source: trip-planner-front/node_modules/async/auto.js@ bdd6491

Last change on this file since bdd6491 was 6a3a178, checked in by Ema <ema_spirova@…>, 3 years ago

initial commit

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File size: 9.6 KB
Line 
1'use strict';
2
3Object.defineProperty(exports, "__esModule", {
4 value: true
5});
6
7exports.default = function (tasks, concurrency, callback) {
8 if (typeof concurrency === 'function') {
9 // concurrency is optional, shift the args.
10 callback = concurrency;
11 concurrency = null;
12 }
13 callback = (0, _once2.default)(callback || _noop2.default);
14 var keys = (0, _keys2.default)(tasks);
15 var numTasks = keys.length;
16 if (!numTasks) {
17 return callback(null);
18 }
19 if (!concurrency) {
20 concurrency = numTasks;
21 }
22
23 var results = {};
24 var runningTasks = 0;
25 var hasError = false;
26
27 var listeners = Object.create(null);
28
29 var readyTasks = [];
30
31 // for cycle detection:
32 var readyToCheck = []; // tasks that have been identified as reachable
33 // without the possibility of returning to an ancestor task
34 var uncheckedDependencies = {};
35
36 (0, _baseForOwn2.default)(tasks, function (task, key) {
37 if (!(0, _isArray2.default)(task)) {
38 // no dependencies
39 enqueueTask(key, [task]);
40 readyToCheck.push(key);
41 return;
42 }
43
44 var dependencies = task.slice(0, task.length - 1);
45 var remainingDependencies = dependencies.length;
46 if (remainingDependencies === 0) {
47 enqueueTask(key, task);
48 readyToCheck.push(key);
49 return;
50 }
51 uncheckedDependencies[key] = remainingDependencies;
52
53 (0, _arrayEach2.default)(dependencies, function (dependencyName) {
54 if (!tasks[dependencyName]) {
55 throw new Error('async.auto task `' + key + '` has a non-existent dependency `' + dependencyName + '` in ' + dependencies.join(', '));
56 }
57 addListener(dependencyName, function () {
58 remainingDependencies--;
59 if (remainingDependencies === 0) {
60 enqueueTask(key, task);
61 }
62 });
63 });
64 });
65
66 checkForDeadlocks();
67 processQueue();
68
69 function enqueueTask(key, task) {
70 readyTasks.push(function () {
71 runTask(key, task);
72 });
73 }
74
75 function processQueue() {
76 if (readyTasks.length === 0 && runningTasks === 0) {
77 return callback(null, results);
78 }
79 while (readyTasks.length && runningTasks < concurrency) {
80 var run = readyTasks.shift();
81 run();
82 }
83 }
84
85 function addListener(taskName, fn) {
86 var taskListeners = listeners[taskName];
87 if (!taskListeners) {
88 taskListeners = listeners[taskName] = [];
89 }
90
91 taskListeners.push(fn);
92 }
93
94 function taskComplete(taskName) {
95 var taskListeners = listeners[taskName] || [];
96 (0, _arrayEach2.default)(taskListeners, function (fn) {
97 fn();
98 });
99 processQueue();
100 }
101
102 function runTask(key, task) {
103 if (hasError) return;
104
105 var taskCallback = (0, _onlyOnce2.default)(function (err, result) {
106 runningTasks--;
107 if (arguments.length > 2) {
108 result = (0, _slice2.default)(arguments, 1);
109 }
110 if (err) {
111 var safeResults = {};
112 (0, _baseForOwn2.default)(results, function (val, rkey) {
113 safeResults[rkey] = val;
114 });
115 safeResults[key] = result;
116 hasError = true;
117 listeners = Object.create(null);
118
119 callback(err, safeResults);
120 } else {
121 results[key] = result;
122 taskComplete(key);
123 }
124 });
125
126 runningTasks++;
127 var taskFn = (0, _wrapAsync2.default)(task[task.length - 1]);
128 if (task.length > 1) {
129 taskFn(results, taskCallback);
130 } else {
131 taskFn(taskCallback);
132 }
133 }
134
135 function checkForDeadlocks() {
136 // Kahn's algorithm
137 // https://en.wikipedia.org/wiki/Topological_sorting#Kahn.27s_algorithm
138 // http://connalle.blogspot.com/2013/10/topological-sortingkahn-algorithm.html
139 var currentTask;
140 var counter = 0;
141 while (readyToCheck.length) {
142 currentTask = readyToCheck.pop();
143 counter++;
144 (0, _arrayEach2.default)(getDependents(currentTask), function (dependent) {
145 if (--uncheckedDependencies[dependent] === 0) {
146 readyToCheck.push(dependent);
147 }
148 });
149 }
150
151 if (counter !== numTasks) {
152 throw new Error('async.auto cannot execute tasks due to a recursive dependency');
153 }
154 }
155
156 function getDependents(taskName) {
157 var result = [];
158 (0, _baseForOwn2.default)(tasks, function (task, key) {
159 if ((0, _isArray2.default)(task) && (0, _baseIndexOf2.default)(task, taskName, 0) >= 0) {
160 result.push(key);
161 }
162 });
163 return result;
164 }
165};
166
167var _arrayEach = require('lodash/_arrayEach');
168
169var _arrayEach2 = _interopRequireDefault(_arrayEach);
170
171var _baseForOwn = require('lodash/_baseForOwn');
172
173var _baseForOwn2 = _interopRequireDefault(_baseForOwn);
174
