ty( $current_lock_value ) ) {
			// Check if time has passed to overwrite the lock - min 5s?
			if ( is_numeric( $current_lock_value ) && ( ( $current_microtime - $current_lock_value ) < self::DEDICATED_SYNC_REQUEST_LOCK_TIMEOUT ) ) {
				// Still in previous lock, quit
				return false;
			}

			// If the value is not numeric (float/current time), we want to just overwrite it and continue.
		}

		// Update. We don't want it to autoload, as we want to fetch it right before the checks.
		\Jetpack_Options::update_raw_option( self::DEDICATED_SYNC_REQUEST_LOCK_OPTION_NAME, $current_microtime, false );
		// Give some time for the update to happen
		usleep( wp_rand( 1000, 3000 ) );

		$updated_value = \Jetpack_Options::get_raw_option( self::DEDICATED_SYNC_REQUEST_LOCK_OPTION_NAME, null );

		if ( $updated_value === $current_microtime ) {
			return $current_microtime;
		}

		return false;
	}

	/**
	 * Attempt to release the request lock.
	 *
	 * @param string $lock_id The request lock that's currently being held.
	 *
	 * @return bool|WP_Error
	 */
	public static function try_release_lock_spawn_request( $lock_id = '' ) {
		// Try to get the lock_id from the current request if it's not supplied.
		if ( empty( $lock_id ) ) {
			$lock_id = self::get_request_lock_id_from_request();
		}

		// If it's still not a valid lock_id, throw an error and let the lock process figure it out.
		if ( empty( $lock_id ) || ! is_numeric( $lock_id ) ) {
			return new WP_Error( 'dedicated_request_lock_invalid', 'Invalid lock_id supplied for unlock' );
		}

		if ( wp_using_ext_object_cache() ) {
			if ( (string) $lock_id === wp_cache_get( self::DEDICATED_SYNC_REQUEST_LOCK_OPTION_NAME, 'jetpack', true ) ) {
				wp_cache_delete( self::DEDICATED_SYNC_REQUEST_LOCK_OPTION_NAME, 'jetpack' );
			}
		}

		// If this is the flow that has the lock, let's release it so we can spawn other requests afterwards
		$current_lock_value = \Jetpack_Options::get_raw_option( self::DEDICATED_SYNC_REQUEST_LOCK_OPTION_NAME, null );
		if ( (string) $lock_id === $current_lock_value ) {
			\Jetpack_Options::delete_raw_option( self::DEDICATED_SYNC_REQUEST_LOCK_OPTION_NAME );
			return true;
		}

		return false;
	}

	/**
	 * Try to get the request lock id from the current request.
	 *
	 * @return array|string|string[]|null
	 */
	public static function get_request_lock_id_from_request() {
		// phpcs:ignore WordPress.Security.NonceVerification.Recommended
		if ( ! isset( $_GET[ self::DEDICATED_SYNC_REQUEST_LOCK_QUERY_PARAM_NAME ] ) || ! is_numeric( $_GET[ self::DEDICATED_SYNC_REQUEST_LOCK_QUERY_PARAM_NAME ] ) ) {
			return null;
		}

		// phpcs:ignore WordPress.Security.NonceVerification.Recommended,WordPress.Security.ValidatedSanitizedInput.InputNotSanitized
		return wp_unslash( $_GET[ self::DEDICATED_SYNC_REQUEST_LOCK_QUERY_PARAM_NAME ] );
	}

	/**
	 * Test Sync spawning functionality by making a request to the
	 * Sync spawning endpoint and storing the result (status code) in a transient.
	 *
	 * @since $$next_version$$
	 *
	 * @return bool True if we got a successful response, false otherwise.
	 */
	public static function can_spawn_dedicated_sync_request() {
		$dedicated_sync_check_transient = self::DEDICATED_SYNC_CHECK_TRANSIENT;

		$dedicated_sync_response_body = get_transient( $dedicated_sync_check_transient );

		if ( false === $dedicated_sync_response_body ) {
			$url  = rest_url( 'jetpack/v4/sync/spawn-sync' );
			$url  = add_query_arg( 'time', time(), $url ); // Enforce Cache busting.
			$args = array(
				'cookies'   => $_COOKIE,
				'timeout'   => 30,
				/** This filter is documented in wp-includes/class-wp-http-streams.php */
				'sslverify' => apply_filters( 'https_local_ssl_verify', false ),
			);

			$response                     = wp_remote_get( $url, $args );
			$dedicated_sync_response_code = wp_remote_retrieve_response_code( $response );
			$dedicated_sync_response_body = trim( wp_remote_retrieve_body( $response ) );

