wp-includes/load.php:804Starts the WordPress object cache.
One hook fires while wp_start_object_cache() runs, in this order:
Filters whether to enable loading of the object-cache.php drop-in.
function wp_start_object_cache() { global $wp_filter; static $first_init = true; // Only perform the following checks once. /** * Filters whether to enable loading of the object-cache.php drop-in. * * This filter runs before it can be used by plugins. It is designed for non-web * runtimes. If false is returned, object-cache.php will never be loaded. * * @since 5.8.0 * * @param bool $enable_object_cache Whether to enable loading object-cache.php (if present). * Default true. */ if ( $first_init && apply_filters( 'enable_loading_object_cache_dropin', true ) ) { if ( ! function_exists( 'wp_cache_init' ) ) { /* * This is the normal situation. First-run of this function. No * caching backend has been loaded. * * We try to load a custom caching backend, and then, if it * results in a wp_cache_init() function existing, we note * that an external object cache is being used. */ if ( file_exists( WP_CONTENT_DIR . '/object-cache.php' ) ) { require_once WP_CONTENT_DIR . '/object-cache.php'; if ( function_exists( 'wp_cache_init' ) ) { wp_using_ext_object_cache( true ); } // Re-initialize any hooks added manually by object-cache.php. if ( $wp_filter ) { $wp_filter = WP_Hook::build_preinitialized_hooks( $wp_filter ); } } } elseif ( ! wp_using_ext_object_cache() && file_exists( WP_CONTENT_DIR . '/object-cache.php' ) ) { /* * Sometimes advanced-cache.php can load object-cache.php before * this function is run. This breaks the function_exists() check * above and can result in wp_using_ext_object_cache() returning * false when actually an external cache is in use. */ wp_using_ext_object_cache( true ); } } if ( ! wp_using_ext_object_cache() ) { require_once ABSPATH . WPINC . '/cache.php'; } require_once ABSPATH . WPINC . '/cache-compat.php'; /* * If cache supports reset, reset instead of init if already * initialized. Reset signals to the cache that global IDs * have changed and it may need to update keys and cleanup caches. */ if ( ! $first_init && function_exists( 'wp_cache_switch_to_blog' ) ) { wp_cache_switch_to_blog( get_current_blog_id() ); } elseif ( function_exists( 'wp_cache_init' ) ) { wp_cache_init(); } if ( function_exists( 'wp_cache_add_global_groups' ) ) { 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',Introduced in 3.0.0. Unchanged from 6.7.7 through 7.1.0.
Signature, return type and hooks compared across 5 parsed releases.
src/wp-includes/load.php, and regenerated for each WordPress release so it tracks the code rather than a snapshot of it.