132 * 133 * // create a queue object with concurrency 2 134 * var q = async.queue(function(task, callback) { 135 * console.log('hello ' + task.name); 136 * callback(); 137 * }, 2); 138 * 139 * // assign a callback 140 * q.drain(function() { 141 * console.log('all items have been processed'); 142 * }); 143 * // or await the end 144 * await q.drain() 145 * 146 * // assign an error callback 147 * q.error(function(err, task) { 148 * console.error('task experienced an error'); 149 * }); 150 * 151 * // add some items to the queue 152 * q.push({name: 'foo'}, function(err) { 153 * console.log('finished processing foo'); 154 * }); 155 * // callback is optional 156 * q.push({name: 'bar'}); 157 * 158 * // add some items to the queue (batch-wise) 159 * q.push([{name: 'baz'},{name: 'bay'},{name: 'bax'}], function(err) { 160 * console.log('finished processing item'); 161 * }); 162 * 163 * // add some items to the front of the queue 164 * q.unshift({name: 'bar'}, function (err) { 165 * console.log('finished processing bar'); 166 * }); 167 */