Changeset 61760

Timestamp:

02/27/2026 07:57:26 PM (5 months 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.

Location:

trunk

Files:

• src/wp-includes/cache-compat.php (modified) (1 diff)
• src/wp-includes/ms-blogs.php (modified) (3 diffs)
• tests/phpunit/tests/multisite/wpCacheSwitchToBlogFallback.php (added)

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;

trunk/src/wp-includes/ms-blogs.php

@@ -536 +536 @@
         $GLOBALS['blog_id']      = $new_blog_id;
 
-        if ( function_exists( 'wp_cache_switch_to_blog' ) ) {
-                wp_cache_switch_to_blog( $new_blog_id );
-        } else {
-                global $wp_object_cache;
-
-                if ( is_object( $wp_object_cache ) && isset( $wp_object_cache->global_groups ) ) {
-                        $global_groups = $wp_object_cache->global_groups;
-                } else {
-                        $global_groups = false;
-                }
-
-                wp_cache_init();
-
-                if ( function_exists( 'wp_cache_add_global_groups' ) ) {
-                        if ( is_array( $global_groups ) ) {
-                                wp_cache_add_global_groups( $global_groups );
-                        } else {
-                                wp_cache_add_global_groups(
-                                        array(
-                                                'blog-details',
-                                                'blog-id-cache',
-                                                'blog-lookup',
-                                                'blog_meta',
-                                                'global-posts',
-                                                'image_editor',
-                                                'networks',
-                                                'network-queries',
-                                                'sites',
-                                                'site-details',
-                                                'site-options',
-                                                'site-queries',
-                                                'site-transient',
-                                                'theme_files',
-                                                'rss',
-                                                'users',
-                                                'user-queries',
-                                                'user_meta',
-                                                'useremail',
-                                                'userlogins',
-                                                'userslugs',
-                                        )
-                                );
-                        }
-
-                        wp_cache_add_non_persistent_groups( array( 'counts', 'plugins', 'theme_json' ) );
-                }
-        }
+        wp_cache_switch_to_blog( $new_blog_id );
 
         /** This filter is documented in wp-includes/ms-blogs.php */
@@ -631 +585 @@
         $GLOBALS['table_prefix'] = $wpdb->get_blog_prefix();
 
-        if ( function_exists( 'wp_cache_switch_to_blog' ) ) {
-                wp_cache_switch_to_blog( $new_blog_id );
-        } else {
-                global $wp_object_cache;
-
-                if ( is_object( $wp_object_cache ) && isset( $wp_object_cache->global_groups ) ) {
-                        $global_groups = $wp_object_cache->global_groups;
-                } else {
-                        $global_groups = false;
-                }
-
-                wp_cache_init();
-
-                if ( function_exists( 'wp_cache_add_global_groups' ) ) {
-                        if ( is_array( $global_groups ) ) {
-                                wp_cache_add_global_groups( $global_groups );
-                        } else {
-                                wp_cache_add_global_groups(
-                                        array(
-                                                'blog-details',
-                                                'blog-id-cache',
-                                                'blog-lookup',
-                                                'blog_meta',
-                                                'global-posts',
-                                                'image_editor',
-                                                'networks',
-                                                'network-queries',
-                                                'sites',
-                                                'site-details',
-                                                'site-options',
-                                                'site-queries',
-                                                'site-transient',
-                                                'theme_files',
-                                                'rss',
-                                                'users',
-                                                'user-queries',
-                                                'user_meta',
-                                                'useremail',
-                                                'userlogins',
-                                                'userslugs',
-                                        )
-                                );
-                        }
-
-                        wp_cache_add_non_persistent_groups( array( 'counts', 'plugins', 'theme_json' ) );
-                }
-        }
+        wp_cache_switch_to_blog( $new_blog_id );
 
         /** This filter is documented in wp-includes/ms-blogs.php */
@@ -686 +594 @@
 
         return true;
+}
+
+/**
+ * Fallback logic for switching cache context when an object cache drop-in lacks
+ * a switch_to_blog() method.
+ *
+ * Reinitializes the cache and restores global/non-persistent groups.
+ *
+ * Used by the wp_cache_switch_to_blog() compatibility function, abstracted only
+ * to allow for unit testing outside of the drop-in plugin inclusion circus.
+ *
+ * @since 7.0.0
+ *
+ * @global WP_Object_Cache $wp_object_cache Object cache global instance.
+ */
+function wp_cache_switch_to_blog_fallback() {
+        global $wp_object_cache;
+
+        $global_groups         = false;
+        $non_persistent_groups = false;
+
+        if ( is_object( $wp_object_cache ) && isset( $wp_object_cache->global_groups ) ) {
+                $global_groups         = array_keys( $wp_object_cache->global_groups );
+                $all_groups            = array_fill_keys( array_keys( $wp_object_cache->cache ), true );
+                $non_persistent_groups = array_keys( array_diff_key( $all_groups, $wp_object_cache->global_groups ) );
+        }
+
+        wp_cache_init();
+
+        if ( function_exists( 'wp_cache_add_global_groups' ) ) {
+                if ( ! is_array( $global_groups ) || empty( $global_groups ) ) {
+                        $global_groups = array(
+                                'blog-details',
+                                'blog-id-cache',
+                                'blog-lookup',
+                                'blog_meta',
+                                'global-posts',
+                                'image_editor',
+                                'networks',
+                                'network-queries',
+                                'sites',
+                                'site-details',
+                                'site-options',
+                                'site-queries',
+                                'site-transient',
+                                'theme_files',
+                                'translation_files',
+                                'rss',
+                                'users',
+                                'user-queries',
+                                'user_meta',
+                                'useremail',
+                                'userlogins',
+                                'userslugs',
+                        );
+                }
+
+                wp_cache_add_global_groups( $global_groups );
+        }
+
+        if ( function_exists( 'wp_cache_add_non_persistent_groups' ) ) {
+                if ( ! is_array( $non_persistent_groups ) || empty( $non_persistent_groups ) ) {
+                        $non_persistent_groups = array(
+                                'counts',
+                                'plugins',
+                                'theme_json',
+                        );
+                }
+
+                wp_cache_add_non_persistent_groups( $non_persistent_groups );
+        }
 }