Re: [log4perl-devel] Revisit of database logging when database connection fails

[Robert J. <yad...@sn...>]

At 01:50 AM 1/8/2007, Mike Schilli wrote:

>By the way, you might want to take a look at mysql_auto_reconnect 
>[snip] wouldn't this solve your problem?

Perhaps it would.  I have to find out what happens when 
mysql_auto_reconnect is turned on, but the actual database or network 
connection is truly down.  Turning on reconnects within Appender::DBI 
caused my perl programs to block while waiting for the reconnection 
-- defeating the purpose of the queuing mechanism (i.e. don't block 
when the database is down!)

I think another problem with my existing code is that the connection 
my wrapper makes is totally separate from the connection that 
Appender::DBI makes.  So even if my wrapper notices the disconnect 
and makes the reconnection -- Appender::DBI still has to 
reconnect.  I still don't know why Appender::DBI failed to reconnect, 
but if the connections in my wrapper and the appender are separate, I 
can see that it makes the probability of error higher.

Perhaps the answer is to write a true subclass of Appender::DBI 
instead of the kludge I came up with.  I think I can just override 
the log() method with my own with something like:

# Begin simplistic Pseudocode
sub log ()
{
         if (not connected2database() ) {
                 # Connection is down
                 buffer_message()
         } else {
                 write2database(@buffered_messages)
         }
}

sub connected2database
{
         if (not $dbh->ping() )
         {
                 # try to reconnect - once
                 eval { connect() }
                 if ($@) {
                         # connection successful, rebuild statement handle
                         return 1;
                 } else {
                         return 0;
                 }
         }
}


-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
Robert Jacobson               ..........................
Flight Ops. Team        Solar Dynamics Observatory (SDO)
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