File:  [LON-CAPA] / loncom / lonsql
Revision 1.70: download - view: text, annotated - select for diffs
Tue Feb 7 05:08:27 2006 UTC (18 years, 1 month ago) by raeburn
Branches: MAIN
CVS tags: HEAD
Add support for student photo import from an institutional repository. Availability of photos of registered students in a course controlled by course environment parameter: 'internal.studentphoto'.  This may be configured to require initial acceptance of conditions of use by course owner.  View classlist in ENRL, and Automated Enrollment Manager now includes option to display thumbnails of student photos.  Nightly enrollment update can import student photos for students added to a course.  Student photos can be updated via the Automated Enrollment Manager.

#!/usr/bin/perl

# The LearningOnline Network
# lonsql - LON TCP-MySQL-Server Daemon for handling database requests.
#
# $Id: lonsql,v 1.70 2006/02/07 05:08:27 raeburn 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

lonsql - LON TCP-MySQL-Server Daemon for handling database requests.

=head1 SYNOPSIS

This script should be run as user=www.  
Note that a lonsql.pid file contains the pid of the parent process.

=head1 OVERVIEW

=head2 Purpose within LON-CAPA

LON-CAPA is meant to distribute A LOT of educational content to A LOT
of people. It is ineffective to directly rely on contents within the
ext2 filesystem to be speedily scanned for on-the-fly searches of
content descriptions. (Simply put, it takes a cumbersome amount of
time to open, read, analyze, and close thousands of files.)

The solution is to index various data fields that are descriptive of
the educational resources on a LON-CAPA server machine in a
database. Descriptive data fields are referred to as "metadata". The
question then arises as to how this metadata is handled in terms of
the rest of the LON-CAPA network without burdening client and daemon
processes.

The obvious solution, using lonc to send a query to a lond process,
doesn't work so well in general as you can see in the following
example:

    lonc= loncapa client process    A-lonc= a lonc process on Server A
    lond= loncapa daemon process

                 database command
    A-lonc  --------TCP/IP----------------> B-lond

The problem emerges that A-lonc and B-lond are kept waiting for the
MySQL server to "do its stuff", or in other words, perform the
conceivably sophisticated, data-intensive, time-sucking database
transaction.  By tying up a lonc and lond process, this significantly
cripples the capabilities of LON-CAPA servers.

The solution is to offload the work onto another process, and use
lonc and lond just for requests and notifications of completed
processing:

                database command

  A-lonc  ---------TCP/IP-----------------> B-lond =====> B-lonsql
         <---------------------------------/                |
           "ok, I'll get back to you..."                    |
                                                            |
                                                            /
  A-lond  <-------------------------------  B-lonc   <======
           "Guess what? I have the result!"

Of course, depending on success or failure, the messages may vary, but
the principle remains the same where a separate pool of children
processes (lonsql's) handle the MySQL database manipulations.

Thus, lonc and lond spend effectively no time waiting on results from
the database.

=head1 Internals

=over 4

=cut

use strict;

use lib '/home/httpd/lib/perl/';
use LONCAPA::Configuration;
use LONCAPA::lonmetadata();

use IO::Socket;
use Symbol;
use POSIX;
use IO::Select;
use IO::File;
use Socket;
use Fcntl;
use Tie::RefHash;
use DBI;
use File::Find;
use localenroll;

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

=pod

=item Global Variables

=over 4

=item dbh

=back

=cut

########################################################
########################################################
my $dbh;

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

=pod 

=item Variables required for forking

=over 4

=item $MAX_CLIENTS_PER_CHILD

The number of clients each child should process.

=item %children 

The keys to %children  are the current child process IDs

=item $children

The current number of children

=back

=cut 

########################################################
########################################################
my $MAX_CLIENTS_PER_CHILD  = 5;   # number of clients each child should process
my %children               = ();  # keys are current child process IDs
my $children               = 0;   # current number of children
                               
###################################################################
###################################################################

=pod

=item Main body of code.

=over 4

=item Read data from loncapa_apache.conf and loncapa.conf.

=item Ensure we can access the database.

=item Determine if there are other instances of lonsql running.

=item Read the hosts file.

=item Create a socket for lonsql.

=item Fork once and dissociate from parent.

=item Write PID to disk.

=item Prefork children and maintain the population of children.

