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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