add etag and caching support to bugreport.cgi

 - Calculate etag based on file modification times and all parameters
 - Set etag everywhere
 - Use reasonable cache retention times
   - 5m minimum
   - 10m for head requests and bug logs
   - 7d for bug attachments (which should never change, really)

diff --git a/cgi/bugreport.cgi b/cgi/bugreport.cgi
index b68eac64b7f9ba7c92d38e0d151ce1431362d18f..86152f978dc0252b6e36b862f0845246a030c37c 100755 (executable)
--- a/cgi/bugreport.cgi
+++ b/cgi/bugreport.cgi
@@ -109,18 +109,55 @@ sub no_such_bug {
     exit 0;
 }
 
+## calculate etag for this bugreport.cgi call
+my $etag;
+## identify the files that we need to look at; if someone just wants the mbox,
+## they don't need to see anything but the buglog; otherwise, track what is
+## necessary for the usertags and things to calculate status.
+
+my @dependent_files = ($buglog);
+my $need_status = 0;
+if (not (($mbox and not $mbox_status_message) or
+        (defined $att and defined $msg))) {
+    $need_status = 1;
+    push @dependent_files,
+       $bug_status,
+       defined $config{version_index} ? $config{version_index}:(),
+       defined $config{binary_source_map} ? $config{binary_source_map}:();
 }
 
-# the log should almost always be newer, but just in case
-my $log_mtime = +(stat $buglog)[9] || time;
-my $status_mtime = +(stat $bug_status)[9] || time;
-my $mtime = strftime '%a, %d %b %Y %T GMT', gmtime(max($status_mtime,$log_mtime));
+## Identify the users required
+for my $user (map {split /[\s*,\s*]+/} make_list($param{users}||[])) {
+    next unless length($user);
+    push @dependent_files,Debbugs::User::usertag_flie_from_email($user);
+}
+if (defined $param{usertag}) {
+    for my $usertag (make_list($param{usertag})) {
+       my ($user, $tag) = split /:/, $usertag, 2;
+       push @dependent_files,Debbugs::User::usertag_flie_from_email($user);
+    }
+}
+$etag =
+    etag_does_not_match(cgi => $q,
+                       additional_data => [grep {defined $_ ? $_ :()}
+                                           values %param
+                                          ],
+                       files => [@dependent_files,
+                                ],
+                      );
+if (not $etag) {
+    print $q->header(-status => 304);
+    print "304: Not modified\n";
+    exit 0;
+}
 
+## if they're just asking for the head, stop here.
 if ($q->request_method() eq 'HEAD' and not defined($att) and not $mbox) {
-     print $q->header(-type => "text/html",
-                     -charset => 'utf-8',
-                     (length $mtime)?(-last_modified => $mtime):(),
-                    );
+    print $q->header(-status => 200,
+                    -cache_control => 'public, max-age=600',
+                    -etag => $etag,
+                    -content_type => 'text/html',
+                   );
      exit 0;
 }
 
@@ -154,10 +191,12 @@ if ($buglog =~ m/\.gz$/) {
 }
 
 
-my %status =
-    %{split_status_fields(get_bug_status(bug=>$ref,
-                                        bugusertags => \%bugusertags,
-                                       ))};
+my %status;
+if ($need_status) {
+    %status = %{split_status_fields(get_bug_status(bug=>$ref,
+                                                  bugusertags => \%bugusertags,
+                                                 ))}
+}
 
 my @records;
 eval{
@@ -182,6 +221,8 @@ if ( $mbox ) {
      my $date = strftime "%a %b %d %T %Y", localtime;
      if (@records > 1) {
         print $q->header(-type => "text/plain",
+                         -cache_control => 'public, max-age=600',
+                         -etag => $etag,
                          content_disposition => qq(attachment; filename="bug_${ref}.mbox"),
                          (length $mtime)?(-last_modified => $mtime):(),
                         );
@@ -189,6 +230,8 @@ if ( $mbox ) {
      else {
          $msg_num++;
          print $q->header(-type => "message/rfc822",
+                          -cache_control => 'public, max-age=86400',
+                          -etag => $etag,
                           content_disposition => qq(attachment; filename="bug_${ref}_message_${msg_num}.mbox"),
                           (length $mtime)?(-last_modified => $mtime):(),
                          );
@@ -264,7 +307,11 @@ END
 else {
      if (defined $att and defined $msg and @records) {
         binmode(STDOUT,":raw");
-         $msg_num++;
+        $msg_num++;
+        ## allow this to be cached for a week
+        print "Status: 200 OK\n";
+        print "Cache-control: public, max-age=604800\n";
+        print "Etag: $etag\n";
          print handle_email_message($records[0],
                                     ref => $ref,
                                     msg_num => $msg_num,
@@ -394,7 +441,8 @@ my $descriptivehead = $indexentry;
 
 print $q->header(-type => "text/html",
                 -charset => 'utf-8',
-                (length $mtime)?(-last_modified => $mtime):(),
+                -cache_control => 'public, max-age=300',
+                -etag => $etag,
                );
 
 print fill_in_template(template => 'cgi/bugreport',