[英]How to monitor mysql connection status in node?
So this is from https://www.npmjs.com/package/mysql ,所以这是来自https://www.npmjs.com/package/mysql ,
var mysql = require('mysql');
var connection = mysql.createConnection({
host : 'example.org',
user : 'bob',
password : 'secret'
});
connection.connect(function(err) {
if (err) {
console.error('error connecting: ' + err.stack);
return;
}
console.log('connected as id ' + connection.threadId);
});
there're 2 parts confuse me,有两个部分让我感到困惑,
is connection.connect() making the real connection? connection.connect() 是真正的连接吗? i see it's checking for error.
我看到它正在检查错误。 But what happens if everything is ok, but i turn off mysql server after 5 minutes, how to monitor the status pls?
但是如果一切正常,我会在 5 分钟后关闭 mysql 服务器,请问如何监控状态? Even for pool events, i don't see the disconnect event.
即使对于池事件,我也看不到断开连接事件。
for the above code, is there a async/await version for connection.connect()?对于上面的代码,connection.connect() 是否有异步/等待版本?
Thanks !谢谢 !
connection.connect is sync you can use it after connection. connection.connect 是同步的,您可以在连接后使用它。 To handle connection errors you can use:
要处理连接错误,您可以使用:
function handleDisconnect() {
connection = mysql.createConnection(db_config); // Recreate the connection, since
// the old one cannot be reused.
connection.connect(function(err) { // The server is either down
if(err) { // or restarting (takes a while sometimes).
console.log('error when connecting to db:', err);
setTimeout(handleDisconnect, 2000); // We introduce a delay before attempting to reconnect,
} // to avoid a hot loop, and to allow our node script to
}); // process asynchronous requests in the meantime.
// If you're also serving http, display a 503 error.
connection.on('error', function(err) {
console.log('db error', err);
if(err.code === 'PROTOCOL_CONNECTION_LOST') { // Connection to the MySQL server is usually
handleDisconnect(); // lost due to either server restart, or a
} else { // connnection idle timeout (the wait_timeout
throw err; // server variable configures this)
}
});
}
By the way everything is explained in node-mysql read me顺便说一句, node-mysql 中解释了所有内容,请阅读我
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