Asynchronous function queue with adjustable concurrency.
This script should not be not be installed directly. It is a library for other scripts to include with the meta directive // @require https://update.greasyfork.org/scripts/482311/1297431/queue.js
// ==UserScript==
// @name queue
// @description Asynchronous function queue with adjustable concurrency.
// @author Jesse Tane
// @namespace https://github.com/jessetane/queue
// @version 7.0.0
// @license MIT
// ==/UserScript==
var { Queue, QueueEvent } = (function (exports) {
'use strict';
const has = Object.prototype.hasOwnProperty;
/**
* Since CustomEvent is only supported in nodejs since version 19,
* you have to create your own class instead of using CustomEvent
* @see https://github.com/nodejs/node/issues/40678
* */
class QueueEvent extends Event {
constructor (name, detail) {
super(name);
this.detail = detail;
}
}
class Queue extends EventTarget {
constructor (options = {}) {
super();
const { concurrency = Infinity, timeout = 0, autostart = false, results = null } = options;
this.concurrency = concurrency;
this.timeout = timeout;
this.autostart = autostart;
this.results = results;
this.pending = 0;
this.session = 0;
this.running = false;
this.jobs = [];
this.timers = [];
this.addEventListener('error', this._errorHandler);
}
_errorHandler (evt) {
this.end(evt.detail.error);
}
pop () {
return this.jobs.pop()
}
shift () {
return this.jobs.shift()
}
indexOf (searchElement, fromIndex) {
return this.jobs.indexOf(searchElement, fromIndex)
}
lastIndexOf (searchElement, fromIndex) {
if (fromIndex !== undefined) return this.jobs.lastIndexOf(searchElement, fromIndex)
return this.jobs.lastIndexOf(searchElement)
}
slice (start, end) {
this.jobs = this.jobs.slice(start, end);
return this
}
reverse () {
this.jobs.reverse();
return this
}
push (...workers) {
const methodResult = this.jobs.push(...workers);
if (this.autostart) this._start();
return methodResult
}
unshift (...workers) {
const methodResult = this.jobs.unshift(...workers);
if (this.autostart) this._start();
return methodResult
}
splice (start, deleteCount, ...workers) {
this.jobs.splice(start, deleteCount, ...workers);
if (this.autostart) this._start();
return this
}
get length () {
return this.pending + this.jobs.length
}
start (callback) {
if (this.running) throw new Error('already started')
let awaiter;
if (callback) {
this._addCallbackToEndEvent(callback);
} else {
awaiter = this._createPromiseToEndEvent();
}
this._start();
return awaiter
}
_start () {
this.running = true;
if (this.pending >= this.concurrency) {
return
}
if (this.jobs.length === 0) {
if (this.pending === 0) {
this.done();
}
return
}
const job = this.jobs.shift();
const session = this.session;
const timeout = (job !== undefined) && has.call(job, 'timeout') ? job.timeout : this.timeout;
let once = true;
let timeoutId = null;
let didTimeout = false;
let resultIndex = null;
const next = (error, ...result) => {
if (once && this.session === session) {
once = false;
this.pending--;
if (timeoutId !== null) {
this.timers = this.timers.filter(tID => tID !== timeoutId);
clearTimeout(timeoutId);
}
if (error) {
this.dispatchEvent(new QueueEvent('error', { error, job }));
} else if (!didTimeout) {
if (resultIndex !== null && this.results !== null) {
this.results[resultIndex] = [...result];
}
this.dispatchEvent(new QueueEvent('success', { result: [...result], job }));
}
if (this.session === session) {
if (this.pending === 0 && this.jobs.length === 0) {
this.done();
} else if (this.running) {
this._start();
}
}
}
};
if (timeout) {
timeoutId = setTimeout(() => {
didTimeout = true;
this.dispatchEvent(new QueueEvent('timeout', { next, job }));
next();
}, timeout);
this.timers.push(timeoutId);
}
if (this.results != null) {
resultIndex = this.results.length;
this.results[resultIndex] = null;
}
this.pending++;
this.dispatchEvent(new QueueEvent('start', { job }));
job.promise = job(next);
if (job.promise !== undefined && typeof job.promise.then === 'function') {
job.promise.then(function (result) {
return next(undefined, result)
}).catch(function (err) {
return next(err || true)
});
}
if (this.running && this.jobs.length > 0) {
this._start();
}
}
stop () {
this.running = false;
}
end (error) {
this.clearTimers();
this.jobs.length = 0;
this.pending = 0;
this.done(error);
}
clearTimers () {
this.timers.forEach(timer => {
clearTimeout(timer);
});
this.timers = [];
}
_addCallbackToEndEvent (cb) {
const onend = evt => {
this.removeEventListener('end', onend);
cb(evt.detail.error, this.results);
};
this.addEventListener('end', onend);
}
_createPromiseToEndEvent () {
return new Promise((resolve, reject) => {
this._addCallbackToEndEvent((error, results) => {
if (error) reject(error);
else resolve(results);
});
})
}
done (error) {
this.session++;
this.running = false;
this.dispatchEvent(new QueueEvent('end', { error }));
}
}
exports.Queue = Queue;
exports.QueueEvent = QueueEvent;
return exports;
})({});