[LON-CAPA-cvs] cvs: modules /gerd/maxima lonmaxima maximatestclient.pl

www lon-capa-cvs@mail.lon-capa.org
Fri, 03 Mar 2006 22:35:12 -0000


This is a MIME encoded message

--www1141425312
Content-Type: text/plain

www		Fri Mar  3 17:35:12 2006 EDT

  Added files:                 
    /modules/gerd/maxima	maximatestclient.pl 

  Modified files:              
    /modules/gerd/maxima	lonmaxima 
  Log:
  Playing some more, having fun
  
  
--www1141425312
Content-Type: text/plain
Content-Disposition: attachment; filename="www-20060303173512.txt"

Index: modules/gerd/maxima/lonmaxima
diff -u modules/gerd/maxima/lonmaxima:1.1 modules/gerd/maxima/lonmaxima:1.2
--- modules/gerd/maxima/lonmaxima:1.1	Fri Mar  3 11:07:34 2006
+++ modules/gerd/maxima/lonmaxima	Fri Mar  3 17:35:09 2006
@@ -3,7 +3,7 @@
 # The LearningOnline Network with CAPA
 # Connect to MAXIMA CAS
 #
-# $Id: lonmaxima,v 1.1 2006/03/03 16:07:34 www Exp $
+# $Id: lonmaxima,v 1.2 2006/03/03 22:35:09 www Exp $
 #
 # Copyright Michigan State University Board of Trustees
 #
@@ -29,12 +29,25 @@
 # 
 # http://www.lon-capa.org/
 #
+
+# global variables
+$PREFORK                = 5;        # number of children to maintain
+$MAX_CLIENTS_PER_CHILD  = 5;        # number of clients each child should process
+%children               = ();       # keys are current child process IDs
+$children               = 0;        # current number of children
  
 use IPC::Open3;
 use IO::Select;
+use IO::Socket;
+use IO::File;
+use Symbol;
+use POSIX;
+use lib '/home/httpd/lib/perl/';
+use LONCAPA::Configuration;
+ 
 # Scary: cannot use strict!!!
 ##### use strict;
-
+ 
 sub maximareply {
     my $cmd=shift;
     my $reply='';
@@ -43,15 +56,14 @@
 
     unless ($cmd=~/\;\n$/) { $cmd.=";\n"; }
     my $pid = open3($cmd_in, $cmd_out, $cmd_err, 'maxima');
+    $children{$pid} = 1;
     
-    $SIG{CHLD} = sub {
-	$exitstatus="$? on $pid\n" if waitpid($pid, 0) > 0;
-    };
-
     print $cmd_in $cmd;
     close $cmd_in;
 
-    my $selector = IO::Select->new( );
+    &status("Command sent");
+
+    my $selector = IO::Select->new();
     $selector->add($cmd_err, $cmd_out);
     
