Annotation of loncom/lonmaxima, revision 1.2
1.1 www 1: #!/usr/bin/perl
2: #
3: # The LearningOnline Network with CAPA
4: # Connect to MAXIMA CAS
5: #
1.2 ! www 6: # $Id: lonmaxima,v 1.1 2006/03/03 16:07:34 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:
! 33: # global variables
! 34: $PREFORK = 5; # number of children to maintain
! 35: $MAX_CLIENTS_PER_CHILD = 5; # number of clients each child should process
! 36: %children = (); # keys are current child process IDs
! 37: $children = 0; # current number of children
1.1 www 38:
39: use IPC::Open3;
40: use IO::Select;
1.2 ! www 41: use IO::Socket;
! 42: use IO::File;
! 43: use Symbol;
! 44: use POSIX;
! 45: use lib '/home/httpd/lib/perl/';
! 46: use LONCAPA::Configuration;
! 47:
1.1 www 48: # Scary: cannot use strict!!!
49: ##### use strict;
1.2 ! www 50:
1.1 www 51: sub maximareply {
52: my $cmd=shift;
53: my $reply='';
54: my $error='';
55: my $exitstatus='';
56:
57: unless ($cmd=~/\;\n$/) { $cmd.=";\n"; }
58: my $pid = open3($cmd_in, $cmd_out, $cmd_err, 'maxima');
1.2 ! www 59: $children{$pid} = 1;
1.1 www 60:
61: print $cmd_in $cmd;
62: close $cmd_in;
63:
1.2 ! www 64: &status("Command sent");
! 65:
! 66: my $selector = IO::Select->new();
1.1 www 67: $selector->add($cmd_err, $cmd_out);
68:
69: while (my @ready = $selector->can_read) {
70: foreach my $fh (@ready) {
71: if (fileno($fh) == fileno($cmd_err)) {
72: $error.=<$cmd_err>;
73: } else {
74: my $line = scalar <$cmd_out>;
75: if ($line=~/^(\(\%o|\s)/) {
76: $line=~s/^\(.*\)/ /;
77: $reply.=$line;
78: }
79: }
80: $selector->remove($fh) if eof($fh);
81: }
82: }
83: close $cmd_out;
84: close $cmd_err;
1.2 ! www 85: &status("Command processed");
1.1 www 86: return ($reply,$error,$exitstatus);
87: }
1.2 ! www 88:
! 89: # ------------------------------------------------------------ Service routines
! 90: sub REAPER { # takes care of dead children
! 91: # and MAXIMA processes
! 92: $SIG{CHLD} = \&REAPER;
! 93: my $pid = wait;
! 94: $children --;
! 95: delete $children{$pid};
! 96: }
! 97:
! 98: sub HUNTSMAN { # signal handler for SIGINT
! 99: local($SIG{CHLD}) = 'IGNORE'; # we're going to kill our children
! 100: kill 'INT' => keys %children;
! 101: unlink($pidfile);
! 102: unlink($port);
! 103: &logthis('---- Shutdown ----');
! 104: exit; # clean up with dignity
! 105: }
! 106:
! 107:
! 108:
! 109: # --------------------------------------------------------------------- Logging
! 110:
! 111: sub logthis {
! 112: my $message=shift;
! 113: my $execdir=$perlvar{'lonDaemons'};
! 114: my $fh=IO::File->new(">>$execdir/logs/lonmaxima.log");
! 115: my $now=time;
! 116: my $local=localtime($now);
! 117: $lastlog=$local.': '.$message;
! 118: print $fh "$local ($$): $message\n";
! 119: }
! 120:
! 121: # -------------------------------------------------------------- Status setting
! 122:
! 123: sub status {
! 124: my $what=shift;
! 125: my $now=time;
! 126: my $local=localtime($now);
! 127: $status=$local.': '.$what;
! 128: $0='lonmaxima: '.$what.' '.$local;
! 129: }
! 130:
! 131: # -------------------------------------------------------- Escape Special Chars
! 132:
! 133: sub escape {
! 134: my $str=shift;
! 135: $str =~ s/(\W)/"%".unpack('H2',$1)/eg;
! 136: return $str;
! 137: }
! 138:
! 139: # ----------------------------------------------------- Un-Escape Special Chars
! 140:
! 141: sub unescape {
! 142: my $str=shift;
! 143: $str =~ s/%([a-fA-F0-9][a-fA-F0-9])/pack("C",hex($1))/eg;
! 144: return $str;
! 145: }
! 146:
! 147: # ------------------------ grabs exception and records it to log before exiting
! 148: sub catchexception {
! 149: my ($signal)=@_;
! 150: $SIG{QUIT}='DEFAULT';
! 151: $SIG{__DIE__}='DEFAULT';
! 152: chomp($signal);
! 153: &logthis("<font color=red>CRITICAL: "
! 154: ."ABNORMAL EXIT. Child $$ died through "
! 155: ."\"$signal\"</font>");
! 156: die("Signal abend");
! 157: }
! 158:
! 159:
! 160:
! 161: # ---------------------------------------------------------------- Main program
! 162: # -------------------------------- Set signal handlers to record abnormal exits
! 163:
! 164:
! 165: $SIG{'QUIT'}=\&catchexception;
! 166: $SIG{__DIE__}=\&catchexception;
! 167:
! 168: # ---------------------------------- Read loncapa_apache.conf and loncapa.conf
