--- loncom/loncnew	2003/09/23 11:22:14	1.25
+++ loncom/loncnew	2003/10/14 15:36:21	1.28
@@ -2,7 +2,7 @@
 # The LearningOnline Network with CAPA
 # lonc maintains the connections to remote computers
 #
-# $Id: loncnew,v 1.25 2003/09/23 11:22:14 foxr Exp $
+# $Id: loncnew,v 1.28 2003/10/14 15:36:21 albertel Exp $
 #
 # Copyright Michigan State University Board of Trustees
 #
@@ -45,6 +45,18 @@
 
 # Change log:
 #    $Log: loncnew,v $
+#    Revision 1.28  2003/10/14 15:36:21  albertel
+#    - making it easier to run loncnew,
+#       /etc/init.d/loncontrol startnew
+#       /etc/init.d/loncontrol restartnew
+#      will now start loncnew in place of lonc
+#
+#    Revision 1.27  2003/10/07 11:23:03  foxr
+#    Installed and tested code to process reinit in parent server.
+#
+#    Revision 1.26  2003/09/30 11:11:17  foxr
+#    Add book-keeping hashes to support the re-init procedure.
+#
 #    Revision 1.25  2003/09/23 11:22:14  foxr
 #    Tested ability to receive sigusr2  This is now logged and must be
 #    properly implemented as a re-read of hosts and re-init of appropriate
@@ -161,6 +173,8 @@ my %perlvar    = %{$perlvarref};
 #  parent and shared variables.
 
 my %ChildHash;			# by pid -> host.
+my %HostToPid;			# By host -> pid.
+my %HostHash;			# by loncapaname -> IP.
 
 
 my $MaxConnectionCount = 10;	# Will get from config later.
@@ -1519,7 +1533,8 @@ sub CreateChild {
     my $pid          = fork;
     if($pid) {			# Parent
 	$RemoteHost = "Parent";
-	$ChildHash{$pid} = $RemoteHost;
+	$ChildHash{$pid} = $host;
+	$HostToPid{$host}= $pid;
 	sigprocmask(SIG_UNBLOCK, $sigset);
 
     } else {			# child.
@@ -1582,6 +1597,7 @@ while (! $HostIterator->end()) {
 
     my $hostentryref = $HostIterator->get();
     CreateChild($hostentryref->[0]);
+    $HostHash{$hostentryref->[0]} = $hostentryref->[4];
     $HostIterator->next();
 }
 $RemoteHost = "Parent Server";
@@ -1604,6 +1620,7 @@ while(1) {
     my $deadchild = wait();
     if(exists $ChildHash{$deadchild}) {	# need to restart.
 	my $deadhost = $ChildHash{$deadchild};
+	delete($HostToPid{$deadhost});
 	delete($ChildHash{$deadchild});
 	Log("WARNING","Lost child pid= ".$deadchild.
 	      "Connected to host ".$deadhost);
@@ -1656,7 +1673,7 @@ Kills off (via sigint) children for host
 
 =item
 
-HUP's children for hosts that already exist (this just forces a status display
+QUITs  children for hosts that already exist (this just forces a status display
 and resets the connection retry count for that host.
 
 =item
@@ -1667,7 +1684,84 @@ the start of the master program and main
 =cut
 
 sub UpdateKids {
+
     Log("INFO", "Updating connections via SIGUSR2");
+
+    #  Just in case we need to kill our own lonc, we wait a few seconds to
+    #  give it a chance to receive and relay lond's response to the 
+    #  re-init command.
+    #
+
+    sleep(2);			# Wait a couple of seconds.
+
+    my %hosts;                   # Indexed by loncapa hostname, value=ip.
+    
+    # Need to re-read  the host table:
+    
+    
+    LondConnection::ReadConfig();
+    my $I = LondConnection::GetHostIterator;
+    while (! $I->end()) {
+	my $item = $I->get();
+	$hosts{$item->[0]} = $item->[4];
+	$I->next();
+    }
+
+    #  The logic below is written for clarity not for efficiency.
+    #  Since I anticipate that this function is only rarely called, that's
+    #  appropriate.  There are certainly ways to combine the loops below,
+    #  and anyone wishing to obscure the logic is welcome to go for it.
+    #  Note that we don't re-direct sigchild.  Instead we do what's needed
+    #  to the data structures that keep track of children to ensure that
+    #  when sigchild is honored, no new child is born.
+    #
+
+    #  For each existing child; if it's host doesn't exist, kill the child.
+
+    foreach my $child (keys %ChildHash) {
+	my $oldhost = $ChildHash{$child};
+	if (!(exists $hosts{$oldhost})) {
+	    Log("CRITICAL", "Killing child for $oldhost  host no longer exists");
+	    delete $ChildHash{$child};
+	    delete $HostToPid{$oldhost};
+	    kill 'QUIT' => $child;
+	}
+    }
+    # For each remaining existing child; if it's host's ip has changed,
+    # Restart the child on the new IP.
+
+    foreach my $child (keys %ChildHash) {
+	my $oldhost = $ChildHash{$child};
+	my $oldip   = $HostHash{$oldhost};
+	if ($hosts{$oldhost} ne $oldip) {
+
+	    # kill the old child.
+
+	    Log("CRITICAL", "Killing child for $oldhost host ip has changed...");
+	    delete $ChildHash{$child};
+	    delete $HostToPid{$oldhost};
+	    kill 'QUIT' => $child;
+
+	    # Do the book-keeping needed to start a new child on the
+	    # new ip.
+
+	    $HostHash{$oldhost} = $hosts{$oldhost};
+	    CreateChild($oldhost);
+	}
+    }
+    # Finally, for each new host, not in the host hash, create a
+    # enter the host and create a new child.
+    # Force a status display of any existing process.
+
+    foreach my $host (keys %hosts) {
+	if(!(exists $HostHash{$host})) {
+	    Log("INFO", "New host $host discovered in hosts.tab...");
+	    $HostHash{$host} = $hosts{$host};
+	    CreateChild($host);
+	} else {
+	    kill 'HUP' => $HostToPid{$host};    # status display.
+	}
+    }
 }
 
 
@@ -1686,7 +1780,7 @@ sub Restart {
     Log("CRITICAL", "Restarting");
     my $execdir = $perlvar{'lonDaemons'};
     unlink("$execdir/logs/lonc.pid");
-    exec("$execdir/lonc");
+    exec("$execdir/loncnew");
 }
 
 =pod