#!/usr/bin/perl
# The LearningOnline Network
# cleanup_database.pl Remove stale temporary search results.
#
# $Id: cleanup_database.pl,v 1.4 2004/06/09 12:39:39 matthew Exp $
#
# Copyright Michigan State University Board of Trustees
#
# This file is part of the LearningOnline Network with CAPA (LON-CAPA).
#
# LON-CAPA is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# LON-CAPA is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with LON-CAPA; if not, write to the Free Software
# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
#
# /home/httpd/html/adm/gpl.txt
#
# http://www.lon-capa.org/
#
#################################################

=pod

=head1 NAME

cleanup_database.pl - Remove temporary tables from the LON-CAPA MySQL database.

=head1 SYNOPSIS

cleanup_database.pl drops tables from the LON-CAPA MySQL database if their 
comment is 'temporary' and they have not been modified in a given number 
of seconds.

=head1 DESCRIPTION

There are two command line arguements possible.  

=over 4

=item help 

Display a brief help message.

=item killtime <time>

The time in seconds that must have passed since the last update of a table
before it will be dropped.

=back

The following invocation is equivalent to the default:

 cleanup_database.pl --killtime 86400

If you desire the immediate cleanup of temporary tables, use the following:

 cleanup_database.pl --killtime 0

Depending on permissions, you may have to run this script as root.

=cut

#################################################

use strict;
use lib '/home/httpd/lib/perl/';
use LONCAPA::Configuration;
use Getopt::Long;
use Time::Local;
use DBI;

my $help = 0;
my $killtime = 86400*2;
GetOptions( "killtime=s" => \$killtime, 
            "help"       => \$help );
if ($help) {
    print <<ENDHELP;
cleanup_database.pl     Cleans up the LON-CAPA MySQL database by removing 
                        temporary tables.
Command line arguements
   --killtime  <number>     The number of seconds a temporary table is allowed
                            to live.  Defaults to 86400 (1 day)
   --help                   Print out this help message.

Examples:

cleanup_database.pl --killtime 0
cleanup_database.pl --killtime 86400

Note:  You will probably need to execute this script as root.

ENDHELP
    exit;
}

# ---------------  Read loncapa_apache.conf and loncapa.conf and get variables
my %perlvar = %{&LONCAPA::Configuration::read_conf('loncapa.conf')};
delete $perlvar{'lonReceipt'}; # remove since sensitive and not needed

my $dbh;
# ------------------------------------- Make sure that database can be accessed
unless ($dbh = DBI->connect("DBI:mysql:loncapa","www",
                            $perlvar{'lonSqlAccess'},
                            {RaiseError=>0,PrintError=>0}
                            )
        ) {
    print "Cannot connect to database!\n";
    exit;
}

my $sth = $dbh->prepare("SHOW TABLE STATUS");
$sth->execute();
my $results = $sth->fetchall_arrayref;

foreach my $array (@$results) {
    next if ($array->[14] ne 'temporary');  # [14] is the comment
    my $name = $array->[0];
    # [10] in status report is creation time.
    # [11] in status report is update (last modification?) time.
    my $tabletime = $array->[11];
    # Times are like: 2002-07-25 10:17:08
    my ($year,$month,$day,$hour,$min,$sec)= 
        ($tabletime =~ /(\d+)-(\d+)-(\d+) (\d+):(\d+):(\d+)/);
    my $epoch_seconds = timelocal($sec,$min,$hour,$day,$month-1,$year-1900);
    if ((time - $epoch_seconds) > $killtime) {
        $dbh->do('DROP TABLE '.$name);
    }
}

# --------------------------------------------------- Close database connection
$dbh->disconnect;