Annotation of loncom/lonmaxima, revision 1.17

1.1       www         1: #!/usr/bin/perl
                      2: #
                      3: # The LearningOnline Network with CAPA
                      4: # Connect to MAXIMA CAS
                      5: #
1.17    ! www         6: # $Id: lonmaxima,v 1.16 2006/03/08 22:30:11 www Exp $
1.1       www         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: #
1.2       www        32: 
1.16      www        33: use Expect; 
1.1       www        34: use IPC::Open3;
                     35: use IO::Select;
1.2       www        36: use IO::Socket;
                     37: use IO::File;
                     38: use Symbol;
                     39: use POSIX;
                     40: use lib '/home/httpd/lib/perl/';
                     41: use LONCAPA::Configuration;
                     42:  
1.3       albertel   43: use strict;
                     44: 
                     45: # global variables
                     46: my $PREFORK                = 5;        # number of children to maintain
1.17    ! www        47: my $MAX_CLIENTS_PER_CHILD  = 50;       # number of clients each child should process
1.3       albertel   48: my %children               = ();       # keys are current child process IDs
                     49: my $children               = 0;        # current number of children
                     50: my $status;                            # string for current status
1.5       albertel   51: my $pidfile;                           # file containg parent process pid
                     52: my $port;                              # path to UNIX socket file
                     53: my %perlvar;                           # configuration file info
                     54: my $lastlog;                           # last string that was logged
1.16      www        55: use vars qw($PREFORK $MAX_CLIENTS_PER_CHILD %children $children $status
1.12      www        56: 	    $pidfile $port %perlvar $lastlog);
1.2       www        57:  
                     58: # ------------------------------------------------------------ Service routines 
                     59: sub REAPER {                        # takes care of dead children 
                     60:                                     # and MAXIMA processes
                     61:     $SIG{CHLD} = \&REAPER;
                     62:     my $pid = wait;
1.6       albertel   63:     $children--;
                     64:     delete($children{$pid});
1.2       www        65: }
                     66:  
                     67: sub HUNTSMAN {                      # signal handler for SIGINT
                     68:     local($SIG{CHLD}) = 'IGNORE';   # we're going to kill our children
1.6       albertel   69:     kill('INT' => keys(%children));
1.2       www        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 {
1.4       albertel   81:     my ($message)=@_;
1.2       www        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 ($$): $message\n";
                     88: }
                     89:  
                     90: # -------------------------------------------------------------- Status setting
                     91:  
                     92: sub status {
1.4       albertel   93:     my ($what)=@_;
1.2       www        94:     my $now=time;
                     95:     my $local=localtime($now);
                     96:     $status=$local.': '.$what;
                     97:     $0='lonmaxima: '.$what.' '.$local;
                     98: }
                     99:  
                    100: # -------------------------------------------------------- Escape Special Chars
                    101:  
                    102: sub escape {
1.4       albertel  103:     my ($str)=@_;
1.2       www       104:     $str =~ s/(\W)/"%".unpack('H2',$1)/eg;
                    105:     return $str;
                    106: }
                    107:  
                    108: # ----------------------------------------------------- Un-Escape Special Chars
                    109:  
                    110: sub unescape {
1.4       albertel  111:     my ($str)=@_;
1.2       www       112:     $str =~ s/%([a-fA-F0-9][a-fA-F0-9])/pack("C",hex($1))/eg;
                    113:     return $str;
                    114: }
                    115:  
                    116: # ------------------------ grabs exception and records it to log before exiting
                    117: sub catchexception {
                    118:     my ($signal)=@_;
                    119:     $SIG{QUIT}='DEFAULT';
                    120:     $SIG{__DIE__}='DEFAULT';
                    121:     chomp($signal);
1.5       albertel  122:     &logthis("<font color=\"red\">CRITICAL: "
                    123: 	     ."ABNORMAL EXIT. Child $$ died through "
                    124: 	     ."\"$signal\"</font>");
1.2       www       125:     die("Signal abend");
                    126: }
1.5       albertel  127: 
1.16      www       128: 
                    129: 
1.2       www       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");
1.3       albertel  139: %perlvar=%{&LONCAPA::Configuration::read_conf('loncapa.conf')};
1.2       www       140:  
                    141: # ----------------------------- Make sure this process is running from user=www
                    142: my $wwwid=getpwnam('www');
                    143: if ($wwwid!=$<) {
1.5       albertel  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.' |\
1.2       www       147:  mailto $emailto -s '$subj' > /dev/null");
1.5       albertel  148:     exit 1;
1.2       www       149: }
                    150:  
                    151: # --------------------------------------------- Check if other instance running
                    152:  
                    153: $pidfile="$perlvar{'lonDaemons'}/logs/lonmaxima.pid";
                    154:  
                    155: if (-e $pidfile) {
1.5       albertel  156:     my $lfh=IO::File->new("$pidfile");
                    157:     my $pide=<$lfh>;
                    158:     chomp($pide);
1.6       albertel  159:     if (kill(0 => $pide)) { die "already running"; }
1.2       www       160: }
1.5       albertel  161: 
1.2       www       162: # ------------------------------------------------------- Listen to UNIX socket
                    163: &status("Opening socket");
                    164:  
                    165: $port = "$perlvar{'lonSockDir'}/maximasock";
                    166:  
                    167: unlink($port);
                    168:  
                    169: 
1.6       albertel  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: }
1.2       www       182:     
                    183:  
                    184: # ---------------------------------------------------- Fork once and dissociate
                    185:  
                    186: my $fpid=fork;
                    187: exit if $fpid;
1.6       albertel  188: die("Couldn't fork: $!") unless defined($fpid);
1.2       www       189:  
                    190: POSIX::setsid() or die "Can't start new session: $!";
                    191:  
                    192: # ------------------------------------------------------- Write our PID on disk
                    193:  
                    194: my $execdir=$perlvar{'lonDaemons'};
1.5       albertel  195: open(PIDSAVE,">$execdir/logs/lonmaxima.pid");
1.2       www       196: print PIDSAVE "$$\n";
                    197: close(PIDSAVE);
                    198: &logthis("<font color='red'>CRITICAL: ---------- Starting ----------</font>");
                    199: &status('Starting');
1.6       albertel  200:      
1.2       www       201: 
1.10      albertel  202: # Install signal handlers.
