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From Nick Kew <n...@webthing.com>
Subject Re: mod_authn_dbd - internal server error after certain idle time
Date Sat, 07 Jul 2007 09:51:47 GMT
On Sat, 07 Jul 2007 05:44:27 -0400
Tom Donovan <donovant@bellatlantic.net> wrote:

> Nick Kew wrote:
> > On Fri, 06 Jul 2007 18:37:07 -0700
> > Matthew Kent <matt@bravenet.com> wrote:
> > 
>   >> think its the mysql_ping reconnection clobbering the prepared
> >> statement
> >> used in mod_authn_dbd.
> > 
> > Buggrit.  I can't see a satisfactory workaround for that.
> > I guess the kludge suggested by Tom Donovan in this thread
> > could be the best practical solution.
> > 
> 
> Alas, after some testing - it seems even that kludge won't be 100% 
> satisfactory.

Heh.  Anyone here have the ear of the MySQL devs?

I've just fired off a question to MySQL:

To: mysql@lists.mysql.com
Subject: Tying actions to (re)opening a connection

The Apache DBD module maintains a dynamic pool of connections.

SQL statements may be defined at system startup.  Such queries
are then treated as prepared statements.  In the MySQL driver,
the sequence is:

    mysql_real_connect
    for each defined SQL statement {
        mysql_stmt_init
        mysql_stmt_prepare
    }

So far, so good.  However, we also need to deal with connections
that go stale.  Our API defines a check_connection function.
mysql_ping is *nearly* right for this, but unfortunately leaves us
(silently) with a new connection without the prepared statements.

It would work perfectly if we could tie a callback to mysql_ping.
Something like:

    int mysql_ping2(MYSQL *mysql,
                    int (*callback)(MYSQL*, void*),
                    void *dptr);

where the callback (if non-null) is invoked whenever mysql_ping
detects a stale connection and reconnects.
    
Is this something you'd consider adding?  Any other suggestions
for a workaround to check the connection now?


-- 
Nick Kew

Application Development with Apache - the Apache Modules Book
http://www.apachetutor.org/

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