--- loncom/Lond.pm	2015/05/22 21:14:59	1.8
+++ loncom/Lond.pm	2018/09/02 01:58:30	1.8.2.1
@@ -1,6 +1,6 @@
 # The LearningOnline Network
 #
-# $Id: Lond.pm,v 1.8 2015/05/22 21:14:59 raeburn Exp $
+# $Id: Lond.pm,v 1.8.2.1 2018/09/02 01:58:30 raeburn Exp $
 #
 # Copyright Michigan State University Board of Trustees
 #
@@ -782,6 +782,34 @@ sub dump_profile_database {
     return $qresult;
 }
 
+sub is_course {
+    my ($cdom,$cnum) = @_;
+
+    return unless (($cdom =~ /^$LONCAPA::match_domain$/) &&
+                   ($cnum =~ /^$LONCAPA::match_courseid$/));
+    my $hashid = $cdom.':'.$cnum;
+    my ($iscourse,$cached) =
+        &Apache::lonnet::is_cached_new('iscourse',$hashid);
+    unless (defined($cached)) {
+        my $hashref =
+            &tie_domain_hash($cdom, "nohist_courseids", &GDBM_WRCREAT());
+        if (ref($hashref) eq 'HASH') {
+            my $esc_key = &escape($cdom.'_'.$cnum);
+            if (exists($hashref->{$esc_key})) {
+                $iscourse = 1;
+            } else {
+                $iscourse = 0;
+            }
+            &Apache::lonnet::do_cache_new('iscourse',$hashid,$iscourse,3600);
+            unless (&untie_domain_hash($hashref)) {
+                &logthis("Failed to untie tied hash for nohist_courseids.db for $cdom");
+            }
+        } else {
+            &logthis("Failed to tie hash for nohist_courseids.db for $cdom");
+        }
+    }
+    return $iscourse;
+}
 
 1;