* currently contains a value for {@code key}, and {@link CacheLoader#load} otherwise. Loading is
   * asynchronous only if {@link CacheLoader#reload} was overridden with an asynchronous
   * implementation.
   *
   * <p>Returns without doing anything if another thread is currently loading the value for {@code

   */
  fun cancel()

  fun interface Factory {
    /**
     * Creates a new web socket and immediately returns it. Creating a web socket initiates an
     * asynchronous process to connect the socket. Once that succeeds or fails, `listener` will be
     * notified. The caller must either close or cancel the returned web socket when it is no longer
     * in use.
     */

    /** The time manager for handling time-related operations. */
    @Resource
    private TimeManager timeManager;

    /** The async manager for handling asynchronous operations. */
    @Resource
    private AsyncManager asyncManager;

    /** The session manager for handling user sessions. */
    @Resource
    private SessionManager sessionManager;

## ASGI‑серверы { #asgi-servers }

Давайте немного углубимся в детали.

FastAPI использует стандарт для построения Python‑веб‑фреймворков и серверов под названием <abbr title="Asynchronous Server Gateway Interface – Асинхронный шлюзовый интерфейс сервера">ASGI</abbr>. FastAPI — ASGI-веб‑фреймворк.

            }

            return response;

        } catch (Exception e) {
            throw new IOException("Witness heartbeat RPC failed", e);
        }
    }

    /**
     * Requests asynchronous notifications from the witness service.
     *
     * @param contextHandle the context handle from registration
     * @return the async notify response containing notifications

///

## Вызов других асинхронных функций { #other-asynchronous-function-calls }

 * ListenableFuture}</a>.
 *
 * <p>This class is GWT-compatible.
 *
 * <h3>Purpose</h3>
 *
 * <p>The main purpose of {@code ListenableFuture} is to help you chain together a graph of
 * asynchronous operations. You can chain them together manually with calls to methods like {@link
 * Futures#transform(ListenableFuture, com.google.common.base.Function, Executor) Futures.transform}

## Servidores ASGI { #asgi-servers }

Vamos nos aprofundar um pouco mais em detalhes.

FastAPI utiliza um padrão para construir frameworks e servidores web em Python chamado <abbr title="Asynchronous Server Gateway Interface – Interface de Gateway de Servidor Assíncrono">ASGI</abbr>. FastAPI é um framework web ASGI.

In this section we'll see how to use other middlewares.

## Adding ASGI middlewares { #adding-asgi-middlewares }

As **FastAPI** is based on Starlette and implements the <abbr title="Asynchronous Server Gateway Interface">ASGI</abbr> specification, you can use any ASGI middleware.

A middleware doesn't have to be made for FastAPI or Starlette to work, as long as it follows the ASGI spec.

Разберём эту фразу по частям в разделах ниже:

* **Асинхронный код**
* **`async` и `await`**
* **Сопрограммы**

## Асинхронный код { #asynchronous-code }