=back

=cut

###################################################################
###################################################################
my $childmaxattempts=10;
my $run =0;              # running counter to generate the query-id
#
# Read loncapa_apache.conf and loncapa.conf
#
my $perlvarref=LONCAPA::Configuration::read_conf('loncapa.conf');
my %perlvar=%{$perlvarref};
#
# Write the /home/www/.my.cnf file 
my $conf_file = '/home/www/.my.cnf';
if (! -e $conf_file) {
    if (open MYCNF, ">$conf_file") {
        print MYCNF <<"ENDMYCNF";
[client]
user=www
password=$perlvar{'lonSqlAccess'}
ENDMYCNF
        close MYCNF;
    } else {
        warn "Unable to write $conf_file, continuing";
    }
}


#
# Make sure that database can be accessed
#
my $dbh;
unless ($dbh = DBI->connect("DBI:mysql:loncapa","www",
                            $perlvar{'lonSqlAccess'},
                            { RaiseError =>0,PrintError=>0})) { 
    print "Cannot connect to database!\n";
    my $emailto="$perlvar{'lonAdmEMail'},$perlvar{'lonSysEMail'}";
    my $subj="LON: $perlvar{'lonHostID'} Cannot connect to database!";
    system("echo 'Cannot connect to MySQL database!' |".
           " mailto $emailto -s '$subj' > /dev/null");

    open(SMP,'>/home/httpd/html/lon-status/mysql.txt');
    print SMP 'time='.time.'&mysql=defunct'."\n";
    close(SMP);

    exit 1;
} else {
    unlink('/home/httpd/html/lon-status/mysql.txt');
    $dbh->disconnect;
}

#
# Check if other instance running
#
my $pidfile="$perlvar{'lonDaemons'}/logs/lonsql.pid";
if (-e $pidfile) {
   my $lfh=IO::File->new("$pidfile");
   my $pide=<$lfh>;
   chomp($pide);
   if (kill 0 => $pide) { die "already running"; }
}

#
# Read hosts file
#
my $thisserver;
my $PREFORK=4; # number of children to maintain, at least four spare
open (CONFIG,"$perlvar{'lonTabDir'}/hosts.tab") || die "Can't read host file";
while (my $configline=<CONFIG>) {
    my ($id,$domain,$role,$name)=split(/:/,$configline);
    $name=~s/\s//g;
    $thisserver=$name if ($id eq $perlvar{'lonHostID'});
    #$PREFORK++;
}
close(CONFIG);
#
#$PREFORK=int($PREFORK/4);

#
# Create a socket to talk to lond
#
my $unixsock = "mysqlsock";
my $localfile="$perlvar{'lonSockDir'}/$unixsock";
my $server;
unlink ($localfile);
unless ($server=IO::Socket::UNIX->new(Local    =>"$localfile",
                                      Type    => SOCK_STREAM,
                                      Listen => 10)) {
    print "in socket error:$@\n";
}

#
# Fork once and dissociate
#
my $fpid=fork;
exit if $fpid;
die "Couldn't fork: $!" unless defined ($fpid);
POSIX::setsid() or die "Can't start new session: $!";

#
# Write our PID on disk
my $execdir=$perlvar{'lonDaemons'};
open (PIDSAVE,">$execdir/logs/lonsql.pid");
print PIDSAVE "$$\n";
close(PIDSAVE);
&logthis("<font color='red'>CRITICAL: ---------- Starting ----------</font>");

#
# Ignore signals generated during initial startup
$SIG{HUP}=$SIG{USR1}='IGNORE';
# Now we are on our own    
#    Fork off our children.
for (1 .. $PREFORK) {
    make_new_child();
}

#
# Install signal handlers.
$SIG{CHLD} = \&REAPER;
$SIG{INT}  = $SIG{TERM} = \&HUNTSMAN;
$SIG{HUP}  = \&HUPSMAN;

#
# And maintain the population.
while (1) {
    sleep;                          # wait for a signal (i.e., child's death)
    for (my $i = $children; $i < $PREFORK; $i++) {
        make_new_child();           # top up the child pool
    }
}

