File:  [LON-CAPA] / loncom / lonsql
Revision 1.91: download - view: text, annotated - select for diffs
Mon Nov 7 18:13:38 2011 UTC (13 years, 1 month ago) by raeburn
Branches: MAIN
CVS tags: language_hyphenation_merge, language_hyphenation, HEAD, BZ4492-merge, BZ4492-feature_horizontal_radioresponse, BZ4492-feature_Support_horizontal_radioresponse, BZ4492-Support_horizontal_radioresponse
- use lonDocRoot perlvar in place of static string: '/home/httpd/html'.

#!/usr/bin/perl

# The LearningOnline Network
# lonsql - LON TCP-MySQL-Server Daemon for handling database requests.
#
# $Id: lonsql,v 1.91 2011/11/07 18:13:38 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;
use LONCAPA::Configuration;
use LONCAPA::lonmetadata();
use Apache::lonnet;

use IO::Socket;
use Symbol;
use POSIX;
use IO::Select;
use DBI;
use File::Find;
use localenroll;
use GDBM_File;

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

=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 %perlvar=%{&LONCAPA::Configuration::read_conf('loncapa.conf')};
#
# 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,">$perlvar{'lonDocRoot'}/lon-status/mysql.txt");
    print SMP 'time='.time.'&mysql=defunct'."\n";
    close(SMP);

    exit 1;
} else {
    unlink("$perlvar{'lonDocRoot'}/lon-status/mysql.txt");
    $dbh->disconnect;
}

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

my $PREFORK=4; # number of children to maintain, at least four spare
#
#$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);
            $userinput=~s/\:($LONCAPA::domain_re)$//;
            my $searchdomain=$1;
            #
	    my ($conserver,$query,
		$arg1,$arg2,$arg3)=split(/&/,$userinput);
	    my $query=unescape($query);
            #
            #send query id which is pid_unixdatetime_runningcounter
	    my $queryid = &Apache::lonnet::hostname($perlvar{'lonHostID'});
	    $queryid .="_".($$)."_";
	    $queryid .= time."_";
	    $queryid .= $run;
	    print $client "$queryid\n";
	    #
	    # &logthis("QUERY: $query - $arg1 - $arg2 - $arg3 - $queryid");
	    # 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);
                    }
                    $result = &escape($result);
                } 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);
		    eval {
			local($SIG{__DIE__})='DEFAULT';
			$locresult = &localenroll::institutional_photos($dom,$crs,\%affiliates,\%replies,'update');
		    };
		    if ($@) {
			$locresult = 'error';
		    }
                }
                $result = &escape($locresult.':');
                if ($locresult) {
                    $result .= &escape(join(':',map{$_.'='.$replies{$_}} keys %replies));
                }
            } elsif ($query eq 'usersearch') {
                my ($srchby,$srchtype,$srchterm);
                if ((&unescape($arg1) eq $searchdomain) &&
                    ($arg2 =~ /\%\%/)) {
                    ($srchby,$srchtype) =
                        map {&unescape($_);} (split(/\%\%/,$arg2));
                    $srchterm = &unescape($arg3);
                } else {
                    ($srchby,$srchtype,$srchterm) =
                        map {&unescape($_);} ($arg1,$arg2,$arg3);
                }
                $result = &do_user_search($searchdomain,$srchby,
                                          $srchtype,$srchterm);
	    } elsif ($query eq 'instdirsearch') {
		$result = &do_inst_dir_search($searchdomain,$arg1,$arg2,$arg3);
            } elsif ($query eq 'getinstuser') {
                $result = &get_inst_user($searchdomain,$arg1,$arg2);
            } 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 {
                    $result = 'success';
                }
            } elsif (($query eq 'portfolio_metadata') || 
                    ($query eq 'portfolio_access')) {
                $result = &portfolio_table_update($query,$arg1,$arg2,
                                                  $arg3);
            } elsif ($query eq 'allusers') {
                my ($uname,$udom) = map {&unescape($_);} ($arg1,$arg2);
                my %userdata;
                my (@data) = split(/\%\%/,$arg3);
                foreach my $item (@data) {
                    my ($key,$value) = split(/=/,$item);
                    $userdata{$key} = &unescape($value);
                }
                $userdata{'username'} = $uname;
                $userdata{'domain'} = $udom;
                $result = &allusers_table_update($query,$uname,$udom,\%userdata);
            } else {
                # Do an sql query
                $result = &do_sql_query($query,$arg1,$arg2,$searchdomain);
            }
            # result does not need to be escaped because it has already been
            # escaped.
            #$result=&escape($result);
            &Apache::lonnet::reply("queryreply:$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;
    }
}