			/**
			 * Limit the size of the body that we save in the transient to avoid cases where an error
			 * occurs and a whole generated HTML page is returned. We don't need to store the whole thing.
			 *
			 * The regexp check is done to make sure we can detect the string even if the body returns some additional
			 * output, like some caching plugins do when they try to pad the request.
			 */
			$regexp = '!' . preg_quote( self::DEDICATED_SYNC_VALIDATION_STRING, '!' ) . '!uis';
			if ( preg_match( $regexp, $dedicated_sync_response_body ) ) {
				$saved_response_body = self::DEDICATED_SYNC_VALIDATION_STRING;
			} else {
				$saved_response_body = time();
			}

			set_transient( $dedicated_sync_check_transient, $saved_response_body, HOUR_IN_SECONDS );

			// Send a bit more information to WordPress.com to help debugging issues.
			if ( $saved_response_body !== self::DEDICATED_SYNC_VALIDATION_STRING ) {
				$data = array(
					'timestamp'      => microtime( true ),
					'response_code'  => $dedicated_sync_response_code,
					'response_body'  => $dedicated_sync_response_body,

					// Send the flow type that was attempted.
					'sync_flow_type' => 'dedicated',
				);

				$sender = Sender::get_instance();

				$sender->send_action( 'jetpack_sync_flow_error_enable', $data );
			}
		}

		return self::DEDICATED_SYNC_VALIDATION_STRING === $dedicated_sync_response_body;
	}

	/**
	 * Disable dedicated sync and set a transient to prevent re-enabling it for some time.
	 *
	 * @return void
	 */
	public static function on_dedicated_sync_lag_not_sending_threshold_reached() {
		set_transient( self::DEDICATED_SYNC_TEMPORARY_DISABLE_FLAG, true, 6 * HOUR_IN_SECONDS );

		Settings::update_settings(
			array(
				'dedicated_sync_enabled' => 0,
			)
		);

		// Inform that we had to temporarily disable Dedicated Sync
		$data = array(
			'timestamp'      => microtime( true ),

			// Send the flow type that was attempted.
			'sync_flow_type' => 'dedicated',
		);

		$sender = Sender::get_instance();

		$sender->send_action( 'jetpack_sync_flow_error_temp_disable', $data );
	}

	/**
	 * Disable or enable Dedicated Sync sender based on the header value returned from WordPress.com
	 *
	 * @param string $dedicated_sync_header The Dedicated Sync header value - `on` or `off`.
	 *
	 * @return bool Whether Dedicated Sync is going to be enabled or not.
	 */
	public static function maybe_change_dedicated_sync_status_from_wpcom_header( $dedicated_sync_header ) {
		$dedicated_sync_enabled = 'on' === $dedicated_sync_header ? 1 : 0;

		// Prevent enabling of Dedicated sync via header flag if we're in an autoheal timeout.
		if ( $dedicated_sync_enabled ) {
			$check_transient = get_transient( self::DEDICATED_SYNC_TEMPORARY_DISABLE_FLAG );

			if ( $check_transient ) {
				// Something happened and Dedicated Sync should not be automatically re-enabled.
				return false;
			}
		}

		Settings::update_settings(
			array(
				'dedicated_sync_enabled' => $dedicated_sync_enabled,
			)
		);

		return Settings::is_dedicated_sync_enabled();
	}
}
<br />
<b>Fatal error</b>:  Uncaught Error: Class 'Automattic\Jetpack\Sync\Dedicated_Sender' not found in /home/healths/public_html/wp-content/plugins/jetpack-social/jetpack_vendor/automattic/jetpack-sync/src/class-actions.php:109
Stack trace:
#0 /home/healths/public_html/wp-content/plugins/jetpack-social/jetpack_vendor/automattic/jetpack-sync/src/class-main.php(89): Automattic\Jetpack\Sync\Actions::init()
#1 /home/healths/public_html/wp-includes/class-wp-hook.php(324): Automattic\Jetpack\Sync\Main::on_plugins_loaded_late()
#2 /home/healths/public_html/wp-includes/class-wp-hook.php(348): WP_Hook-&gt;apply_filters()
#3 /home/healths/public_html/wp-includes/plugin.php(517): WP_Hook-&gt;do_action()
#4 /home/healths/public_html/wp-settings.php(550): do_action()
#5 /home/healths/public_html/wp-config.php(99): require_once('/home/healths/p...')
#6 /home/healths/public_html/wp-load.php(50): require_once('/home/healths/p...')
#7 /home/healths/public_html/wp-blog-header.php(13): require_once('/home/healths/p...')
#8 /home/healths/public_html/index.php in <b>/home/healths/public_html/wp-content/plugins/jetpack-social/jetpack_vendor/automattic/jetpack-sync/src/class-actions.php</b> on line <b>109</b><br />