name : class-wp-metadata-lazyloader.php <?php /** * Meta API: WP_Metadata_Lazyloader class * * @package WordPress * @subpackage Meta * @since 4.5.0 */ /** * Core class used for lazy-loading object metadata. * * When loading many objects of a given type, such as posts in a WP_Query loop, it often makes * sense to prime various metadata caches at the beginning of the loop. This means fetching all * relevant metadata with a single database query, a technique that has the potential to improve * performance dramatically in some cases. * * In cases where the given metadata may not even be used in the loop, we can improve performance * even more by only priming the metadata cache for affected items the first time a piece of metadata * is requested - ie, by lazy-loading it. So, for example, comment meta may not be loaded into the * cache in the comments section of a post until the first time get_comment_meta() is called in the * context of the comment loop. * * WP uses the WP_Metadata_Lazyloader class to queue objects for metadata cache priming. The class * then detects the relevant get_*_meta() function call, and queries the metadata of all queued objects. * * Do not access this class directly. Use the wp_metadata_lazyloader() function. * * @since 4.5.0 */ #[AllowDynamicProperties] class WP_Metadata_Lazyloader { /** * Pending objects queue. * * @since 4.5.0 * @var array */ protected $pending_objects; /** * Settings for supported object types. * * @since 4.5.0 * @var array */ protected $settings = array(); /** * Constructor. * * @since 4.5.0 */ public function __construct() { $this->settings = array( 'term' => array( 'filter' => 'get_term_metadata', 'callback' => array( $this, 'lazyload_meta_callback' ), ), 'comment' => array( 'filter' => 'get_comment_metadata', 'callback' => array( $this, 'lazyload_meta_callback' ), ), 'blog' => array( 'filter' => 'get_blog_metadata', 'callback' => array( $this, 'lazyload_meta_callback' ), ), ); } /** * Adds objects to the metadata lazy-load queue. * * @since 4.5.0 * * @param string $object_type Type of object whose meta is to be lazy-loaded. Accepts 'term' or 'comment'. * @param array $object_ids Array of object IDs. * @return void|WP_Error WP_Error on failure. */ public function queue_objects( $object_type, $object_ids ) { if ( ! isset( $this->settings[ $object_type ] ) ) { return new WP_Error( 'invalid_object_type', __( 'Invalid object type.' ) ); } $type_settings = $this->settings[ $object_type ]; if ( ! isset( $this->pending_objects[ $object_type ] ) ) { $this->pending_objects[ $object_type ] = array(); } foreach ( $object_ids as $object_id ) { // Keyed by ID for faster lookup. if ( ! isset( $this->pending_objects[ $object_type ][ $object_id ] ) ) { $this->pending_objects[ $object_type ][ $object_id ] = 1; } } add_filter( $type_settings['filter'], $type_settings['callback'], 10, 5 ); /** * Fires after objects are added to the metadata lazy-load queue. * * @since 4.5.0 * * @param array $object_ids Array of object IDs. * @param string $object_type Type of object being queued. * @param WP_Metadata_Lazyloader $lazyloader The lazy-loader object. */ do_action( 'metadata_lazyloader_queued_objects', $object_ids, $object_type, $this ); } /** * Resets lazy-load queue for a given object type. * * @since 4.5.0 * * @param string $object_type Object type. Accepts 'comment' or 'term'. * @return void|WP_Error WP_Error on failure. */ public function reset_queue( $object_type ) { if ( ! isset( $this->settings[ $object_type ] ) ) { return new WP_Error( 'invalid_object_type', __( 'Invalid object type.' ) ); } $type_settings = $this->settings[ $object_type ]; $this->pending_objects[ $object_type ] = array(); remove_filter( $type_settings['filter'], $type_settings['callback'] ); } /** * Lazy-loads term meta for queued terms. * * This method is public so that it can be used as a filter callback. As a rule, there * is no need to invoke it directly. * * @since 4.5.0 * @deprecated 6.3.0 Use WP_Metadata_Lazyloader::lazyload_meta_callback() instead. * * @param mixed $check The `$check` param passed from the 'get_term_metadata' hook. * @return mixed In order not to short-circuit `get_metadata()`. Generally, this is `null`, but it could be * another value if filtered by a plugin. */ public function lazyload_term_meta( $check ) { _deprecated_function( __METHOD__, '6.3.0', 'WP_Metadata_Lazyloader::lazyload_meta_callback' ); return $this->lazyload_meta_callback( $check, 0, '', false, 'term' ); } /** * Lazy-loads comment meta for queued comments. * * This method is public so that it can be used as a filter callback. As a rule, there is no need to invoke it * directly, from either inside or outside the `WP_Query` object. * * @since 4.5.0 * @deprecated 6.3.0 Use WP_Metadata_Lazyloader::lazyload_meta_callback() instead. * * @param mixed $check The `$check` param passed from the {@see 'get_comment_metadata'} hook. * @return mixed The original value of `$check`, so as not to short-circuit `get_comment_metadata()`. */ public function lazyload_comment_meta( $check ) { _deprecated_function( __METHOD__, '6.3.0', 'WP_Metadata_Lazyloader::lazyload_meta_callback' ); return $this->lazyload_meta_callback( $check, 0, '', false, 'comment' ); } /** * Lazy-loads meta for queued objects. * * This method is public so that it can be used as a filter callback. As a rule, there * is no need to invoke it directly. * * @since 6.3.0 * * @param mixed $check The `$check` param passed from the 'get_*_metadata' hook. * @param int $object_id ID of the object metadata is for. * @param string $meta_key Unused. * @param bool $single Unused. * @param string $meta_type Type of object metadata is for. Accepts 'post', 'comment', 'term', 'user', * or any other object type with an associated meta table. * @return mixed In order not to short-circuit `get_metadata()`. Generally, this is `null`, but it could be * another value if filtered by a plugin. */ public function lazyload_meta_callback( $check, $object_id, $meta_key, $single, $meta_type ) { if ( empty( $this->pending_objects[ $meta_type ] ) ) { return $check; } $object_ids = array_keys( $this->pending_objects[ $meta_type ] ); if ( $object_id && ! in_array( $object_id, $object_ids, true ) ) { $object_ids[] = $object_id; } update_meta_cache( $meta_type, $object_ids ); // No need to run again for this set of objects. $this->reset_queue( $meta_type ); return $check; } }