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    1: #!/usr/bin/perl
    2: #
    3: # The LearningOnline Network with CAPA
    4: # Connect to MAXIMA CAS
    5: #
    6: # $Id: lonmaxima,v 1.21 2006/05/10 02:21:19 www Exp $
    7: #
    8: # Copyright Michigan State University Board of Trustees
    9: #
   10: # This file is part of the LearningOnline Network with CAPA (LON-CAPA).
   11: #
   12: # LON-CAPA is free software; you can redistribute it and/or modify
   13: # it under the terms of the GNU General Public License as published by
   14: # the Free Software Foundation; either version 2 of the License, or
   15: # (at your option) any later version.
   16: #
   17: # LON-CAPA is distributed in the hope that it will be useful,
   18: # but WITHOUT ANY WARRANTY; without even the implied warranty of
   19: # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   20: # GNU General Public License for more details.
   21: #
   22: # You should have received a copy of the GNU General Public License
   23: # along with LON-CAPA; if not, write to the Free Software
   24: # Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
   25: #
   26: # /home/httpd/html/adm/gpl.txt
   27: #
   28: 
   29: # 
   30: # http://www.lon-capa.org/
   31: #
   32: 
   33: use Expect; 
   34: use IO::Select;
   35: use IO::Socket;
   36: use IO::File;
   37: use Symbol;
   38: use POSIX;
   39: use lib '/home/httpd/lib/perl/';
   40: use LONCAPA::Configuration;
   41:  
   42: use strict;
   43: 
   44: # global variables
   45: my $PREFORK                = 5;        # number of children to maintain
   46: my $MAX_CLIENTS_PER_CHILD  = 50;       # number of clients each child should process
   47: my %children               = ();       # keys are current child process IDs
   48: my $children               = 0;        # current number of children
   49: my $status;                            # string for current status
   50: my $pidfile;                           # file containg parent process pid
   51: my $port;                              # path to UNIX socket file
   52: my %perlvar;                           # configuration file info
   53: my $lastlog;                           # last string that was logged
   54: 
   55: use vars qw($PREFORK $MAX_CLIENTS_PER_CHILD %children $children $status
   56: 	    $pidfile $port %perlvar $lastlog);
   57:  
   58: # ------------------------------------------------------------ Service routines 
   59: sub REAPER {                        # takes care of dead children 
   60:                                     # and MAXIMA processes
   61:     $SIG{CHLD} = \&REAPER;
   62:     my $pid = wait;
   63:     $children--;
   64:     delete($children{$pid});
   65: }
   66:  
   67: sub HUNTSMAN {                      # signal handler for SIGINT
   68:     local($SIG{CHLD}) = 'IGNORE';   # we're going to kill our children
   69:     kill('INT' => keys(%children));
   70:     unlink($pidfile);
   71:     unlink($port);
   72:     &logthis('---- Shutdown ----');
   73:     exit;                           # clean up with dignity
   74: }
   75: 
   76: 
   77:  
   78: # --------------------------------------------------------------------- Logging
   79:  
   80: sub logthis {
   81:     my ($message)=@_;
   82:     my $execdir=$perlvar{'lonDaemons'};
   83:     my $fh=IO::File->new(">>$execdir/logs/lonmaxima.log");
   84:     my $now=time;
   85:     my $local=localtime($now);
   86:     $lastlog=$local.': '.$message;
   87:     print $fh "$local ($$): $message\n";
   88: }
   89:  
   90: # -------------------------------------------------------------- Status setting
   91:  
   92: sub status {
   93:     my ($what)=@_;
   94:     my $now=time;
   95:     my $local=localtime($now);
   96:     $status=$local.': '.$what;
