Node.js mysql 连接池使用事务自动回收连接

var mysql = require('mysql'),
    Connection = require('mysql/lib/Connection.js');

var pool = mysql.createPool({
    host: '127.0.0.1',
    database: 'myDB',
    port: 3306,
    user: 'root',
    password: 'root',
    debug: false,
    connectionLimit: 3
});



var execPool = function() {
    pool.getConnection(function(err, conn) {
        transAutoRelease(conn);

        conn.beginTransaction(function(err) {
            if (err) throw err;
            conn.query("INSERT INTO test(id,name,date,test) values(1,'123',now(),1)",
                function(err, ret) {
                    if (err) {
                        console.error(err);
                        conn.rollback(function() {});
                    } else {
                        console.log(ret);
                        conn.query('UPDATE test set id=12321312 where id=1', function(err, ret) {
                            if (err) {
                                console.error(err);
                                conn.rollback(function() {

                                });
                            } else {
                                conn.commit(function() {
                                    console.log('success' + JSON.stringify(ret));
                                });
                            }
                        });

                    }
                });
        });
    });
}

function after(fn, cb) { return function() {
        fn.apply(this, arguments);
        cb();
    }
}

function transAutoRelease(conn) { 
    if (conn.commit == Connection.prototype.commit)
        conn.commit = after(conn.commit, release);
    if (conn.rollback == Connection.prototype.rollback)
        conn.rollback = after(conn.rollback, release);

    function release() {
        if (conn) {
            conn.release();
        }
    }
}


var intervalStartProcess = function() {
    setInterval(function() {
        execPool();
    }, 1000);
}
for (var i = 5 - 1; i >= 0; i--) {
    intervalStartProcess(); 
}