--- loncom/auth/lonauth.pm	2010/08/12 21:31:10	1.101.8.2
+++ loncom/auth/lonauth.pm	2011/09/27 20:18:45	1.101.8.7
@@ -1,7 +1,7 @@
 # The LearningOnline Network
 # User Authentication Module
 #
-# $Id: lonauth.pm,v 1.101.8.2 2010/08/12 21:31:10 raeburn Exp $
+# $Id: lonauth.pm,v 1.101.8.7 2011/09/27 20:18:45 raeburn Exp $
 #
 # Copyright Michigan State University Board of Trustees
 #
@@ -276,7 +276,8 @@ sub handler {
     my $tmpinfo=Apache::lonnet::reply('tmpget:'.$form{'logtoken'},
                                       $form{'serverid'});
 
-    if (($tmpinfo=~/^error/) || ($tmpinfo eq 'con_lost')) {
+    if (($tmpinfo=~/^error/) || ($tmpinfo eq 'con_lost') ||
+       ($tmpinfo eq 'no_such_host')) {
 	&failed($r,'Information needed to verify your login information is missing, inaccessible or expired.',\%form);
         return OK;
     } else {
@@ -362,7 +363,9 @@ sub handler {
             &Apache::lonnet::get_dom('configuration',['usercreation'],$form{'udom'});
         if (grep(/^login$/,@cancreate)) {
             my $domdesc = &Apache::lonnet::domain($form{'udom'},'description');
-            &check_can_host($r,\%form,'no_account_on_host',$domdesc);
+            unless (&check_can_host($r,\%form,'no_account_on_host',$domdesc)) {
+                return OK;     
+            }
             my $start_page = 
                 &Apache::loncommon::start_page('Create a user account in LON-CAPA',
                                                '',{'no_inline_link'   => 1,});
@@ -415,18 +418,61 @@ sub handler {
 	}
     }
 
-    &check_can_host($r,\%form,$authhost);
-
     if ($r->dir_config("lonBalancer") eq 'yes') {
-	&success($r,$form{'uname'},$form{'udom'},$authhost,'noredirect',undef,
-		 \%form);
-        my ($otherserver) = &Apache::lonnet::choose_server($form{'udom'});
-	$r->internal_redirect('/adm/switchserver?otherserver='.$otherserver);
+        my $otherserver = &Apache::lonnet::spareserver(30000,undef,1,$form{'udom'});
+        if (!$otherserver) {
+            ($otherserver) = &Apache::lonnet::choose_server($form{'udom'});
+        }
+        if ($otherserver) {
+            &success($r,$form{'uname'},$form{'udom'},$authhost,'noredirect',undef,
+                     \%form);
+            $r->internal_redirect('/adm/switchserver?otherserver='.$otherserver.'&origurl='.$firsturl);
+        } else {
+            $r->print(&noswitch());
+        }
+        return OK;
     } else {
-	&success($r,$form{'uname'},$form{'udom'},$authhost,$firsturl,undef,
-		 \%form);
+        if (!&check_can_host($r,\%form,$authhost)) {
+            my ($otherserver) = &Apache::lonnet::choose_server($form{'udom'});
+            if ($otherserver) {
+                &success($r,$form{'uname'},$form{'udom'},$authhost,'noredirect',undef,
+                         \%form);
+                $r->internal_redirect('/adm/switchserver?otherserver='.$otherserver.'&origurl='.$firsturl);
+            } else {
+                $r->print(&noswitch());
+            }
+            return OK;
+        }
+# ------------------------------------------------------- Do the load balancing
+
+# ---------------------------------------------------------- Determine own load
+        my $loadlim = $r->dir_config('lonLoadLim');
+        my $loadavg;
+        {
+            my $loadfile=Apache::File->new('/proc/loadavg');
+            $loadavg=<$loadfile>;
+        }
+        $loadavg =~ s/\s.*//g;
+        my $loadpercent=sprintf("%.1f",100*$loadavg/$loadlim);
+        my $userloadpercent=&Apache::lonnet::userload();
+
+# ---------------------------------------------------------- Are we overloaded?
+        if ((($userloadpercent>100.0)||($loadpercent>100.0))) {
+            my $unloaded=Apache::lonnet::spareserver($loadpercent,$userloadpercent,1,$form{'udom'});
+            if (!$unloaded) {
+                ($unloaded) = &Apache::lonnet::choose_server($form{'udom'});
+            }
+            if ($unloaded) {
+                &success($r,$form{'uname'},$form{'udom'},$authhost,'noredirect',
+                         undef,\%form);
+                $r->internal_redirect('/adm/switchserver?otherserver='.$unloaded.'&origurl='.$firsturl);
+                return OK;
+            }
+        }
+        &success($r,$form{'uname'},$form{'udom'},$authhost,$firsturl,undef,
+                 \%form);
+        return OK;
     }
-    return OK;
 }
 
 sub check_can_host {
@@ -435,7 +481,11 @@ sub check_can_host {
     my $canhost = 1;
     my $lonhost = $r->dir_config('lonHostID');
     my $udom = $form->{'udom'};
-    my @intdoms = &Apache::lonnet::get_internet_names($lonhost);
+    my @intdoms;
+    my $internet_names = &Apache::lonnet::get_internet_names($lonhost);
+    if (ref($internet_names) eq 'ARRAY') {
+        @intdoms = @{$internet_names};
+    }
     my $uprimary_id = &Apache::lonnet::domain($udom,'primary');
     my $uint_dom = &Apache::lonnet::internet_dom($uprimary_id);
     unless ($uint_dom ne '' && grep(/^\Q$uint_dom\E$/,@intdoms)) {
@@ -457,7 +507,9 @@ sub check_can_host {
     }
     unless ($canhost) {
         if ($authhost eq 'no_account_on_host') {
-            my ($login_host,$hostname) = &Apache::lonnet::choose_server($udom);
+            my $checkloginvia = 1;
+            my ($login_host,$hostname) =
+                &Apache::lonnet::choose_server($udom,$checkloginvia);
             &Apache::loncommon::content_type($r,'text/html');
             $r->send_http_header;
             if ($login_host ne '') {
@@ -477,7 +529,6 @@ sub check_can_host {
                           '<p>'.&mt('Currently a LON-CAPA server is not available within the [_1] domain for you to log-in to, to create an account.',$domdesc).'</p>'.
                           &Apache::loncommon::end_page());
             }
-            return OK;
         } else {
             &success($r,$form->{'uname'},$udom,$authhost,'noredirect',undef,
                      $form);
@@ -485,6 +536,16 @@ sub check_can_host {
             $r->internal_redirect('/adm/switchserver?otherserver='.$otherserver);
         }
     }
+    return $canhost;
+}
+
+sub noswitch {
+    my $result = &Apache::loncommon::start_page('Access to LON-CAPA unavailable').
+                 '<h3>'.&mt('Session unavailable').'</h3>'.
+                 &mt('This LON-CAPA server is unable to host your session.').'<br />'.
+                 '<p>'.&mt('Currently no other LON-CAPA server is available to host your session either.').'</p>'.
+                 &Apache::loncommon::end_page();
+    return $result;
 }
 
 1;