Annotation of loncom/lonmaxima, revision 1.15

1.1       www         1: #!/usr/bin/perl
                      2: #
                      3: # The LearningOnline Network with CAPA
                      4: # Connect to MAXIMA CAS
                      5: #
1.15    ! www         6: # $Id: lonmaxima,v 1.14 2006/03/08 14:22:14 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: 
1.1       www        33:  
                     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
1.12      www        46: my $STARTPORT              = 5664;     # port for first child's server
1.3       albertel   47: my $PREFORK                = 5;        # number of children to maintain
                     48: my $MAX_CLIENTS_PER_CHILD  = 5;        # number of clients each child should process
                     49: my %children               = ();       # keys are current child process IDs
1.12      www        50: my %usedmaximaports        = ();       # keys are the used maximaports
1.3       albertel   51: my $children               = 0;        # current number of children
                     52: my $status;                            # string for current status
1.5       albertel   53: my $pidfile;                           # file containg parent process pid
                     54: my $port;                              # path to UNIX socket file
                     55: my %perlvar;                           # configuration file info
                     56: my $lastlog;                           # last string that was logged
1.12      www        57: use vars qw($PREFORK $MAX_CLIENTS_PER_CHILD %children $children %usedmaximaports $status
                     58: 	    $pidfile $port %perlvar $lastlog);
1.2       www        59:  
                     60: # ------------------------------------------------------------ Service routines 
                     61: sub REAPER {                        # takes care of dead children 
                     62:                                     # and MAXIMA processes
                     63:     $SIG{CHLD} = \&REAPER;
                     64:     my $pid = wait;
1.6       albertel   65:     $children--;
1.14      www        66:     &logthis("Child $pid for port or process $children{$pid} died");
1.12      www        67:     delete($usedmaximaports{$children{$pid}});
1.6       albertel   68:     delete($children{$pid});
1.2       www        69: }
                     70:  
                     71: sub HUNTSMAN {                      # signal handler for SIGINT
                     72:     local($SIG{CHLD}) = 'IGNORE';   # we're going to kill our children
1.6       albertel   73:     kill('INT' => keys(%children));
1.2       www        74:     unlink($pidfile);
                     75:     unlink($port);
                     76:     &logthis('---- Shutdown ----');
                     77:     exit;                           # clean up with dignity
                     78: }
                     79: 
                     80: 
                     81:  
                     82: # --------------------------------------------------------------------- Logging
                     83:  
                     84: sub logthis {
1.4       albertel   85:     my ($message)=@_;
1.2       www        86:     my $execdir=$perlvar{'lonDaemons'};
                     87:     my $fh=IO::File->new(">>$execdir/logs/lonmaxima.log");
                     88:     my $now=time;
                     89:     my $local=localtime($now);
                     90:     $lastlog=$local.': '.$message;
                     91:     print $fh "$local ($$): $message\n";
                     92: }
                     93:  
                     94: # -------------------------------------------------------------- Status setting
                     95:  
                     96: sub status {
1.4       albertel   97:     my ($what)=@_;
1.2       www        98:     my $now=time;
                     99:     my $local=localtime($now);
                    100:     $status=$local.': '.$what;
                    101:     $0='lonmaxima: '.$what.' '.$local;
                    102: }
                    103:  
                    104: # -------------------------------------------------------- Escape Special Chars
                    105:  
                    106: sub escape {
1.4       albertel  107:     my ($str)=@_;
1.2       www       108:     $str =~ s/(\W)/"%".unpack('H2',$1)/eg;
                    109:     return $str;
                    110: }
                    111:  
                    112: # ----------------------------------------------------- Un-Escape Special Chars
                    113:  
                    114: sub unescape {
1.4       albertel  115:     my ($str)=@_;
1.2       www       116:     $str =~ s/%([a-fA-F0-9][a-fA-F0-9])/pack("C",hex($1))/eg;
                    117:     return $str;
                    118: }
                    119:  
                    120: # ------------------------ grabs exception and records it to log before exiting
                    121: sub catchexception {
                    122:     my ($signal)=@_;
                    123:     $SIG{QUIT}='DEFAULT';
                    124:     $SIG{__DIE__}='DEFAULT';
                    125:     chomp($signal);
1.5       albertel  126:     &logthis("<font color=\"red\">CRITICAL: "
                    127: 	     ."ABNORMAL EXIT. Child $$ died through "
                    128: 	     ."\"$signal\"</font>");
1.2       www       129:     die("Signal abend");
                    130: }
1.5       albertel  131: 
1.2       www       132: # ---------------------------------------------------------------- Main program
                    133: # -------------------------------- Set signal handlers to record abnormal exits
                    134:  
                    135:  
                    136: $SIG{'QUIT'}=\&catchexception;
