Annotation of loncom/lonmaxima, revision 1.8
1.1 www 1: #!/usr/bin/perl
2: #
3: # The LearningOnline Network with CAPA
4: # Connect to MAXIMA CAS
5: #
1.8 ! albertel 6: # $Id: lonmaxima,v 1.7 2006/03/04 02:33:54 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
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
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 $lastlog; # last string that was logged
1.3 albertel 55: use vars qw($PREFORK $MAX_CLIENTS_PER_CHILD %children $children $status
1.8 ! albertel 56: $pidfile $port %perlvar $lastlog);
1.2 www 57:
1.1 www 58: sub maximareply {
1.4 albertel 59: my ($cmd) = @_;
1.1 www 60: my $reply='';
61: my $error='';
62: my $exitstatus='';
63:
64: unless ($cmd=~/\;\n$/) { $cmd.=";\n"; }
1.5 albertel 65:
66: my ($cmd_in, $cmd_out, $cmd_err);
1.8 ! albertel 67: my $maximapid = open3($cmd_in, $cmd_out, $cmd_err, 'maxima');
1.7 www 68: $children{$maximapid} = 1;
1.1 www 69:
70: print $cmd_in $cmd;
1.5 albertel 71: close($cmd_in);
1.1 www 72:
1.2 www 73: &status("Command sent");
74:
1.7 www 75: $SIG{ALRM} = sub { kill 9 => $maximapid; };
76: alarm(5);
77: no strict 'refs';
78:
1.8 ! albertel 79: my $selector = IO::Select->new();
1.7 www 80:
1.1 www 81: $selector->add($cmd_err, $cmd_out);
82:
1.6 albertel 83: while (my @ready = $selector->can_read()) {
1.1 www 84: foreach my $fh (@ready) {
85: if (fileno($fh) == fileno($cmd_err)) {
86: $error.=<$cmd_err>;
87: } else {
1.6 albertel 88: my $line = scalar(<$cmd_out>);
1.1 www 89: if ($line=~/^(\(\%o|\s)/) {
1.5 albertel 90: $line=~s/^\(.*\)/ /;
91: $reply.=$line;
92: }
1.1 www 93: }
94: $selector->remove($fh) if eof($fh);
95: }
96: }
1.7 www 97: alarm(0);
98: $SIG{ALRM} = 'DEFAULT';
1.5 albertel 99: close($cmd_out);
100: close($cmd_err);
1.7 www 101: use strict 'refs';
1.2 www 102: &status("Command processed");
1.1 www 103: return ($reply,$error,$exitstatus);
104: }
1.2 www 105:
106: # ------------------------------------------------------------ Service routines
107: sub REAPER { # takes care of dead children
108: # and MAXIMA processes
109: $SIG{CHLD} = \&REAPER;
110: my $pid = wait;
1.6 albertel 111: $children--;
112: delete($children{$pid});
1.2 www 113: }
114:
115: sub HUNTSMAN { # signal handler for SIGINT
116: local($SIG{CHLD}) = 'IGNORE'; # we're going to kill our children
1.6 albertel 117: kill('INT' => keys(%children));
1.2 www 118: unlink($pidfile);
119: unlink($port);
120: &logthis('---- Shutdown ----');
121: exit; # clean up with dignity
122: }
123:
124:
125:
126: # --------------------------------------------------------------------- Logging
127:
128: sub logthis {
1.4 albertel 129: my ($message)=@_;
1.2 www 130: my $execdir=$perlvar{'lonDaemons'};
131: my $fh=IO::File->new(">>$execdir/logs/lonmaxima.log");
132: my $now=time;
133: my $local=localtime($now);
134: $lastlog=$local.': '.$message;
135: print $fh "$local ($$): $message\n";
136: }
137:
138: # -------------------------------------------------------------- Status setting
139:
140: sub status {
1.4 albertel 141: my ($what)=@_;
1.2 www 142: my $now=time;
143: my $local=localtime($now);
144: $status=$local.': '.$what;
145: $0='lonmaxima: '.$what.' '.$local;
146: }
147:
148: # -------------------------------------------------------- Escape Special Chars
149:
150: sub escape {
1.4 albertel 151: my ($str)=@_;
1.2 www 152: $str =~ s/(\W)/"%".unpack('H2',$1)/eg;
153: return $str;
154: }
155:
156: # ----------------------------------------------------- Un-Escape Special Chars
157:
158: sub unescape {
1.4 albertel 159: my ($str)=@_;
1.2 www 160: $str =~ s/%([a-fA-F0-9][a-fA-F0-9])/pack("C",hex($1))/eg;
161: return $str;
162: }
163:
164: # ------------------------ grabs exception and records it to log before exiting
165: sub catchexception {
166: my ($signal)=@_;
167: $SIG{QUIT}='DEFAULT';
168: $SIG{__DIE__}='DEFAULT';
169: chomp($signal);
1.5 albertel 170: &logthis("<font color=\"red\">CRITICAL: "
171: ."ABNORMAL EXIT. Child $$ died through "
172: ."\"$signal\"</font>");
1.2 www 173: die("Signal abend");
174: }
1.5 albertel 175:
1.2 www 176:
177:
178: # ---------------------------------------------------------------- Main program
179: # -------------------------------- Set signal handlers to record abnormal exits
180:
181:
182: $SIG{'QUIT'}=\&catchexception;
183: $SIG{__DIE__}=\&catchexception;
184:
185: # ---------------------------------- Read loncapa_apache.conf and loncapa.conf
