--- loncom/localize/lonlocal.pm	2008/12/12 04:29:35	1.50.2.1
+++ loncom/localize/lonlocal.pm	2010/02/12 14:20:41	1.50.2.3
@@ -1,7 +1,7 @@
 # The LearningOnline Network with CAPA
 # Localization routines
 #
-# $Id: lonlocal.pm,v 1.50.2.1 2008/12/12 04:29:35 raeburn Exp $
+# $Id: lonlocal.pm,v 1.50.2.3 2010/02/12 14:20:41 raeburn Exp $
 #
 # Copyright Michigan State University Board of Trustees
 #
@@ -340,15 +340,24 @@ sub get_language_handle {
 
 # ========================================================== Localize localtime
 sub gettimezone {
-    my $timezone; 
-    if ($Apache::lonnet::env{'course.'.$Apache::lonnet::env{'request.course.id'}.'.timezone'}) {
-        $timezone = $Apache::lonnet::env{'course.'.$Apache::lonnet::env{'request.course.id'}.'.timezone'};    
-    } elsif ($Apache::lonnet::env{'request.course.id'} ne '') {
-        my $cdom = $Apache::lonnet::env{'course.'.$Apache::lonnet::env{'request.course.id'}.'.domain'};
-        if ($cdom ne '') {
-            my %domdefaults = &Apache::lonnet::get_domain_defaults($cdom);
-            if ($domdefaults{'timezone_def'} ne '') {
-                $timezone = $domdefaults{'timezone_def'};
+    my ($timezone) = @_;
+    if ($timezone ne '') {
+        if (!DateTime::TimeZone->is_valid_name($timezone)) {
+            $timezone = 'local';
+        }
+        return $timezone;
+    }
+    my $cid = $Apache::lonnet::env{'request.course.id'};
+    if ($cid ne '') {
+        if ($Apache::lonnet::env{'course.'.$cid.'.timezone'}) {
+            $timezone = $Apache::lonnet::env{'course.'.$cid.'.timezone'};
+        } else {
+            my $cdom = $Apache::lonnet::env{'course.'.$cid.'.domain'};
+            if ($cdom ne '') {
+                my %domdefaults = &Apache::lonnet::get_domain_defaults($cdom);
+                if ($domdefaults{'timezone_def'} ne '') {
+                    $timezone = $domdefaults{'timezone_def'};
+                }
             }
         }
     } elsif ($Apache::lonnet::env{'request.role.domain'} ne '') {
@@ -373,7 +382,7 @@ sub gettimezone {
 }
 
 sub locallocaltime {
-    my $thistime=shift;
+    my ($thistime,$timezone) = @_;
     if (!defined($thistime) || $thistime eq '') {
 	return &mt('Never');
     }
@@ -387,7 +396,16 @@ sub locallocaltime {
     }
 
     my $dt = DateTime->from_epoch(epoch => $thistime)
-                     ->set_time_zone(&gettimezone());
+                     ->set_time_zone(&gettimezone($timezone));
+
+    # TimeZone tries to determine the 'local' timezone from $ENV{TZ} if this
+    # fails it searches through various system files. Under certain
+    # circumstances this is an extremly expensive operation.
+    # So after the first run we store the timezone in $ENV{TZ} to significantly
+    # speed up future lookups.
+    $ENV{TZ} = $dt->time_zone()->name()
+        if (! $ENV{TZ} && gettimezone($timezone) eq 'local');
+
     if ((&current_language=~/^en/) || (!$lh)) {
 
 	return $dt->strftime("%a %b %e %I:%M:%S %P %Y (%Z)");