Response caching uses HTTP headers for all configuration. You can add request headers like `Cache-Control: max-stale=3600` and OkHttp's cache will honor them. Your webserver configures how long responses are cached with its own response headers, like `Cache-Control: max-age=9600`. There are cache headers to force a cached response, force a network response, or force the network response to be validated with a conditional GET.

    // ===================================================================================
    //                                                                    Control Override
    //                                                                    ================
    @Override
    public String asTableDbName() {
        return asEsIndexType();
    }

    @Override

* `expose_headers` - 指示可以被浏览器访问的响应头。默认为 `[]`。
* `max_age` - 设定浏览器缓存 CORS 响应的最长时间，单位是秒。默认为 `600`。

中间件响应两种特定类型的 HTTP 请求……

### CORS 预检请求

这是些带有 `Origin` 和 `Access-Control-Request-Method` 请求头的 `OPTIONS` 请求。

在这种情况下，中间件将拦截传入的请求并进行响应，出于提供信息的目的返回一个使用了适当的 CORS headers 的 `200` 或 `400` 响应。

### 简单请求

任何带有 `Origin` 请求头的请求。在这种情况下，中间件将像平常一样传递请求，但是在响应中包含适当的 CORS headers。

## 更多信息

 * are choreographed via the various methods on this class.
 *
 * <p>A "lock-like object" is really any object that may be used for concurrency control. If the
 * {@link #callAndAssertBlocks} method is ever called in a test, the lock-like object must have a
 * method equivalent to {@link java.util.concurrent.locks.ReentrantLock#hasQueuedThread(Thread)}. If

  /** Settings we communicate to the peer. */
  val okHttpSettings =
    Settings().apply {
      // Flow control was designed more for servers, or proxies than edge clients. If we are a client,
      // set the flow control window to 16MiB.  This avoids thrashing window updates every 64KiB, yet
      // small enough to avoid blowing up the heap.
      if (builder.client) {

- Restores priority of static control plane pods in the cluster/gce/manifests control-plane manifests ([#89970](https://github.com/kubernetes/kubernetes/pull/89970), [@liggitt](https://github.com/liggitt)) [SIG Cluster Lifecycle and Node]

### Other (Cleanup or Flake)

   * UncheckedTimeoutException} to the caller.
   *
   * <p>It is important to note that the primary purpose of the proxy object is to return control to
   * the caller when the timeout elapses; aborting the target method call is of secondary concern.
   * The particular nature and strength of the guarantees made by the proxy is

O middleware responde a dois tipos específicos de solicitação HTTP...

### Requisições CORS pré-voo (preflight)

Estas são quaisquer solicitações `OPTIONS` com cabeçalhos `Origin` e `Access-Control-Request-Method`.

Nesse caso, o middleware interceptará a solicitação recebida e responderá com cabeçalhos CORS apropriados e uma resposta `200` ou `400` para fins informativos.

### Requisições Simples

 *
 *  * Tabs, newlines, form feeds and carriage returns are skipped.
 *
 *  * In queries, ' ' is encoded to '+' and '+' is encoded to "%2B".
 *
 *  * Characters in `encodeSet` are percent-encoded.
 *
 *  * Control characters and non-ASCII characters are percent-encoded.
 *
 *  * All other characters are copied without transformation.
 *
 * @param alreadyEncoded true to leave '%' as-is; false to convert it to '%25'.

 *
 * <p>This class is usually preferable to {@link AtomicLong} when multiple threads update a common
 * sum that is used for purposes such as collecting statistics, not for fine-grained synchronization
 * control. Under low update contention, the two classes have similar characteristics. But under
 * high contention, expected throughput of this class is significantly higher, at the expense of
 * higher space consumption.
 *