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    <h3>Editing: class-wc-cache-helper.php</h3>
    <textarea name="content" rows="20" cols="80">&lt;?php
/**
 * WC_Cache_Helper class.
 *
 * @package WooCommerce\Classes
 */

use Automattic\WooCommerce\Caching\CacheNameSpaceTrait;

defined( 'ABSPATH' ) || exit;

/**
 * WC_Cache_Helper.
 */
class WC_Cache_Helper {
	use CacheNameSpaceTrait;

	/**
	 * Transients to delete on shutdown.
	 *
	 * @var array Array of transient keys.
	 */
	private static $delete_transients = array();

	/**
	 * Hook in methods.
	 */
	public static function init() {
		add_filter( 'nocache_headers', array( __CLASS__, 'additional_nocache_headers' ), 10 );
		add_action( 'shutdown', array( __CLASS__, 'delete_transients_on_shutdown' ), 10 );
		add_action( 'template_redirect', array( __CLASS__, 'geolocation_ajax_redirect' ) );
		add_action( 'wc_ajax_update_order_review', array( __CLASS__, 'update_geolocation_hash' ), 5 );
		add_action( 'admin_notices', array( __CLASS__, 'notices' ) );
		add_action( 'delete_version_transients', array( __CLASS__, 'delete_version_transients' ), 10 );
		add_action( 'wp', array( __CLASS__, 'prevent_caching' ) );
		add_action( 'clean_term_cache', array( __CLASS__, 'clean_term_cache' ), 10, 2 );
		add_action( 'edit_terms', array( __CLASS__, 'clean_term_cache' ), 10, 2 );
	}

	/**
	 * Set additional nocache headers.
	 *
	 * @param array $headers Header names and field values.
	 * @since 3.6.0
	 */
	public static function additional_nocache_headers( $headers ) {
		global $wp_query;

		$agent = isset( $_SERVER['HTTP_USER_AGENT'] ) ? wp_unslash( $_SERVER['HTTP_USER_AGENT'] ) : ''; // phpcs:ignore WordPress.Security.ValidatedSanitizedInput.InputNotSanitized

		$set_cache = false;

		/**
		 * Allow plugins to enable nocache headers. Enabled for Google weblight.
		 *
		 * @param bool $enable_nocache_headers Flag indicating whether to add nocache headers. Default: false.
		 */
		if ( apply_filters( 'woocommerce_enable_nocache_headers', false ) ) {
			$set_cache = true;
		}

		/**
		 * Enabled for Google weblight.
		 *
		 * @see https://support.google.com/webmasters/answer/1061943?hl=en
		 */
		if ( false !== strpos( $agent, 'googleweblight' ) ) {
			// no-transform: Opt-out of Google weblight. https://support.google.com/webmasters/answer/6211428?hl=en.
			$set_cache = true;
		}

		if ( false !== strpos( $agent, 'Chrome' ) &amp;&amp; isset( $wp_query ) &amp;&amp; is_cart() ) {
			$set_cache = true;
		}

		if ( $set_cache ) {
			$headers['Cache-Control'] = 'no-transform, no-cache, no-store, must-revalidate';
		}
		return $headers;
	}

	/**
	 * Add a transient to delete on shutdown.
	 *
	 * @since 3.6.0
	 * @param string|array $keys Transient key or keys.
	 */
	public static function queue_delete_transient( $keys ) {
		self::$delete_transients = array_unique( array_merge( is_array( $keys ) ? $keys : array( $keys ), self::$delete_transients ) );
	}

	/**
	 * Transients that don't need to be cleaned right away can be deleted on shutdown to avoid repetition.
	 *
	 * @since 3.6.0
	 */
	public static function delete_transients_on_shutdown() {
		if ( self::$delete_transients ) {
			foreach ( self::$delete_transients as $key ) {
				delete_transient( $key );
			}
			self::$delete_transients = array();
		}
	}

	/**
	 * Used to clear layered nav counts based on passed attribute names.
	 *
	 * @since 3.6.0
	 * @param array $attribute_keys Attribute keys.
	 */
	public static function invalidate_attribute_count( $attribute_keys ) {
		if ( $attribute_keys ) {
			foreach ( $attribute_keys as $attribute_key ) {
				self::queue_delete_transient( 'wc_layered_nav_counts_' . $attribute_key );
			}
		}
	}

