Current File : //usr/lib/node_modules/ncm-ng/lib/queue/memory.js
'use strict'
exports.get = get
async function get (name, options) {
return new MemoryQueue(name, options)
}
// implementation of an in-memory queue
class MemoryQueue {
constructor (name, options) {
this._name = name
this._options = options
this._messages = []
this._readMessages = new Map()
this._handle = 0
}
get buffered () {
return 0
}
// post a message to the queue
async post (message, options) {
return this.postMulti([message], options)
}
// post multiple messages to the queue
async postMulti (messages, options) {
if (!Array.isArray(messages)) throw new Error('messages argument must be an array')
if (messages.length === 0) return
for (let message of messages) {
this._handle++
const item = {
handle: this._handle,
message: message
}
this._messages.push(item)
}
}
// read a message from the queue
async read (options) {
if (this._messages.length === 0) return null
const result = this._messages.shift()
this._readMessages.set(result.handle, result)
return result
}
// delete a previously read message
async delete (handle) {
const item = this._readMessages.get(handle)
if (item == null) throw new Error(`item with handle ${handle} not available`)
this._readMessages.delete(handle)
}
// get some queue statistics
async getStats () {
return {
visible: this._messages.length,
notVisible: this._readMessages.size
}
}
// return string representation of this object
toString () {
return `${this.constructor.name}[${this._name}]`
}
}
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