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

=pod

=item &make_new_child

Inputs: None

Returns: None

=cut

########################################################
########################################################
sub make_new_child {
    my $pid;
    my $sigset;
    #
    # block signal for fork
    $sigset = POSIX::SigSet->new(SIGINT);
    sigprocmask(SIG_BLOCK, $sigset)
        or die "Can't block SIGINT for fork: $!\n";
    #
    die "fork: $!" unless defined ($pid = fork);
    #
    if ($pid) {
        # Parent records the child's birth and returns.
        sigprocmask(SIG_UNBLOCK, $sigset)
            or die "Can't unblock SIGINT for fork: $!\n";
        $children{$pid} = 1;
        $children++;
        return;
    } else {
        # Child can *not* return from this subroutine.
        $SIG{INT} = 'DEFAULT';      # make SIGINT kill us as it did before
        # unblock signals
        sigprocmask(SIG_UNBLOCK, $sigset)
            or die "Can't unblock SIGINT for fork: $!\n";
        #open database handle
	# making dbh global to avoid garbage collector
	unless ($dbh = DBI->connect("DBI:mysql:loncapa","www",
                                    $perlvar{'lonSqlAccess'},
                                    { RaiseError =>0,PrintError=>0})) { 
            sleep(10+int(rand(20)));
            &logthis("<font color='blue'>WARNING: Couldn't connect to database".
                     ": $@</font>");
                     #  "($st secs): $@</font>");
            print "database handle error\n";
            exit;
        }
	# make sure that a database disconnection occurs with 
        # ending kill signals
	$SIG{TERM}=$SIG{INT}=$SIG{QUIT}=$SIG{__DIE__}=\&DISCONNECT;
        # handle connections until we've reached $MAX_CLIENTS_PER_CHILD
        for (my $i=0; $i < $MAX_CLIENTS_PER_CHILD; $i++) {
            my $client = $server->accept() or last;
            # do something with the connection
	    $run = $run+1;
	    my $userinput = <$client>;
	    chomp($userinput);
            #
	    my ($conserver,$query,
		$arg1,$arg2,$arg3)=split(/&/,$userinput);
	    my $query=unescape($query);
            #
            #send query id which is pid_unixdatetime_runningcounter
	    my $queryid = $thisserver;
	    $queryid .="_".($$)."_";
	    $queryid .= time."_";
	    $queryid .= $run;
	    print $client "$queryid\n";
	    #
	    # &logthis("QUERY: $query - $arg1 - $arg2 - $arg3");
	    sleep 1;
            #
            my $result='';
            #
            # At this point, query is received, query-ID assigned and sent 
            # back, $query eq 'logquery' will mean that this is a query 
            # against log-files
            if (($query eq 'userlog') || ($query eq 'courselog')) {
                # beginning of log query
                my $udom    = &unescape($arg1);
                my $uname   = &unescape($arg2);
                my $command = &unescape($arg3);
                my $path    = &propath($udom,$uname);
                if (-e "$path/activity.log") {
                    if ($query eq 'userlog') {
                        $result=&userlog($path,$command);
                    } else {
                        $result=&courselog($path,$command);
                    }
                } else {
                    &logthis('Unable to do log query: '.$uname.'@'.$udom);
                    $result='no_such_file';
                }
                # end of log query
            } elsif (($query eq 'fetchenrollment') || 
                                           ($query eq 'institutionalphotos')) {
                # retrieve institutional class lists
                my $dom = &unescape($arg1);
                my %affiliates = ();
                my %replies = ();
                my $locresult = '';
                my $querystr = &unescape($arg3);
                foreach (split/%%/,$querystr) {
                    if (/^([^=]+)=([^=]+)$/) {
                        @{$affiliates{$1}} = split/,/,$2;
                    }
                }
                if ($query eq 'fetchenrollment') { 
                    $locresult = &localenroll::fetch_enrollment($dom,\%affiliates,\%replies);
                } elsif ($query eq 'institutionalphotos') {
                    my $crs = &unescape($arg2);
                    $locresult = &localenroll::institutional_photos($dom,$crs,\%affiliates,\%replies,'update');
                }
                $result = &escape($locresult.':');
                if ($locresult) {
                    $result .= &escape(join(':',map{$_.'='.$replies{$_}} keys %replies));
                }
            } elsif ($query eq 'prepare activity log') {
                my ($cid,$domain) = map {&unescape($_);} ($arg1,$arg2);
                &logthis('preparing activity log tables for '.$cid);
                my $command = 
                    qq{$perlvar{'lonDaemons'}/parse_activity_log.pl -course=$cid -domain=$domain};
                system($command);
                &logthis($command);
                my $returnvalue = $?>>8;
                if ($returnvalue) {
                    $result = 'error: parse_activity_log.pl returned '.
                        $returnvalue;
                } else {
                    $result = 'success';
                }
            } else {
                # Do an sql query
                $result = &do_sql_query($query,$arg1,$arg2);
            }
            # result does not need to be escaped because it has already been
            # escaped.
            #$result=&escape($result);
            &reply("queryreply:$queryid:$result",$conserver);
        }
        # tidy up gracefully and finish
        #
        # close the database handle
	$dbh->disconnect
            or &logthis("<font color='blue'>WARNING: Couldn't disconnect".
                        " from database  $DBI::errstr : $@</font>");
        # this exit is VERY important, otherwise the child will become
        # a producer of more and more children, forking yourself into
        # process death.
        exit;
    }
}

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

=pod

=item &do_sql_query

Runs an sql metadata table query.

