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https://issues.apache.org/jira/browse/HDDS-14356?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Ivan Andika updated HDDS-14356:
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Summary: Support OM Service Framework (was: Support OM Stateful Service
Framework)
> Support OM Service Framework
> ----------------------------
>
> Key: HDDS-14356
> URL: https://issues.apache.org/jira/browse/HDDS-14356
> Project: Apache Ozone
> Issue Type: Improvement
> Reporter: Ivan Andika
> Assignee: Ivan Andika
> Priority: Major
>
> Currently, SCM HA already implemented its own SCM stateful service framework
> in classes such as SCMServiceManager (with its notifyStatusChanged
> implementation to respond to Ratis related events),
> StatefulServiceStateManager, etc. We can implement it for OM HA to implement
> stateful service.
> We have implemented this internally a long time ago, particularly for OM Key
> Trash HDDS-11256 , where the key recovery service is required to store the
> user-requested key recovery configuration to all OM nodes (similar to
> ContainerBalancerConfiguration in Container Balancer HA) and only the leader
> key trash recovery service should be running at any time. Previously, we did
> not contribute this to community since there is currently no valid use case
> (AFAIK all OM background services are stateless). However, it seems that S3
> object lifecycle feature might require this feature (e.g.
> KeyLifecycleService). Therefore, we can contribute this to the community
> since there is now a valid use case.
> The main overview and purpose of the stateful service are:
> # Persist and replicate service configuration
> ** The interface is implemented in {{OMStatefulService}} and implemented by
> {{OMStatefulServiceStateManager}}
> ** OM uses {{SetServiceConfiguration}} request to persistently save the OM
> service framework
> *** OM request and response: {{OMSetServiceConfigurationRequest}} and
> {{OMSetServiceConfigurationResponse}}
> *** Table: statefulServiceConfigTable ({{{}Table<String, ByteString>{}}})
> # Notification mechanism when there are leader changes
> ** This is to ensure that only leader stateful service is running
> ** {{OMServiceManager#notifyStatusChanged}} and
> {{OMService#notifyStatusChanged}} to notify the stateful service whenever
> there is a change in leader
> ** {{OzoneManagerStateMachine}} Event APIs ({{{}notifyNotLeader{}}},
> {{{}notifyLeaderChanged{}}}, {{{}notifyTermIndexUpdated,
> notifyLeaderReady{}}}) will trigger the {{notifyStatusChanged}}
> *** The notification implementation is similar to {{SCMStateMachine}}
> *** {{notifyTermIndexUpdated}} is only done if there is a configuration
> change (i.e. OM transfer leadership, OM ratis ring update)
>
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