projeto-hit/TEST_SERVER1/api/helpers/mysql_conn.js

const dotenv = require('dotenv');
dotenv.config({ path: `${process.cwd()}/.env` });
const path = require('path')


function mysql_conn(config) {
    // Ubicua Plataform - MYSQL Module
    try {
        var mysql_npm = require('mysql');
    } catch (err) {
        console.log("Cannot find `mysql` module. Is it installed ? Try `npm install mysql` or `npm install`.");
    }
 
    var db_config = {
        host: config.DB_HOST,
        user: config.DB_USER,
        password: config.DB_PASS,
        database: config.DB,
        charset: 'utf8mb4_general_ci',
        port: config.DB_PORT
    };



    //-
    //- Create the connection variable
    //-
    var connection = mysql_npm.createPool(db_config); 


    //-
    //- Establish a new connection
    //-
    connection.getConnection(function (err) {
        if (err) {
            // mysqlErrorHandling(connection, err);
            console.log("\n\t *** Cannot establish a connection with the database. ***");

            connection = reconnect(connection);
        } else {
            console.log("\n\t *** New connection established with the database. ***")
        }
    });


    //-
    //- Reconnection function
    //-
    function reconnect(connection) {
        console.log("\n New connection tentative...");

        //- Create a new one
        connection = mysql_npm.createPool(db_config);

        //- Try to reconnect
        connection.getConnection(function (err) {
            if (err) {
                //- Try to connect every 2 seconds.
                setTimeout(reconnect(connection), 2000);
            } else {
                console.log("\n\t *** New connection established with the database. ***")
                return connection;
            }
        });
    }


    //-
    //- Error listener
    //-
    connection.on('error', function (err) {

        //-
        //- The server close the connection.
        //-
        if (err.code === "PROTOCOL_CONNECTION_LOST") {
            console.log("/!\\ Cannot establish a connection with the database. /!\\ (" + err.code + ")");
            return reconnect(connection);
        }

        else if (err.code === "PROTOCOL_ENQUEUE_AFTER_QUIT") {
            console.log("/!\\ Cannot establish a connection with the database. /!\\ (" + err.code + ")");
            return reconnect(connection);
        }

        else if (err.code === "PROTOCOL_ENQUEUE_AFTER_FATAL_ERROR") {
            console.log("/!\\ Cannot establish a connection with the database. /!\\ (" + err.code + ")");
            return reconnect(connection);
        }

        else if (err.code === "PROTOCOL_ENQUEUE_HANDSHAKE_TWICE") {
            console.log("/!\\ Cannot establish a connection with the database. /!\\ (" + err.code + ")");
        }

        else {
            console.log("/!\\ Cannot establish a connection with the database. /!\\ (" + err.code + ")");
            return reconnect(connection);
        }

    });

    return connection
}


//-
//- Export
//-
module.exports = mysql_conn;