nodejs 連接mysql 集群,開啟事務，事務回滾封裝

mysql.js



const mysql = require("mysql");
const poolCluster = mysql.createPoolCluster({
    removeNodeErrorCount: 1, // Remove the node immediately when connection fails.
    defaultSelector: "RR" //RR,RANDOM,ORDER
});
const mysqlNodes = {
        node1: {
            host: "mysql_host",
            port: 3306,
            user: "root",
            password: "mysql_password",
            database: "my_test_database",
            charset: "utf8",
            waitForConnections: true,
            connectionLimit: 10,
            queueLimit: 0
        },
        node2: {
            host: "mysql_host",
            port: 3306,
            user: "root",
            password: "mysql_password",
            database: "my_test_database",
            charset: "utf8",
            waitForConnections: true,
            connectionLimit: 10,
            queueLimit: 0
        },
        node3: {
            host: "mysql_host",
            port: 3306,
            user: "root",
            password: "mysql_password",
            database: "my_test_database",
            charset: "utf8",
            waitForConnections: true,
            connectionLimit: 10,
            queueLimit: 0
        }
};
for (let node in mysqlNodes) {
    poolCluster.add(`${node}`, mysqlNodes[`${node}`]);
}

class MysqlModel {
    /**
     * 實例化mysql
     */
    getConnection() {
        return new Promise((resolve, reject) => {
            poolCluster.getConnection(function (err, connection) {
                if (err) {
                    reject(err);
                } else {
                   console.log(60, 'mysql連接成功')
                    resolve([
                        connection,
                        poolCluster
                    ]);
                }
            })
        })
    }

}

async function mysqlDBUtil() {
    try {
        const db = new MysqlModel();
        const [conn, pool] = await db.getConnection();
        /**
         * 回滾事務
         */
        const rollback = async function () {
            conn.rollback();
            console.log('mysql事務發生回滾......rollback')
        }

        /**
         * 數據庫操作
         * @param {} sql
         * @param {*} options
         */
        const query = function (sql, options) {
            return new Promise((resolve, reject) => {
                conn.query(sql, options, function (error, results, fields) {
                    if (error) {
                        reject(error);
                    } else {
                        resolve(results);
                    }
                })
            })
        }

        /**
         *提交事務
         */
        const commit = function () {
            return new Promise((resolve, reject) => {
                conn.commit(function (err) {
                    if (err) {
                        reject(err);
                    }else{
                        console.log('mysql事務提交......commit')
                        resolve(true);
                    }
                });
            })
        }
        /**
         * 關閉連接池，mysql2的包自己不會釋放
         */
        const close = async function () {
            conn.release();
            console.log('mysql連接池釋放.....release');
        }
        return {
            rollback,
            commit,
            close,
            query
        }
    } catch (error) {
        throw error;
    }
}
module.exports = mysqlDBUtil;

//調用
var express = require("express");
var router = express.Router();
const mysqlUtil = require("../mysql");
/*
 * 可以在MYSQL中執行show status like 'Threads%',查看連接數
*/
router.get("/", async function (req, res, next) {
  for (let i = 0; i < 5000; i++) {
    const db = await mysqlUtil();
    const sql = "select * from user limit 0,100";
    const result = await db.query(sql);
    await db.close();
    console.log(i, result)
  }
  res.send('ok');
});

module.exports = router;