sub do_user_search {
    my ($domain,$srchby,$srchtype,$srchterm) = @_;
    my $result;
    my $quoted_dom = $dbh->quote( $domain );
    my ($query,$quoted_srchterm,@fields);
    my ($table_columns,$table_indices) =
        &LONCAPA::lonmetadata::describe_metadata_storage('allusers');
    foreach my $coldata (@{$table_columns}) {
        push(@fields,$coldata->{'name'});
    }
    my $fieldlist = join(',',@fields);
    $query = "SELECT $fieldlist FROM allusers WHERE (domain = $quoted_dom AND ";
    if ($srchby eq 'lastfirst') {
        my ($fraglast,$fragfirst) = split(/,/,$srchterm);
        $fragfirst =~ s/^\s+//;
        $fraglast =~ s/\s+$//;
        if ($srchtype eq 'exact') {
            $query .= 'lastname = '.$dbh->quote($fraglast).
                      ' AND firstname = '.$dbh->quote($fragfirst);
        } elsif ($srchtype eq 'begins') {
            $query .= 'lastname LIKE '.$dbh->quote($fraglast.'%').
                      ' AND firstname LIKE '.$dbh->quote($fragfirst.'%');
        } else {
            $query .= 'lastname LIKE '.$dbh->quote('%'.$fraglast.'%').
                      ' AND firstname LIKE '.$dbh->quote('%'.$fragfirst.'%');
        }
    } else {
        my %srchfield = (
                          uname    => 'username',
                          lastname => 'lastname',
                        );
        if ($srchtype eq 'exact') {
            $query .= $srchfield{$srchby}.' = '.$dbh->quote($srchterm);
        } elsif ($srchtype eq 'begins') {
             $query .= $srchfield{$srchby}.' LIKE '.$dbh->quote($srchterm.'%');
        } else {
             $query .= $srchfield{$srchby}.' LIKE '.$dbh->quote('%'.$srchterm.'%');
        }
    }
    $query .= ") ORDER BY username ";
    my $sth = $dbh->prepare($query);
    if ($sth->execute()) {
        my @results;
        while (my @row = $sth->fetchrow_array) {
            my @items;
            for (my $i=0; $i<@row; $i++) {
                push(@items,&escape($fields[$i]).'='.&escape($row[$i]));
            }
            my $userstr = join(':', @items);
            push(@results,&escape($userstr));
        }
        $sth->finish;
        $result = join('&',@results);
    } else {
        &logthis('<font color="blue">'.
                'WARNING: Could not retrieve from database:'.
        $sth->errstr().'</font>');
    }
    return $result;
}

sub do_inst_dir_search {
    my ($domain,$srchby,$srchterm,$srchtype) = @_;
    $srchby   = &unescape($srchby);
    $srchterm = &unescape($srchterm);
    $srchtype = &unescape($srchtype);
    my (%instusers,%instids,$result,$response);
    eval {
        local($SIG{__DIE__})='DEFAULT';
        $result=&localenroll::get_userinfo($domain,undef,undef,\%instusers,
					   \%instids,undef,$srchby,$srchterm,
					   $srchtype);
    };
    if ($result eq 'ok') {
        if (%instusers) {
            foreach my $key (keys(%instusers)) {
                my $usrstr = &Apache::lonnet::freeze_escape($instusers{$key});
                $response .=&escape(&escape($key).'='.$usrstr).'&';
            }
        }
        $response=~s/\&$//;
    } else {
        $response = 'unavailable';
    }
    return $response;
}