! 169: &status("Read loncapa.conf and loncapa_apache.conf");
! 170: my $perlvarref=LONCAPA::Configuration::read_conf('loncapa.conf');
! 171: %perlvar=%{$perlvarref};
! 172: undef $perlvarref;
! 173:
! 174: # ----------------------------- Make sure this process is running from user=www
! 175: my $wwwid=getpwnam('www');
! 176: if ($wwwid!=$<) {
! 177: my $emailto="$perlvar{'lonAdmEMail'},$perlvar{'lonSysEMail'}";
! 178: my $subj="LON: $currenthostid User ID mismatch";
! 179: system("echo 'User ID mismatch. lonmaxima must be run as user www.' |\
! 180: mailto $emailto -s '$subj' > /dev/null");
! 181: exit 1;
! 182: }
! 183:
! 184: # --------------------------------------------- Check if other instance running
! 185:
! 186: $pidfile="$perlvar{'lonDaemons'}/logs/lonmaxima.pid";
! 187:
! 188: if (-e $pidfile) {
! 189: my $lfh=IO::File->new("$pidfile");
! 190: my $pide=<$lfh>;
! 191: chomp($pide);
! 192: if (kill 0 => $pide) { die "already running"; }
! 193: }
! 194: # ------------------------------------------------------- Listen to UNIX socket
! 195: &status("Opening socket");
! 196:
! 197: $port = "$perlvar{'lonSockDir'}/maximasock";
! 198:
! 199: unlink($port);
! 200:
! 201:
! 202: unless (
! 203: $server = IO::Socket::UNIX->new(Local => $port,
! 204: Type => SOCK_STREAM,
! 205: Listen => 10 )
! 206: ) {
! 207: my $st=120+int(rand(240));
! 208: &logthis(
! 209: "<font color=blue>WARNING: ".
! 210: "Can't make server socket ($st secs): .. exiting</font>");
! 211: sleep($st);
! 212: exit;
! 213: };
! 214:
! 215:
! 216: # ---------------------------------------------------- Fork once and dissociate
! 217:
! 218: my $fpid=fork;
! 219: exit if $fpid;
! 220: die "Couldn't fork: $!" unless defined ($fpid);
! 221:
! 222: POSIX::setsid() or die "Can't start new session: $!";
! 223:
! 224: # ------------------------------------------------------- Write our PID on disk
! 225:
! 226: my $execdir=$perlvar{'lonDaemons'};
! 227: open (PIDSAVE,">$execdir/logs/lonmaxima.pid");
! 228: print PIDSAVE "$$\n";
! 229: close(PIDSAVE);
! 230: &logthis("<font color='red'>CRITICAL: ---------- Starting ----------</font>");
! 231: &status('Starting');
! 232:
! 233:
! 234:
! 235:
! 236:
! 237: # Fork off our children.
! 238: for (1 .. $PREFORK) {
! 239: make_new_child( );
! 240: }
! 241:
! 242: # Install signal handlers.
! 243: $SIG{CHLD} = \&REAPER;
! 244: $SIG{INT} = $SIG{TERM} = \&HUNTSMAN;
! 245:
! 246: # And maintain the population.
! 247: while (1) {
! 248: &status('Parent process, sleeping');
! 249: sleep; # wait for a signal (i.e., child's death)
! 250: for ($i = $children; $i < $PREFORK; $i++) {
! 251: &status('Parent process, starting child');
! 252: make_new_child( ); # top up the child pool
! 253: }
! 254: }
! 255:
! 256: sub make_new_child {
! 257: my $pid;
! 258: my $sigset;
! 259:
! 260: # block signal for fork
! 261: $sigset = POSIX::SigSet->new(SIGINT);
! 262: sigprocmask(SIG_BLOCK, $sigset)
! 263: or die "Can't block SIGINT for fork: $!\n";
! 264:
! 265: die "fork: $!" unless defined ($pid = fork);
! 266:
! 267: if ($pid) {
! 268: # Parent records the child's birth and returns.
! 269: sigprocmask(SIG_UNBLOCK, $sigset)
! 270: or die "Can't unblock SIGINT for fork: $!\n";
! 271: $children{$pid} = 1;
! 272: $children++;
! 273: return;
! 274: } else {
! 275: # Child can *not* return from this subroutine.
! 276: $SIG{INT} = 'DEFAULT'; # make SIGINT kill us as it did before
! 277:
! 278: # unblock signals
! 279: sigprocmask(SIG_UNBLOCK, $sigset)
! 280: or die "Can't unblock SIGINT for fork: $!\n";
! 281:
! 282: # handle connections until we've reached $MAX_CLIENTS_PER_CHILD
! 283: for ($i=0; $i < $MAX_CLIENTS_PER_CHILD; $i++) {
! 284: &status('Accepting connections');
! 285: $client = $server->accept( ) or last;
! 286: while ($cmd=<$client>) {
! 287: &status('Processing command');
! 288: print $client &escape((&maximareply(&unescape($cmd)))[0])."\n";
! 289: }
! 290: }
! 291:
! 292: # tidy up gracefully and finish
1.1 www 293:
1.2 ! www 294: # this exit is VERY important, otherwise the child will become
! 295: # a producer of more and more children, forking yourself into
! 296: # process death.
! 297: exit;
! 298: }
! 299: }
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