unction complete() {
		// unschedule the cron healthcheck
		$this->clear_scheduled_event();
	}


	/**
	 * Schedule cron healthcheck
	 *
	 * @since 4.4.0
	 * @param array $schedules
	 * @return array
	 */
	public function schedule_cron_healthcheck( $schedules ) {
		$interval = property_exists( $this, 'cron_interval' ) ? $this->cron_interval : 5;
		/**
		 * Filter cron health check interval
		 *
		 * @since 4.4.0
		 * @param int $interval Interval in minutes
		 */
		$interval = apply_filters( "{$this->identifier}_cron_interval", $interval );
		// adds every 5 minutes to the existing schedules.
		$schedules[ $this->identifier . '_cron_interval' ] = [
			'interval' => MINUTE_IN_SECONDS * $interval,
			/* translators: %d - interval in minutes. */
			'display'  => sprintf( __( 'Every %d Minutes', 'facebook-for-woocommerce' ), $interval ),
		];
		return $schedules;
	}


	/**
	 * Handle cron healthcheck
	 *
	 * Restart the background process if not already running
	 * and data exists in the queue.
	 *
	 * @since 4.4.0
	 */
	public function handle_cron_healthcheck() {
		if ( $this->is_process_running() ) {
			// background process already running
			exit;
		}
		if ( $this->is_queue_empty() ) {
			// no data to process
			$this->clear_scheduled_event();
			exit;
		}
		$this->dispatch();
	}


	/**
	 * Schedule cron health check event
	 *
	 * @since 4.4.0
	 */
	protected function schedule_event() {
		if ( ! wp_next_scheduled( $this->cron_hook_identifier ) ) {
			// schedule the health check to fire after 30 seconds from now, as to not create a race condition
			// with job process lock on servers that fire & handle cron events instantly
			wp_schedule_event( time() + 30, $this->cron_interval_identifier, $this->cron_hook_identifier );
		}
	}


	/**
	 * Clear scheduled health check event
	 *
	 * @since 4.4.0
	 */
	protected function clear_scheduled_event() {
		$timestamp = wp_next_scheduled( $this->cron_hook_identifier );
		if ( $timestamp ) {
			wp_unschedule_event( $timestamp, $this->cron_hook_identifier );
		}
	}


	/**
	 * Process an item from job data
	 *
	 * Implement this method to perform any actions required on each
	 * item in job data.
	 *
	 * @since 4.4.2
	 *
	 * @param mixed            $item Job data item to iterate over
	 * @param \stdClass|object $job Job instance
	 * @return mixed
	 */
	abstract protected function process_item( $item, $job );


	/**
	 * Handles PHP shutdown, say after a fatal error.
	 *
	 * @since 4.5.0
	 *
	 * @param \stdClass|object $job the job being processed
	 */
	public function handle_shutdown( $job ) {
		$error = error_get_last();
		// if shutting down because of a fatal error, fail the job
		if ( $error && E_ERROR === $error['type'] ) {
			$this->fail_job( $job, $error['message'] );
			$this->unlock_process();
		}
	}


	/**
	 * Update a job option in options database.
	 *
	 * @since 4.6.3
	 *
	 * @param \stdClass|object $job the job instance to update in database
	 * @return int|bool number of rows updated or false on failure, see wpdb::update()
	 */
	private function update_job_option( $job ) {
		global $wpdb;

		return $wpdb->update(
			$wpdb->options,
			[ 'option_value' => wp_json_encode( $job ) ],
			[ 'option_name' => "{$this->identifier}_job_{$job->id}" ]
		);
	}


	/** Debug & Testing Methods ***********************************************/


	/**
	 * Tests the background handler's connection.
	 *
	 * @since 4.8.0
	 *
	 * @return bool
	 */
	public function test_connection() {
		$test_url = add_query_arg( 'action', "{$this->identifier}_test", admin_url( 'admin-ajax.php' ) );
		$result   = wp_safe_remote_get( $test_url );
		$body     = ! is_wp_error( $result ) ? wp_remote_retrieve_body( $result ) : null;
		// some servers may add a UTF8-BOM at the beginning of the response body, so we check if our test
		// string is included in the body, as an equal check would produce a false negative test result
		return $body && Helper::str_exists( $body, '[TEST_LOOPBACK]' );
	}