sub get_inst_user {
    my ($domain,$uname,$id) = @_;
    $uname = &unescape($uname);
    $id = &unescape($id);
    my (%instusers,%instids,$result,$response);
    eval {
        local($SIG{__DIE__})='DEFAULT';
        $result=&localenroll::get_userinfo($domain,$uname,$id,\%instusers,
                                           \%instids);
    };
    if ($result eq 'ok') {
        if (keys(%instusers) > 0) {
            foreach my $key (keys(%instusers)) {
                my $usrstr = &Apache::lonnet::freeze_escape($instusers{$key});
                $response .= &escape(&escape($key).'='.$usrstr).'&';
            }
        }
        $response=~s/\&$//;
    } else {
        $response = 'unavailable';
    }
    return $response;
}

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

=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,$customshow,$searchdomain) = @_;

#
# limit to searchdomain if given and table is metadata
#
    if (($searchdomain) && ($query=~/FROM metadata/)) {
	$query.=' HAVING (domain="'.$searchdomain.'")';
    }
#    &logthis('doing query ('.$searchdomain.')'.$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) {
        open(my $fh,$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

sub portfolio_table_update { 
    my ($query,$arg1,$arg2,$arg3) = @_;
    my %tablenames = (
                       'portfolio'   => 'portfolio_metadata',
                       'access'      => 'portfolio_access',
                       'addedfields' => 'portfolio_addedfields',
                     );
    my $result = 'ok';
    my $tablechk = &check_table($query);
    if ($tablechk == 0) {
        my $request =
   &LONCAPA::lonmetadata::create_metadata_storage($query,$query);
        $dbh->do($request);
        if ($dbh->err) {
            &logthis("create $query".
                     " ERROR: ".$dbh->errstr);
                     $result = 'error';
        }
    }
    if ($result eq 'ok') {
        my ($uname,$udom,$group) = split(/:/,&unescape($arg1));
        my $file_name = &unescape($arg2);
        my $action = $arg3;
        my $is_course = 0;
        if ($group ne '') {
            $is_course = 1;
        }
        my $urlstart = '/uploaded/'.$udom.'/'.$uname;
        my $pathstart = &propath($udom,$uname).'/userfiles';
        my ($fullpath,$url);
        if ($is_course) {
            $fullpath = $pathstart.'/groups/'.$group.'/portfolio'.
                        $file_name;
            $url = $urlstart.'/groups/'.$group.'/portfolio'.$file_name;
        } else {
            $fullpath = $pathstart.'/portfolio'.$file_name;
            $url = $urlstart.'/portfolio'.$file_name;
        }
        if ($query eq 'portfolio_metadata') {
            if ($action eq 'delete') {
                my %loghash = &LONCAPA::lonmetadata::process_portfolio_metadata($dbh,undef,\%tablenames,$url,$fullpath,$is_course,$udom,$uname,$group,'update');
            } elsif (-e $fullpath.'.meta') {
                my %loghash = &LONCAPA::lonmetadata::process_portfolio_metadata($dbh,undef,\%tablenames,$url,$fullpath,$is_course,$udom,$uname,$group,'update');
                if (keys(%loghash) > 0) {
                    &portfolio_logging(%loghash);
                }
            }
        } elsif ($query eq 'portfolio_access') {
            my %access = &get_access_hash($uname,$udom,$group.$file_name);
            my %loghash =
     &LONCAPA::lonmetadata::process_portfolio_access_data($dbh,undef,
         \%tablenames,$url,$fullpath,\%access,'update');
            if (keys(%loghash) > 0) {
                &portfolio_logging(%loghash);
            } else {
                my $available = 0;
                foreach my $key (keys(%access)) {
                    my ($num,$scope,$end,$start) =
                        ($key =~ /^([^:]+):([a-z]+)_(\d*)_?(\d*)$/);
                    if ($scope eq 'public' || $scope eq 'guest') {
                        $available = 1;
                        last;
                    }
                }
                if ($available) {
                    # Retrieve current values
                    my $condition = 'url='.$dbh->quote("$url");
                    my ($error,$row) =
    &LONCAPA::lonmetadata::lookup_metadata($dbh,$condition,undef,
                                           'portfolio_metadata');
                    if (!$error) {
                        if (!(ref($row->[0]) eq 'ARRAY')) {  
                            my %loghash =
     &LONCAPA::lonmetadata::process_portfolio_metadata($dbh,undef,
         \%tablenames,$url,$fullpath,$is_course,$udom,$uname,$group);
                            if (keys(%loghash) > 0) {
                                &portfolio_logging(%loghash);
                            }
                        } 
                    }
                }
            }
        }
    }
    return $result;
}