   97:     $0='lonmaxima: '.$what.' '.$local;
   98: }
   99:  
  100: # -------------------------------------------------------- Escape Special Chars
  101:  
  102: sub escape {
  103:     my ($str)=@_;
  104:     $str =~ s/(\W)/"%".unpack('H2',$1)/eg;
  105:     return $str;
  106: }
  107:  
  108: # ----------------------------------------------------- Un-Escape Special Chars
  109:  
  110: sub unescape {
  111:     my ($str)=@_;
  112:     $str =~ s/%([a-fA-F0-9][a-fA-F0-9])/pack("C",hex($1))/eg;
  113:     return $str;
  114: }
  115:  
  116: # ------------------------ grabs exception and records it to log before exiting
  117: sub catchexception {
  118:     my ($signal)=@_;
  119:     $SIG{QUIT}='DEFAULT';
  120:     $SIG{__DIE__}='DEFAULT';
  121:     chomp($signal);
  122:     &logthis("<font color=\"red\">CRITICAL: "
  123: 	     ."ABNORMAL EXIT. Child $$ died through "
  124: 	     ."\"$signal\"</font>");
  125:     die("Signal abend");
  126: }
  127: 
  128: 
  129: 
  130: # ---------------------------------------------------------------- Main program
  131: # -------------------------------- Set signal handlers to record abnormal exits
  132:  
  133:  
  134: $SIG{'QUIT'}=\&catchexception;
  135: $SIG{__DIE__}=\&catchexception;
  136:  
  137: # ---------------------------------- Read loncapa_apache.conf and loncapa.conf
  138: &status("Read loncapa.conf and loncapa_apache.conf");
  139: %perlvar=%{&LONCAPA::Configuration::read_conf('loncapa.conf')};
  140:  
  141: # ----------------------------- Make sure this process is running from user=www
  142: my $wwwid=getpwnam('www');
  143: if ($wwwid!=$<) {
  144:     my $emailto="$perlvar{'lonAdmEMail'},$perlvar{'lonSysEMail'}";
  145:     my $subj="LON: User ID mismatch";
  146:     system("echo 'User ID mismatch.  lonmaxima must be run as user www.' |\
  147:  mailto $emailto -s '$subj' > /dev/null");
  148:     exit 1;
  149: }
  150:  
  151: # --------------------------------------------- Check if other instance running
  152:  
  153: $pidfile="$perlvar{'lonDaemons'}/logs/lonmaxima.pid";
  154:  
  155: if (-e $pidfile) {
  156:     my $lfh=IO::File->new("$pidfile");
  157:     my $pide=<$lfh>;
  158:     chomp($pide);
  159:     if (kill(0 => $pide)) { die "already running"; }
  160: }
  161: 
  162: # ------------------------------------------------------- Listen to UNIX socket
  163: &status("Opening socket");
  164:  
  165: $port = "$perlvar{'lonSockDir'}/maximasock";
  166:  
  167: unlink($port);
  168:  
  169: 
  170: my $server = IO::Socket::UNIX->new(Local  => $port,
  171: 				   Type   => SOCK_STREAM,
  172: 				   Listen => 10 );
  173: if (!$server) {
  174:     my $st=120+int(rand(240));
  175: 
  176:     &logthis("<font color=blue>WARNING: ".
  177: 	     "Can't make server socket ($st secs):  .. exiting</font>");
  178: 
  179:     sleep($st);
  180:     exit;
  181: }
  182:     
  183:  
  184: # ---------------------------------------------------- Fork once and dissociate
  185:  
  186: my $fpid=fork;
  187: exit if $fpid;
  188: die("Couldn't fork: $!") unless defined($fpid);
  189:  
  190: POSIX::setsid() or die "Can't start new session: $!";
  191:  
  192: # ------------------------------------------------------- Write our PID on disk
  193:  
  194: my $execdir=$perlvar{'lonDaemons'};
  195: open(PIDSAVE,">$execdir/logs/lonmaxima.pid");
  196: print PIDSAVE "$$\n";
  197: close(PIDSAVE);
  198: &logthis("<font color='red'>CRITICAL: ---------- Starting ----------</font>");
  199: &status('Starting');
  200:      
  201: 
  202: # Install signal handlers.
  203: $SIG{CHLD} = \&REAPER;
  204: $SIG{INT}  = $SIG{TERM} = \&HUNTSMAN;
  205:  
  206: # Fork off our children.
  207: for (1 .. $PREFORK) {
  208:     &make_new_child($server);
  209: }
  210:  
  211: # And maintain the population.
