Provide a way to listen to the events of mirroring #1057
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Motivation: Mirroring failure is only recorded as a warning, but there is a need to handle it in a different way. For example, it can be recorded in metrics or end-users can be notified immediately. `MirrorListener` is provided as an extension point to utilize various events occurring in the mirror. Modifications: - Introduce `MirrorListener` whose implementations can be loaded dynamically via Java SPI. - `onStart()`, `onComplete()` and `onError()` events are added. - The default behavior is preserved in `DefaultMirrorListener` which is only used when no custom `MirrorListener` is configured. Result: You can now use `MirrorListener` to listen to `Mirror` events.
| /** | ||
| * Invoked when the {@link Mirror} operation is failed. | ||
| */ | ||
| void onError(Mirror mirror, Throwable cause); |
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Optional; Personally, I feel like MirrorResult could be useful for onError as well since it contains information on mirrorId, triggeredTime, etc....
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Fixed to pass MirrorTask which contains those properties.
| @@ -62,6 +66,19 @@ public final class MirrorSchedulingService implements MirroringService { | |||
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| private static final Logger logger = LoggerFactory.getLogger(MirrorSchedulingService.class); | |||
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| private static final MirrorListener mirrorListener; | |||
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Note) I understood that MirrorListener isn't invoked for manually triggered mirrors from MirrorServiceV1.
While this may make sense in terms of our purpose (monitoring), it may be confusing since a Mirror has been done yet MirrorListener isn't invoked.
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Good point. Let me scheduled flag to methods of MirrorListener.
| /** | ||
| * Invoked when the {@link Mirror} operation is started. | ||
| */ | ||
| void onStart(Mirror mirror); |
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Optional; If a MirrorTask is passed at onStart which contains a mirrorId, users may be able to differentiate the flow of a single Mirror across multiple callbacks via mirrorId. This may be useful since multiple mirrors may be run in a single leader with the introduction of zone-aware mirroring.
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mirrorId means the ID for a single mirroring task, not Mirror#id(), right?
This may be useful since multiple mirrors may be run in a single leader with the introduction of zone-aware mirroring.
Sorry, I didn't understand this. Did you mean multiple mirrors can be run concurrently? Could you elaborate on this, please?
Motivation:
Mirroring failure is only recorded as a warning, but there is a need to handle it in a different way. For example, it can be recorded in metrics or end-users can be notified immediately.
MirrorListeneris provided as an extension point to utilize various events occurring in the mirror.Modifications:
MirrorListenerwhose implementations can be loaded dynamically via Java SPI.onStart(),onComplete()andonError()events are added.DefaultMirrorListenerwhich is only used when no customMirrorListeneris configured.Result:
You can now use
MirrorListenerto listen toMirrorevents.