func init() {
	// Inject metrics.
	ioutilx.OsOpenFile = OpenFile
	ioutilx.OpenFileDirectIO = OpenFileDirectIO
	ioutilx.OsOpen = Open
}

type osMetrics struct {
	// All fields must be accessed atomically and aligned.
	operations [osMetricLast]uint64
	latency    [osMetricLast]lockedLastMinuteLatency
}

// time an os action.
func (o *osMetrics) time(s osMetric) func() {
	startTime := time.Now()

     *
     * @param visitor the visitor to call back, must not be {@code null}
     * @return {@code true} to visit siblings nodes of this node as well, {@code false} to skip siblings
     */
    boolean accept(@Nonnull NodeVisitor visitor);

    /**
     * Returns a new tree starting at this node, filtering the children.
     * Note that this node will not be filtered and only the children
     * and its descendant will be checked.

    CountDownLatch valueAndCloserSet = new CountDownLatch(1);
    closingFuture.finishToValueAndCloser(
        new ValueAndCloserConsumer<V>() {
          @Override
          public void accept(ValueAndCloser<V> valueAndCloser) {
            ClosingFutureFinishToValueAndCloserTest.this.valueAndCloser = valueAndCloser;
            valueAndCloserSet.countDown();
          }
        },

Si una request entrante no se valida correctamente, se enviará un response `400`.

## `GZipMiddleware` { #gzipmiddleware }

Maneja responses GZip para cualquier request que incluya `"gzip"` en el header `Accept-Encoding`.

El middleware manejará tanto responses estándar como en streaming.

{* ../../docs_src/advanced_middleware/tutorial003_py39.py hl[2,6] *}

Se soportan los siguientes argumentos:

Если входящий запрос не проходит валидацию, будет отправлен ответ `400`.

## `GZipMiddleware` { #gzipmiddleware }

Обрабатывает GZip‑ответы для любых запросов, которые включают `"gzip"` в заголовке `Accept-Encoding`.

Это middleware обрабатывает как обычные, так и потоковые ответы.

{* ../../docs_src/advanced_middleware/tutorial003_py39.py hl[2,6] *}

Поддерживаются следующие аргументы:

            writer.accept(CLIReportingUtils.showVersionMinimal());
        } else if (context.invokerRequest.effectiveVerbose()) {
            writer.accept(CLIReportingUtils.showVersion(
                    ProcessHandle.current().info().commandLine().orElse(null), describe(context.terminal)));

        } else {
            writer.accept(CLIReportingUtils.showVersion());
        }
    }

	case http.StatusUnauthorized:
		return User{}, ErrAccessTokenExpired
	}
	return User{}, fmt.Errorf("Unable to lookup - keycloak user lookup returned %v", resp.Status)
}

// Option is a function type that accepts a pointer Target
type Option func(*KeycloakProvider)

// WithTransport provide custom transport
func WithTransport(transport http.RoundTripper) Option {
	return func(p *KeycloakProvider) {
		p.client = http.Client{

   *     State#TERMINATED} when this method is called then this will throw an IllegalStateException.
   * @since 15.0
   */
  @SuppressWarnings("GoodTime") // should accept a java.time.Duration
  void awaitRunning(long timeout, TimeUnit unit) throws TimeoutException;

  /**
   * Waits for the {@link Service} to reach the {@linkplain State#TERMINATED terminated state}.
   *

Se uma requisição recebida não for validada corretamente, uma resposta `400` será enviada.

## `GZipMiddleware` { #gzipmiddleware }

Gerencia respostas GZip para qualquer requisição que inclua `"gzip"` no cabeçalho `Accept-Encoding`.

O middleware lidará com respostas padrão e de streaming.

{* ../../docs_src/advanced_middleware/tutorial003_py39.py hl[2,6] *}

Os seguintes argumentos são suportados:

支持以下参数：

* `allowed_hosts` - 允许的域名（主机名）列表。`*.example.com` 等通配符域名可以匹配子域名，或使用 `allowed_hosts=["*"]` 允许任意主机名，或省略中间件。

如果传入的请求没有通过验证，则发送 `400` 响应。

## `GZipMiddleware`

处理 `Accept-Encoding` 请求头中包含 `gzip` 请求的 GZip 响应。

中间件会处理标准响应与流响应。

{* ../../docs_src/advanced_middleware/tutorial003.py hl[2,6] *}

支持以下参数：

* `minimum_size` - 小于最小字节的响应不使用 GZip。 默认值是 `500`。

## 其它中间件