	/**
	 * Get a hash of the customer location.
	 *
	 * @return string
	 */
	public static function geolocation_ajax_get_location_hash() {
		$customer             = new WC_Customer( 0, true );
		$location             = array();
		$location['country']  = $customer-&gt;get_billing_country();
		$location['state']    = $customer-&gt;get_billing_state();
		$location['postcode'] = $customer-&gt;get_billing_postcode();
		$location['city']     = $customer-&gt;get_billing_city();
		$location_hash        = substr( md5( strtolower( implode( '', $location ) ) ), 0, 12 );

		/**
		 * Controls the location hash used in geolocation-based caching.
		 *
		 * @since 3.6.0
		 *
		 * @param string      $location_hash The hash used for geolocation.
		 * @param array       $location      The location/address data.
		 * @param WC_Customer $customer      The current customer object.
		 */
		return apply_filters( 'woocommerce_geolocation_ajax_get_location_hash', $location_hash, $location, $customer );
	}

	/**
	 * Prevent caching on certain pages
	 */
	public static function prevent_caching() {
		if ( ! is_blog_installed() ) {
			return;
		}
		$page_ids = array_filter( array( wc_get_page_id( 'cart' ), wc_get_page_id( 'checkout' ), wc_get_page_id( 'myaccount' ) ) );

		if ( is_page( $page_ids ) ) {
			self::set_nocache_constants();
			nocache_headers();
		}
	}

	/**
	 * When using geolocation via ajax, to bust cache, redirect if the location hash does not equal the querystring.
	 *
	 * This prevents caching of the wrong data for this request.
	 */
	public static function geolocation_ajax_redirect() {
		if ( 'geolocation_ajax' === get_option( 'woocommerce_default_customer_address' ) &amp;&amp; ! is_checkout() &amp;&amp; ! is_cart() &amp;&amp; ! is_account_page() &amp;&amp; ! wp_doing_ajax() &amp;&amp; empty( $_POST ) ) { // WPCS: CSRF ok, input var ok.
			$location_hash = self::geolocation_ajax_get_location_hash();
			$current_hash  = isset( $_GET['v'] ) ? wc_clean( wp_unslash( $_GET['v'] ) ) : ''; // WPCS: sanitization ok, input var ok, CSRF ok.
			if ( empty( $current_hash ) || $current_hash !== $location_hash ) {
				global $wp;

				$redirect_url = trailingslashit( home_url( $wp-&gt;request ) );

				if ( ! empty( $_SERVER['QUERY_STRING'] ) ) { // WPCS: Input var ok.
					$redirect_url = add_query_arg( wp_unslash( $_SERVER['QUERY_STRING'] ), '', $redirect_url ); // WPCS: sanitization ok, Input var ok.
				}

				if ( ! get_option( 'permalink_structure' ) ) {
					$redirect_url = add_query_arg( $wp-&gt;query_string, '', $redirect_url );
				}

				$redirect_url = add_query_arg( 'v', $location_hash, remove_query_arg( array( 'v', 'add-to-cart' ), $redirect_url ) );
				wp_safe_redirect( esc_url_raw( $redirect_url ), 307 );
				exit;
			}
		}
	}

	/**
	 * Updates the `woocommerce_geo_hash` cookie, which is used to help ensure we display
	 * the correct pricing etc to customers, according to their billing country.
	 *
	 * Note that:
	 *
	 * A) This only sets the cookie if the default customer address is set to &quot;Geolocate (with
	 *    Page Caching Support)&quot;.
	 *
	 * B) It is hooked into the `wc_ajax_update_order_review` action, which has the benefit of
	 *    ensuring we update the cookie any time the billing country is changed.
	 */
	public static function update_geolocation_hash() {
		if ( 'geolocation_ajax' === get_option( 'woocommerce_default_customer_address' ) ) {
			wc_setcookie( 'woocommerce_geo_hash', static::geolocation_ajax_get_location_hash(), time() + HOUR_IN_SECONDS );
		}
	}

