Cache Events are exposed via the EventListener API.  Typical scenarios are below.

### Cache Hit

In the ideal scenario the cache can fulfill the request without any conditional call to the network.
This will skip the normal events such as DNS, connecting to the network, and downloading the response body.

As recommended by the HTTP RFC the max age of a document is defaulted to 10% of the 

# Extending OpenAPI

There are some cases where you might need to modify the generated OpenAPI schema.

In this section you will see how.

## The normal process

The normal (default) process, is as follows.

A `FastAPI` application (instance) has an `.openapi()` method that is expected to return the OpenAPI schema.

      log.put("normal task running")
      return@schedule -1L
    }

    queue.idleLatch().await(500, TimeUnit.MILLISECONDS)

    assertThat(log.take()).isEqualTo("failing task running")
    assertThat(log.take()).isEqualTo("uncaught exception: java.lang.RuntimeException: boom!")
    assertThat(log.take()).isEqualTo("normal task running")
    assertThat(log).isEmpty()
  }

As `get_db()` is a normal `def` function, **FastAPI** will make it run in a threadpool, with a *copy* of the "context", holding the same value for the context variable (the `dict` with the reset database state). Then it can add database state to that `dict`, like the connection, etc.

### Other utility functions

Any other utility function that you call directly can be created with normal `def` or `async def` and FastAPI won't affect the way you call it.

## HTTPX

Even if your **FastAPI** application uses normal `def` functions instead of `async def`, it is still an `async` application underneath.

```Python hl_lines="2  7  9"
{!../../../docs_src/custom_response/tutorial006c.py!}
```

### `StreamingResponse`

Takes an async generator or a normal generator/iterator and streams the response body.

```Python hl_lines="2  14"
{!../../../docs_src/custom_response/tutorial007.py!}
```

#### Using `StreamingResponse` with file-like objects

    ```Python hl_lines="1  2  12-16"
    {!> ../../../docs_src/extra_data_types/tutorial001.py!}
    ```

Note that the parameters inside the function have their natural data type, and you can, for example, perform normal date manipulations, like:

=== "Python 3.10+"

    ```Python hl_lines="18-19"
    {!> ../../../docs_src/extra_data_types/tutorial001_an_py310.py!}
    ```

=== "Python 3.9+"

  optional string subresource = 1;

  // responseKind describes the group, version, and kind of the serialization schema for the object type this endpoint typically returns.
  // Some subresources do not return normal resources, these will have null return types.
  optional k8s.io.apimachinery.pkg.apis.meta.v1.GroupVersionKind responseKind = 2;

  // acceptedTypes describes the kinds that this endpoint accepts.

    Você o coloca em cima de uma função. Como um chapéu decorativo (acho que é daí que vem o termo).

    Um "decorador" pega a função abaixo e faz algo com ela.

    Em nosso caso, este decorador informa ao **FastAPI** que a função abaixo corresponde a **rota** `/` com uma **operação** `get`.

    É o "**decorador de rota**".

Você também pode usar as outras operações:

* `@app.post()`
* `@app.put()`