1: #!/usr/bin/perl
2: #
3: # The LearningOnline Network with CAPA
4: # Connect to MAXIMA CAS
5: #
6: # $Id: lonmaxima,v 1.3 2006/03/03 23:25:47 albertel Exp $
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: #
32:
33:
34: use IPC::Open3;
35: use IO::Select;
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:
43: use strict;
44:
45: # global variables
46: my $PREFORK = 5; # number of children to maintain
47: my $MAX_CLIENTS_PER_CHILD = 5; # number of clients each child should process
48: my %children = (); # keys are current child process IDs
49: my $children = 0; # current number of children
50: my $status; # string for current status
51:
52: use vars qw($PREFORK $MAX_CLIENTS_PER_CHILD %children $children $status
53: $cmd_in $cmd_out $cmd_err $pidfile $port %perlvar $lastlog
54: $currenthostid $client $server $cmd
55: );
56:
57: sub maximareply {
58: my $cmd=shift;
59: my $reply='';
60: my $error='';
61: my $exitstatus='';
62:
63: unless ($cmd=~/\;\n$/) { $cmd.=";\n"; }
64: my $pid = open3($cmd_in, $cmd_out, $cmd_err, 'maxima');
65: $children{$pid} = 1;
66:
67: print $cmd_in $cmd;
68: close $cmd_in;
69:
70: &status("Command sent");
71:
72: my $selector = IO::Select->new();
73: $selector->add($cmd_err, $cmd_out);
74:
75: while (my @ready = $selector->can_read) {
76: foreach my $fh (@ready) {
77: if (fileno($fh) == fileno($cmd_err)) {
78: $error.=<$cmd_err>;
79: } else {
80: my $line = scalar <$cmd_out>;
81: if ($line=~/^(\(\%o|\s)/) {
82: $line=~s/^\(.*\)/ /;
83: $reply.=$line;
84: }
85: }
86: $selector->remove($fh) if eof($fh);
87: }
88: }
89: close $cmd_out;
90: close $cmd_err;
91: &status("Command processed");
92: return ($reply,$error,$exitstatus);
93: }
94:
95: # ------------------------------------------------------------ Service routines
96: sub REAPER { # takes care of dead children
97: # and MAXIMA processes
98: $SIG{CHLD} = \&REAPER;
99: my $pid = wait;
100: $children --;
101: delete $children{$pid};
102: }
103:
104: sub HUNTSMAN { # signal handler for SIGINT
105: local($SIG{CHLD}) = 'IGNORE'; # we're going to kill our children
106: kill 'INT' => keys %children;
107: unlink($pidfile);
108: unlink($port);
109: &logthis('---- Shutdown ----');
110: exit; # clean up with dignity
111: }
112:
113:
114:
115: # --------------------------------------------------------------------- Logging
116:
117: sub logthis {
118: my $message=shift;
119: my $execdir=$perlvar{'lonDaemons'};
120: my $fh=IO::File->new(">>$execdir/logs/lonmaxima.log");
121: my $now=time;
122: my $local=localtime($now);
123: $lastlog=$local.': '.$message;
124: print $fh "$local ($$): $message\n";
125: }
126:
127: # -------------------------------------------------------------- Status setting
128:
129: sub status {
130: my $what=shift;
131: my $now=time;
132: my $local=localtime($now);
133: $status=$local.': '.$what;
134: $0='lonmaxima: '.$what.' '.$local;
135: }
136:
137: # -------------------------------------------------------- Escape Special Chars
138:
139: sub escape {
140: my $str=shift;
141: $str =~ s/(\W)/"%".unpack('H2',$1)/eg;
142: return $str;
143: }
144:
145: # ----------------------------------------------------- Un-Escape Special Chars
146:
147: sub unescape {
148: my $str=shift;
149: $str =~ s/%([a-fA-F0-9][a-fA-F0-9])/pack("C",hex($1))/eg;
150: return $str;
151: }
152:
153: # ------------------------ grabs exception and records it to log before exiting
154: sub catchexception {
155: my ($signal)=@_;
156: $SIG{QUIT}='DEFAULT';
157: $SIG{__DIE__}='DEFAULT';
158: chomp($signal);
159: &logthis("<font color=red>CRITICAL: "
160: ."ABNORMAL EXIT. Child $$ died through "
161: ."\"$signal\"</font>");
162: die("Signal abend");
163: }
164:
165:
166:
167: # ---------------------------------------------------------------- Main program
168: # -------------------------------- Set signal handlers to record abnormal exits
169:
170:
171: $SIG{'QUIT'}=\&catchexception;
