--- loncom/lonmaxima	2006/03/08 03:18:42	1.12
+++ loncom/lonmaxima	2006/03/08 12:57:30	1.13
@@ -3,7 +3,7 @@
 # The LearningOnline Network with CAPA
 # Connect to MAXIMA CAS
 #
-# $Id: lonmaxima,v 1.12 2006/03/08 03:18:42 www Exp $
+# $Id: lonmaxima,v 1.13 2006/03/08 12:57:30 www Exp $
 #
 # Copyright Michigan State University Board of Trustees
 #
@@ -37,6 +37,8 @@ use IO::Socket;
 use IO::File;
 use Symbol;
 use POSIX;
+use Fcntl;
+use Socket;
 use lib '/home/httpd/lib/perl/';
 use LONCAPA::Configuration;
  
@@ -57,22 +59,6 @@ my $lastlog;                           #
 use vars qw($PREFORK $MAX_CLIENTS_PER_CHILD %children $children %usedmaximaports $status
 	    $pidfile $port %perlvar $lastlog);
  
-sub maximareply {
-    my ($cmd,$maximaclient,$maximapid) = @_;
-    my $reply='';
-    while (my $line=<$maximaclient>) {
-       $reply.=$line;
-    }
-    unless ($cmd=~/\;\n$/) { $cmd.=";\n"; }
-    print $maximaclient $cmd;
-    &status("Command sent to $maximapid");
-    while (my $line=<$maximaclient>) {
-       $reply.=$line;
-    }
-    &status("Command processed by $maximapid");
-    return $reply;
-}
- 
 # ------------------------------------------------------------ Service routines 
 sub REAPER {                        # takes care of dead children 
                                     # and MAXIMA processes
@@ -144,7 +130,17 @@ sub catchexception {
     die("Signal abend");
 }
 
-
+# -------------------------------------------------- make a socket non-blocking
+sub nonblock {
+    my $socket = shift;
+    my $flags;
+    if (ref($socket)) { 
+       $flags = fcntl($socket, F_GETFL, 0)
+            or die "Can't get flags for socket: $!\n";
+       fcntl($socket, F_SETFL, $flags | O_NONBLOCK)
+            or die "Can't make socket nonblocking: $!\n";
+    }
+}
 
 # ---------------------------------------------------------------- Main program
 # -------------------------------- Set signal handlers to record abnormal exits
@@ -275,27 +271,34 @@ sub make_new_child {
                                               Reuse     => 1,
                                               Listen    => 10 )
                         or die "making socket: $@\n";
+        &nonblock($maximaserver);
+        my $maximaselect=IO::Select->new($maximaserver);
 
         # open MAXIMA to talk to that port
         my ($cmd_in, $cmd_out, $cmd_err);
         my $maximapid = open3($cmd_in, $cmd_out, $cmd_err, "maxima -s $maximaport");
         $children{$maximapid} = 1;
-
         my $prompt=<$cmd_out>;
         &logthis("Maxima $maximapid: $prompt");
 
+        # hopefully, MAXIMA calls us back
         &status("Waiting $maximapid on $maximaport");
-        # Hopefully, MAXIMA calls us back
         my $maximaclient=$maximaserver->accept();
+        $maximaselect->add($maximaclient);
+        &nonblock($maximaclient);
         &status("$maximapid on $maximaport connected.");
         &logthis("Maxima $maximapid on port $maximaport connected.");
-
-        # Absorb initial prompts     
-        &logthis(&maximareply("0;\n",$maximaclient,$maximapid));
- 
-        # Ready for action  
-	
-        &process_requests($server,$maximaclient,$maximapid);
+        &logthis('Initial reply: '.&maximareply($maximaselect));
+        # handle connections until we've reached $MAX_CLIENTS_PER_CHILD
+        for (my $i=0; $i < $MAX_CLIENTS_PER_CHILD; $i++) {
+            &status('Accepting connections for '.$maximapid.' on '.$maximaport);
+            my $client = $server->accept()     or last;
+            while (my $cmd=<$client>) {
+                &status('Processing command by '.$maximapid.' on '.$maximaport);
+                print $maximaclient &unescape($cmd).";\n";
+                print $client &escape(&maximareply($maximaselect))."\n";
+            }
+        }
 
         # tidy up gracefully and finish
 
@@ -310,15 +313,14 @@ sub make_new_child {
     }
 }
 
-sub process_requests {
-    my ($server,$maximaclient,$maximapid) = @_;
-    # handle connections until we've reached $MAX_CLIENTS_PER_CHILD
-    for (my $i=0; $i < $MAX_CLIENTS_PER_CHILD; $i++) {
-	&status('Accepting connections for '.$maximapid.' on '.$maximaport);     
-	my $client = $server->accept()     or last;
-	while (my $cmd=<$client>) {
-	    &status('Processing command by '.$maximapid.' on '.$maximaport);
-	    print $client &escape((&maximareply(&unescape($cmd),$maximaclient,$maximapid))[0])."\n";
-	}
-    }    
+sub maximareply {
+   my ($maximaselect)=@_;
+   my $output='';
+   foreach my $ready ($maximaselect->can_read(1)) {
+       my $data = '';
+       my $rv   = $ready->recv($data, POSIX::BUFSIZ, 0);
+       $output.=$data;
+   }
+   return $output;
 }
+