### Notification metrics

Metrics about the MinIO notification functionality.

| Path            | Description                                    |
|-----------------|------------------------------------------------|
| `/notification` | Metrics related to notification functionality. |

#### `/notification`

   * Cache.asMap().putIfAbsent} after loading has completed; if another value was associated with
   * {@code key} while the new value was loading then a removal notification will be sent for the
   * new value.
   *
   * <p>If the cache loader associated with this cache is known not to throw checked exceptions,
   * then prefer {@link #getUnchecked} over this method.
   *

> NOTE: Bucket versioning is automatically enabled for all new and existing buckets on all replicated sites.

The following Bucket features will **not be replicated**, is designed to differ between sites:

- Bucket notification configuration
- Bucket lifecycle (ILM) configuration

## Pre-requisites

    RemovalListener<Integer, Integer> countingListener =
        new RemovalListener<Integer, Integer>() {
          @Override
          public void onRemoval(RemovalNotification<Integer, Integer> notification) {
            switch (notification.getCause()) {
              case EXPIRED:
                stats[0]++;
                break;
              case EXPLICIT:
                stats[1]++;
                break;

labels.handlerName=Handler Name
labels.handlerParameter=Parameters
labels.handlerScript=Scripts
labels.popularWord=Popular words
labels.ignoreFailureType=Ignored Failure Type
labels.lastAccessTime=Last Accessed
labels.notificationTo=Notification To
labels.num=Num
labels.pn=Page Number
labels.protocolScheme=Scheme
labels.purgeByBots=Purge By Bots
labels.logLevel=Log Level
labels.purgeSearchLogDay=Purge Search Log
labels.query=Query

	err    error
}

// healRoutine receives heal tasks, to heal buckets, objects and format.json
type healRoutine struct {
	tasks   chan healTask
	workers int
}

func activeListeners() int {
	// Bucket notification and http trace are not costly, it is okay to ignore them
	// while counting the number of concurrent connections
	return int(globalHTTPListen.Subscribers()) + int(globalTrace.Subscribers())
}

		return nil, time.Time{}, BucketLifecycleNotFound{Bucket: bucket}
	}
	return meta.lifecycleConfig, meta.LifecycleConfigUpdatedAt, nil
}

// GetNotificationConfig returns configured notification config
// The returned object may not be modified.
func (sys *BucketMetadataSys) GetNotificationConfig(bucket string) (*event.Config, error) {
	meta, _, err := sys.GetConfig(GlobalContext, bucket)
	if err != nil {

        if (form != null) {
            form.clearSecurityInfo();
        }
        return asHtml(virtualHost(path_Login_IndexJsp)).renderWith(data -> {
            RenderDataUtil.register(data, "notification", fessConfig.getNotificationLogin());
            saveToken();
        });
    }

    @Execute
    public HtmlResponse login(final LoginForm form) {
        validate(form, messages -> {}, () -> asIndexPage(form));

```Python hl_lines="14"
{!../../docs_src/background_tasks/tutorial001.py!}
```

`.add_task()` 接收以下参数：

* 在后台运行的任务函数(`write_notification`)。
* 应按顺序传递给任务函数的任意参数序列(`email`)。
* 应传递给任务函数的任意关键字参数(`message="some notification"`)。

## 依赖注入

使用 `BackgroundTasks` 也适用于依赖注入系统，你可以在多个级别声明 `BackgroundTasks` 类型的参数：在 *路径操作函数* 里，在依赖中(可依赖)，在子依赖中，等等。

**FastAPI** 知道在每种情况下该做什么以及如何复用同一对象，因此所有后台任务被合并在一起并且随后在后台运行：

//// tab | Python 3.10+

			Description:     "publish bucket notifications to webhook endpoints",
			MultipleTargets: true,
		},
		config.HelpKV{
			Key:             config.NotifyAMQPSubSys,
			Description:     "publish bucket notifications to AMQP endpoints",
			MultipleTargets: true,
		},
		config.HelpKV{
			Key:             config.NotifyKafkaSubSys,
			Description:     "publish bucket notifications to Kafka endpoints",
			MultipleTargets: true,