                    137: $SIG{__DIE__}=\&catchexception;
                    138:  
                    139: # ---------------------------------- Read loncapa_apache.conf and loncapa.conf
                    140: &status("Read loncapa.conf and loncapa_apache.conf");
1.3       albertel  141: %perlvar=%{&LONCAPA::Configuration::read_conf('loncapa.conf')};
1.2       www       142:  
                    143: # ----------------------------- Make sure this process is running from user=www
                    144: my $wwwid=getpwnam('www');
                    145: if ($wwwid!=$<) {
1.5       albertel  146:     my $emailto="$perlvar{'lonAdmEMail'},$perlvar{'lonSysEMail'}";
                    147:     my $subj="LON: User ID mismatch";
                    148:     system("echo 'User ID mismatch.  lonmaxima must be run as user www.' |\
1.2       www       149:  mailto $emailto -s '$subj' > /dev/null");
1.5       albertel  150:     exit 1;
1.2       www       151: }
                    152:  
                    153: # --------------------------------------------- Check if other instance running
                    154:  
                    155: $pidfile="$perlvar{'lonDaemons'}/logs/lonmaxima.pid";
                    156:  
                    157: if (-e $pidfile) {
1.5       albertel  158:     my $lfh=IO::File->new("$pidfile");
                    159:     my $pide=<$lfh>;
                    160:     chomp($pide);
1.6       albertel  161:     if (kill(0 => $pide)) { die "already running"; }
1.2       www       162: }
1.5       albertel  163: 
1.2       www       164: # ------------------------------------------------------- Listen to UNIX socket
                    165: &status("Opening socket");
                    166:  
                    167: $port = "$perlvar{'lonSockDir'}/maximasock";
                    168:  
                    169: unlink($port);
                    170:  
                    171: 
1.6       albertel  172: my $server = IO::Socket::UNIX->new(Local  => $port,
                    173: 				   Type   => SOCK_STREAM,
                    174: 				   Listen => 10 );
                    175: if (!$server) {
                    176:     my $st=120+int(rand(240));
                    177: 
                    178:     &logthis("<font color=blue>WARNING: ".
                    179: 	     "Can't make server socket ($st secs):  .. exiting</font>");
                    180: 
                    181:     sleep($st);
                    182:     exit;
                    183: }
1.2       www       184:     
                    185:  
                    186: # ---------------------------------------------------- Fork once and dissociate
                    187:  
                    188: my $fpid=fork;
                    189: exit if $fpid;
1.6       albertel  190: die("Couldn't fork: $!") unless defined($fpid);
1.2       www       191:  
                    192: POSIX::setsid() or die "Can't start new session: $!";
                    193:  
                    194: # ------------------------------------------------------- Write our PID on disk
                    195:  
                    196: my $execdir=$perlvar{'lonDaemons'};
1.5       albertel  197: open(PIDSAVE,">$execdir/logs/lonmaxima.pid");
1.2       www       198: print PIDSAVE "$$\n";
                    199: close(PIDSAVE);
                    200: &logthis("<font color='red'>CRITICAL: ---------- Starting ----------</font>");
                    201: &status('Starting');
1.6       albertel  202:      
1.2       www       203: 
1.10      albertel  204: # Install signal handlers.
                    205: $SIG{CHLD} = \&REAPER;
                    206: $SIG{INT}  = $SIG{TERM} = \&HUNTSMAN;
1.12      www       207: 
                    208: my $maximaport=$STARTPORT; 
1.2       www       209: # Fork off our children.
                    210: for (1 .. $PREFORK) {
1.12      www       211:     &make_new_child($server,$maximaport);
                    212:     $maximaport++;
1.2       www       213: }
                    214:  
                    215: # And maintain the population.
                    216: while (1) {
                    217:     &status('Parent process, sleeping');
                    218:     sleep;                          # wait for a signal (i.e., child's death)
1.3       albertel  219:     for (my $i = $children; $i < $PREFORK; $i++) {
1.2       www       220:         &status('Parent process, starting child');
1.12      www       221:         my $newport;
1.14      www       222:         &logthis("Current pool: ".join(', ',keys %usedmaximaports));
                    223:         foreach my $testport ($STARTPORT .. $STARTPORT+$PREFORK-1) {
                    224:             if (!$usedmaximaports{$testport}) { $newport=$testport; }
                    225:         }
                    226:         if ($newport) {
                    227:            &make_new_child($server,$newport);           # top up the child pool
1.12      www       228:         }
1.2       www       229:     }
                    230: }
                    231:                                                                                 
                    232: sub make_new_child {
1.12      www       233:     my ($server,$maximaport) = @_;
1.4       albertel  234: 
1.2       www       235:     # block signal for fork
1.4       albertel  236:     my $sigset = POSIX::SigSet->new(SIGINT);
1.2       www       237:     sigprocmask(SIG_BLOCK, $sigset)
1.6       albertel  238:         or die("Can't block SIGINT for fork: $!\n");
1.2       www       239:      
1.6       albertel  240:     die("fork: $!") unless defined(my $pid = fork);
1.2       www       241:      
                    242:     if ($pid) {
                    243:         # Parent records the child's birth and returns.
