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https://issues.apache.org/jira/browse/IGNITE-20477?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17793630#comment-17793630
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Mirza Aliev edited comment on IGNITE-20477 at 12/22/23 2:57 PM:
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Please be aware of TODOs with this ticket that were added to the codebase after
https://issues.apache.org/jira/browse/IGNITE-20310 was merged
was (Author: maliev):
Please be aware of TODOs with this ticket that was added to the codebase after
https://issues.apache.org/jira/browse/IGNITE-20310 was merged
> Async component start
> ---------------------
>
> Key: IGNITE-20477
> URL: https://issues.apache.org/jira/browse/IGNITE-20477
> Project: Ignite
> Issue Type: Task
> Reporter: Aleksandr Polovtcev
> Priority: Major
> Labels: ignite-3
>
> Currently all Ignite components start synchronously (see
> {{IgniteComponent#start}}). This is inconvenient, because some components can
> complete their startup only when Meta Storage has initialized all Version
> Values (see {{IgniteImpl#recoverComponentsStateOnStart}}). Because of this,
> some components employ a hack which consists of having a "special" Versioned
> Value, which is injected with a future that gets resolved only after the
> enclosing component completes its startup (see {{startVv}} in
> {{TableManager}} or {{IndexManager}}). This blocks the Watch Processor inside
> Meta Storage, preventing it from processing further updates.
> This problem with this approach that it is quite cryptic and hard to
> understand. Instead I propose to do the following:
> # Change the signature of {{IgniteComponent#start}} to
> {{CompletableFuture<Void> start()}}.
> # All actions in the components startup will be divided into two categories:
> sync actions, that can be executed synchronously in order for the component
> to be usable by other components during their startup, and async actions,
> which need to wait for any of the Versioned Values to be initialized by the
> Meta Storage. Such async actions should be wrapped in a {{CompletableFuture}}
> and returned from the {{start}} method.
> # {{IgniteImpl}} startup procedure should be updated to collect the futures
> from all components and wait for their completion inside
> {{recoverComponentsStateOnStart}}, after
> {{metaStorageMgr.notifyRevisionUpdateListenerOnStart()}} has been called, but
> before Watches are deployed ({{metaStorageMgr.deployWatches()}})
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