1: #!/usr/bin/perl
2: #
3: # The LearningOnline Network with CAPA
4: # Connect to MAXIMA CAS
5: #
6: # $Id: lonmaxima,v 1.14 2006/03/08 14:22:14 www 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 Fcntl;
41: use Socket;
42: use lib '/home/httpd/lib/perl/';
43: use LONCAPA::Configuration;
44:
45: use strict;
46:
47: # global variables
48: my $STARTPORT = 5664; # port for first child's server
49: my $PREFORK = 5; # number of children to maintain
50: my $MAX_CLIENTS_PER_CHILD = 5; # number of clients each child should process
51: my %children = (); # keys are current child process IDs
52: my %usedmaximaports = (); # keys are the used maximaports
53: my $children = 0; # current number of children
54: my $status; # string for current status
55: my $pidfile; # file containg parent process pid
56: my $port; # path to UNIX socket file
57: my %perlvar; # configuration file info
58: my $lastlog; # last string that was logged
59: use vars qw($PREFORK $MAX_CLIENTS_PER_CHILD %children $children %usedmaximaports $status
60: $pidfile $port %perlvar $lastlog);
61:
62: # ------------------------------------------------------------ Service routines
63: sub REAPER { # takes care of dead children
64: # and MAXIMA processes
65: $SIG{CHLD} = \&REAPER;
66: my $pid = wait;
67: $children--;
68: &logthis("Child $pid for port or process $children{$pid} died");
69: delete($usedmaximaports{$children{$pid}});
70: delete($children{$pid});
71: }
72:
73: sub HUNTSMAN { # signal handler for SIGINT
74: local($SIG{CHLD}) = 'IGNORE'; # we're going to kill our children
75: kill('INT' => keys(%children));
76: unlink($pidfile);
77: unlink($port);
78: &logthis('---- Shutdown ----');
79: exit; # clean up with dignity
80: }
81:
82:
83:
84: # --------------------------------------------------------------------- Logging
85:
86: sub logthis {
87: my ($message)=@_;
88: my $execdir=$perlvar{'lonDaemons'};
89: my $fh=IO::File->new(">>$execdir/logs/lonmaxima.log");
90: my $now=time;
91: my $local=localtime($now);
92: $lastlog=$local.': '.$message;
93: print $fh "$local ($$): $message\n";
94: }
95:
96: # -------------------------------------------------------------- Status setting
97:
98: sub status {
99: my ($what)=@_;
100: my $now=time;
101: my $local=localtime($now);
102: $status=$local.': '.$what;
103: $0='lonmaxima: '.$what.' '.$local;
104: }
105:
106: # -------------------------------------------------------- Escape Special Chars
107:
108: sub escape {
109: my ($str)=@_;
110: $str =~ s/(\W)/"%".unpack('H2',$1)/eg;
111: return $str;
112: }
113:
114: # ----------------------------------------------------- Un-Escape Special Chars
115:
116: sub unescape {
117: my ($str)=@_;
118: $str =~ s/%([a-fA-F0-9][a-fA-F0-9])/pack("C",hex($1))/eg;
119: return $str;
120: }
121:
122: # ------------------------ grabs exception and records it to log before exiting
123: sub catchexception {
124: my ($signal)=@_;
125: $SIG{QUIT}='DEFAULT';
126: $SIG{__DIE__}='DEFAULT';
127: chomp($signal);
128: &logthis("<font color=\"red\">CRITICAL: "
129: ."ABNORMAL EXIT. Child $$ died through "
130: ."\"$signal\"</font>");
131: die("Signal abend");
132: }
133:
134: # -------------------------------------------------- make a socket non-blocking
135: sub nonblock {
136: my $socket = shift;
137: my $flags;
138: if (ref($socket)) {
139: $flags = fcntl($socket, F_GETFL, 0)
140: or die "Can't get flags for socket: $!\n";
141: fcntl($socket, F_SETFL, $flags | O_NONBLOCK)
142: or die "Can't make socket nonblocking: $!\n";
143: }
144: }
145:
146: # ---------------------------------------------------------------- Main program
147: # -------------------------------- Set signal handlers to record abnormal exits
148:
149:
150: $SIG{'QUIT'}=\&catchexception;
151: $SIG{__DIE__}=\&catchexception;
152:
153: # ---------------------------------- Read loncapa_apache.conf and loncapa.conf
154: &status("Read loncapa.conf and loncapa_apache.conf");
155: %perlvar=%{&LONCAPA::Configuration::read_conf('loncapa.conf')};
156:
157: # ----------------------------- Make sure this process is running from user=www
158: my $wwwid=getpwnam('www');
159: if ($wwwid!=$<) {
160: my $emailto="$perlvar{'lonAdmEMail'},$perlvar{'lonSysEMail'}";
161: my $subj="LON: User ID mismatch";
162: system("echo 'User ID mismatch. lonmaxima must be run as user www.' |\
163: mailto $emailto -s '$subj' > /dev/null");
164: exit 1;
165: }
166:
167: # --------------------------------------------- Check if other instance running
168:
169: $pidfile="$perlvar{'lonDaemons'}/logs/lonmaxima.pid";
170:
171: if (-e $pidfile) {
172: my $lfh=IO::File->new("$pidfile");
173: my $pide=<$lfh>;
174: chomp($pide);
175: if (kill(0 => $pide)) { die "already running"; }
176: }
177:
178: # ------------------------------------------------------- Listen to UNIX socket
179: &status("Opening socket");
180:
181: $port = "$perlvar{'lonSockDir'}/maximasock";
182:
183: unlink($port);
184:
185:
186: my $server = IO::Socket::UNIX->new(Local => $port,
187: Type => SOCK_STREAM,
188: Listen => 10 );
189: if (!$server) {
190: my $st=120+int(rand(240));
191:
192: &logthis("<font color=blue>WARNING: ".
