Node.js实现mysql连接池使用事务自动回收连接的方

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.mit(function() {
                  console.log('suess' + JSON.stringify(ret));
                });
              }
            });
          }
        });
    });
  });
}
function after(fn, cb) { return function() {
    fn.apply(this, arguments);
    cb();
  }
}
function transAutoRelease(conn) {
  if (conn.mit == Connection.prototype.mit)
    conn.mit = after(conn.mit, 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();
}