budibase/packages/server/src/workflows/queue/inMemoryQueue.js

45 lines
1.2 KiB
JavaScript

let events = require("events")
// Bull works with a Job wrapper around all messages that contains a lot more information about
// the state of the message, implement this for the sake of maintaining API consistency
function newJob(queue, message) {
return {
timestamp: Date.now(),
queue: queue,
data: message,
}
}
// designed to replicate Bull (https://github.com/OptimalBits/bull) in memory as a sort of mock
class InMemoryQueue {
// opts is not used by this as there is no real use case when in memory, but is the same API as Bull
constructor(name, opts) {
this._name = name
this._opts = opts
this._messages = []
this._emitter = new events.EventEmitter()
}
// same API as bull, provide a callback and it will respond when messages are available
process(func) {
this._emitter.on("message", async () => {
if (this._messages.length <= 0) {
return
}
let msg = this._messages.shift()
let resp = func(msg)
if (resp.then != null) {
await resp
}
})
}
// simply puts a message to the queue and emits to the queue for processing
add(msg) {
this._messages.push(newJob(this._name, msg))
this._emitter.emit("message")
}
}
module.exports = InMemoryQueue