Fetch promotions in a WP Cron job (#51650)

* Getting promotions in a WP Cron job to make them async. We don't want this request to affect the performance of wp-admin. See https://github.com/woocommerce/woocommerce/pull/47262#pullrequestreview-2241835763.

* Changelog.

* Made callback method `update_promotions` public.

* Linter errors. Whitespace.

plugins/woocommerce/changelog/update-wccom-21774-update-promotions-async

@@ -0,0 +1,4 @@
+Significance: minor
+Type: update
+
+Changed how we fetch WooCommerce promotions. We're doing it async so as not to affect the loading of wp-admin.

plugins/woocommerce/includes/admin/class-wc-admin-marketplace-promotions.php

@@ -15,6 +15,7 @@ if ( ! defined( 'ABSPATH' ) ) {
  */
 class WC_Admin_Marketplace_Promotions {
 
+	const CRON_NAME           = 'woocommerce_marketplace_cron_fetch_promotions';
 	const TRANSIENT_NAME      = 'woocommerce_marketplace_promotions_v2';
 	const TRANSIENT_LIFE_SPAN = DAY_IN_SECONDS;
 	const PROMOTIONS_API_URL  = 'https://woocommerce.com/wp-json/wccom-extensions/3.0/promotions';
@@ -39,7 +40,16 @@ class WC_Admin_Marketplace_Promotions {
 	public static function init() {
 		// A legacy hook that can be triggered by action scheduler.
 		add_action( 'woocommerce_marketplace_fetch_promotions', array( __CLASS__, 'clear_deprecated_action' ) );
-		add_action( 'woocommerce_marketplace_fetch_promotions_clear', array( __CLASS__, 'clear_scheduled_event' ) );
+		add_action(
+			'woocommerce_marketplace_fetch_promotions_clear',
+			array(
+				__CLASS__,
+				'clear_deprecated_scheduled_event',
+			)
+		);
+
+		// Fetch promotions from the API and store them in a transient.
+		add_action( self::CRON_NAME, array( __CLASS__, 'update_promotions' ) );
 
 		if (
 			defined( 'DOING_AJAX' ) && DOING_AJAX
@@ -53,24 +63,33 @@ class WC_Admin_Marketplace_Promotions {
 			return;
 		}
 
-		self::maybe_update_promotions();
+		self::schedule_cron_event();
+
+		register_deactivation_hook( WC_PLUGIN_FILE, array( __CLASS__, 'clear_cron_event' ) );
 
 		self::$locale = ( self::$locale ?? get_user_locale() ) ?? 'en_US';
 		self::maybe_show_bubble_promotions();
 	}
 
 	/**
-	 * Fetch promotions from the API and store them in a transient.
+	 * Schedule a daily cron event to fetch promotions.
-	 * Fetching can be suppressed by the `woocommerce_marketplace_suppress_promotions` filter.
+	 *
+	 * @version 9.5.0
 	 *
 	 * @return void
 	 */
-	private static function maybe_update_promotions() {
+	private static function schedule_cron_event() {
-		// Fetch promotions if they're not in the transient.
+		if ( ! wp_next_scheduled( self::CRON_NAME ) ) {
-		if ( false !== get_transient( self::TRANSIENT_NAME ) ) {
+			wp_schedule_event( time(), 'daily', self::CRON_NAME );
-			return;
+		}
 	}
 
+	/**
+	 * Fetch promotions from the API and store them in a transient.
+	 *
+	 * @return void
+	 */
+	public static function update_promotions() {
 		// Fetch promotions from the API.
 		$promotions = self::fetch_marketplace_promotions();
 		set_transient( self::TRANSIENT_NAME, $promotions, self::TRANSIENT_LIFE_SPAN );
@@ -326,12 +345,24 @@ class WC_Admin_Marketplace_Promotions {
 	}
 
 	/**
-	 * Clear the scheduled action that was used to fetch promotions in WooCommerce 8.8.
+	 * When WooCommerce is disabled, clear the WP Cron event we use to fetch promotions.
-	 * It's no longer needed as a transient is used to store the data.
+	 *
+	 * @version 9.5.0
 	 *
 	 * @return void
 	 */
-	public static function clear_scheduled_event() {
+	public static function clear_cron_event() {
+		$timestamp = wp_next_scheduled( self::CRON_NAME );
+		wp_unschedule_event( $timestamp, self::CRON_NAME );
+	}
+
+	/**
+	 * Clear deprecated scheduled action that was used to fetch promotions in WooCommerce 8.8.
+	 * Replaced with a transient in WooCommerce 9.0.
+	 *
+	 * @return void
+	 */
+	public static function clear_deprecated_scheduled_event() {
 		if ( function_exists( 'as_unschedule_all_actions' ) ) {
 			as_unschedule_all_actions( 'woocommerce_marketplace_fetch_promotions' );
 		}