141 lines
4.2 KiB
TypeScript
141 lines
4.2 KiB
TypeScript
import events from "events"
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import { timeout } from "../../utils"
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/**
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* Bull works with a Job wrapper around all messages that contains a lot more information about
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* the state of the message, this object constructor implements the same schema of Bull jobs
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* for the sake of maintaining API consistency.
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* @param {string} queue The name of the queue which the message will be carried on.
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* @param {object} message The JSON message which will be passed back to the consumer.
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* @returns {Object} A new job which can now be put onto the queue, this is mostly an
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* internal structure so that an in memory queue can be easily swapped for a Bull queue.
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*/
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function newJob(queue: string, message: any) {
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return {
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timestamp: Date.now(),
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queue: queue,
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data: message,
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}
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}
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/**
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* This is designed to replicate Bull (https://github.com/OptimalBits/bull) in memory as a sort of mock.
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* It is relatively simple, using an event emitter internally to register when messages are available
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* to the consumers - in can support many inputs and many consumers.
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*/
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class InMemoryQueue {
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_name: string
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_opts?: any
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_messages: any[]
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_emitter: EventEmitter
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_runCount: number
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_addCount: number
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/**
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* The constructor the queue, exactly the same as that of Bulls.
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* @param {string} name The name of the queue which is being configured.
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* @param {object|null} opts This is not used by the in memory queue as there is no real use
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* case when in memory, but is the same API as Bull
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*/
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constructor(name: string, opts = null) {
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this._name = name
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this._opts = opts
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this._messages = []
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this._emitter = new events.EventEmitter()
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this._runCount = 0
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this._addCount = 0
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}
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/**
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* Same callback API as Bull, each callback passed to this will consume messages as they are
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* available. Please note this is a queue service, not a notification service, so each
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* consumer will receive different messages.
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* @param {function<object>} func The callback function which will return a "Job", the same
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* as the Bull API, within this job the property "data" contains the JSON message. Please
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* note this is incredibly limited compared to Bull as in reality the Job would contain
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* a lot more information about the queue and current status of Bull cluster.
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*/
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process(func: any) {
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this._emitter.on("message", async () => {
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if (this._messages.length <= 0) {
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return
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}
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let msg = this._messages.shift()
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let resp = func(msg)
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if (resp.then != null) {
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await resp
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}
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this._runCount++
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})
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}
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// simply puts a message to the queue and emits to the queue for processing
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/**
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* Simple function to replicate the add message functionality of Bull, putting
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* a new message on the queue. This then emits an event which will be used to
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* return the message to a consumer (if one is attached).
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* @param {object} msg A message to be transported over the queue, this should be
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* a JSON message as this is required by Bull.
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* @param {boolean} repeat serves no purpose for the import queue.
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*/
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// eslint-disable-next-line no-unused-vars
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add(msg: any, repeat: boolean) {
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if (typeof msg !== "object") {
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throw "Queue only supports carrying JSON."
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}
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this._messages.push(newJob(this._name, msg))
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this._addCount++
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this._emitter.emit("message")
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}
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/**
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* replicating the close function from bull, which waits for jobs to finish.
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*/
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async close() {
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return []
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}
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/**
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* This removes a cron which has been implemented, this is part of Bull API.
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* @param {string} cronJobId The cron which is to be removed.
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*/
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removeRepeatableByKey(cronJobId: string) {
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// TODO: implement for testing
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console.log(cronJobId)
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}
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/**
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* Implemented for tests
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*/
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getRepeatableJobs() {
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return []
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}
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// eslint-disable-next-line no-unused-vars
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removeJobs(pattern: string) {
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// no-op
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}
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/**
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* Implemented for tests
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*/
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async clean() {
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return []
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}
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async getJob() {
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return {}
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}
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on() {
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// do nothing
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}
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async waitForCompletion() {
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do {
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await timeout(50)
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} while (this._addCount < this._runCount)
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}
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}
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export = InMemoryQueue
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