sub get_access_hash {
    my ($uname,$udom,$file) = @_;
    my $hashref = &tie_user_hash($udom,$uname,'file_permissions',
                                 &GDBM_READER());
    my %curr_perms;
    my %access; 
    if ($hashref) {
        while (my ($key,$value) = each(%$hashref)) {
            $key = &unescape($key);
            next if ($key =~ /^error: 2 /);
            $curr_perms{$key}=&Apache::lonnet::thaw_unescape($value);
        }
        if (!&untie_user_hash($hashref)) {
            &logthis("error: ".($!+0)." untie (GDBM) Failed");
        }
    } else {
        &logthis("error: ".($!+0)." tie (GDBM) Failed");
    }
    if (keys(%curr_perms) > 0) {
        if (ref($curr_perms{$file."\0".'accesscontrol'}) eq 'HASH') {
            foreach my $acl (keys(%{$curr_perms{$file."\0".'accesscontrol'}})) {
                $access{$acl} = $curr_perms{$file."\0".$acl};
            }
        }
    }
    return %access;
}

sub allusers_table_update {
    my ($query,$uname,$udom,$userdata) = @_;
    my %tablenames = (
                       'allusers'   => 'allusers',
                     );
    my $result = 'ok';
    my $tablechk = &check_table($query);
    if ($tablechk == 0) {
        my $request =
   &LONCAPA::lonmetadata::create_metadata_storage($query,$query);
        $dbh->do($request);
        if ($dbh->err) {
            &logthis("create $query".
                     " ERROR: ".$dbh->errstr);
                     $result = 'error';
        }
    }
    if ($result eq 'ok') {
        my %loghash = 
            &LONCAPA::lonmetadata::process_allusers_data($dbh,undef,
                \%tablenames,$uname,$udom,$userdata,'update');
        foreach my $key (keys(%loghash)) {
            &logthis($loghash{$key});
        }
    }
    return $result;
}

###########################################
sub check_table {
    my ($table_id) = @_;
    my $sth=$dbh->prepare('SHOW TABLES');
    $sth->execute();
    my $aref = $sth->fetchall_arrayref;
    $sth->finish();
    if ($sth->err()) {
        &logthis("fetchall_arrayref after SHOW TABLES".
            " ERROR: ".$sth->errstr);
        return undef;
    }
    my $result = 0;
    foreach my $table (@{$aref}) {
        if ($table->[0] eq $table_id) { 
            $result = 1;
            last;
        }
    }
    return $result;
}

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

sub portfolio_logging {
    my (%portlog) = @_;
    foreach my $key (keys(%portlog)) {
        if (ref($portlog{$key}) eq 'HASH') {
            foreach my $item (keys(%{$portlog{$key}})) {
                &logthis($portlog{$key}{$item});
            }
        }
    }
}


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

=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'};
    open(my $fh,">>$execdir/logs/lonsql.log");
    my $now=time;
    my $local=localtime($now);
    print $fh "$local ($$): $message\n";
}

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

=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 &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 'Role') && ($log !~/^Role/))
                                                             { $include=0; }
        if (($filters{'action'} eq 'log') && ($log!~/^Log/)) { $include=0; }
        if (($filters{'action'} eq 'check') && ($log!~/^Check/)) 
                                                             { $include=0; }
        if ($include) {
	   push(@results,$timestamp.':'.$host.':'.&escape($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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