186: &status("Read loncapa.conf and loncapa_apache.conf");
1.3 albertel 187: %perlvar=%{&LONCAPA::Configuration::read_conf('loncapa.conf')};
1.2 www 188:
189: # ----------------------------- Make sure this process is running from user=www
190: my $wwwid=getpwnam('www');
191: if ($wwwid!=$<) {
1.5 albertel 192: my $emailto="$perlvar{'lonAdmEMail'},$perlvar{'lonSysEMail'}";
193: my $subj="LON: User ID mismatch";
194: system("echo 'User ID mismatch. lonmaxima must be run as user www.' |\
1.2 www 195: mailto $emailto -s '$subj' > /dev/null");
1.5 albertel 196: exit 1;
1.2 www 197: }
198:
199: # --------------------------------------------- Check if other instance running
200:
201: $pidfile="$perlvar{'lonDaemons'}/logs/lonmaxima.pid";
202:
203: if (-e $pidfile) {
1.5 albertel 204: my $lfh=IO::File->new("$pidfile");
205: my $pide=<$lfh>;
206: chomp($pide);
1.6 albertel 207: if (kill(0 => $pide)) { die "already running"; }
1.2 www 208: }
1.5 albertel 209:
1.2 www 210: # ------------------------------------------------------- Listen to UNIX socket
211: &status("Opening socket");
212:
213: $port = "$perlvar{'lonSockDir'}/maximasock";
214:
215: unlink($port);
216:
217:
1.6 albertel 218: my $server = IO::Socket::UNIX->new(Local => $port,
219: Type => SOCK_STREAM,
220: Listen => 10 );
221: if (!$server) {
222: my $st=120+int(rand(240));
223:
224: &logthis("<font color=blue>WARNING: ".
225: "Can't make server socket ($st secs): .. exiting</font>");
226:
227: sleep($st);
228: exit;
229: }
1.2 www 230:
231:
232: # ---------------------------------------------------- Fork once and dissociate
233:
234: my $fpid=fork;
235: exit if $fpid;
1.6 albertel 236: die("Couldn't fork: $!") unless defined($fpid);
1.2 www 237:
238: POSIX::setsid() or die "Can't start new session: $!";
239:
240: # ------------------------------------------------------- Write our PID on disk
241:
242: my $execdir=$perlvar{'lonDaemons'};
1.5 albertel 243: open(PIDSAVE,">$execdir/logs/lonmaxima.pid");
1.2 www 244: print PIDSAVE "$$\n";
245: close(PIDSAVE);
246: &logthis("<font color='red'>CRITICAL: ---------- Starting ----------</font>");
247: &status('Starting');
1.6 albertel 248:
1.2 www 249:
250: # Fork off our children.
251: for (1 .. $PREFORK) {
1.5 albertel 252: &make_new_child($server);
1.2 www 253: }
254:
255: # Install signal handlers.
256: $SIG{CHLD} = \&REAPER;
257: $SIG{INT} = $SIG{TERM} = \&HUNTSMAN;
258:
259: # And maintain the population.
260: while (1) {
261: &status('Parent process, sleeping');
262: sleep; # wait for a signal (i.e., child's death)
1.3 albertel 263: for (my $i = $children; $i < $PREFORK; $i++) {
1.2 www 264: &status('Parent process, starting child');
1.5 albertel 265: &make_new_child($server); # top up the child pool
1.2 www 266: }
267: }
268:
269: sub make_new_child {
1.5 albertel 270: my ($server) = @_;
1.4 albertel 271:
1.2 www 272: # block signal for fork
1.4 albertel 273: my $sigset = POSIX::SigSet->new(SIGINT);
1.2 www 274: sigprocmask(SIG_BLOCK, $sigset)
1.6 albertel 275: or die("Can't block SIGINT for fork: $!\n");
1.2 www 276:
1.6 albertel 277: die("fork: $!") unless defined(my $pid = fork);
1.2 www 278:
279: if ($pid) {
280: # Parent records the child's birth and returns.
281: sigprocmask(SIG_UNBLOCK, $sigset)
1.6 albertel 282: or die("Can't unblock SIGINT for fork: $!\n");
1.2 www 283: $children{$pid} = 1;
284: $children++;
285: return;
286: } else {
287: # Child can *not* return from this subroutine.
288: $SIG{INT} = 'DEFAULT'; # make SIGINT kill us as it did before
289:
290: # unblock signals
291: sigprocmask(SIG_UNBLOCK, $sigset)
1.6 albertel 292: or die("Can't unblock SIGINT for fork: $!\n");
1.4 albertel 293:
1.5 albertel 294: &process_requests($server);
1.4 albertel 295:
1.2 www 296: # tidy up gracefully and finish
1.1 www 297:
1.2 www 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: }
1.4 albertel 304:
305: sub process_requests {
1.5 albertel 306: my ($server) = @_;
1.4 albertel 307: # handle connections until we've reached $MAX_CLIENTS_PER_CHILD
308: for (my $i=0; $i < $MAX_CLIENTS_PER_CHILD; $i++) {
309: &status('Accepting connections');
1.5 albertel 310: my $client = $server->accept() or last;
311: while (my $cmd=<$client>) {
1.4 albertel 312: &status('Processing command');
313: print $client &escape((&maximareply(&unescape($cmd)))[0])."\n";
314: }
315: }
316: }
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