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289 lines
9.6 KiB
289 lines
9.6 KiB
'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 (tasks, concurrency, callback) { |
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if (typeof concurrency === 'function') { |
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// concurrency is optional, shift the args. |
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callback = concurrency; |
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concurrency = null; |
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} |
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callback = (0, _once2.default)(callback || _noop2.default); |
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var keys = (0, _keys2.default)(tasks); |
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var numTasks = keys.length; |
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if (!numTasks) { |
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return callback(null); |
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} |
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if (!concurrency) { |
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concurrency = numTasks; |
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} |
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var results = {}; |
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var runningTasks = 0; |
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var hasError = false; |
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var listeners = Object.create(null); |
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var readyTasks = []; |
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// for cycle detection: |
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var readyToCheck = []; // tasks that have been identified as reachable |
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// without the possibility of returning to an ancestor task |
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var uncheckedDependencies = {}; |
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(0, _baseForOwn2.default)(tasks, function (task, key) { |
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if (!(0, _isArray2.default)(task)) { |
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// no dependencies |
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enqueueTask(key, [task]); |
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readyToCheck.push(key); |
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return; |
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} |
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var dependencies = task.slice(0, task.length - 1); |
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var remainingDependencies = dependencies.length; |
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if (remainingDependencies === 0) { |
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enqueueTask(key, task); |
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readyToCheck.push(key); |
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return; |
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} |
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uncheckedDependencies[key] = remainingDependencies; |
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(0, _arrayEach2.default)(dependencies, function (dependencyName) { |
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if (!tasks[dependencyName]) { |
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throw new Error('async.auto task `' + key + '` has a non-existent dependency `' + dependencyName + '` in ' + dependencies.join(', ')); |
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} |
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addListener(dependencyName, function () { |
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remainingDependencies--; |
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if (remainingDependencies === 0) { |
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enqueueTask(key, task); |
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} |
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}); |
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}); |
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}); |
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checkForDeadlocks(); |
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processQueue(); |
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function enqueueTask(key, task) { |
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readyTasks.push(function () { |
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runTask(key, task); |
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}); |
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} |
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function processQueue() { |
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if (readyTasks.length === 0 && runningTasks === 0) { |
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return callback(null, results); |
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} |
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while (readyTasks.length && runningTasks < concurrency) { |
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var run = readyTasks.shift(); |
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run(); |
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} |
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} |
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function addListener(taskName, fn) { |
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var taskListeners = listeners[taskName]; |
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if (!taskListeners) { |
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taskListeners = listeners[taskName] = []; |
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} |
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taskListeners.push(fn); |
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} |
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function taskComplete(taskName) { |
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var taskListeners = listeners[taskName] || []; |
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(0, _arrayEach2.default)(taskListeners, function (fn) { |
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fn(); |
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}); |
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processQueue(); |
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} |
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function runTask(key, task) { |
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if (hasError) return; |
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var taskCallback = (0, _onlyOnce2.default)(function (err, result) { |
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runningTasks--; |
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if (arguments.length > 2) { |
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result = (0, _slice2.default)(arguments, 1); |
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} |
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if (err) { |
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var safeResults = {}; |
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(0, _baseForOwn2.default)(results, function (val, rkey) { |
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safeResults[rkey] = val; |
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}); |
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safeResults[key] = result; |
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hasError = true; |
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listeners = Object.create(null); |
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callback(err, safeResults); |
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} else { |
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results[key] = result; |
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taskComplete(key); |
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} |
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}); |
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runningTasks++; |
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var taskFn = (0, _wrapAsync2.default)(task[task.length - 1]); |
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if (task.length > 1) { |
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taskFn(results, taskCallback); |
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} else { |
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taskFn(taskCallback); |
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} |
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} |
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function checkForDeadlocks() { |
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// Kahn's algorithm |
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// https://en.wikipedia.org/wiki/Topological_sorting#Kahn.27s_algorithm |
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// http://connalle.blogspot.com/2013/10/topological-sortingkahn-algorithm.html |
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var currentTask; |
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var counter = 0; |
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while (readyToCheck.length) { |
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currentTask = readyToCheck.pop(); |
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counter++; |
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(0, _arrayEach2.default)(getDependents(currentTask), function (dependent) { |
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if (--uncheckedDependencies[dependent] === 0) { |
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readyToCheck.push(dependent); |
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} |
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}); |
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} |
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if (counter !== numTasks) { |