Inputs: $query, $custom, $customshow

Returns: A string containing escaped results.

=cut

########################################################
########################################################
{
    my @metalist;

sub process_file {
    if ( -e $_ &&  # file exists
         -f $_ &&  # and is a normal file
         /\.meta$/ &&  # ends in meta
         ! /^.+\.\d+\.[^\.]+\.meta$/  # is not a previous version
         ) {
        push(@metalist,$File::Find::name);
    }
}

sub do_sql_query {
    my ($query,$custom,$customshow) = @_;
#    &logthis('doing query '.$query);
    $custom     = &unescape($custom);
    $customshow = &unescape($customshow);
    #
    @metalist = ();
    #
    my $result = '';
    my @results = ();
    my @files;
    my $subsetflag=0;
    #
    if ($query) {
        #prepare and execute the query
        my $sth = $dbh->prepare($query);
        unless ($sth->execute()) {
            &logthis('<font color="blue">'.
                     'WARNING: Could not retrieve from database:'.
                     $sth->errstr().'</font>');
        } else {
            my $aref=$sth->fetchall_arrayref;
            foreach my $row (@$aref) {
                push @files,@{$row}[3] if ($custom or $customshow);
                my @b=map { &escape($_); } @$row;
                push @results,join(",", @b);
                # Build up the @files array with the LON-CAPA urls 
                # of the resources.
            }
        }
    }
    # do custom metadata searching here and build into result
    return join("&",@results) if (! ($custom or $customshow));
    # Only get here if there is a custom query or custom show request
    &logthis("Doing custom query for $custom");
    if ($query) {
        @metalist=map {
            $perlvar{'lonDocRoot'}.$_.'.meta';
        } @files;
    } else {
        my $dir = "$perlvar{'lonDocRoot'}/res/$perlvar{'lonDefDomain'}";
        @metalist=(); 
        opendir(RESOURCES,$dir);
        my @homeusers=grep {
            &ishome($dir.'/'.$_);
        } grep {!/^\.\.?$/} readdir(RESOURCES);
        closedir RESOURCES;
        # Define the
        foreach my $user (@homeusers) {
            find (\&process_file,$dir.'/'.$user);
        }
    } 
    # if file is indicated in sql database and
    #     not part of sql-relevant query, do not pattern match.
    #
    # if file is not in sql database, output error.
    #
    # if file is indicated in sql database and is
    #     part of query result list, then do the pattern match.
    my $customresult='';
    my @results;
    foreach my $metafile (@metalist) {
        my $fh=IO::File->new($metafile);
        my @lines=<$fh>;
        my $stuff=join('',@lines);
        if ($stuff=~/$custom/s) {
            foreach my $f ('abstract','author','copyright',
                           'creationdate','keywords','language',
                           'lastrevisiondate','mime','notes',
                           'owner','subject','title') {
                $stuff=~s/\n?\<$f[^\>]*\>.*?<\/$f[^\>]*\>\n?//s;
            }
            my $mfile=$metafile; 
            my $docroot=$perlvar{'lonDocRoot'};
            $mfile=~s/^$docroot//;
            $mfile=~s/\.meta$//;
            unless ($query) {
                my $q2="SELECT * FROM metadata WHERE url ".
                    " LIKE BINARY '?'";
                my $sth = $dbh->prepare($q2);
                $sth->execute($mfile);
                my $aref=$sth->fetchall_arrayref;
                foreach my $a (@$aref) {
                    my @b=map { &escape($_)} @$a;
                    push @results,join(",", @b);
                }
            }
            # &logthis("found: $stuff");
            $customresult.='&custom='.&escape($mfile).','.
                escape($stuff);
        }
    }
    $result=join("&",@results) unless $query;
    $result.=$customresult;
    #
    return $result;
} # End of &do_sql_query

} # End of scoping curly braces for &process_file and &do_sql_query
########################################################
########################################################

=pod

=item &logthis

Inputs: $message, the message to log

Returns: nothing

Writes $message to the logfile.

