# Concurrency ve async / await

*path operasyon fonksiyonu* için `async def `sözdizimi,  asenkron kod, eşzamanlılık ve paralellik hakkında bazı ayrıntılar.

## Aceleniz mi var?

<abbr title="too long; didn't read"><strong>TL;DR:</strong></abbr>

Eğer `await` ile çağrılması gerektiğini belirten üçüncü taraf kütüphaneleri kullanıyorsanız, örneğin:

```Python
results = await some_library()
```

    stream = io.BytesIO(b"data")
    file = UploadFile(filename="file", file=stream, size=4)
    assert await file.read() == b"data"
    assert file.size == 4
    await file.write(b" and more data!")
    assert await file.read() == b""
    assert file.size == 19
    await file.seek(0)
    assert await file.read() == b"data and more data!"

    return value


@app.websocket("/ws")
async def get_value_by_ws(
    websocket: WebSocket, value: int = Depends(extract_value_from_http_connection)
):
    await websocket.accept()
    await websocket.send_json(value)
    await websocket.close()


client = TestClient(app)


def test_value_extracting_by_http():
    response = client.get("/http")
    assert response.status_code == 200

            waiting.countDown()
            result = daemonConnection.receive(20, TimeUnit.SECONDS)
            received.countDown()
        }
        waiting.await()
        Thread.sleep(500)
        connection.queueIncoming("incoming")
        received.await()

        then:
        result instanceof Received
        result.message == "incoming"
    }

    def "receive blocks until connection stopped"() {

</html>
"""


@app.get("/")
async def get():
    return HTMLResponse(html)


@app.websocket("/ws")
async def websocket_endpoint(websocket: WebSocket):
    await websocket.accept()
    while True:
        data = await websocket.receive_text()

abstract class ForwardingCondition implements Condition {
  abstract Condition delegate();

  @Override
  public void await() throws InterruptedException {
    delegate().await();
  }

  @Override
  public boolean await(long time, TimeUnit unit) throws InterruptedException {
    return delegate().await(time, unit);
  }

  @Override
  public void awaitUninterruptibly() {
    delegate().awaitUninterruptibly();
  }

    exit_limiter = CapacityLimiter(1)
    try:
        yield await run_in_threadpool(cm.__enter__)
    except Exception as e:
        ok = bool(
            await anyio.to_thread.run_sync(
                cm.__exit__, type(e), e, None, limiter=exit_limiter
            )
        )
        if not ok:
            raise e
    else:
        await anyio.to_thread.run_sync(

    cookie_or_token: str = Depends(get_cookie_or_token),
):
    await websocket.accept()
    while True:
        data = await websocket.receive_text()
        await websocket.send_text(
            f"Session cookie or query token value is: {cookie_or_token}"
        )
        if q is not None:
            await websocket.send_text(f"Query parameter q is: {q}")

```Python
results = await some_library()
```

В этом случае *функции обработки пути* необходимо объявлять с использованием синтаксиса `async def`:

```Python hl_lines="2"
@app.get('/')
async def read_results():
    results = await some_library()
    return results
```

!!! note
    `await` можно использовать только внутри функций, объявленных с использованием `async def`.

---

app = FastAPI()


@app.on_event("startup")
async def startup():
    await database.connect()


@app.on_event("shutdown")
async def shutdown():
    await database.disconnect()


@app.get("/notes/", response_model=List[Note])
async def read_notes():
    query = notes.select()
    return await database.fetch_all(query)


@app.post("/notes/", response_model=Note)