[英]How to monitor mysql connection status in node?
所以這是來自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);
});
有兩個部分讓我感到困惑,
connection.connect() 是真正的連接嗎? 我看到它正在檢查錯誤。 但是如果一切正常,我會在 5 分鍾后關閉 mysql 服務器,請問如何監控狀態? 即使對於池事件,我也看不到斷開連接事件。
對於上面的代碼,connection.connect() 是否有異步/等待版本?
謝謝 !
connection.connect 是同步的,您可以在連接后使用它。 要處理連接錯誤,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)
}
});
}
順便說一句, node-mysql 中解釋了所有內容,請閱讀我
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