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