=cut

########################################################
########################################################
sub logthis {
    my $message=shift;
    my $execdir=$perlvar{'lonDaemons'};
    my $fh=IO::File->new(">>$execdir/logs/lonsql.log");
    my $now=time;
    my $local=localtime($now);
    print $fh "$local ($$): $message\n";
}

# -------------------------------------------------- Non-critical communication

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

=pod

=item &subreply

Sends a command to a server.  Called only by &reply.

Inputs: $cmd,$server

Returns: The results of the message or 'con_lost' on error.

=cut

########################################################
########################################################
sub subreply {
    my ($cmd,$server)=@_;
    my $peerfile="$perlvar{'lonSockDir'}/$server";
    my $sclient=IO::Socket::UNIX->new(Peer    =>"$peerfile",
                                      Type    => SOCK_STREAM,
                                      Timeout => 10)
       or return "con_lost";
    print $sclient "$cmd\n";
    my $answer=<$sclient>;
    chomp($answer);
    $answer="con_lost" if (!$answer);
    return $answer;
}

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

=pod

=item &reply

Sends a command to a server.

Inputs: $cmd,$server

Returns: The results of the message or 'con_lost' on error.

=cut

########################################################
########################################################
sub reply {
  my ($cmd,$server)=@_;
  my $answer;
  if ($server ne $perlvar{'lonHostID'}) { 
    $answer=subreply($cmd,$server);
    if ($answer eq 'con_lost') {
	$answer=subreply("ping",$server);
        $answer=subreply($cmd,$server);
    }
  } else {
    $answer='self_reply';
    $answer=subreply($cmd,$server);
  } 
  return $answer;
}

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

=pod

=item &escape

Escape special characters in a string.

Inputs: string to escape

Returns: The input string with special characters escaped.

=cut

########################################################
########################################################
sub escape {
    my $str=shift;
    $str =~ s/(\W)/"%".unpack('H2',$1)/eg;
    return $str;
}

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

=pod

=item &unescape

Unescape special characters in a string.

Inputs: string to unescape

Returns: The input string with special characters unescaped.

=cut

########################################################
########################################################
sub unescape {
    my $str=shift;
    $str =~ s/%([a-fA-F0-9][a-fA-F0-9])/pack("C",hex($1))/eg;
    return $str;
}

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

=pod

=item &ishome

Determine if the current machine is the home server for a user.
The determination is made by checking the filesystem for the users information.

Inputs: $author

Returns: 0 - this is not the authors home server, 1 - this is.

=cut

########################################################
########################################################
sub ishome {
    my $author=shift;
    $author=~s/\/home\/httpd\/html\/res\/([^\/]*)\/([^\/]*).*/$1\/$2/;
    my ($udom,$uname)=split(/\//,$author);
    my $proname=propath($udom,$uname);
    if (-e $proname) {
	return 1;
    } else {
        return 0;
    }
}

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

=pod

=item &propath

Inputs: user name, user domain

Returns: The full path to the users directory.

=cut

########################################################
########################################################
sub propath {
    my ($udom,$uname)=@_;
    $udom=~s/\W//g;
    $uname=~s/\W//g;
    my $subdir=$uname.'__';
    $subdir =~ s/(.)(.)(.).*/$1\/$2\/$3/;
    my $proname="$perlvar{'lonUsersDir'}/$udom/$subdir/$uname";
    return $proname;
} 

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

=pod

=item &courselog

Inputs: $path, $command

Returns: unescaped string of values.

