How to keep a connection alive

[vieraci]

Hi,

I'm wanting to start a database connection at the start of an app and keep it open for all methods and classes that I'm #including in my project.

First I went about it by creating the connection in the Main source file outside of any class declarations and then declaring it external in other source files.

// Main cpp file 
#include <mysql++>

mysql::Connection * conn;

// Class definitions follow, I open the connection in Main()
if (!(conn.connect("dbName", "localhost", "user", "pwd"))) {
...

This works ok within the same source file and although it compiles, the connection is not open in any function defined outside the file (in another source file).

Second method I tried was to pass the mysql::Connecti on * conn as a parameter: // Call MyFn from a method in Main source file:
MyFn(this, &conn);

connection appears alive but but the app crashes when I execute the query:

// Function def in Another source file
void myFn(wxFrame *frame, Connection *conn)
{
   mysqlpp::Query query = conn.query();  <--- THIS is probably the cause !?
// set up query code...
// execute
   mysqlpp::StoreQueryResult res = query.store();  // <--- Exception happens here

Can anyone help me please ?

[ronverdonk]

Use the pconnect, if that exists in your class.

Ronald

[vieraci]

Use the pconnect, if that exists in your class.

Ronald

I don't find any reference to pconnection anywhere. Is it a MySQL object ?

[ronverdonk]

You will have to look in your programming language reference for the function to open a 'persistent connection'. Like in PHP it is command mysql_pconnect(), as opposed to command mysql_connect().

Ronald

[chaarmann]

You can use a connection-pool.

A connection pool is a thread (or process) that keeps a list of all connections. It has functions for con=pool.borrow Coonnection() and pool.returnConn ection(con) .
It uses a periodic cleanup-function to go through all connections inside the list and closes the ones which are not used for a certain time.

[vieraci]

Thanks, I'll read up on the connection pools