--- loncom/lonnet/perl/lonnet.pm	2011/08/09 01:06:33	1.1128
+++ loncom/lonnet/perl/lonnet.pm	2011/08/09 01:35:24	1.1129
@@ -1,7 +1,7 @@
 # The LearningOnline Network
 # TCP networking package
 #
-# $Id: lonnet.pm,v 1.1128 2011/08/09 01:06:33 raeburn Exp $
+# $Id: lonnet.pm,v 1.1129 2011/08/09 01:35:24 raeburn Exp $
 #
 # Copyright Michigan State University Board of Trustees
 #
@@ -1185,6 +1185,224 @@ sub spares_for_offload  {
     return;
 }
 
+sub get_lonbalancer_config {
+    my ($servers) = @_;
+    my ($currbalancer,$currtargets);
+    if (ref($servers) eq 'HASH') {
+        foreach my $server (keys(%{$servers})) {
+            my %what = (
+                         spareid => 1,
+                         perlvar => 1,
+                       );
+            my ($result,$returnhash) = &get_remote_globals($server,\%what);
+            if ($result eq 'ok') {
+                if (ref($returnhash) eq 'HASH') {
+                    if (ref($returnhash->{'perlvar'}) eq 'HASH') {
+                        if ($returnhash->{'perlvar'}->{'lonBalancer'} eq 'yes') {
+                            $currbalancer = $server;
+                            $currtargets = {};
+                            if (ref($returnhash->{'spareid'}) eq 'HASH') {
+                                if (ref($returnhash->{'spareid'}->{'primary'}) eq 'ARRAY') {
+                                    $currtargets->{'primary'} = $returnhash->{'spareid'}->{'primary'};
+                                }
+                                if (ref($returnhash->{'spareid'}->{'default'}) eq 'ARRAY') {
+                                    $currtargets->{'default'} = $returnhash->{'spareid'}->{'default'};
+                                }
+                            }
+                            last;
+                        }
+                    }
+                }
+            }
+        }
+    }
+    return ($currbalancer,$currtargets);
+}
+
+sub check_loadbalancing {
+    my ($uname,$udom) = @_;
+    my ($is_balancer,$dom_in_use,$homeintdom,$rule_in_effect,
+        $offloadto,$otherserver);
+    my $lonhost = $perlvar{'lonHostID'};
+    my $uprimary_id = &Apache::lonnet::domain($udom,'primary');
+    my $uintdom = &Apache::lonnet::internet_dom($uprimary_id);
+    my $intdom = &Apache::lonnet::internet_dom($lonhost);
+    my $serverhomedom = &host_domain($lonhost);
+
+    my $cachetime = 60*60*24;
+
+    if (($uintdom ne '') && ($uintdom eq $intdom)) {
+        $dom_in_use = $udom;
+        $homeintdom = 1;
+    } else {
+        $dom_in_use = $serverhomedom;
+    }
+    my ($result,$cached)=&is_cached_new('loadbalancing',$dom_in_use);
+    unless (defined($cached)) {
+        my %domconfig =
+            &Apache::lonnet::get_dom('configuration',['loadbalancing'],$dom_in_use);
+        if (ref($domconfig{'loadbalancing'}) eq 'HASH') {
+            $result = &do_cache_new('loadbalancing',$dom_in_use,$domconfig{'usersessions'}{'loadbalancing'},$cachetime);
+        }
+    }
+    if (ref($result) eq 'HASH') {
+        my $currbalancer = $result->{'lonhost'};
+        my $currtargets = $result->{'targets'};
+        my $currrules = $result->{'rules'};
+        if ($currbalancer ne '') {
+            my @hosts = &current_machine_ids();
+            if (grep(/^\Q$currbalancer\E$/,@hosts)) {
+                $is_balancer = 1;
+            }
+        }
+        if ($is_balancer) {
+            if (ref($currrules) eq 'HASH') {
+                if ($homeintdom) {
+                    if ($uname ne '') {
+                        if (($currrules->{'_LC_adv'} ne '') || ($currrules->{'_LC_author'} ne '')) {
+                            my ($is_adv,$is_author) = &is_advanced_user($udom,$uname);
+                            if (($currrules->{'_LC_author'} ne '') && ($is_author)) {
+                                $rule_in_effect = $currrules->{'_LC_author'};
+                            } elsif (($currrules->{'_LC_adv'} ne '') && ($is_adv)) {
+                                $rule_in_effect = $currrules->{'_LC_adv'}
+                            }
+                        }
+                        if ($rule_in_effect eq '') {
+                            my %userenv = &userenvironment($udom,$uname,'inststatus');
+                            if ($userenv{'inststatus'} ne '') {
+                                my @statuses = map { &unescape($_); } split(/:/,$userenv{'inststatus'});
+                                my ($othertitle,$usertypes,$types) =
+                                    &Apache::loncommon::sorted_inst_types($udom);
+                                if (ref($types) eq 'ARRAY') {
+                                    foreach my $type (@{$types}) {
+                                        if (grep(/^\Q$type\E$/,@statuses)) {
+                                            if (exists($currrules->{$type})) {
+                                                $rule_in_effect = $currrules->{$type};
+                                            }
+                                        }
+                                    }
+                                }
