Annotation of loncom/lonmaxima, revision 1.13
1.1 www 1: #!/usr/bin/perl
2: #
3: # The LearningOnline Network with CAPA
4: # Connect to MAXIMA CAS
5: #
1.13 ! www 6: # $Id: lonmaxima,v 1.12 2006/03/08 03:18:42 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;
1.13 ! www 40: use Fcntl;
! 41: use Socket;
1.2 www 42: use lib '/home/httpd/lib/perl/';
43: use LONCAPA::Configuration;
44:
1.3 albertel 45: use strict;
46:
47: # global variables
1.12 www 48: my $STARTPORT = 5664; # port for first child's server
1.3 albertel 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
1.12 www 52: my %usedmaximaports = (); # keys are the used maximaports
1.3 albertel 53: my $children = 0; # current number of children
54: my $status; # string for current status
1.5 albertel 55: my $pidfile; # file containg parent process pid
56: my $port; # path to UNIX socket file
57: my %perlvar; # configuration file info
58: my $lastlog; # last string that was logged
1.12 www 59: use vars qw($PREFORK $MAX_CLIENTS_PER_CHILD %children $children %usedmaximaports $status
60: $pidfile $port %perlvar $lastlog);
1.2 www 61:
62: # ------------------------------------------------------------ Service routines
63: sub REAPER { # takes care of dead children
64: # and MAXIMA processes
65: $SIG{CHLD} = \&REAPER;
66: my $pid = wait;
1.6 albertel 67: $children--;
1.12 www 68: delete($usedmaximaports{$children{$pid}});
1.6 albertel 69: delete($children{$pid});
1.2 www 70: }
71:
72: sub HUNTSMAN { # signal handler for SIGINT
73: local($SIG{CHLD}) = 'IGNORE'; # we're going to kill our children
1.6 albertel 74: kill('INT' => keys(%children));
1.2 www 75: unlink($pidfile);
76: unlink($port);
77: &logthis('---- Shutdown ----');
78: exit; # clean up with dignity
79: }
80:
81:
82:
83: # --------------------------------------------------------------------- Logging
84:
85: sub logthis {
1.4 albertel 86: my ($message)=@_;
1.2 www 87: my $execdir=$perlvar{'lonDaemons'};
88: my $fh=IO::File->new(">>$execdir/logs/lonmaxima.log");
89: my $now=time;
90: my $local=localtime($now);
91: $lastlog=$local.': '.$message;
92: print $fh "$local ($$): $message\n";
93: }
94:
95: # -------------------------------------------------------------- Status setting
96:
97: sub status {
1.4 albertel 98: my ($what)=@_;
1.2 www 99: my $now=time;
100: my $local=localtime($now);
101: $status=$local.': '.$what;
102: $0='lonmaxima: '.$what.' '.$local;
103: }
104:
105: # -------------------------------------------------------- Escape Special Chars
106:
107: sub escape {
1.4 albertel 108: my ($str)=@_;
1.2 www 109: $str =~ s/(\W)/"%".unpack('H2',$1)/eg;
110: return $str;
111: }
112:
113: # ----------------------------------------------------- Un-Escape Special Chars
114:
115: sub unescape {
1.4 albertel 116: my ($str)=@_;
1.2 www 117: $str =~ s/%([a-fA-F0-9][a-fA-F0-9])/pack("C",hex($1))/eg;
118: return $str;
119: }
120:
121: # ------------------------ grabs exception and records it to log before exiting
122: sub catchexception {
123: my ($signal)=@_;
124: $SIG{QUIT}='DEFAULT';
125: $SIG{__DIE__}='DEFAULT';
126: chomp($signal);
1.5 albertel 127: &logthis("<font color=\"red\">CRITICAL: "
128: ."ABNORMAL EXIT. Child $$ died through "
129: ."\"$signal\"</font>");
1.2 www 130: die("Signal abend");
131: }
1.5 albertel 132:
