Annotation of loncom/lonmaxima, revision 1.19

1.1       www         1: #!/usr/bin/perl
                      2: #
                      3: # The LearningOnline Network with CAPA
                      4: # Connect to MAXIMA CAS
                      5: #
1.19    ! www         6: # $Id: lonmaxima,v 1.18 2006/05/10 01:08:01 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 $lastlog;                           # last string that was logged
1.18      www        55: 
1.16      www        56: use vars qw($PREFORK $MAX_CLIENTS_PER_CHILD %children $children $status
1.12      www        57: 	    $pidfile $port %perlvar $lastlog);
1.2       www        58:  
                     59: # ------------------------------------------------------------ Service routines 
                     60: sub REAPER {                        # takes care of dead children 
                     61:                                     # and MAXIMA processes
                     62:     $SIG{CHLD} = \&REAPER;
                     63:     my $pid = wait;
1.6       albertel   64:     $children--;
                     65:     delete($children{$pid});
1.2       www        66: }
                     67:  
                     68: sub HUNTSMAN {                      # signal handler for SIGINT
                     69:     local($SIG{CHLD}) = 'IGNORE';   # we're going to kill our children
1.6       albertel   70:     kill('INT' => keys(%children));
1.2       www        71:     unlink($pidfile);
                     72:     unlink($port);
                     73:     &logthis('---- Shutdown ----');
                     74:     exit;                           # clean up with dignity
                     75: }
                     76: 
                     77: 
                     78:  
                     79: # --------------------------------------------------------------------- Logging
                     80:  
                     81: sub logthis {
1.4       albertel   82:     my ($message)=@_;
1.2       www        83:     my $execdir=$perlvar{'lonDaemons'};
                     84:     my $fh=IO::File->new(">>$execdir/logs/lonmaxima.log");
                     85:     my $now=time;
                     86:     my $local=localtime($now);
                     87:     $lastlog=$local.': '.$message;
                     88:     print $fh "$local ($$): $message\n";
                     89: }
                     90:  
                     91: # -------------------------------------------------------------- Status setting
                     92:  
                     93: sub status {
1.4       albertel   94:     my ($what)=@_;
1.2       www        95:     my $now=time;
                     96:     my $local=localtime($now);
                     97:     $status=$local.': '.$what;
                     98:     $0='lonmaxima: '.$what.' '.$local;
                     99: }
                    100:  
                    101: # -------------------------------------------------------- Escape Special Chars
                    102:  
                    103: sub escape {
1.4       albertel  104:     my ($str)=@_;
1.2       www       105:     $str =~ s/(\W)/"%".unpack('H2',$1)/eg;
                    106:     return $str;
                    107: }
                    108:  
                    109: # ----------------------------------------------------- Un-Escape Special Chars
                    110:  
                    111: sub unescape {
1.4       albertel  112:     my ($str)=@_;
1.2       www       113:     $str =~ s/%([a-fA-F0-9][a-fA-F0-9])/pack("C",hex($1))/eg;
                    114:     return $str;
                    115: }
                    116:  
                    117: # ------------------------ grabs exception and records it to log before exiting
                    118: sub catchexception {
                    119:     my ($signal)=@_;
                    120:     $SIG{QUIT}='DEFAULT';
                    121:     $SIG{__DIE__}='DEFAULT';
                    122:     chomp($signal);
1.5       albertel  123:     &logthis("<font color=\"red\">CRITICAL: "
                    124: 	     ."ABNORMAL EXIT. Child $$ died through "
                    125: 	     ."\"$signal\"</font>");
1.2       www       126:     die("Signal abend");
                    127: }
1.5       albertel  128: 
1.16      www       129: 
                    130: 
1.2       www       131: # ---------------------------------------------------------------- Main program
                    132: # -------------------------------- Set signal handlers to record abnormal exits
                    133:  
                    134:  
                    135: $SIG{'QUIT'}=\&catchexception;
                    136: $SIG{__DIE__}=\&catchexception;
                    137:  
                    138: # ---------------------------------- Read loncapa_apache.conf and loncapa.conf
                    139: &status("Read loncapa.conf and loncapa_apache.conf");
1.3       albertel  140: %perlvar=%{&LONCAPA::Configuration::read_conf('loncapa.conf')};
1.2       www       141:  
                    142: # ----------------------------- Make sure this process is running from user=www
                    143: my $wwwid=getpwnam('www');
                    144: if ($wwwid!=$<) {
1.5       albertel  145:     my $emailto="$perlvar{'lonAdmEMail'},$perlvar{'lonSysEMail'}";
                    146:     my $subj="LON: User ID mismatch";
                    147:     system("echo 'User ID mismatch.  lonmaxima must be run as user www.' |\
1.2       www       148:  mailto $emailto -s '$subj' > /dev/null");
1.5       albertel  149:     exit 1;
1.2       www       150: }
                    151:  
                    152: # --------------------------------------------- Check if other instance running
                    153:  
                    154: $pidfile="$perlvar{'lonDaemons'}/logs/lonmaxima.pid";
                    155:  
                    156: if (-e $pidfile) {
1.5       albertel  157:     my $lfh=IO::File->new("$pidfile");
                    158:     my $pide=<$lfh>;
                    159:     chomp($pide);
1.6       albertel  160:     if (kill(0 => $pide)) { die "already running"; }
1.2       www       161: }
1.5       albertel  162: 
1.2       www       163: # ------------------------------------------------------- Listen to UNIX socket
                    164: &status("Opening socket");
                    165:  
                    166: $port = "$perlvar{'lonSockDir'}/maximasock";
                    167:  
                    168: unlink($port);
                    169:  
                    170: 
1.6       albertel  171: my $server = IO::Socket::UNIX->new(Local  => $port,
                    172: 				   Type   => SOCK_STREAM,
                    173: 				   Listen => 10 );
                    174: if (!$server) {
                    175:     my $st=120+int(rand(240));
                    176: 
                    177:     &logthis("<font color=blue>WARNING: ".