	/**
	 * Handles the connection test request.
	 *
	 * @since 4.8.0
	 */
	public function handle_connection_test_response() {
		echo '[TEST_LOOPBACK]';
		exit;
	}


	/**
	 * Adds the WooCommerce debug tool.
	 *
	 * @since 4.8.0
	 *
	 * @param array $tools WooCommerce core tools
	 * @return array
	 */
	public function add_debug_tool( $tools ) {
		// this key is not unique to the plugin to avoid duplicate tools
		$tools['sv_wc_background_job_test'] = [
			'name'     => __( 'Background Processing Test', 'facebook-for-woocommerce' ),
			'button'   => __( 'Run Test', 'facebook-for-woocommerce' ),
			'desc'     => __( 'This tool will test whether your server is capable of processing background jobs.', 'facebook-for-woocommerce' ),
			'callback' => [ $this, 'run_debug_tool' ],
		];

		return $tools;
	}


	/**
	 * Runs the test connection debug tool.
	 *
	 * @since 4.8.0
	 *
	 * @return string
	 */
	public function run_debug_tool() {
		if ( $this->test_connection() ) {
			$this->debug_message = esc_html__( 'Success! You should be able to process background jobs.', 'facebook-for-woocommerce' );
			$result              = true;
		} else {
			$this->debug_message = esc_html__( 'Could not connect. Please ask your hosting company to ensure your server has loopback connections enabled.', 'facebook-for-woocommerce' );
			$result              = false;
		}

		return $result;
	}


	/**
	 * Translate the tool success message.
	 *
	 * This can be removed in favor of returning the message string in `run_debug_tool()`
	 *  when WC 3.1 is required, though that means the message will always be "success" styled.
	 *
	 * @since 4.8.0
	 *
	 * @param string $translated the text to output
	 * @param string $original the original text
	 * @param string $domain the textdomain
	 * @return string the updated text
	 */
	public function translate_success_message( $translated, $original, $domain ) {
		if ( 'woocommerce' === $domain && ( 'Tool ran.' === $original || 'There was an error calling %s' === $original ) ) {
			$translated = $this->debug_message;
		}
		return $translated;
	}


	/** Helper Methods ********************************************************/


	/**
	 * Gets the job handler identifier.
	 *
	 * @since 4.8.0
	 *
	 * @return string
	 */
	public function get_identifier() {
		return $this->identifier;
	}
}
1 - Uncaught Error: Class 'WooCommerce\Facebook\Framework\Utilities\BackgroundJobHandler' not found in /home/st20space2tech/public_html/site/wp-content/plugins/facebook-for-woocommerce/includes/Products/Sync/Background.php:17
Stack trace:
#0 /home/st20space2tech/public_html/site/wp-content/plugins/facebook-for-woocommerce/vendor/composer/ClassLoader.php(576): include()
#1 /home/st20space2tech/public_html/site/wp-content/plugins/facebook-for-woocommerce/vendor/composer/ClassLoader.php(427): Composer\Autoload\{closure}('/home/st20space...')
#2 [internal function]: Composer\Autoload\ClassLoader->loadClass('WooCommerce\\Fac...')
#3 /home/st20space2tech/public_html/site/wp-content/plugins/facebook-for-woocommerce/class-wc-facebookcommerce.php(216): spl_autoload_call('WooCommerce\\Fac...')
#4 /home/st20space2tech/public_html/site/wp-content/plugins/facebook-for-woocommerce/class-wc-facebookcommerce.php(161): WC_Facebookcommerce->init()
#5 /home/st20space2tech/public_html/site/wp-content/plugins/facebook-for-woocommerce - /home/st20space2tech/public_html/site/wp-content/plugins/facebook-for-woocommerce/includes/Products/Sync/Background.php - 17