1.13 ! www 133: # -------------------------------------------------- make a socket non-blocking
! 134: sub nonblock {
! 135: my $socket = shift;
! 136: my $flags;
! 137: if (ref($socket)) {
! 138: $flags = fcntl($socket, F_GETFL, 0)
! 139: or die "Can't get flags for socket: $!\n";
! 140: fcntl($socket, F_SETFL, $flags | O_NONBLOCK)
! 141: or die "Can't make socket nonblocking: $!\n";
! 142: }
! 143: }
1.2 www 144:
145: # ---------------------------------------------------------------- Main program
146: # -------------------------------- Set signal handlers to record abnormal exits
147:
148:
149: $SIG{'QUIT'}=\&catchexception;
150: $SIG{__DIE__}=\&catchexception;
151:
152: # ---------------------------------- Read loncapa_apache.conf and loncapa.conf
153: &status("Read loncapa.conf and loncapa_apache.conf");
1.3 albertel 154: %perlvar=%{&LONCAPA::Configuration::read_conf('loncapa.conf')};
1.2 www 155:
156: # ----------------------------- Make sure this process is running from user=www
157: my $wwwid=getpwnam('www');
158: if ($wwwid!=$<) {
1.5 albertel 159: my $emailto="$perlvar{'lonAdmEMail'},$perlvar{'lonSysEMail'}";
160: my $subj="LON: User ID mismatch";
161: system("echo 'User ID mismatch. lonmaxima must be run as user www.' |\
1.2 www 162: mailto $emailto -s '$subj' > /dev/null");
1.5 albertel 163: exit 1;
1.2 www 164: }
165:
166: # --------------------------------------------- Check if other instance running
167:
168: $pidfile="$perlvar{'lonDaemons'}/logs/lonmaxima.pid";
169:
170: if (-e $pidfile) {
1.5 albertel 171: my $lfh=IO::File->new("$pidfile");
172: my $pide=<$lfh>;
173: chomp($pide);
1.6 albertel 174: if (kill(0 => $pide)) { die "already running"; }
1.2 www 175: }
1.5 albertel 176:
1.2 www 177: # ------------------------------------------------------- Listen to UNIX socket
178: &status("Opening socket");
179:
180: $port = "$perlvar{'lonSockDir'}/maximasock";
181:
182: unlink($port);
183:
184:
1.6 albertel 185: my $server = IO::Socket::UNIX->new(Local => $port,
186: Type => SOCK_STREAM,
187: Listen => 10 );
188: if (!$server) {
189: my $st=120+int(rand(240));
190:
191: &logthis("<font color=blue>WARNING: ".
192: "Can't make server socket ($st secs): .. exiting</font>");
193:
194: sleep($st);
195: exit;
196: }
1.2 www 197:
198:
199: # ---------------------------------------------------- Fork once and dissociate
200:
201: my $fpid=fork;
202: exit if $fpid;
1.6 albertel 203: die("Couldn't fork: $!") unless defined($fpid);
1.2 www 204:
205: POSIX::setsid() or die "Can't start new session: $!";
206:
207: # ------------------------------------------------------- Write our PID on disk
208:
209: my $execdir=$perlvar{'lonDaemons'};
1.5 albertel 210: open(PIDSAVE,">$execdir/logs/lonmaxima.pid");
1.2 www 211: print PIDSAVE "$$\n";
212: close(PIDSAVE);
213: &logthis("<font color='red'>CRITICAL: ---------- Starting ----------</font>");
214: &status('Starting');
1.6 albertel 215:
1.2 www 216:
1.10 albertel 217: # Install signal handlers.
218: $SIG{CHLD} = \&REAPER;
219: $SIG{INT} = $SIG{TERM} = \&HUNTSMAN;
1.12 www 220:
221: my $maximaport=$STARTPORT;
1.2 www 222: # Fork off our children.
223: for (1 .. $PREFORK) {
1.12 www 224: &make_new_child($server,$maximaport);
225: $maximaport++;
1.2 www 226: }
227:
228: # And maintain the population.
