Enable serving from cache whilst revalidate, and if error

Author: ranguard

lib/MetaCPAN/Web/Controller/Root.pm

@@ -113,6 +113,13 @@ Attempt to render a view, if needed.
 sub end : ActionClass('RenderView') {
     my ( $self, $c ) = @_;
 
+    # This will only affect if `cdn_max_age` has been set.
+    # https://www.fastly.com/documentation/guides/concepts/edge-state/cache/stale/
+    # If it has then do revalidation in the background
+    $c->cdn_stale_while_revalidate('1d');
+    # And if there is still an error serve from cache
+    $c->cdn_stale_if_error('1y');
+
     # for normal errors, try to render the internal_error page rather
     my @error = @{ $c->error };
     if ( @error && !$c->debug ) {