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'use strict';
import arrayEach from 'lodash/_arrayEach';
import forOwn from 'lodash/forOwn';
import indexOf from 'lodash/indexOf';
import isArray from 'lodash/isArray';
import okeys from 'lodash/keys';
import noop from 'lodash/noop';
import once from 'lodash/once';
import rest from 'lodash/rest';
import onlyOnce from './internal/onlyOnce';
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 = {};
var readyTasks = [];
forOwn(tasks, function (task, key) {
if (!isArray(task)) {
// no dependencies
enqueueTask(key, [task]);
return;
}
var dependencies = task.slice(0, task.length - 1);
var remainingDependencies = dependencies.length;
checkForDeadlocks();
function checkForDeadlocks() {
var len = dependencies.length;
var dep;
while (len--) {
if (!(dep = tasks[dependencies[len]])) {
throw new Error('async.auto task `' + key +
'` has non-existent dependency in ' +
dependencies.join(', '));
}
if (isArray(dep) && indexOf(dep, key) >= 0) {
throw new Error('async.auto task `' + key +
'`Has cyclic dependencies');
}
}
}
arrayEach(dependencies, function (dependencyName) {
addListener(dependencyName, function () {
remainingDependencies--;
if (remainingDependencies === 0) {
enqueueTask(key, task);
}
});
});
});
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 = [];
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);
}
}
}
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