     while (my @ready = $selector->can_read) {
@@ -70,8 +82,218 @@
     }
     close $cmd_out;
     close $cmd_err;
+    &status("Command processed");
     return ($reply,$error,$exitstatus);
 }
+ 
+# ------------------------------------------------------------ Service routines 
+sub REAPER {                        # takes care of dead children 
+                                    # and MAXIMA processes
+    $SIG{CHLD} = \&REAPER;
+    my $pid = wait;
+    $children --;
+    delete $children{$pid};
+}
+ 
+sub HUNTSMAN {                      # signal handler for SIGINT
+    local($SIG{CHLD}) = 'IGNORE';   # we're going to kill our children
+    kill 'INT' => keys %children;
+    unlink($pidfile);
+    unlink($port);
+    &logthis('---- Shutdown ----');
+    exit;                           # clean up with dignity
+}
+
+
+ 
+# --------------------------------------------------------------------- Logging
+ 
+sub logthis {
+    my $message=shift;
+    my $execdir=$perlvar{'lonDaemons'};
+    my $fh=IO::File->new(">>$execdir/logs/lonmaxima.log");
+    my $now=time;
+    my $local=localtime($now);
+    $lastlog=$local.': '.$message;
+    print $fh "$local ($$): $message\n";
+}
+ 
+# -------------------------------------------------------------- Status setting
+ 
+sub status {
+    my $what=shift;
+    my $now=time;
+    my $local=localtime($now);
+    $status=$local.': '.$what;
+    $0='lonmaxima: '.$what.' '.$local;
+}
+ 
+# -------------------------------------------------------- Escape Special Chars
+ 
+sub escape {
+    my $str=shift;
+    $str =~ s/(\W)/"%".unpack('H2',$1)/eg;
+    return $str;
+}
+ 
+# ----------------------------------------------------- Un-Escape Special Chars
+ 
+sub unescape {
+    my $str=shift;
+    $str =~ s/%([a-fA-F0-9][a-fA-F0-9])/pack("C",hex($1))/eg;
+    return $str;
+}
+ 
+# ------------------------ grabs exception and records it to log before exiting
+sub catchexception {
+    my ($signal)=@_;
+    $SIG{QUIT}='DEFAULT';
+    $SIG{__DIE__}='DEFAULT';
+    chomp($signal);
+    &logthis("<font color=red>CRITICAL: "
+     ."ABNORMAL EXIT. Child $$ died through "
+     ."\"$signal\"</font>");
+    die("Signal abend");
+}
+ 
+
+
+# ---------------------------------------------------------------- Main program
+# -------------------------------- Set signal handlers to record abnormal exits
+ 
+ 
+$SIG{'QUIT'}=\&catchexception;
+$SIG{__DIE__}=\&catchexception;
+ 
+# ---------------------------------- Read loncapa_apache.conf and loncapa.conf
+&status("Read loncapa.conf and loncapa_apache.conf");
+my $perlvarref=LONCAPA::Configuration::read_conf('loncapa.conf');
+%perlvar=%{$perlvarref};
+undef $perlvarref;
+ 
+# ----------------------------- Make sure this process is running from user=www
+my $wwwid=getpwnam('www');
+if ($wwwid!=$<) {
+   my $emailto="$perlvar{'lonAdmEMail'},$perlvar{'lonSysEMail'}";
+   my $subj="LON: $currenthostid User ID mismatch";
+   system("echo 'User ID mismatch.  lonmaxima must be run as user www.' |\
+ mailto $emailto -s '$subj' > /dev/null");
+   exit 1;
+}
+ 
+# --------------------------------------------- Check if other instance running
+ 
+$pidfile="$perlvar{'lonDaemons'}/logs/lonmaxima.pid";
+ 
+if (-e $pidfile) {
+   my $lfh=IO::File->new("$pidfile");
+   my $pide=<$lfh>;
+   chomp($pide);
+   if (kill 0 => $pide) { die "already running"; }
+}
+# ------------------------------------------------------- Listen to UNIX socket
+&status("Opening socket");
+ 
+$port = "$perlvar{'lonSockDir'}/maximasock";
+ 
+unlink($port);
+ 
+
+unless (
+  $server = IO::Socket::UNIX->new(Local  => $port,
+                                  Type   => SOCK_STREAM,
+                                  Listen => 10 )
+   ) {
+       my $st=120+int(rand(240));
+       &logthis(
+         "<font color=blue>WARNING: ".
+         "Can't make server socket ($st secs):  .. exiting</font>");
+       sleep($st);
+       exit;
+     };
+    
+ 
+# ---------------------------------------------------- Fork once and dissociate
+ 
+my $fpid=fork;
+exit if $fpid;
+die "Couldn't fork: $!" unless defined ($fpid);
+ 
+POSIX::setsid() or die "Can't start new session: $!";
+ 
+# ------------------------------------------------------- Write our PID on disk
+ 
+my $execdir=$perlvar{'lonDaemons'};
+open (PIDSAVE,">$execdir/logs/lonmaxima.pid");
+print PIDSAVE "$$\n";
+close(PIDSAVE);
+&logthis("<font color='red'>CRITICAL: ---------- Starting ----------</font>");
+&status('Starting');
+ 
+ 
+
+
+     
+# Fork off our children.
+for (1 .. $PREFORK) {
+    make_new_child( );
+}
+ 
+# Install signal handlers.
+$SIG{CHLD} = \&REAPER;
+$SIG{INT}  = $SIG{TERM} = \&HUNTSMAN;
+ 
+# And maintain the population.
+while (1) {
+    &status('Parent process, sleeping');
+    sleep;                          # wait for a signal (i.e., child's death)
+    for ($i = $children; $i < $PREFORK; $i++) {
+        &status('Parent process, starting child');
+        make_new_child( );           # top up the child pool
+    }
+}
+                                                                                
+sub make_new_child {
+    my $pid;
+    my $sigset;
+     
+    # block signal for fork
+    $sigset = POSIX::SigSet->new(SIGINT);
+    sigprocmask(SIG_BLOCK, $sigset)
+        or die "Can't block SIGINT for fork: $!\n";
+     
+    die "fork: $!" unless defined ($pid = fork);
+     
+    if ($pid) {
+        # Parent records the child's birth and returns.
+        sigprocmask(SIG_UNBLOCK, $sigset)
+            or die "Can't unblock SIGINT for fork: $!\n";
+        $children{$pid} = 1;
+        $children++;
+        return;
+    } else {
+        # Child can *not* return from this subroutine.
+        $SIG{INT} = 'DEFAULT';      # make SIGINT kill us as it did before
+     
+        # unblock signals
+        sigprocmask(SIG_UNBLOCK, $sigset)
+            or die "Can't unblock SIGINT for fork: $!\n";
+         
+        # handle connections until we've reached $MAX_CLIENTS_PER_CHILD
+        for ($i=0; $i < $MAX_CLIENTS_PER_CHILD; $i++) {
+	    &status('Accepting connections');     
+            $client = $server->accept( )     or last;
+            while ($cmd=<$client>) {
+		&status('Processing command');
+		print $client &escape((&maximareply(&unescape($cmd)))[0])."\n";
+	    }
+        }
+     
+        # tidy up gracefully and finish
 
-print join("\n----\n",&maximareply('1234'));
-print join("\n----\n",&maximareply('x0: 5;x1: 7;integrate (x^2, x, x0, x1);'));
+        # this exit is VERY important, otherwise the child will become
+        # a producer of more and more children, forking yourself into
+        # process death.
+        exit;
+    }
+}

Index: modules/gerd/maxima/maximatestclient.pl
+++ modules/gerd/maxima/maximatestclient.pl
use IO::Socket;
my $socket=IO::Socket::UNIX->new(Peer    => '/home/httpd/sockets/maximasock',
				 Type    => SOCK_STREAM,
				 Timeout => 10);

while ($in=<STDIN>) {
    chomp($in);
    print $socket &escape($cmd)."\n";
    print &unescape(<$socket>);
}
close($socket);

# -------------------------------------------------------- Escape Special Chars
 
sub escape {
    my $str=shift;
    $str =~ s/(\W)/"%".unpack('H2',$1)/eg;
    return $str;
}
 
# ----------------------------------------------------- Un-Escape Special Chars
 
sub unescape {
    my $str=shift;
    $str =~ s/%([a-fA-F0-9][a-fA-F0-9])/pack("C",hex($1))/eg;
    return $str;
}
 

--www1141425312--