DBD::Proxy breaking die within eval strangeness

From: Mark Addison (Mark.Addison_at_itn.co.uk)
Date: 01/19/05

  • Next message: Graeme St. Clair: "RE: Problem with connecting to an Oracle database using Perl" 
    Date: Wed, 19 Jan 2005 17:37:42 -0000
To: <dbi-users@perl.org>

    Hello,

    I'm having a very strange problem with DBD::Proxy and have ended
    up with brain meltdown - so now its your turn ;-)

    Basically, if I use DBD::Proxy to connect to a database (just doing
    a 'use DBD::Proxy' isn't enough), then localise $dbh->{AutoCommit}
    within an eval (to locally turn on transactions), die seems to break
    such that the die works (is catchable with eval) but it looses
    the value for $@, so doesn't actually look like an error.

    I've got it down to the following test script:

        #!/usr/bin/perl
        
        use strict;
        use DBI;
        
        # This connect must work to see the error
        my $dbh = DBI->connect() || die "Failed to connect: $DBI::errstr\n";
        
        eval {
            die "BANG!!!";
            print "Hello\n";
        };
        print "AutoCommit default Error:$@\n";
        
        eval {
            local $dbh->{ AutoCommit } = 0; # This breaks die!
            die "BANG!!!";
            print "Hello\n";
        };
        print "Local AutoCommit off Error:$@\n";

    If I run this with a normal DBD it works as expected. e.g.

     $ DBI_DSN='dbi:mysql:host=localhost;database=test' ./test.pl
     AutoCommit default Error:BANG!!! at ./test.pl line 10.
     Local AutoCommit off Error:BANG!!! at ./test.pl line 17.

    If I use DBD::Proxy it fails

     $
    DBI_DSN='dbi:Proxy:hostname=localhost;port12400;dsn=dbi:mysql:host=local
    host;database=test' ./test.pl
     AutoCommit default Error:BANG!!! at ./test.pl line 10.
     Local AutoCommit off Error:

    i.e. in the 2nd eval the die happens (we don't see Hello printed) but $@
    is
    empty.

    I've tried this using a proxy server running locally to mysql as well
    as a remote one talking to sqlserver with ODBC and get the same result,
    so I think its down to DBD::Proxy.

    After days looking at this I can't work out wtf is going on. DBD::Proxy
    is full of local $SIG{__DIE__}='DEFAULT' code but doesn't ever set it to
    anything else.

    I get the same result on 2 machines with the following setups

    perl v5.8.0 sun4-solaris
    DBI 1.46
    DBD::Proxy 0.2004
    DBI::ProxyServer 0.3005

    perl v5.6.1 i386-freebsd
    DBI 1.43
    DBD::Proxy 0.2004
    DBI::ProxyServer 0.3005

    cheers,
    mark 

    --
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  • Next message: Graeme St. Clair: "RE: Problem with connecting to an Oracle database using Perl"