Mongo4Manager

const chalk = require('chalk')
// used to keep the connection to mongo alive
// tested with mongodb@4 nodejs driver
class Mongo4Manager {
    mongoHandle = null

    constructor(dsn, connectionOptions = {},retryInterval = 1000, pingInterval = 1000) {
        this.connectionOptions = connectionOptions
        this.dsn = dsn
        this.retryInterval = retryInterval
        this.pingInterval = pingInterval
    }

    client() {
        return this.mongoHandle
    }

    pinger(handle, pingInterval, that) {
        // console.log(`pinger(${pingInterval})`)
        setTimeout(() => {
            if (handle)
                handle.db("admin").command({ ping: 1 }).then((x) => {
                    // console.log(`Starting new pinger`, x)
                    this.pinger(handle, pingInterval,that)
                }).catch(err => {
                    console.log(chalk.red(err.toString()), 'MONGO PING')
                    // detected an error
                    that.connect()
                    return
                })
        }, pingInterval)
    }


    connect() {
        const { MongoClient } = require("mongodb")
        console.log(chalk.yellow(`connect()`))
        this.mclient = new MongoClient(this.dsn, { heartbeatFrequencyMS: 5000, serverSelectionTimeoutMS: 5000, ...this.connectionOptions })
        this.mclient.connect().then(async () => {
            console.log(chalk.green.inverse("Connected successfully to mongodb server"))
            this.mongoHandle = this.mclient
            this.pinger(this.mongoHandle, this.pingInterval,this)
        }).catch(err => {
            this.mongoHandle = false
            console.log(chalk.red(err.toString()),'CONNECT')
            console.log(`Will reconnect after ${this.retryInterval} ms`)
            setTimeout(() => { this.connect(), this.retryInterval })
        })
    }
}

module.exports = Mongo4Manager