Changeset 61760 for trunk/src/wp-includes/cache-compat.php

Timestamp:

02/27/2026 07:57:26 PM (4 weeks ago)

Author:

johnjamesjacoby

Message:

Cache API: Introduce fallback for when the wp_cache_switch_to_blog() function is missing.

This commit protects against an edge-case where a persistent object-cache drop-in plugin not including its own wp_cache_switch_to_blog() function would cause non-persistent cache groups to go missing when switching between sites, and includes the following changes:

• A new wp_cache_switch_to_blog_fallback() function in ms-blogs.php which abstracts duplicated code from switch_to_blog() and restore_current_blog() for easier unit testing
• A new wpCacheSwitchToBlogFallback.php file with approximately 25 new unit tests
• Conditionally declares wp_cache_switch_to_blog() in cache-compat.php only if it does not already exist, either via core's cache.php or a drop-in plugin

With this change, WordPress no longer needs to check if the wp_cache_switch_to_blog() function exists (because it always will) so those checks have been removed.

Props ethitter, jeremyfelt, johnjamesjacoby, markjaquith, nacin, ozgursar, r1k0.

Fixes #23290.

File:

• trunk/src/wp-includes/cache-compat.php (modified) (1 diff)

trunk/src/wp-includes/cache-compat.php

@@ -313 +313 @@
     }
 endif;
+
+if ( ! function_exists( 'wp_cache_switch_to_blog' ) ) :
+    /**
+     * Used when switch_to_blog() and restore_current_blog() are called, but
+     * only when a persistent object cache drop-in plugin has omitted the
+     * wp_cache_switch_to_blog() function that was introduced in 3.5.0.
+     *
+     * @link https://core.trac.wordpress.org/ticket/23290
+     *
+     * @since 7.0.0
+     *
+     * @global WP_Object_Cache $wp_object_cache Object cache global instance.
+     *
+     * @param int $blog_id Site ID.
+     */
+    function wp_cache_switch_to_blog( $blog_id ) {
+        global $wp_object_cache;
+
+        // Attempt to use the drop-in object cache method if it exists.
+        if ( method_exists( $wp_object_cache, 'switch_to_blog' ) ) {
+            $wp_object_cache->switch_to_blog( $blog_id );
+            return;
+        }
+
+        /*
+         * Perform a fallback blog switch, which will reinitialize the caches
+         * for the new blog ID.
+         */
+        wp_cache_switch_to_blog_fallback( $blog_id );
+    }
+endif;