wp_scheduled_delete()

function wp_scheduled_delete() {
	global $wpdb;

	$delete_timestamp = time() - ( DAY_IN_SECONDS * EMPTY_TRASH_DAYS );

	$posts_to_delete = $wpdb->get_results($wpdb->prepare("SELECT post_id FROM $wpdb->postmeta WHERE meta_key = '_wp_trash_meta_time' AND meta_value < %d", $delete_timestamp), ARRAY_A);

	foreach ( (array) $posts_to_delete as $post ) {
		$post_id = (int) $post['post_id'];
		if ( !$post_id )
			continue;

		$del_post = get_post($post_id);

		if ( !$del_post || 'trash' != $del_post->post_status ) {
			delete_post_meta($post_id, '_wp_trash_meta_status');
			delete_post_meta($post_id, '_wp_trash_meta_time');
		} else {
			wp_delete_post($post_id);
		}
	}

	$comments_to_delete = $wpdb->get_results($wpdb->prepare("SELECT comment_id FROM $wpdb->commentmeta WHERE meta_key = '_wp_trash_meta_time' AND meta_value < %d", $delete_timestamp), ARRAY_A);

	foreach ( (array) $comments_to_delete as $comment ) {
		$comment_id = (int) $comment['comment_id'];
		if ( !$comment_id )
			continue;

		$del_comment = get_comment($comment_id);

		if ( !$del_comment || 'trash' != $del_comment->comment_approved ) {
			delete_comment_meta($comment_id, '_wp_trash_meta_time');
			delete_comment_meta($comment_id, '_wp_trash_meta_status');
		} else {
			wp_delete_comment( $del_comment );
		}
	}
}