TODO added
[poolifier.git] / lib / dynamic.js
1 'use strict'
2 const FixedThreadPool = require('./fixed')
3
4 /**
5 * A thread pool with a min/max number of threads , is possible to execute tasks in sync or async mode as you prefer. <br>
6 * This thread pool will create new workers when the other ones are busy, until the max number of threads,
7 * when the max number of threads is reached, an exception will be thrown.
8 * This pool will select the worker thread in a round robin fashion. <br>
9 * @author Alessandro Pio Ardizio
10 * @since 0.0.1
11 */
12 class DynamicThreadPool extends FixedThreadPool {
13 /**
14 *
15 * @param {Number} min Min number of threads that will be always active
16 * @param {Number} max Max number of threads that will be active
17 * @param {Object} an object with possible options for example maxConcurrency
18 */
19 constructor (min, max, filename, opts) {
20 super(min, filename, opts)
21 this.max = max
22 }
23
24 _chooseWorker () {
25 let worker
26 for (const entry of this.tasks) {
27 if (entry[1] === 0) {
28 worker = entry[0]
29 break
30 }
31 }
32
33 if (worker) {
34 // a worker is free, use it
35 return worker
36 } else {
37 if (this.workers.length === this.max) {
38 throw new Error('Max number of threads reached !!!')
39 }
40 // all workers are busy create a new worker
41 const worker = this._newWorker()
42 worker.port2.on('message', (message) => {
43 if (message.kill) {
44 worker.postMessage({ kill: 1 })
45 worker.terminate()
46 }
47 })
48 return worker
49 }
50 }
51 }
52
53 module.exports = DynamicThreadPool