193: "Can't make server socket ($st secs): .. exiting</font>");
194:
195: sleep($st);
196: exit;
197: }
198:
199:
200: # ---------------------------------------------------- Fork once and dissociate
201:
202: my $fpid=fork;
203: exit if $fpid;
204: die("Couldn't fork: $!") unless defined($fpid);
205:
206: POSIX::setsid() or die "Can't start new session: $!";
207:
208: # ------------------------------------------------------- Write our PID on disk
209:
210: my $execdir=$perlvar{'lonDaemons'};
211: open(PIDSAVE,">$execdir/logs/lonmaxima.pid");
212: print PIDSAVE "$$\n";
213: close(PIDSAVE);
214: &logthis("<font color='red'>CRITICAL: ---------- Starting ----------</font>");
215: &status('Starting');
216:
217:
218: # Install signal handlers.
219: $SIG{CHLD} = \&REAPER;
220: $SIG{INT} = $SIG{TERM} = \&HUNTSMAN;
221:
222: my $maximaport=$STARTPORT;
223: # Fork off our children.
224: for (1 .. $PREFORK) {
225: &make_new_child($server,$maximaport);
226: $maximaport++;
227: }
228:
229: # And maintain the population.
230: while (1) {
231: &status('Parent process, sleeping');
232: sleep; # wait for a signal (i.e., child's death)
233: for (my $i = $children; $i < $PREFORK; $i++) {
234: &status('Parent process, starting child');
235: my $newport;
236: &logthis("Current pool: ".join(', ',keys %usedmaximaports));
237: foreach my $testport ($STARTPORT .. $STARTPORT+$PREFORK-1) {
238: if (!$usedmaximaports{$testport}) { $newport=$testport; }
239: }
240: if ($newport) {
241: &make_new_child($server,$newport); # top up the child pool
242: }
243: }
244: }
245:
246: sub make_new_child {
247: my ($server,$maximaport) = @_;
248:
249: # block signal for fork
250: my $sigset = POSIX::SigSet->new(SIGINT);
251: sigprocmask(SIG_BLOCK, $sigset)
252: or die("Can't block SIGINT for fork: $!\n");
253:
254: die("fork: $!") unless defined(my $pid = fork);
255:
256: if ($pid) {
257: # Parent records the child's birth and returns.
258: sigprocmask(SIG_UNBLOCK, $sigset)
259: or die("Can't unblock SIGINT for fork: $!\n");
260: $children{$pid} = $maximaport;
261: $children++;
262: $usedmaximaports{$maximaport}=1;
263: return;
264: } else {
265: &logthis("Starting child on port $maximaport");
266: # Child can *not* return from this subroutine.
267: $SIG{INT} = 'DEFAULT'; # make SIGINT kill us as it did before
268:
269: # unblock signals
270: sigprocmask(SIG_UNBLOCK, $sigset)
271: or die("Can't unblock SIGINT for fork: $!\n");
272:
273: # open the MAXIMA port
274: my $maximaserver = IO::Socket::INET->new(LocalPort => $maximaport,
275: Type => SOCK_STREAM,
276: Proto => 'tcp',
277: Reuse => 1,
278: Listen => 10 )
279: or die "making socket: $@\n";
280: &nonblock($maximaserver);
281: my $maximaselect=IO::Select->new($maximaserver);
282: sleep(2);
283:
284: # open MAXIMA to talk to that port
285: my ($cmd_in, $cmd_out, $cmd_err);
286: my $maximapid = open3($cmd_in, $cmd_out, $cmd_err, "maxima -s $maximaport");
287: $children{$maximapid} = "Maxima $maximapid port $maximaport";
288: my $prompt=<$cmd_out>;
289: &logthis("Maxima $maximapid: $prompt");
290:
291: # hopefully, MAXIMA calls us back
292: &status("Waiting $maximapid on $maximaport");
293: my $maximaclient=$maximaserver->accept();
294: $maximaselect->add($maximaclient);
295: &nonblock($maximaclient);
296: &status("$maximapid on $maximaport connected.");
297: &logthis("Maxima $maximapid on port $maximaport connected.");
298: &logthis('Initial reply: '.&maximareply($maximaselect));
299: # handle connections until we've reached $MAX_CLIENTS_PER_CHILD
300: for (my $i=0; $i < $MAX_CLIENTS_PER_CHILD; $i++) {
301: &status('Accepting connections for '.$maximapid.' on '.$maximaport);
302: my $client = $server->accept() or last;
303: while (my $cmd=<$client>) {
304: &status('Processing command by '.$maximapid.' on '.$maximaport);
305: print $maximaclient &unescape($cmd).";\n";
306: print $client &escape(&maximareply($maximaselect))."\n";
307: }
308: }
309:
310: # tidy up gracefully and finish
311:
312: if (ref($cmd_out)) { close($cmd_out); }
313: if (ref($cmd_err)) { close($cmd_err); }
314: if (ref($cmd_in)) { close($cmd_in); }
315:
316: # this exit is VERY important, otherwise the child will become
317: # a producer of more and more children, forking yourself into
318: # process death.
319: exit;
320: }
321: }
322:
323: sub maximareply {
324: my ($maximaselect)=@_;
325: my $output='';
326: foreach my $ready ($maximaselect->can_read(1)) {
327: my $data = '';
328: my $rv = $ready->recv($data, POSIX::BUFSIZ, 0);
329: $output.=$data;
330: }
331: return $output;
332: }
333:
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