                    244:         sigprocmask(SIG_UNBLOCK, $sigset)
1.6       albertel  245:             or die("Can't unblock SIGINT for fork: $!\n");
1.12      www       246:         $children{$pid} = $maximaport;
1.2       www       247:         $children++;
1.14      www       248:         $usedmaximaports{$maximaport}=1;
1.2       www       249:         return;
                    250:     } else {
1.14      www       251:         &logthis("Starting child on port $maximaport");
1.2       www       252:         # Child can *not* return from this subroutine.
                    253:         $SIG{INT} = 'DEFAULT';      # make SIGINT kill us as it did before
                    254:      
                    255:         # unblock signals
                    256:         sigprocmask(SIG_UNBLOCK, $sigset)
1.6       albertel  257:             or die("Can't unblock SIGINT for fork: $!\n");
1.12      www       258:         
                    259:         # open the MAXIMA port
                    260:         my $maximaserver = IO::Socket::INET->new(LocalPort => $maximaport,
                    261:                                               Type      => SOCK_STREAM,
                    262:                                               Proto     => 'tcp',
                    263:                                               Reuse     => 1,
                    264:                                               Listen    => 10 )
                    265:                         or die "making socket: $@\n";
1.13      www       266:         my $maximaselect=IO::Select->new($maximaserver);
1.15    ! www       267:         sleep(1);
1.12      www       268: 
                    269:         # open MAXIMA to talk to that port
                    270:         my ($cmd_in, $cmd_out, $cmd_err);
                    271:         my $maximapid = open3($cmd_in, $cmd_out, $cmd_err, "maxima -s $maximaport");
1.14      www       272:         $children{$maximapid} = "Maxima $maximapid port $maximaport";
1.12      www       273:         my $prompt=<$cmd_out>;
                    274:         &logthis("Maxima $maximapid: $prompt");
                    275: 
1.13      www       276:         # hopefully, MAXIMA calls us back
1.12      www       277:         &status("Waiting $maximapid on $maximaport");
                    278:         my $maximaclient=$maximaserver->accept();
1.15    ! www       279:         $maximaclient->blocking(0);
1.13      www       280:         $maximaselect->add($maximaclient);
1.12      www       281:         &status("$maximapid on $maximaport connected.");
                    282:         &logthis("Maxima $maximapid on port $maximaport connected.");
1.15    ! www       283:         sleep(2);
        !           284: 
1.13      www       285:         &logthis('Initial reply: '.&maximareply($maximaselect));
                    286:         # handle connections until we've reached $MAX_CLIENTS_PER_CHILD
                    287:         for (my $i=0; $i < $MAX_CLIENTS_PER_CHILD; $i++) {
                    288:             &status('Accepting connections for '.$maximapid.' on '.$maximaport);
                    289:             my $client = $server->accept()     or last;
                    290:             while (my $cmd=<$client>) {
                    291:                 &status('Processing command by '.$maximapid.' on '.$maximaport);
1.15    ! www       292:                 &maximawrite($maximaselect,&unescape($cmd).";\n");
1.13      www       293:                 print $client &escape(&maximareply($maximaselect))."\n";
                    294:             }
                    295:         }
1.4       albertel  296: 
1.12      www       297:         # tidy up gracefully and finish
1.4       albertel  298: 
1.12      www       299:         if (ref($cmd_out)) { close($cmd_out); }
                    300:         if (ref($cmd_err)) { close($cmd_err); }
                    301:         if (ref($cmd_in)) { close($cmd_in); }
1.1       www       302: 
1.2       www       303:         # this exit is VERY important, otherwise the child will become
                    304:         # a producer of more and more children, forking yourself into
                    305:         # process death.
                    306:         exit;
                    307:     }
                    308: }
1.4       albertel  309: 
1.13      www       310: sub maximareply {
                    311:    my ($maximaselect)=@_;
                    312:    my $output='';
1.15    ! www       313:    
1.13      www       314:    foreach my $ready ($maximaselect->can_read(1)) {
                    315:        my $data = '';
                    316:        my $rv   = $ready->recv($data, POSIX::BUFSIZ, 0);
                    317:        $output.=$data;
                    318:    }
                    319:    return $output;
1.4       albertel  320: }
1.13      www       321: 
1.15    ! www       322: sub maximawrite {
        !           323:    my ($maximaselect,$cmd)=@_;
        !           324:    my $ready=($maximaselect->can_write(1));
        !           325:    if (ref($ready)) {
        !           326:       print $ready $cmd;
        !           327:    } else {
        !           328:       &logthis("Cannot write: ".&maximareply($maximaselect));
        !           329:    }
        !           330: }
        !           331: 
        !           332: 

FreeBSD-CVSweb <freebsd-cvsweb@FreeBSD.org>