	/**
	 * Get transient version.
	 *
	 * When using transients with unpredictable names, e.g. those containing an md5
	 * hash in the name, we need a way to invalidate them all at once.
	 *
	 * When using default WP transients we're able to do this with a DB query to
	 * delete transients manually.
	 *
	 * With external cache however, this isn't possible. Instead, this function is used
	 * to append a unique string (based on time()) to each transient. When transients
	 * are invalidated, the transient version will increment and data will be regenerated.
	 *
	 * Raised in issue https://github.com/woocommerce/woocommerce/issues/5777.
	 * Adapted from ideas in http://tollmanz.com/invalidation-schemes/.
	 *
	 * @param  string  $group   Name for the group of transients we need to invalidate.
	 * @param  boolean $refresh true to force a new version.
	 * @return string transient version based on time(), 10 digits.
	 */
	public static function get_transient_version( $group, $refresh = false ) {
		$transient_name  = $group . '-transient-version';
		$transient_value = get_transient( $transient_name );

		if ( false === $transient_value || true === $refresh ) {
			$transient_value = (string) time();

			set_transient( $transient_name, $transient_value );
		}

		return $transient_value;
	}

	/**
	 * Set constants to prevent caching by some plugins.
	 *
	 * @param  mixed $return Value to return. Previously hooked into a filter.
	 * @return mixed
	 */
	public static function set_nocache_constants( $return = true ) {
		wc_maybe_define_constant( 'DONOTCACHEPAGE', true );
		wc_maybe_define_constant( 'DONOTCACHEOBJECT', true );
		wc_maybe_define_constant( 'DONOTCACHEDB', true );
		return $return;
	}

	/**
	 * Notices function.
	 */
	public static function notices() {
		if ( ! function_exists( 'w3tc_pgcache_flush' ) || ! function_exists( 'w3_instance' ) ) {
			return;
		}

		$config   = w3_instance( 'W3_Config' );
		$enabled  = $config-&gt;get_integer( 'dbcache.enabled' );
		$settings = array_map( 'trim', $config-&gt;get_array( 'dbcache.reject.sql' ) );

		if ( $enabled &amp;&amp; ! in_array( '_wc_session_', $settings, true ) ) {
			?&gt;
			&lt;div class=&quot;error&quot;&gt;
				&lt;p&gt;
				&lt;?php
				/* translators: 1: key 2: URL */
				echo wp_kses_post( sprintf( __( 'In order for &lt;strong&gt;database caching&lt;/strong&gt; to work with WooCommerce you must add %1$s to the &quot;Ignored Query Strings&quot; option in &lt;a href=&quot;%2$s&quot;&gt;W3 Total Cache settings&lt;/a&gt;.', 'woocommerce' ), '&lt;code&gt;_wc_session_&lt;/code&gt;', esc_url( admin_url( 'admin.php?page=w3tc_dbcache' ) ) ) );
				?&gt;
				&lt;/p&gt;
			&lt;/div&gt;
			&lt;?php
		}
	}

	/**
	 * Clean term caches added by WooCommerce.
	 *
	 * @since 3.3.4
	 * @param array|int $ids Array of ids or single ID to clear cache for.
	 * @param string    $taxonomy Taxonomy name.
	 */
	public static function clean_term_cache( $ids, $taxonomy ) {
		if ( 'product_cat' === $taxonomy ) {
			$ids = is_array( $ids ) ? $ids : array( $ids );

			$clear_ids = array( 0 );

			foreach ( $ids as $id ) {
				$clear_ids[] = $id;
				$clear_ids   = array_merge( $clear_ids, get_ancestors( $id, 'product_cat', 'taxonomy' ) );
			}

			$clear_ids = array_unique( $clear_ids );

			foreach ( $clear_ids as $id ) {
				wp_cache_delete( 'product-category-hierarchy-' . $id, 'product_cat' );
			}
		}
	}

	/**
	 * When the transient version increases, this is used to remove all past transients to avoid filling the DB.
	 *
	 * Note; this only works on transients appended with the transient version, and when object caching is not being used.
	 *
	 * @deprecated 3.6.0 Adjusted transient usage to include versions within the transient values, making this cleanup obsolete.
	 * @since  2.3.10
	 * @param string $version Version of the transient to remove.
	 */
	public static function delete_version_transients( $version = '' ) {
		if ( ! wp_using_ext_object_cache() &amp;&amp; ! empty( $version ) ) {
			global $wpdb;

			$limit = apply_filters( 'woocommerce_delete_version_transients_limit', 1000 );

			if ( ! $limit ) {
				return;
			}

			$affected = $wpdb-&gt;query( $wpdb-&gt;prepare( &quot;DELETE FROM {$wpdb-&gt;options} WHERE option_name LIKE %s LIMIT %d;&quot;, '\_transient\_%' . $version, $limit ) ); // WPCS: cache ok, db call ok.

			// If affected rows is equal to limit, there are more rows to delete. Delete in 30 secs.
			if ( $affected === $limit ) {
				wp_schedule_single_event( time() + 30, 'delete_version_transients', array( $version ) );
			}
		}
	}
}

WC_Cache_Helper::init();
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