                    178: 	     "Can't make server socket ($st secs):  .. exiting</font>");
                    179: 
                    180:     sleep($st);
                    181:     exit;
                    182: }
1.2       www       183:     
                    184:  
                    185: # ---------------------------------------------------- Fork once and dissociate
                    186:  
                    187: my $fpid=fork;
                    188: exit if $fpid;
1.6       albertel  189: die("Couldn't fork: $!") unless defined($fpid);
1.2       www       190:  
                    191: POSIX::setsid() or die "Can't start new session: $!";
                    192:  
                    193: # ------------------------------------------------------- Write our PID on disk
                    194:  
                    195: my $execdir=$perlvar{'lonDaemons'};
1.5       albertel  196: open(PIDSAVE,">$execdir/logs/lonmaxima.pid");
1.2       www       197: print PIDSAVE "$$\n";
                    198: close(PIDSAVE);
                    199: &logthis("<font color='red'>CRITICAL: ---------- Starting ----------</font>");
                    200: &status('Starting');
1.6       albertel  201:      
1.2       www       202: 
1.10      albertel  203: # Install signal handlers.
                    204: $SIG{CHLD} = \&REAPER;
                    205: $SIG{INT}  = $SIG{TERM} = \&HUNTSMAN;
1.16      www       206:  
1.2       www       207: # Fork off our children.
                    208: for (1 .. $PREFORK) {
1.16      www       209:     &make_new_child($server);
1.2       www       210: }
                    211:  
                    212: # And maintain the population.
                    213: while (1) {
                    214:     &status('Parent process, sleeping');
                    215:     sleep;                          # wait for a signal (i.e., child's death)
1.3       albertel  216:     for (my $i = $children; $i < $PREFORK; $i++) {
1.2       www       217:         &status('Parent process, starting child');
1.16      www       218:         &make_new_child($server);           # top up the child pool
1.2       www       219:     }
                    220: }
                    221:                                                                                 
                    222: sub make_new_child {
1.16      www       223:     my ($server) = @_;
1.4       albertel  224: 
1.2       www       225:     # block signal for fork
1.4       albertel  226:     my $sigset = POSIX::SigSet->new(SIGINT);
1.2       www       227:     sigprocmask(SIG_BLOCK, $sigset)
1.6       albertel  228:         or die("Can't block SIGINT for fork: $!\n");
1.2       www       229:      
1.6       albertel  230:     die("fork: $!") unless defined(my $pid = fork);
1.2       www       231:      
                    232:     if ($pid) {
                    233:         # Parent records the child's birth and returns.
                    234:         sigprocmask(SIG_UNBLOCK, $sigset)
1.6       albertel  235:             or die("Can't unblock SIGINT for fork: $!\n");
1.16      www       236:         $children{$pid} = 1;
1.2       www       237:         $children++;
                    238:         return;
                    239:     } else {
                    240:         # Child can *not* return from this subroutine.
                    241:         $SIG{INT} = 'DEFAULT';      # make SIGINT kill us as it did before
                    242:      
                    243:         # unblock signals
                    244:         sigprocmask(SIG_UNBLOCK, $sigset)
1.6       albertel  245:             or die("Can't unblock SIGINT for fork: $!\n");
1.15      www       246: 
1.17      www       247:         &logthis('New process started');
                    248: 
1.16      www       249:         my $command=Expect->spawn('maxima');
                    250:         $command->log_stdout(0);
                    251: 
                    252:         &getmaximaoutput($command);
                    253: 
1.13      www       254:         for (my $i=0; $i < $MAX_CLIENTS_PER_CHILD; $i++) {
1.16      www       255:            &status('Accepting connections');
                    256:            my $client = $server->accept()     or last;
1.17      www       257:            print $command "kill(all);reset();\n";
1.19    ! www       258:            &sync($command);
1.16      www       259:            while (my $cmd=<$client>) {
                    260:               &status('Processing command');
1.17      www       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:                  $command->hard_close();     
                    268:                  exit;
1.19    ! www       269:               }	      
        !           270: 	      &sync($command);
1.17      www       271:               &status('Waiting for commands');
1.16      www       272:            }
1.13      www       273:         }
1.4       albertel  274: 
1.12      www       275:         # tidy up gracefully and finish
1.4       albertel  276: 
1.16      www       277:         $command->soft_close();
1.1       www       278: 
1.2       www       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: }
1.4       albertel  285: 
1.18      www       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/) || ($output=~/^Error\:/)) {
                    296: 		return;
                    297: 	    }
                    298: 	}
                    299:     }
                    300: }
                    301: 
1.16      www       302: sub getmaximaoutput {
                    303:     my ($command)=@_;
1.17      www       304:     my (undef,$error,undef,$output)=$command->expect(20, -re => '\(\%i\d+\)');
                    305:     if ($error) {
                    306:        return 'Error: '.$error;
                    307:     }
1.16      www       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;
1.15      www       321: }

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