  212: while (1) {
  213:     &status('Parent process, sleeping');
  214:     sleep;                          # wait for a signal (i.e., child's death)
  215:     for (my $i = $children; $i < $PREFORK; $i++) {
  216:         &status('Parent process, starting child');
  217:         &make_new_child($server);           # top up the child pool
  218:     }
  219: }
  220:                                                                                 
  221: sub make_new_child {
  222:     my ($server) = @_;
  223: 
  224:     # block signal for fork
  225:     my $sigset = POSIX::SigSet->new(SIGINT);
  226:     sigprocmask(SIG_BLOCK, $sigset)
  227:         or die("Can't block SIGINT for fork: $!\n");
  228:      
  229:     die("fork: $!") unless defined(my $pid = fork);
  230:      
  231:     if ($pid) {
  232:         # Parent records the child's birth and returns.
  233:         sigprocmask(SIG_UNBLOCK, $sigset)
  234:             or die("Can't unblock SIGINT for fork: $!\n");
  235:         $children{$pid} = 1;
  236:         $children++;
  237:         return;
  238:     } else {
  239:         # Child can *not* return from this subroutine.
  240:         $SIG{INT} = 'DEFAULT';      # make SIGINT kill us as it did before
  241:      
  242:         # unblock signals
  243:         sigprocmask(SIG_UNBLOCK, $sigset)
  244:             or die("Can't unblock SIGINT for fork: $!\n");
  245: 
  246:         &logthis('New process started');
  247: 
  248:         my $command=Expect->spawn('maxima');
  249:         $command->log_stdout(0);
  250: 
  251:         &getmaximaoutput($command);
  252: 
  253:         for (my $i=0; $i < $MAX_CLIENTS_PER_CHILD; $i++) {
  254:            &status('Accepting connections');
  255:            my $client = $server->accept()     or last;
  256:            print $command "kill(all);reset();\n";
  257: 	   &getmaximaoutput($command);
  258:            &sync($command);
  259:            while (my $cmd=<$client>) {
  260:               &status('Processing command');
  261:               print $command &unescape($cmd);
  262:               my $reply=&getmaximaoutput($command);
  263:               print $client &escape($reply)."\n";
  264:               if ($reply=~/^Error\:/) {
  265:                  &logthis('Died through '.$reply);
  266:                  $client->close();
  267:                  $command->hard_close();     
  268:                  exit;
  269:               }	      
  270: 	      &sync($command);
  271:               &status('Waiting for commands');
  272:            }
  273:         }
  274: 
  275:         # tidy up gracefully and finish
  276: 
  277:         $command->soft_close();
  278: 
  279:         # this exit is VERY important, otherwise the child will become
  280:         # a producer of more and more children, forking yourself into
  281:         # process death.
  282:         exit;
  283:     }
  284: }
  285: 
  286: {
  287:     my $counter;
  288:     sub sync {
  289: 	my ($command)=@_;
  290: 	$counter++;
  291: 	my $expect=$counter.time;
  292: 	print $command "$expect;\n";
  293: 	while (1) {
  294: 	    my $output=&getmaximaoutput($command);
  295: 	    if (($output=~/\Q$expect\E/) || ($output=~/^Error\:/)) {
  296: 		return;
  297: 	    }
  298: 	}
  299:     }
  300: }
  301: 
  302: sub getmaximaoutput {
  303:     my ($command)=@_;
  304:     my (undef,$error,undef,$output)=$command->expect(20, -re => '\(\%i\d+\)');
  305:     if ($error) {
  306:        return 'Error: '.$error;
  307:     }
  308:     my $foundoutput=0;
  309:     my $realoutput='';
  310:     foreach my $line (split(/\n/,$output)) {
  311:        if ($line=~/\;/) { $foundoutput=1; next; }
  312:        if (!$foundoutput) { next; }
  313:        my ($label)=($line=~s/^(\(\%o\d+\))//);
  314:        if ($label) {
  315:           $label=~s/\S/ /g;
  316:           $line=$label.$line;
  317:        }
  318:        $realoutput.=$line."\n";
  319:     }
  320:     return $realoutput;
  321: }