Ticket #27538: 27538.3.patch

src/wp-includes/widgets.php

@@ -122 +122 @@
                 return 'widget-' . $this->id_base . '-' . $this->number . '-' . $field_name;
         }
 
+        /**
+         * Constructs a hash that is unique to the widget instance.
+         *
+         * This function can be used by widget classes to create a cache key
+         * for caching the widget output, assuming that the output is uniquely
+         * determined by the provided display arguments and widget instance
+         * settings. For a usage example, see WP_Widget_Recent_Posts::widget().
+         *
+         * @since 3.9.0
+         *
+         * @param array $args Display arguments including before_title, after_title, before_widget, and after_widget.
+         * @param array $instance The settings for the particular instance of the widget.
+         * @return string A hash based on the provided display arguments and instance settings.
+         */
+        function hash($args, $instance) {
+                // The hash must be unique to the provided display arguments
+                // and instance settings, but the order doesn't matter.
+                ksort( $args );
+                ksort( $instance );
+                return wp_hash( serialize( $args ) . serialize( $instance ) );
+        }
+
         // Private Functions. Don't worry about these.
 
         function _register() {

src/wp-includes/default-widgets.php

@@ -668 +668 @@
                 if ( ! isset( $args['widget_id'] ) )
                         $args['widget_id'] = $this->id;
 
-                if ( isset( $cache[ $args['widget_id'] ] ) ) {
-                        echo $cache[ $args['widget_id'] ];
+                $cache_key = $this->hash( $args, $instance );
+                if ( isset( $cache[ $cache_key ] ) ) {
+                        echo $cache[ $cache_key ];
                         return;
                 }
 
@@ -723 +724 @@
 
                 endif;
 
-                $cache[$args['widget_id']] = ob_get_flush();
+                $cache[$cache_key] = ob_get_flush();
                 wp_cache_set('widget_recent_posts', $cache, 'widget');
         }
 
@@ -815 +816 @@
                 if ( ! isset( $args['widget_id'] ) )
                         $args['widget_id'] = $this->id;
 
-                if ( isset( $cache[ $args['widget_id'] ] ) ) {
-                        echo $cache[ $args['widget_id'] ];
+                $cache_key = $this->hash( $args, $instance );
+                if ( isset( $cache[ $cache_key ] ) ) {
+                        echo $cache[ $cache_key ];
                         return;
                 }
 
@@ -865 +867 @@
                 $output .= $after_widget;
 
                 echo $output;
-                $cache[$args['widget_id']] = $output;
+                $cache[$cache_key] = $output;
                 wp_cache_set('widget_recent_comments', $cache, 'widget');
         }