Asynchronous function queue with adjustable concurrency.
От
Този скрипт не може да бъде инсталиран директно. Това е библиотека за други скриптове и може да бъде използвана с мета-директива // @require https://update.greasyfork.org/scripts/482311/1296481/queue.js
// Source: https://github.com/jessetane/queue
// Licensed under MIT License
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 }))
}
}