Delete Expired EE4 Session Transients plugin

espresso-delete-transients.php

<?php
/*
  Plugin Name: Event Espresso - Delete Expired EE4 Session Transients
  Plugin URI: http://www.eventespresso.com/
  Description: Deletes Expired EE4 Session Transients. Requires version of Event Espresso 4 and greater.
  Version: 0.0.1
  Author: Event Espresso
  Author URI: http://www.eventespresso.com

  Copyright (c) 2014  Event Espresso  All Rights Reserved.

     This program is free software; you can redistribute it and/or modify
     it under the terms of the GNU General Public License as published by
     the Free Software Foundation; either version 2 of the License, or
     (at your option) any later version.

     This program is distributed in the hope that it will be useful,
     but WITHOUT ANY WARRANTY; without even the implied warranty of
     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
     GNU General Public License for more details.

     You should have received a copy of the GNU General Public License
     along with this program; if not, write to the Free Software
     Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 */
/**
 * delete_expired_ee4_session_transients
 */
function delete_expired_ee4_session_transients() {
	if ( ! defined( 'DOING_AJAX') || ! DOING_AJAX ) {
		global $wpdb;
		$expiration = current_time( 'timestamp' );
		$SQL = "
			 	SELECT option_name
			 	FROM {$wpdb->options}
			 	WHERE option_name
			 	LIKE '\_transient\_timeout\_ee\_ssn\_%'
			 	AND option_value < {$expiration}
			 	LIMIT 2;
			";
		$expired_sessions = $wpdb->get_col( $SQL );
		$IN = array();
		foreach( $expired_sessions as $expired_session ) {
			$IN[] = "'" . $expired_session . "'";
			$IN[] = "'" . str_replace( '_transient_timeout_', '', $expired_session ) . "'";
		}
		$IN = implode( ', ', $IN );
		if ( ! empty( $IN )) {
			$SQL = "
					DELETE FROM {$wpdb->options}
					WHERE option_name
					IN ( $IN );
				 ";
			$results = $wpdb->query( $SQL );
			if ( $results ) {
				echo 'deleted ' . count( $results ) . ' expired session transients<br />';
				delete_expired_ee4_session_transients();
			}
		}
	}
}
add_action( 'shutdown', 'delete_expired_ee4_session_transients', 999 );