| Maximum object size                                                             | 50 TiB                                                                          |

import junit.framework.TestCase;

/**
 * Unit test for {@link FakeTimeLimiter}.
 *
 * @author Jens Nyman
 */
public class FakeTimeLimiterTest extends TestCase {

  private static final int DELAY_MS = 50;
  private static final String RETURN_VALUE = "abc";

  private TimeLimiter timeLimiter;

  @Override
  protected void setUp() throws Exception {
    super.setUp();
    timeLimiter = new FakeTimeLimiter();
  }

-shadow:0 .5rem 1rem rgba(0,0,0,.15)!important}.shadow-lg{box-shadow:0 1rem 3rem rgba(0,0,0,.175)!important}.shadow-none{box-shadow:none!important}.w-25{width:25%!important}.w-50{width:50%!important}.w-75{width:75%!important}.w-100{width:100%!important}.w-auto{width:auto!important}.h-25{height:25%!important}.h-50{height:50%!important}.h-75{height:75%!important}.h-100{height:100%!important}.h-auto{height:auto!important}.mw-100{max-width:100%!important}.mh-100{max-height:100%!important}.min-vw-100...

- cloud.google.com/go/automl: v1.12.0 → v1.13.1
- cloud.google.com/go/baremetalsolution: v0.5.0 → v1.1.1
- cloud.google.com/go/batch: v0.7.0 → v1.3.1
- cloud.google.com/go/beyondcorp: v0.5.0 → v1.0.0
- cloud.google.com/go/bigquery: v1.50.0 → v1.53.0
- cloud.google.com/go/billing: v1.13.0 → v1.16.0
- cloud.google.com/go/binaryauthorization: v1.5.0 → v1.6.1
- cloud.google.com/go/certificatemanager: v1.6.0 → v1.7.1

查询参数 `q` 的类型为 `str`，默认值为 `None`，因此它是可选的。

## 额外的校验

我们打算添加约束条件：即使 `q` 是可选的，但只要提供了该参数，则该参数值**不能超过50个字符的长度**。

### 导入 `Query`

为此，首先从 `fastapi` 导入 `Query`：

```Python hl_lines="1"
{!../../docs_src/query_params_str_validations/tutorial002.py!}
```

## 使用 `Query` 作为默认值

现在，将 `Query` 用作查询参数的默认值，并将它的 `max_length` 参数设置为 50：

```Python hl_lines="9"
{!../../docs_src/query_params_str_validations/tutorial002.py!}
```

            new Callable<@Nullable Void>() {
              @Override
              public @Nullable Void call() throws InterruptedException {
                new Producer(q, 50).call();
                new Interrupter(mainThread).run();
                new Producer(q, 50).call();
                return null;
              }
            });
    List<Object> buf = newArrayList();

                    <mxGeometry x="480" y="768" width="230" height="50" as="geometry"/>
                </mxCell>
                <mxCell id="30" value="" style="rounded=0;whiteSpace=wrap;html=1;strokeWidth=3;" parent="1" vertex="1">
                    <mxGeometry x="1130" y="810" width="150" height="50" as="geometry"/>
                </mxCell>
            </root>
        </mxGraphModel>
    </diagram>

  private static final int[] ints = new int[ARRAY_SIZE];

  @BeforeExperiment
  void setUp() {
    for (int i = 0; i < ARRAY_SIZE; i++) {
      exponent[i] = randomExponent();
      factorial[i] = RANDOM_SOURCE.nextInt(50);
      binomial[i] = RANDOM_SOURCE.nextInt(factorial[i] + 1);
      positive[i] = randomPositiveBigInteger(Integer.SIZE - 1).intValue();
      nonnegative[i] = randomNonNegativeBigInteger(Integer.SIZE - 1).intValue();

-shadow:0 .5rem 1rem rgba(0,0,0,.15)!important}.shadow-lg{box-shadow:0 1rem 3rem rgba(0,0,0,.175)!important}.shadow-none{box-shadow:none!important}.w-25{width:25%!important}.w-50{width:50%!important}.w-75{width:75%!important}.w-100{width:100%!important}.w-auto{width:auto!important}.h-25{height:25%!important}.h-50{height:50%!important}.h-75{height:75%!important}.h-100{height:100%!important}.h-auto{height:auto!important}.mw-100{max-width:100%!important}.mh-100{max-height:100%!important}.min-vw-100...

		// so decrease the timeout towards 25 % of maximum time spent.
		max = max * 125 / 100

		timeout := atomic.LoadInt64(&dt.timeout)
		if max < time.Duration(timeout) {
			// Move 50% toward the max.
			timeout = (int64(max) + timeout) / 2
		}
		if timeout < dt.minimum {
			timeout = dt.minimum
		}
		atomic.StoreInt64(&dt.timeout, timeout)
	}