                    203: $SIG{CHLD} = \&REAPER;
                    204: $SIG{INT}  = $SIG{TERM} = \&HUNTSMAN;
1.16      www       205:  
1.2       www       206: # Fork off our children.
                    207: for (1 .. $PREFORK) {
1.16      www       208:     &make_new_child($server);
1.2       www       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)
1.3       albertel  215:     for (my $i = $children; $i < $PREFORK; $i++) {
1.2       www       216:         &status('Parent process, starting child');
1.16      www       217:         &make_new_child($server);           # top up the child pool
1.2       www       218:     }
                    219: }
                    220:                                                                                 
                    221: sub make_new_child {
1.16      www       222:     my ($server) = @_;
1.4       albertel  223: 
1.2       www       224:     # block signal for fork
1.4       albertel  225:     my $sigset = POSIX::SigSet->new(SIGINT);
1.2       www       226:     sigprocmask(SIG_BLOCK, $sigset)
1.6       albertel  227:         or die("Can't block SIGINT for fork: $!\n");
1.2       www       228:      
1.6       albertel  229:     die("fork: $!") unless defined(my $pid = fork);
1.2       www       230:      
                    231:     if ($pid) {
                    232:         # Parent records the child's birth and returns.
                    233:         sigprocmask(SIG_UNBLOCK, $sigset)
1.6       albertel  234:             or die("Can't unblock SIGINT for fork: $!\n");
1.16      www       235:         $children{$pid} = 1;
1.2       www       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)
1.6       albertel  244:             or die("Can't unblock SIGINT for fork: $!\n");
1.15      www       245: 
1.17    ! www       246:         &logthis('New process started');
        !           247: 
1.16      www       248:         my $command=Expect->spawn('maxima');
                    249:         $command->log_stdout(0);
                    250: 
                    251:         &getmaximaoutput($command);
                    252: 
1.13      www       253:         for (my $i=0; $i < $MAX_CLIENTS_PER_CHILD; $i++) {
1.16      www       254:            &status('Accepting connections');
                    255:            my $client = $server->accept()     or last;
1.17    ! www       256:            print $command "kill(all);reset();\n";
        !           257:            &getmaximaoutput($command);
1.16      www       258:            while (my $cmd=<$client>) {
                    259:               &status('Processing command');
1.17    ! www       260:               print $command &unescape($cmd);
        !           261:               my $reply=&getmaximaoutput($command);
        !           262:               print $client &escape($reply)."\n";
        !           263:               if ($reply=~/^Error\:/) {
        !           264:                  &logthis('Died through '.$reply);
        !           265:                  $client->close();
        !           266:                  $command->hard_close();     
        !           267:                  exit;
        !           268:               }
        !           269:               &status('Waiting for commands');
1.16      www       270:            }
1.13      www       271:         }
1.4       albertel  272: 
1.12      www       273:         # tidy up gracefully and finish
1.4       albertel  274: 
1.16      www       275:         $command->soft_close();
1.1       www       276: 
1.2       www       277:         # this exit is VERY important, otherwise the child will become
                    278:         # a producer of more and more children, forking yourself into
                    279:         # process death.
                    280:         exit;
                    281:     }
                    282: }
1.4       albertel  283: 
1.16      www       284: sub getmaximaoutput {
                    285:     my ($command)=@_;
1.17    ! www       286:     my (undef,$error,undef,$output)=$command->expect(20, -re => '\(\%i\d+\)');
        !           287:     if ($error) {
        !           288:        return 'Error: '.$error;
        !           289:     }
1.16      www       290:     my $foundoutput=0;
                    291:     my $realoutput='';
                    292:     foreach my $line (split(/\n/,$output)) {
                    293:        if ($line=~/\;/) { $foundoutput=1; next; }
                    294:        if (!$foundoutput) { next; }
                    295:        my ($label)=($line=~s/^(\(\%o\d+\))//);
                    296:        if ($label) {
                    297:           $label=~s/\S/ /g;
                    298:           $line=$label.$line;
                    299:        }
                    300:        $realoutput.=$line."\n";
                    301:     }
                    302:     return $realoutput;
1.15      www       303: }

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