################################################################################
sub session_access_log_directory () {
        "$preconf->{_}->{docroot}session_access_logs";
}
################################################################################
sub session_access_log_filename () {
        session_access_log_directory . "/$_REQUEST{sid}.4k";
}
################################################################################
sub session_access_logs_purge {
         
        my %session = ();
         
        my $directory = session_access_log_directory;
        opendir (DIR, $directory) or die "Can't opendir $directory:$!\n";
        while (my $file_name = readdir (DIR)) { 
                $file_name =~ /\.4k$/ and $session {$`} = \$directory;
                 
        }
         
        closedir (DIR);
         
        sql_select_loop ('SELECT id FROM sessions', sub {
         
                delete $session {$i -> {id}};
                 
        });
         
        foreach (keys %session) { eval {
         
                unlink "$directory/$_.4k";
                 
        }}
         
}
################################################################################
sub session_access_log_get {
         
        my $buf;
         
        open (F, session_access_log_filename) or return undef;
         
        seek (F, ($_[0] - 1) << 12, 0);
         
        read (F, $buf, 4096);
        close (F);
         
        return $buf =~ / / ? $` : $buf;
}
################################################################################
sub session_access_log_append {
        my ($href) = @_;
        my $filename = session_access_log_filename;
         
        open (F, ">>$filename") or die "Can't append to $filename:$!";
         
        print F $href;
         
        my $no = (tell F) >> 12;
         
        close (F);
         
        return $no;
}
################################################################################
sub session_access_log_set {
        my ($href) = @_;
        $href =~ s{^https?\://}{};
         
        if ($href =~ /[\/\?]/) {
                 
                $href = $& . $';
         
        }
                 
        foreach my $key (qw(
                _salt
                salt
                sid
                id___query
                __next_query_string
        )) {
         
                $href =~ s{\&?${key}=[\d\.]+}{}g;
         
        }
         
        $href = substr $href, 0, 4095;
        $href .= (' ' x (4095 - length $href));
         
        $href .= "\015";
         
        my $filename = session_access_log_filename;
         
        -f $filename or return session_access_log_append ($href);
         
        my $size = -s $filename;
         
        if ($size % 4096) {
         
                unlink $filename;
                 
                return session_access_log_append ($href);               
         
        }
         
        my $max = $size >> 12;
         
        my $min = $max > 16 ? $max - 16 : 1;
         
        my $n;
         
        my $buf;
         
        open (F, "$filename") or die "Can't read $filename:$!";
        for (my $i = $max; $i >= $min; $i --) {
         
                seek (F, ($i - 1) << 12, 0);
                read (F, $buf, 4096);
                 
                $buf eq $href or next;
                 
                $n = $i;
                 
                last;
         
        }
         
        close (F);
         
        return $n ? $n : session_access_log_append ($href);
}
1;