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throw new Error('async.auto cannot execute tasks due to a recursive dependency'); |
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} |
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} |
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function getDependents(taskName) { |
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var result = []; |
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(0, _baseForOwn2.default)(tasks, function (task, key) { |
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if ((0, _isArray2.default)(task) && (0, _baseIndexOf2.default)(task, taskName, 0) >= 0) { |
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result.push(key); |
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} |
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}); |
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return result; |
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} |
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}; |
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var _arrayEach = require('lodash/_arrayEach'); |
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var _arrayEach2 = _interopRequireDefault(_arrayEach); |
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var _baseForOwn = require('lodash/_baseForOwn'); |
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var _baseForOwn2 = _interopRequireDefault(_baseForOwn); |
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var _baseIndexOf = require('lodash/_baseIndexOf'); |
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var _baseIndexOf2 = _interopRequireDefault(_baseIndexOf); |
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var _isArray = require('lodash/isArray'); |
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var _isArray2 = _interopRequireDefault(_isArray); |
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var _keys = require('lodash/keys'); |
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var _keys2 = _interopRequireDefault(_keys); |
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var _noop = require('lodash/noop'); |
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var _noop2 = _interopRequireDefault(_noop); |
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var _slice = require('./internal/slice'); |
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var _slice2 = _interopRequireDefault(_slice); |
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var _once = require('./internal/once'); |
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var _once2 = _interopRequireDefault(_once); |
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var _onlyOnce = require('./internal/onlyOnce'); |
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var _onlyOnce2 = _interopRequireDefault(_onlyOnce); |
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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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* Determines the best order for running the {@link AsyncFunction}s in `tasks`, based on |
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* their requirements. Each function can optionally depend on other functions |
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* being completed first, and each function is run as soon as its requirements |
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* are satisfied. |
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* |
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* If any of the {@link AsyncFunction}s pass an error to their callback, the `auto` sequence |
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* will stop. Further tasks will not execute (so any other functions depending |
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* on it will not run), and the main `callback` is immediately called with the |
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* error. |
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* |
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* {@link AsyncFunction}s also receive an object containing the results of functions which |
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* have completed so far as the first argument, if they have dependencies. If a |
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* task function has no dependencies, it will only be passed a callback. |
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* |
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* @name auto |
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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 {Object} tasks - An object. Each of its properties is either a |
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* function or an array of requirements, with the {@link AsyncFunction} itself the last item |
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* in the array. The object's key of a property serves as the name of the task |
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* defined by that property, i.e. can be used when specifying requirements for |
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* other tasks. The function receives one or two arguments: |
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* * a `results` object, containing the results of the previously executed |
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* functions, only passed if the task has any dependencies, |
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* * a `callback(err, result)` function, which must be called when finished, |
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* passing an `error` (which can be `null`) and the result of the function's |
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* execution. |
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* @param {number} [concurrency=Infinity] - An optional `integer` for |
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* determining the maximum number of tasks that can be run in parallel. By |
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* default, as many as possible. |
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* @param {Function} [callback] - An optional callback which is called when all |
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* the tasks have been completed. It receives the `err` argument if any `tasks` |
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* pass an error to their callback. Results are always returned; however, if an |
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* error occurs, no further `tasks` will be performed, and the results object |
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* will only contain partial results. Invoked with (err, results). |
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* @returns undefined |
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* @example |
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* |
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* async.auto({ |
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* // this function will just be passed a callback |
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* readData: async.apply(fs.readFile, 'data.txt', 'utf-8'), |
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* showData: ['readData', function(results, cb) { |
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* // results.readData is the file's contents |
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* // ... |
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* }] |
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* }, callback); |
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* |
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* async.auto({ |
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* get_data: function(callback) { |
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* console.log('in get_data'); |
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* // async code to get some data |
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* callback(null, 'data', 'converted to array'); |
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* }, |
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* make_folder: function(callback) { |
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* console.log('in make_folder'); |
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* // async code to create a directory to store a file in |
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* // this is run at the same time as getting the data |
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* callback(null, 'folder'); |
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* }, |
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* write_file: ['get_data', 'make_folder', function(results, callback) { |
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* console.log('in write_file', JSON.stringify(results)); |
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* // once there is some data and the directory exists, |
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* // write the data to a file in the directory |
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* callback(null, 'filename'); |
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* }], |
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* email_link: ['write_file', function(results, callback) { |
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* console.log('in email_link', JSON.stringify(results)); |
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* // once the file is written let's email a link to it... |
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* // results.write_file contains the filename returned by write_file. |
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* callback(null, {'file':results.write_file, 'email':'user@example.com'}); |
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* }] |
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* }, function(err, results) { |
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* console.log('err = ', err); |
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* console.log('results = ', results); |
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* }); |
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*/ |