+                            } else {
+                                if (exists($currrules->{'default'})) {
+                                    $rule_in_effect = $currrules->{'default'};
+                                }
+                            }
+                        }
+                    } else {
+                        if (exists($currrules->{'default'})) {
+                            $rule_in_effect = $currrules->{'default'};
+                        }
+                    }
+                } else {
+                    if ($currrules->{'_LC_external'} ne '') {
+                        $rule_in_effect = $currrules->{'_LC_external'};
+                    }
+                }
+                $offloadto = &get_loadbalancer_targets($rule_in_effect,$currtargets,
+                                                       $uname,$udom);
+            }
+        }
+    } elsif (($homeintdom) && ($udom ne $serverhomedom)) {
+        my ($result,$cached)=&is_cached_new('loadbalancing',$serverhomedom);
+        unless (defined($cached)) {
+            my %domconfig =
+                &Apache::lonnet::get_dom('configuration',['loadbalancing'],$serverhomedom);
+            if (ref($domconfig{'loadbalancing'}) eq 'HASH') {
+                $result = &do_cache_new('loadbalancing',$dom_in_use,$domconfig{'usersessions'}{'loadbalancing'},$cachetime);
+            }
+        }
+        if (ref($result) eq 'HASH') {
+            my $currbalancer = $result->{'lonhost'};
+            my $currtargets = $result->{'targets'};
+            my $currrules = $result->{'rules'};
+
+            if ($currbalancer eq $lonhost) {
+                $is_balancer = 1;
+                if (ref($currrules) eq 'HASH') {
+                    if ($currrules->{'_LC_internetdom'} ne '') {
+                        $rule_in_effect = $currrules->{'_LC_internetdom'};
+                    }
+                }
+                $offloadto = &get_loadbalancer_targets($rule_in_effect,$currtargets,
+                                                       $uname,$udom);
+            }
+        } else {
+            if ($perlvar{'lonBalancer'} eq 'yes') {
+                $is_balancer = 1;
+                $offloadto = &this_host_spares($dom_in_use);
+            }
+        }
+    } else {
+        if ($perlvar{'lonBalancer'} eq 'yes') {
+            $is_balancer = 1;
+            $offloadto = &this_host_spares($dom_in_use);
+        }
+    }
+    my $lowest_load = 30000;
+    if (ref($offloadto) eq 'HASH') {
+        if (ref($offloadto->{'primary'}) eq 'ARRAY') {
+            foreach my $try_server (@{$offloadto->{'primary'}}) {
+                ($otherserver,$lowest_load) =
+                    &compare_server_load($try_server,$otherserver,$lowest_load);
+            }
+        }
+        my $found_server = ($otherserver ne '' && $lowest_load < 100);
+
+        if (!$found_server) {
+            if (ref($offloadto->{'default'}) eq 'ARRAY') {
+                foreach my $try_server (@{$offloadto->{'default'}}) {
+                    ($otherserver,$lowest_load) =
+                        &compare_server_load($try_server,$otherserver,$lowest_load);
+                }
+            }
+        }
+    } elsif (ref($offloadto) eq 'ARRAY') {
+        if (@{$offloadto} == 1) {
+            $otherserver = $offloadto->[0];
+        } elsif (@{$offloadto} > 1) {
+            foreach my $try_server (@{$offloadto}) {
+                ($otherserver,$lowest_load) =
+                    &compare_server_load($try_server,$otherserver,$lowest_load);
+            }
+        }
+    }
+    return ($is_balancer,$otherserver);
+}
+
+sub get_loadbalancer_targets {
+    my ($rule_in_effect,$currtargets,$uname,$udom) = @_;
+    my $offloadto;
+    if ($rule_in_effect eq '') {
+        $offloadto = $currtargets;
+    } else {
+        if ($rule_in_effect eq 'homeserver') {
+            my $homeserver = &homeserver($uname,$udom);
+            if ($homeserver ne 'no_host') {
+                $offloadto = [$homeserver];
+            }
+        } elsif ($rule_in_effect eq 'externalbalancer') {
+            my %domconfig =
+                &Apache::lonnet::get_dom('configuration',['loadbalancing'],$udom);
+            if (ref($domconfig{'loadbalancing'}) eq 'HASH') {
+                if ($domconfig{'loadbalancing'}{'lonhost'} ne '') {
+                    if (&hostname($domconfig{'loadbalancing'}{'lonhost'}) ne '') {
+                        $offloadto = [$domconfig{'loadbalancing'}{'lonhost'}];
+                    }
+                }
+            } else {
+                my %servers = &dom_servers($udom);
+                my ($remotebalancer,$remotetargets) = &get_lonbalancer_config(\%servers);
+                if (&hostname($remotebalancer) ne '') {
+                    $offloadto = [$remotebalancer];
+                }
+            }
+        } elsif (&hostname($rule_in_effect) ne '') {
+            $offloadto = [$rule_in_effect];
+        }
+    }
+    return $offloadto;
+}
+
 sub internet_dom_servers {
     my ($dom) = @_;
     my (%uniqservers,%servers);