default-no-db-transients.php

<?php
/*
Plugin Name: No transients in database
Version: 1.0.0
Description: Prevent transients from being stored in the database when external object cache is being used
Plugin URI: https://beapi.fr
Author: Be API
Author URI: https://beapi.fr

----

Copyright 2025 Be API Technical team (humans@beapi.fr)

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
*/

namespace BeAPI;

if ( ! defined( 'ABSPATH' ) ) {
	exit;
}
/**
 * Class to prevent transients from being stored in the database
 * since we're using Redis for object caching
 */
class NoTransients {
	/**
	 * Initialize the class and set up hooks
	 */
	public function __construct() {
		// Prevent transients from being retrieved
		add_filter( 'pre_option', [ $this, 'prevent_transient_retrieval' ], 10, 2 );

		// Remove transients from alloptions
		add_filter( 'alloptions', [ $this, 'remove_transients_from_alloptions' ] );

		// Prevent new transients from being added
		add_action( 'added_option', [ $this, 'delete_transient_option' ] );

		// Prevent transients from being updated
		add_action( 'updated_option', [ $this, 'delete_transient_option' ] );
		
		// Set up cleanup cron job
		add_action( 'init', [ $this, 'setup_cleanup_cron' ] );

		// Show admin notice if no external object cache is being used
		add_action( 'admin_notices', [ $this, 'show_admin_notice' ] );

		// Clean up transients from the database
		add_action( 'beapi_clean_transients', [ $this, 'cleanup_transients' ] );
	}

	/**
	 * Make transients appear expired by returning 0 for timeout options
	 *
	 * @param mixed $pre The pre-option value
	 * @param string $option The option name
     * 
	 * @return mixed The modified pre-option value
	 */
	public function prevent_transient_retrieval( $pre, $option ) {
		// If it's a transient timeout, return 0 to make it appear expired
		if ( str_starts_with( $option, '_transient_timeout' ) ) {
			return 0;
		}

		return $pre;
	}

	/**
	 * Remove transients from alloptions array and delete them from database
	 * This is because alloptions is called into the get_transient function, and expiration is not checked if the transient is in alloptions.
	 *
	 * @param array $alloptions The array of all autoloaded options
	 * @return array The filtered options array
	 */
	public function remove_transients_from_alloptions( $alloptions ) {
		foreach ( $alloptions as $option => $value ) {
			if ( ! str_starts_with( $option, '_transient' ) ) {
				continue;
			}

			unset( $alloptions[ $option ] );
			delete_option( $option );
		}

		return $alloptions;
	}

	/**
	 * Delete transient options when they're added or updated
	 *
	 * @param string $option The option name
	 * @param mixed $value The option value
	 */
	public function delete_transient_option( $option ) {
		if ( str_starts_with( $option, '_transient' ) ) {
			delete_option( $option );
		}
	}

	/**
	 * Set up weekly cron job to clean up transients
	 */
	public function setup_cleanup_cron() {
		if ( ! wp_next_scheduled( 'beapi_clean_transients' ) ) {
			wp_schedule_event( time(), 'weekly', 'beapi_clean_transients' );
		}
	}

	/**
	 * Clean up all transients from the database
	 */
	public function cleanup_transients() {
		global $wpdb;

		// Delete all transients
		$wpdb->query( "DELETE FROM $wpdb->options WHERE option_name LIKE '_transient_%'" );
	}

	/**
	 * Show admin notice if no external object cache is being used
	 * The removal of transients when not object cache is a big performance issue
	 */
	public function show_admin_notice() {
		if ( wp_using_ext_object_cache() || ! current_user_can( 'manage_options' ) ) {
			return;
		}

		echo '<div class="notice notice-error"><p style="font-size: 40px;">Beware transients are not written in database. Please remove <strong>' . esc_html( wp_basename( __FILE__ ) ) . '</strong> from the mu-plugins folder.</p></div>';
	}
}

new NoTransients();