Fix stale client caching of history pages with $wgShowUpdateMarker enabled

Change-Id: I5b9d986e4f34166f2a1602129d2e01573bfe7ac5

diff --git a/includes/Title.php b/includes/Title.php
index a956ca2..b9b1bb7 100644 (file)
--- a/includes/Title.php
+++ b/includes/Title.php
@@ -4262,7 +4262,7 @@ class Title implements LinkTarget, IDBAccessObject {
         * Get the timestamp when this page was updated since the user last saw it.
         *
         * @param User|null $user
-        * @return string|null
+        * @return string|bool|null String timestamp, false if not watched, null if nothing is unseen
         */
        public function getNotificationTimestamp( $user = null ) {
                global $wgUser;

diff --git a/includes/actions/HistoryAction.php b/includes/actions/HistoryAction.php
index 4df2f56..958ec06 100644 (file)
--- a/includes/actions/HistoryAction.php
+++ b/includes/actions/HistoryAction.php
@@ -148,10 +148,17 @@ class HistoryAction extends FormlessAction {
                $out = $this->getOutput();
                $request = $this->getRequest();
 
-               /**
-                * Allow client caching.
-                */
-               if ( $out->checkLastModified( $this->page->getTouched() ) ) {
+               // Allow client-side HTTP caching of the history page.
+               // But, always ignore this cache if the (logged-in) user has this page on their watchlist
+               // and has one or more unseen revisions. Otherwise, we might be showing stale update markers.
+               // The Last-Modified for the history page does not change when user's markers are cleared,
+               // so going from "some unseen" to "all seen" would not clear the cache.
+               // But, when all of the revisions are marked as seen, then only way for new unseen revision
+               // markers to appear, is for the page to be edited, which updates page_touched/Last-Modified.
+               if (
+                       !$this->hasUnseenRevisionMarkers() &&
+                       $out->checkLastModified( $this->page->getTouched() )
+               ) {
                        return null; // Client cache fresh and headers sent, nothing more to do.
                }
 
@@ -305,6 +312,16 @@ class HistoryAction extends FormlessAction {
                return null;
        }
 
+       /**
+        * @return bool Page is watched by and has unseen revision for the user
+        */
+       private function hasUnseenRevisionMarkers() {
+               return (
+                       $this->getContext()->getConfig()->get( 'ShowUpdatedMarker' ) &&
+                       $this->getTitle()->getNotificationTimestamp( $this->getUser() )
+               );
+       }
+
        /**
         * Fetch an array of revisions, specified by a given limit, offset and
         * direction. This is now only used by the feeds. It was previously