update_post_thumbnail_cache( WP_Query $wp_query = null )

104function update_post_thumbnail_cache( $wp_query = null ) {105	if ( ! $wp_query ) {106		$wp_query = $GLOBALS['wp_query'];107	}108 109	if ( $wp_query->thumbnails_cached ) {110		return;111	}112 113	$thumb_ids = array();114 115	/*116	 * $wp_query may contain an array of post objects or post IDs.117	 *118	 * This ensures the cache is primed for all post objects to avoid119	 * `get_post()` calls in `get_the_post_thumbnail()` triggering an120	 * additional database call for each post.121	 */122	$parent_post_ids = array();123	foreach ( $wp_query->posts as $post ) {124		if ( $post instanceof WP_Post ) {125			$parent_post_ids[] = $post->ID;126		} elseif ( is_int( $post ) ) {127			$parent_post_ids[] = $post;128		}129	}130	_prime_post_caches( $parent_post_ids, false, true );131 132	foreach ( $wp_query->posts as $post ) {133		$id = get_post_thumbnail_id( $post );134		if ( $id ) {135			$thumb_ids[] = $id;136		}137	}138 139	if ( ! empty( $thumb_ids ) ) {140		_prime_post_caches( $thumb_ids, false, true );141	}142 143	$wp_query->thumbnails_cached = true;144}