--- loncom/lonnet/perl/lonnet.pm	2018/09/04 20:22:43	1.1172.2.97
+++ loncom/lonnet/perl/lonnet.pm	2018/09/06 14:31:22	1.1172.2.98
@@ -1,7 +1,7 @@
 # The LearningOnline Network
 # TCP networking package
 #
-# $Id: lonnet.pm,v 1.1172.2.97 2018/09/04 20:22:43 raeburn Exp $
+# $Id: lonnet.pm,v 1.1172.2.98 2018/09/06 14:31:22 raeburn Exp $
 #
 # Copyright Michigan State University Board of Trustees
 #
@@ -2878,6 +2878,72 @@ sub externalssi {
     }
 }
 
+# If the local copy of a replicated resource is outdated, trigger a
+# connection from the homeserver to flush the delayed queue. If no update
+# happens, remove local copies of outdated resource (and corresponding
+# metadata file).
+
+sub remove_stale_resfile {
+    my ($url) = @_;
+    my $removed;
+    if ($url=~m{^/res/($match_domain)/($match_username)/}) {
+        my $audom = $1;
+        my $auname = $2;
+        unless (($url =~ /\.\d+\.\w+$/) || ($url =~ m{^/res/lib/templates/})) {
+            my $homeserver = &homeserver($auname,$audom);
+            unless (($homeserver eq 'no_host') ||
+                    (grep { $_ eq $homeserver } &current_machine_ids())) {
+                my $fname = &filelocation('',$url);
+                if (-e $fname) {
+                    my $ua=new LWP::UserAgent;
+                    $ua->timeout(5);
+                    my $protocol = $protocol{$homeserver};
+                    $protocol = 'http' if ($protocol ne 'https');
+                    my $hostname = &hostname($homeserver);
+                    if ($hostname) {
+                        my $uri = $protocol.'://'.$hostname.'/raw/'.&declutter($url);
+                        my $request=new HTTP::Request('HEAD',$uri);
+                        my $response=$ua->request($request);
+                        if ($response->is_success()) {
+                            my $remmodtime = &HTTP::Date::str2time( $response->header('Last-modified') );
+                            my $locmodtime = (stat($fname))[9];
+                            if ($locmodtime < $remmodtime) {
+                                my $stale;
+                                my $answer = &reply('pong',$homeserver);
+                                if ($answer eq $homeserver.':'.$perlvar{'lonHostID'}) {
+                                    sleep(0.2);
+                                    $locmodtime = (stat($fname))[9];
+                                    if ($locmodtime < $remmodtime) {
+                                        my $posstransfer = $fname.'.in.transfer';
+                                        if ((-e $posstransfer) && ($remmodtime < (stat($posstransfer))[9])) {
+                                            $removed = 1;
+                                        } else {
+                                            $stale = 1;
+                                        }
+                                    } else {
+                                        $removed = 1;
+                                    }
+                                } else {
+                                    $stale = 1;
+                                }
+                                if ($stale) {
+                                    unlink($fname);
+                                    if ($uri!~/\.meta$/) {
+                                        unlink($fname.'.meta');
+                                    }
+                                    &reply("unsub:$fname",$homeserver);
+                                    $removed = 1;
+                                }
+                            }
+                        }
+                    }
+                }
+            }
+        }
+    }
+    return $removed;
+}
+
 # -------------------------------- Allow a /uploaded/ URI to be vouched for
 
 sub allowuploaded {