diff options
Diffstat (limited to 'node_modules/async/auto.js')
| -rw-r--r-- | node_modules/async/auto.js | 333 |
1 files changed, 333 insertions, 0 deletions
diff --git a/node_modules/async/auto.js b/node_modules/async/auto.js new file mode 100644 index 0000000..c4a85d4 --- /dev/null +++ b/node_modules/async/auto.js @@ -0,0 +1,333 @@ +'use strict'; + +Object.defineProperty(exports, "__esModule", { + value: true +}); +exports.default = auto; + +var _once = require('./internal/once.js'); + +var _once2 = _interopRequireDefault(_once); + +var _onlyOnce = require('./internal/onlyOnce.js'); + +var _onlyOnce2 = _interopRequireDefault(_onlyOnce); + +var _wrapAsync = require('./internal/wrapAsync.js'); + +var _wrapAsync2 = _interopRequireDefault(_wrapAsync); + +var _promiseCallback = require('./internal/promiseCallback.js'); + +function _interopRequireDefault(obj) { return obj && obj.__esModule ? obj : { default: obj }; } + +/** + * 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 {Promise} a promise, if a callback is not passed + * @example + * + * //Using Callbacks + * async.auto({ + * get_data: function(callback) { + * // async code to get some data + * callback(null, 'data', 'converted to array'); + * }, + * make_folder: function(callback) { + * // 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) { + * // 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) { + * // once the file is written let's email a link to it... + * callback(null, {'file':results.write_file, 'email':'user@example.com'}); + * }] + * }, function(err, results) { + * if (err) { + * console.log('err = ', err); + * } + * console.log('results = ', results); + * // results = { + * // get_data: ['data', 'converted to array'] + * // make_folder; 'folder', + * // write_file: 'filename' + * // email_link: { file: 'filename', email: 'user@example.com' } + * // } + * }); + * + * //Using Promises + * 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) { + * // 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) { + * // once the file is written let's email a link to it... + * callback(null, {'file':results.write_file, 'email':'user@example.com'}); + * }] + * }).then(results => { + * console.log('results = ', results); + * // results = { + * // get_data: ['data', 'converted to array'] + * // make_folder; 'folder', + * // write_file: 'filename' + * // email_link: { file: 'filename', email: 'user@example.com' } + * // } + * }).catch(err => { + * console.log('err = ', err); + * }); + * + * //Using async/await + * async () => { + * try { + * let results = await async.auto({ + * get_data: function(callback) { + * // async code to get some data + * callback(null, 'data', 'converted to array'); + * }, + * make_folder: function(callback) { + * // 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) { + * // 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) { + * // once the file is written let's email a link to it... + * callback(null, {'file':results.write_file, 'email':'user@example.com'}); + * }] + * }); + * console.log('results = ', results); + * // results = { + * // get_data: ['data', 'converted to array'] + * // make_folder; 'folder', + * // write_file: 'filename' + * // email_link: { file: 'filename', email: 'user@example.com' } + * // } + * } + * catch (err) { + * console.log(err); + * } + * } + * + */ +function auto(tasks, concurrency, callback) { + if (typeof concurrency !== 'number') { + // concurrency is optional, shift the args. + callback = concurrency; + concurrency = null; + } + callback = (0, _once2.default)(callback || (0, _promiseCallback.promiseCallback)()); + var numTasks = Object.keys(tasks).length; + if (!numTasks) { + return callback(null); + } + if (!concurrency) { + concurrency = numTasks; + } + + var results = {}; + var runningTasks = 0; + var canceled = false; + 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 = {}; + + Object.keys(tasks).forEach(key => { + var task = tasks[key]; + if (!Array.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; + + dependencies.forEach(dependencyName => { + if (!tasks[dependencyName]) { + throw new Error('async.auto task `' + key + '` has a non-existent dependency `' + dependencyName + '` in ' + dependencies.join(', ')); + } + addListener(dependencyName, () => { + remainingDependencies--; + if (remainingDependencies === 0) { + enqueueTask(key, task); + } + }); + }); + }); + + checkForDeadlocks(); + processQueue(); + + function enqueueTask(key, task) { + readyTasks.push(() => runTask(key, task)); + } + + function processQueue() { + if (canceled) return; + 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] || []; + taskListeners.forEach(fn => fn()); + processQueue(); + } + + function runTask(key, task) { + if (hasError) return; + + var taskCallback = (0, _onlyOnce2.default)((err, ...result) => { + runningTasks--; + if (err === false) { + canceled = true; + return; + } + if (result.length < 2) { + [result] = result; + } + if (err) { + var safeResults = {}; + Object.keys(results).forEach(rkey => { + safeResults[rkey] = results[rkey]; + }); + safeResults[key] = result; + hasError = true; + listeners = Object.create(null); + if (canceled) return; + 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++; + getDependents(currentTask).forEach(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 = []; + Object.keys(tasks).forEach(key => { + const task = tasks[key]; + if (Array.isArray(task) && task.indexOf(taskName) >= 0) { + result.push(key); + } + }); + return result; + } + + return callback[_promiseCallback.PROMISE_SYMBOL]; +} +module.exports = exports['default'];
\ No newline at end of file |