172: $SIG{__DIE__}=\&catchexception;
173:
174: # ---------------------------------- Read loncapa_apache.conf and loncapa.conf
175: &status("Read loncapa.conf and loncapa_apache.conf");
176: %perlvar=%{&LONCAPA::Configuration::read_conf('loncapa.conf')};
177:
178: # ----------------------------- Make sure this process is running from user=www
179: my $wwwid=getpwnam('www');
180: if ($wwwid!=$<) {
181: my $emailto="$perlvar{'lonAdmEMail'},$perlvar{'lonSysEMail'}";
182: my $subj="LON: $currenthostid User ID mismatch";
183: system("echo 'User ID mismatch. lonmaxima must be run as user www.' |\
184: mailto $emailto -s '$subj' > /dev/null");
185: exit 1;
186: }
187:
188: # --------------------------------------------- Check if other instance running
189:
190: $pidfile="$perlvar{'lonDaemons'}/logs/lonmaxima.pid";
191:
192: if (-e $pidfile) {
193: my $lfh=IO::File->new("$pidfile");
194: my $pide=<$lfh>;
195: chomp($pide);
196: if (kill 0 => $pide) { die "already running"; }
197: }
198: # ------------------------------------------------------- Listen to UNIX socket
199: &status("Opening socket");
200:
201: $port = "$perlvar{'lonSockDir'}/maximasock";
202:
203: unlink($port);
204:
205:
206: unless (
207: $server = IO::Socket::UNIX->new(Local => $port,
208: Type => SOCK_STREAM,
209: Listen => 10 )
210: ) {
211: my $st=120+int(rand(240));
212: &logthis(
213: "<font color=blue>WARNING: ".
214: "Can't make server socket ($st secs): .. exiting</font>");
215: sleep($st);
216: exit;
217: };
218:
219:
220: # ---------------------------------------------------- Fork once and dissociate
221:
222: my $fpid=fork;
223: exit if $fpid;
224: die "Couldn't fork: $!" unless defined ($fpid);
225:
226: POSIX::setsid() or die "Can't start new session: $!";
227:
228: # ------------------------------------------------------- Write our PID on disk
229:
230: my $execdir=$perlvar{'lonDaemons'};
231: open (PIDSAVE,">$execdir/logs/lonmaxima.pid");
232: print PIDSAVE "$$\n";
233: close(PIDSAVE);
234: &logthis("<font color='red'>CRITICAL: ---------- Starting ----------</font>");
235: &status('Starting');
236:
237:
238:
239:
240:
241: # Fork off our children.
242: for (1 .. $PREFORK) {
243: make_new_child( );
244: }
245:
246: # Install signal handlers.
247: $SIG{CHLD} = \&REAPER;
248: $SIG{INT} = $SIG{TERM} = \&HUNTSMAN;
249:
250: # And maintain the population.
251: while (1) {
252: &status('Parent process, sleeping');
253: sleep; # wait for a signal (i.e., child's death)
254: for (my $i = $children; $i < $PREFORK; $i++) {
255: &status('Parent process, starting child');
256: make_new_child( ); # top up the child pool
257: }
258: }
259:
260: sub make_new_child {
261: my $pid;
262: my $sigset;
263:
264: # block signal for fork
265: $sigset = POSIX::SigSet->new(SIGINT);
266: sigprocmask(SIG_BLOCK, $sigset)
267: or die "Can't block SIGINT for fork: $!\n";
268:
269: die "fork: $!" unless defined ($pid = fork);
270:
271: if ($pid) {
272: # Parent records the child's birth and returns.
273: sigprocmask(SIG_UNBLOCK, $sigset)
274: or die "Can't unblock SIGINT for fork: $!\n";
275: $children{$pid} = 1;
276: $children++;
277: return;
278: } else {
279: # Child can *not* return from this subroutine.
280: $SIG{INT} = 'DEFAULT'; # make SIGINT kill us as it did before
281:
282: # unblock signals
283: sigprocmask(SIG_UNBLOCK, $sigset)
284: or die "Can't unblock SIGINT for fork: $!\n";
285:
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');
289: $client = $server->accept( ) or last;
290: while ($cmd=<$client>) {
291: &status('Processing command');
292: print $client &escape((&maximareply(&unescape($cmd)))[0])."\n";
293: }
294: }
295:
296: # tidy up gracefully and finish
297:
298: # this exit is VERY important, otherwise the child will become
299: # a producer of more and more children, forking yourself into
300: # process death.
301: exit;
302: }
303: }
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