229: while (1) {
230: &status('Parent process, sleeping');
231: sleep; # wait for a signal (i.e., child's death)
1.3 albertel 232: for (my $i = $children; $i < $PREFORK; $i++) {
1.2 www 233: &status('Parent process, starting child');
1.12 www 234: my $newport;
235: foreach $newport ($STARTPORT .. $STARTPORT+$PREFORK-1) {
236: if (!defined($usedmaximaports{$newport})) { last; }
237: }
238: &make_new_child($server,$newport); # top up the child pool
1.2 www 239: }
240: }
241:
242: sub make_new_child {
1.12 www 243: my ($server,$maximaport) = @_;
1.4 albertel 244:
1.2 www 245: # block signal for fork
1.4 albertel 246: my $sigset = POSIX::SigSet->new(SIGINT);
1.2 www 247: sigprocmask(SIG_BLOCK, $sigset)
1.6 albertel 248: or die("Can't block SIGINT for fork: $!\n");
1.2 www 249:
1.6 albertel 250: die("fork: $!") unless defined(my $pid = fork);
1.2 www 251:
252: if ($pid) {
253: # Parent records the child's birth and returns.
254: sigprocmask(SIG_UNBLOCK, $sigset)
1.6 albertel 255: or die("Can't unblock SIGINT for fork: $!\n");
1.12 www 256: $children{$pid} = $maximaport;
1.2 www 257: $children++;
258: return;
259: } else {
260: # Child can *not* return from this subroutine.
261: $SIG{INT} = 'DEFAULT'; # make SIGINT kill us as it did before
262:
263: # unblock signals
264: sigprocmask(SIG_UNBLOCK, $sigset)
1.6 albertel 265: or die("Can't unblock SIGINT for fork: $!\n");
1.12 www 266:
267: # open the MAXIMA port
268: my $maximaserver = IO::Socket::INET->new(LocalPort => $maximaport,
269: Type => SOCK_STREAM,
270: Proto => 'tcp',
271: Reuse => 1,
272: Listen => 10 )
273: or die "making socket: $@\n";
1.13 ! www 274: &nonblock($maximaserver);
! 275: my $maximaselect=IO::Select->new($maximaserver);
1.12 www 276:
277: # open MAXIMA to talk to that port
278: my ($cmd_in, $cmd_out, $cmd_err);
279: my $maximapid = open3($cmd_in, $cmd_out, $cmd_err, "maxima -s $maximaport");
280: $children{$maximapid} = 1;
281: my $prompt=<$cmd_out>;
282: &logthis("Maxima $maximapid: $prompt");
283:
1.13 ! www 284: # hopefully, MAXIMA calls us back
1.12 www 285: &status("Waiting $maximapid on $maximaport");
286: my $maximaclient=$maximaserver->accept();
1.13 ! www 287: $maximaselect->add($maximaclient);
! 288: &nonblock($maximaclient);
1.12 www 289: &status("$maximapid on $maximaport connected.");
290: &logthis("Maxima $maximapid on port $maximaport connected.");
1.13 ! www 291: &logthis('Initial reply: '.&maximareply($maximaselect));
! 292: # handle connections until we've reached $MAX_CLIENTS_PER_CHILD
! 293: for (my $i=0; $i < $MAX_CLIENTS_PER_CHILD; $i++) {
! 294: &status('Accepting connections for '.$maximapid.' on '.$maximaport);
! 295: my $client = $server->accept() or last;
! 296: while (my $cmd=<$client>) {
! 297: &status('Processing command by '.$maximapid.' on '.$maximaport);
! 298: print $maximaclient &unescape($cmd).";\n";
! 299: print $client &escape(&maximareply($maximaselect))."\n";
! 300: }
! 301: }
1.4 albertel 302:
1.12 www 303: # tidy up gracefully and finish
1.4 albertel 304:
1.12 www 305: if (ref($cmd_out)) { close($cmd_out); }
306: if (ref($cmd_err)) { close($cmd_err); }
307: if (ref($cmd_in)) { close($cmd_in); }
1.1 www 308:
1.2 www 309: # this exit is VERY important, otherwise the child will become
310: # a producer of more and more children, forking yourself into
311: # process death.
312: exit;
313: }
314: }
1.4 albertel 315:
1.13 ! www 316: sub maximareply {
! 317: my ($maximaselect)=@_;
! 318: my $output='';
! 319: foreach my $ready ($maximaselect->can_read(1)) {
! 320: my $data = '';
! 321: my $rv = $ready->recv($data, POSIX::BUFSIZ, 0);
! 322: $output.=$data;
! 323: }
! 324: return $output;
1.4 albertel 325: }
1.13 ! www 326:
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