Created
December 1, 2017 01:29
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Reconnect to MySQL Server when it was disconnected incidentally (Thanks to post @flaxbrane at issue https://github.com/mysqljs/mysql/issues/1478)
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| //- MYSQL Module | |
| try{ | |
| var mysql_npm = require('mysql'); | |
| }catch(err){ | |
| console.log("Cannot find `mysql` module. Is it installed ? Try `npm install mysql` or `npm install`."); | |
| } | |
| //- Connection configuration | |
| var db_config = { | |
| host : 'localhost', | |
| user : 'app', | |
| password : 'super secret password', | |
| database : 'app' | |
| }; | |
| //- Create the connection variable | |
| var connection = mysql_npm.createConnection(db_config); | |
| //- Establish a new connection | |
| connection.connect(function(err){ | |
| if(err) { | |
| // mysqlErrorHandling(connection, err); | |
| console.log("\n\t *** Cannot establish a connection with the database. ***"); | |
| connection = reconnect(connection); | |
| }else { | |
| console.log("\n\t *** New connection established with the database. ***") | |
| } | |
| }); | |
| //- Reconnection function | |
| function reconnect(connection){ | |
| console.log("\n New connection tentative..."); | |
| //- Destroy the current connection variable | |
| if(connection) connection.destroy(); | |
| //- Create a new one | |
| var connection = mysql_npm.createConnection(db_config); | |
| //- Try to reconnect | |
| connection.connect(function(err){ | |
| if(err) { | |
| //- Try to connect every 2 seconds. | |
| setTimeout(reconnect, 2000); | |
| }else { | |
| console.log("\n\t *** New connection established with the database. ***") | |
| return connection; | |
| } | |
| }); | |
| } | |
| //- Error listener | |
| connection.on('error', function(err) { | |
| //- The server close the connection. | |
| if(err.code === "PROTOCOL_CONNECTION_LOST"){ | |
| console.log("/!\\ Cannot establish a connection with the database. /!\\ ("+err.code+")"); | |
| connection = reconnect(connection); | |
| } | |
| //- Connection in closing | |
| else if(err.code === "PROTOCOL_ENQUEUE_AFTER_QUIT"){ | |
| console.log("/!\\ Cannot establish a connection with the database. /!\\ ("+err.code+")"); | |
| connection = reconnect(connection); | |
| } | |
| //- Fatal error : connection variable must be recreated | |
| else if(err.code === "PROTOCOL_ENQUEUE_AFTER_FATAL_ERROR"){ | |
| console.log("/!\\ Cannot establish a connection with the database. /!\\ ("+err.code+")"); | |
| connection = reconnect(connection); | |
| } | |
| //- Error because a connection is already being established | |
| else if(err.code === "PROTOCOL_ENQUEUE_HANDSHAKE_TWICE"){ | |
| console.log("/!\\ Cannot establish a connection with the database. /!\\ ("+err.code+")"); | |
| } | |
| //- Anything else | |
| else{ | |
| console.log("/!\\ Cannot establish a connection with the database. /!\\ ("+err.code+")"); | |
| connection = reconnect(connection); | |
| } | |
| }); |
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