=cut

########################################################
########################################################
sub courselog {
    my ($path,$command)=@_;
    my %filters=();
    foreach (split(/\:/,&unescape($command))) {
	my ($name,$value)=split(/\=/,$_);
        $filters{$name}=$value;
    }
    my @results=();
    open(IN,$path.'/activity.log') or return ('file_error');
    while (my $line=<IN>) {
        chomp($line);
        my ($timestamp,$host,$log)=split(/\:/,$line);
#
# $log has the actual log entries; currently still escaped, and
# %26(timestamp)%3a(url)%3a(user)%3a(domain)
# then additionally
# %3aPOST%3a(name)%3d(value)%3a(name)%3d(value)
# or
# %3aCSTORE%3a(name)%3d(value)%26(name)%3d(value)
#
# get delimiter between timestamped entries to be &&&
        $log=~s/\%26(\d+)\%3a/\&\&\&$1\%3a/g;
# now go over all log entries 
        foreach (split(/\&\&\&/,&unescape($log))) {
	    my ($time,$res,$uname,$udom,$action,@values)=split(/\:/,$_);
            my $values=&unescape(join(':',@values));
            $values=~s/\&/\:/g;
            $res=&unescape($res);
            my $include=1;
            if (($filters{'username'}) && ($uname ne $filters{'username'})) 
                                                               { $include=0; }
            if (($filters{'domain'}) && ($udom ne $filters{'domain'})) 
                                                               { $include=0; }
            if (($filters{'url'}) && ($res!~/$filters{'url'}/)) 
                                                               { $include=0; }
            if (($filters{'start'}) && ($time<$filters{'start'})) 
                                                               { $include=0; }
            if (($filters{'end'}) && ($time>$filters{'end'})) 
                                                               { $include=0; }
            if (($filters{'action'} eq 'view') && ($action)) 
                                                               { $include=0; }
            if (($filters{'action'} eq 'submit') && ($action ne 'POST')) 
                                                               { $include=0; }
            if (($filters{'action'} eq 'grade') && ($action ne 'CSTORE')) 
                                                               { $include=0; }
            if ($include) {
	       push(@results,($time<1000000000?'0':'').$time.':'.$res.':'.
                                            $uname.':'.$udom.':'.
                                            $action.':'.$values);
            }
       }
    }
    close IN;
    return join('&',sort(@results));
}

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

=pod

=item &userlog

Inputs: $path, $command

Returns: unescaped string of values.

=cut

########################################################
########################################################
sub userlog {
    my ($path,$command)=@_;
    my %filters=();
    foreach (split(/\:/,&unescape($command))) {
	my ($name,$value)=split(/\=/,$_);
        $filters{$name}=$value;
    }
    my @results=();
    open(IN,$path.'/activity.log') or return ('file_error');
    while (my $line=<IN>) {
        chomp($line);
        my ($timestamp,$host,$log)=split(/\:/,$line);
        $log=&unescape($log);
        my $include=1;
        if (($filters{'start'}) && ($timestamp<$filters{'start'})) 
                                                             { $include=0; }
        if (($filters{'end'}) && ($timestamp>$filters{'end'})) 
                                                             { $include=0; }
        if (($filters{'action'} eq 'log') && ($log!~/^Log/)) { $include=0; }
        if (($filters{'action'} eq 'check') && ($log!~/^Check/)) 
                                                             { $include=0; }
        if ($include) {
	   push(@results,$timestamp.':'.$log);
        }
    }
    close IN;
    return join('&',sort(@results));
}

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

=pod

=item Functions required for forking

=over 4

=item REAPER

REAPER takes care of dead children.

=item HUNTSMAN

Signal handler for SIGINT.

=item HUPSMAN

Signal handler for SIGHUP

=item DISCONNECT

Disconnects from database.

=back

=cut

########################################################
########################################################
sub REAPER {                   # takes care of dead children
    $SIG{CHLD} = \&REAPER;
    my $pid = wait;
    $children --;
    &logthis("Child $pid died");
    delete $children{$pid};
}

sub HUNTSMAN {                      # signal handler for SIGINT
    local($SIG{CHLD}) = 'IGNORE';   # we're going to kill our children
    kill 'INT' => keys %children;
    my $execdir=$perlvar{'lonDaemons'};
    unlink("$execdir/logs/lonsql.pid");
    &logthis("<font color='red'>CRITICAL: Shutting down</font>");
    $unixsock = "mysqlsock";
    my $port="$perlvar{'lonSockDir'}/$unixsock";
    unlink($port);
    exit;                           # clean up with dignity
}

sub HUPSMAN {                      # signal handler for SIGHUP
    local($SIG{CHLD}) = 'IGNORE';  # we're going to kill our children
    kill 'INT' => keys %children;
    close($server);                # free up socket
    &logthis("<font color='red'>CRITICAL: Restarting</font>");
    my $execdir=$perlvar{'lonDaemons'};
    $unixsock = "mysqlsock";
    my $port="$perlvar{'lonSockDir'}/$unixsock";
    unlink($port);
    exec("$execdir/lonsql");         # here we go again
}

sub DISCONNECT {
    $dbh->disconnect or 
    &logthis("<font color='blue'>WARNING: Couldn't disconnect from database ".
             " $DBI::errstr : $@</font>");
    exit;
}


=pod

=back

=cut

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