175var _baseIndexOf = require('lodash/_baseIndexOf');
176
177var _baseIndexOf2 = _interopRequireDefault(_baseIndexOf);
178
179var _isArray = require('lodash/isArray');
180
181var _isArray2 = _interopRequireDefault(_isArray);
182
183var _keys = require('lodash/keys');
184
185var _keys2 = _interopRequireDefault(_keys);
186
187var _noop = require('lodash/noop');
188
189var _noop2 = _interopRequireDefault(_noop);
190
191var _slice = require('./internal/slice');
192
193var _slice2 = _interopRequireDefault(_slice);
194
195var _once = require('./internal/once');
196
197var _once2 = _interopRequireDefault(_once);
198
199var _onlyOnce = require('./internal/onlyOnce');
200
201var _onlyOnce2 = _interopRequireDefault(_onlyOnce);
202
203var _wrapAsync = require('./internal/wrapAsync');
204
205var _wrapAsync2 = _interopRequireDefault(_wrapAsync);
206
207function _interopRequireDefault(obj) { return obj && obj.__esModule ? obj : { default: obj }; }
208
209module.exports = exports['default'];
210
211/**
212 * Determines the best order for running the {@link AsyncFunction}s in `tasks`, based on
213 * their requirements. Each function can optionally depend on other functions
214 * being completed first, and each function is run as soon as its requirements
215 * are satisfied.
216 *
217 * If any of the {@link AsyncFunction}s pass an error to their callback, the `auto` sequence
218 * will stop. Further tasks will not execute (so any other functions depending
219 * on it will not run), and the main `callback` is immediately called with the
220 * error.
221 *
222 * {@link AsyncFunction}s also receive an object containing the results of functions which
223 * have completed so far as the first argument, if they have dependencies. If a
224 * task function has no dependencies, it will only be passed a callback.
225 *
226 * @name auto
227 * @static
228 * @memberOf module:ControlFlow
229 * @method
230 * @category Control Flow
231 * @param {Object} tasks - An object. Each of its properties is either a
232 * function or an array of requirements, with the {@link AsyncFunction} itself the last item
233 * in the array. The object's key of a property serves as the name of the task
234 * defined by that property, i.e. can be used when specifying requirements for
235 * other tasks. The function receives one or two arguments:
236 * * a `results` object, containing the results of the previously executed
237 * functions, only passed if the task has any dependencies,
238 * * a `callback(err, result)` function, which must be called when finished,
239 * passing an `error` (which can be `null`) and the result of the function's
240 * execution.
241 * @param {number} [concurrency=Infinity] - An optional `integer` for
242 * determining the maximum number of tasks that can be run in parallel. By
243 * default, as many as possible.
244 * @param {Function} [callback] - An optional callback which is called when all
245 * the tasks have been completed. It receives the `err` argument if any `tasks`
246 * pass an error to their callback. Results are always returned; however, if an
247 * error occurs, no further `tasks` will be performed, and the results object
248 * will only contain partial results. Invoked with (err, results).
249 * @returns undefined
250 * @example
251 *
252 * async.auto({
253 * // this function will just be passed a callback
254 * readData: async.apply(fs.readFile, 'data.txt', 'utf-8'),
255 * showData: ['readData', function(results, cb) {
256 * // results.readData is the file's contents
257 * // ...
258 * }]
259 * }, callback);
260 *
261 * async.auto({
262 * get_data: function(callback) {
263 * console.log('in get_data');
264 * // async code to get some data
265 * callback(null, 'data', 'converted to array');
266 * },
267 * make_folder: function(callback) {
268 * console.log('in make_folder');
269 * // async code to create a directory to store a file in
270 * // this is run at the same time as getting the data
271 * callback(null, 'folder');
272 * },
273 * write_file: ['get_data', 'make_folder', function(results, callback) {
274 * console.log('in write_file', JSON.stringify(results));
275 * // once there is some data and the directory exists,
276 * // write the data to a file in the directory
277 * callback(null, 'filename');
278 * }],
279 * email_link: ['write_file', function(results, callback) {
280 * console.log('in email_link', JSON.stringify(results));
281 * // once the file is written let's email a link to it...
282 * // results.write_file contains the filename returned by write_file.
283 * callback(null, {'file':results.write_file, 'email':'user@example.com'});
284 * }]
285 * }, function(err, results) {
286 * console.log('err = ', err);
287 * console.log('results = ', results);
288 * });
289 */
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