*
     * Performance: O(1) operation using concurrent queue
     *
     * @return a byte buffer for SMB operations
     * @throws IllegalStateException if buffer size exceeds maximum allowed
     */
    static public byte[] getBuffer() {
        // Try to get from cache first - O(1) operation
        byte[] buf = bufferQueue.poll();
        if (buf != null) {

{* ../../docs_src/openapi_callbacks/tutorial001_py310.py hl[1,23] *}

### Create the callback *path operation* { #create-the-callback-path-operation }

To create the callback *path operation* use the same `APIRouter` you created above.

It should look just like a normal FastAPI *path operation*:

* It should probably have a declaration of the body it should receive, e.g. `body: InvoiceEvent`.

{* ../../docs_src/openapi_callbacks/tutorial001_py310.py hl[1,23] *}

### Crea la *path operation* del callback { #create-the-callback-path-operation }

Para crear la *path operation* del callback usa el mismo `APIRouter` que creaste arriba.

Debería verse como una *path operation* normal de FastAPI:

* Probablemente debería tener una declaración del body que debería recibir, por ejemplo `body: InvoiceEvent`.

## Dokümantasyon Özeti ve Açıklaması - OpenAPI

     * Any file name change in the watched directory or subtree causes a change notification wait operation to return.
     * Changes include renaming, creating, or deleting a file.
     */
    int FILE_NOTIFY_CHANGE_FILE_NAME = 0x00000001;

    /**
     * Any directory-name change in the watched directory or subtree causes a change notification wait operation to
     * return. Changes include creating or deleting a directory.
     */

But we can still add _more_ `tags` that will be applied to a specific *path operation*, and also some extra `responses` specific to that *path operation*:

{* ../../docs_src/bigger_applications/app_an_py39/routers/items.py hl[30:31] title["app/routers/items.py"] *}

/// tip

## 簡単な使い方

見てみると、*path*と*operation*が一致した時に*path operation関数*が宣言されていて、**FastAPI** が正しいパラメータで関数を呼び出してリクエストからデータを抽出する処理をしています。

実は、すべての（あるいはほとんどの）Webフレームワークは、このように動作します。

これらの関数を直接呼び出すことはありません。これらの関数はフレームワーク（この場合は、**FastAPI**）によって呼び出されます。

依存性注入システムでは、**FastAPI** に*path operation*もまた、*path operation関数*の前に実行されるべき他の何かに「依存」していることを伝えることができ、**FastAPI** がそれを実行し、結果を「注入」することを引き受けます。

And all these thousands of *path operations* can be as small as 3 lines:

{* ../../docs_src/security/tutorial002_an_py310.py hl[30:32] *}

## Recap { #recap }

You can now get the current user directly in your *path operation function*.

We are already halfway there.

We just need to add a *path operation* for the user/client to actually send the `username` and `password`.

Y todas estas miles de *path operations* pueden ser tan pequeñas como 3 líneas:

{* ../../docs_src/security/tutorial002_an_py310.py hl[30:32] *}

## Resumen { #recap }

Ahora puedes obtener el usuario actual directamente en tu *path operation function*.

Ya estamos a mitad de camino.

Solo necesitamos agregar una *path operation* para que el usuario/cliente envíe realmente el `username` y `password`.

                            * `security_scopes.scopes` will contain `["me"]` for the *path operation* `read_users_me`, because it is declared in the dependency `get_current_active_user`.