purge_transients.php

<?php


function isa_add_cron_recurrence_interval( $schedules ) {
 
    $schedules['every_single_minute'] = array(
            'interval'  => MINUTE_IN_SECONDS,
            'display'   => __( 'Every Single Minute', 'textdomain' )
    );
     
    return $schedules;
}
add_filter( 'cron_schedules', 'isa_add_cron_recurrence_interval' );

// Schedule the CRON Job to purge all expired transients

if (!wp_next_scheduled('purge_popup_transients_cron')) {

	/**
	 * wp_schedule_event
	 *
	 * @param - When to start the CRON job
	 * @param - The interval in for each subsequent run
	 * @param - The name of the CRON JOB
	 */

	wp_schedule_event( time(), 'every_single_minute', 'purge_popup_transients_cron');
}

add_action( 'purge_popup_transients_cron',  'purge_transients', 10 ,2);

/**
 * Deletes all transients that have expired
 *
 * @access public
 * @static
 * @return void
 */
function purge_transients($older_than = '1 minute', $safemode = true) {

	global $wpdb;
	$older_than_time = strtotime('-' . $older_than);

	/**
	 * Only check if the transients are older than the specified time
	 */

	if ( $older_than_time > time() || $older_than_time < 1 ) {
		return false;
	}

	/**
	 * Get all the expired transients
	 *
	 * @var mixed
	 * @access public
	 */
	$transients = $wpdb->get_col(
		$wpdb->prepare( "
				SELECT REPLACE(option_name, '_transient_timeout_', '') AS transient_name
				FROM {$wpdb->options}
				WHERE option_name LIKE '\_transient\_timeout\__%%'
					AND option_value < %s
		", $older_than_time)
	);

	/**
	 * If safemode is ON just use the default WordPress get_transient() function
	 * to delete the expired transients
	 */

	if ( $safemode ) {
		foreach( $transients as $transient ) {
			get_transient($transient);
		}
	}

	/**
	 * If safemode is OFF the just manually delete all the transient rows in the database
	 */

	else {
		$options_names = array();
		foreach($transients as $transient) {
			$options_names[] = '_transient_' . $transient;
			$options_names[] = '_transient_timeout_' . $transient;
		}
		if ($options_names) {
			$options_names = array_map(array($wpdb, 'escape'), $options_names);
			$options_names = "'". implode("','", $options_names) ."'";

			$result = $wpdb->query( "DELETE FROM {$wpdb->options} WHERE option_name IN ({$options_names})" );
			if (!$result) {
				return false;
			}
		}
	}

	return $transients;
}