Repository navigation
Expand file tree
/
Copy pathauto.js
More file actions
256 lines (232 loc) · 8.57 KB
/
Copy pathauto.js
File metadata and controls
256 lines (232 loc) · 8.57 KB
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
import arrayEach from 'lodash/_arrayEach';
import forOwn from 'lodash/_baseForOwn';
import indexOf from 'lodash/_baseIndexOf';
import isArray from 'lodash/isArray';
import okeys from 'lodash/keys';
import noop from 'lodash/noop';
import rest from './internal/rest';
import once from './internal/once';
import onlyOnce from './internal/onlyOnce';
/**
* Determines the best order for running the functions 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 functions 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.
*
* Functions 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 function 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);
* });
*/
export default function (tasks, concurrency, callback) {
if (typeof concurrency === 'function') {
// concurrency is optional, shift the args.
callback = concurrency;
concurrency = null;
}
callback = once(callback || noop);
var keys = okeys(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 = {};
forOwn(tasks, function (task, key) {
if (!isArray(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;
arrayEach(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] || [];
arrayEach(taskListeners, function (fn) {
fn();
});
processQueue();
}
function runTask(key, task) {
if (hasError) return;
var taskCallback = onlyOnce(rest(function(err, args) {
runningTasks--;
if (args.length <= 1) {
args = args[0];
}
if (err) {
var safeResults = {};
forOwn(results, function(val, rkey) {
safeResults[rkey] = val;
});
safeResults[key] = args;
hasError = true;
listeners = Object.create(null);
callback(err, safeResults);
} else {
results[key] = args;
taskComplete(key);
}
}));
runningTasks++;
var taskFn = 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++;
arrayEach(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 = [];
forOwn(tasks, function (task, key) {
if (isArray(task) && indexOf(task, taskName, 0) >= 0) {
result.push(key);
}
});
return result;
}
}