#!/usr/bin/perl

use strict;
use warnings;
use threads;
use DBI;

my ($firstUserConn, $firstSth, $firstResult);
my ($secondUserConn, $secondSth, $secondUserResult);

# first user starts to connect
$firstUserConn = DBI->connect('DBI:mysql:world', 'fatguy', 'ugalay') ||
        die "couldn't connect: $DBI::errstr";

# the first user is locking the tables for an update or whatever
$firstSth = $firstUserConn->do('lock tables City write');

# another client needs to read some city stuff
#$secondUserConn = DBI->connect('DBI:mysql:world', 'littlecoat', 'skinnbones') ||
#       die "couldn't connect: $DBI::errstr";

# actually, the second client needs to read a LOT of city stuff ;)
# by doing this, i'm going to simulate a constant flow of traffic
# hopefully, the site has an uptime expectancy of forever, so
# we'll keep simulating page hits... FOREVER!
# we'll do one page hit every second...

#while (1) {
#       $secondSth = $secondUserConn->prepare('select * from City');
#       $secondSth->execute();
#       while ($secondUserResult = $secondSth->fetchrow_hashref()) {
#               print "$secondUserResult->{'ID'} $secondUserResult->{'Name'} $secondUserResult->{'CountryCode'} $secondUserResult->{'District'} $secondUserResult->{'Population'}\n";
#       }
#       $secondSth->finish();
#       sleep(1);
#}


my @bigugly;
for (my $i = 1; $i <= 100; $i++) {
        $bigugly[$i] = threads->new(\&makeQuery);
        $bigugly[$i]->detach;
}

# okay this is to keep the connections open...
while (1) {
        sleep(1);
}


# oh yeah, not that we'll actually get to this point, but firstuser will eventually finish his lock. ;)
# it's true that i never did any sort of writes for him.
# the only important thing for this exercise was the lock from the first user,
# not necessarily the raw updates
$firstUserConn->disconnect();

sub makeQuery {
        # don't care about the return val of the select
        # just creating a job to wait on the write lock
        $secondUserConn = DBI->connect('DBI:mysql:world', 'littlecoat', 'skinnbones') ||
                die "couldn't connect: $DBI::errstr";
        $secondUserConn->do('select * from City');
        $secondUserConn->disconnect();

}