[DNM]

[lidezhu]

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[gemini-code-assist]

Summary of Changes

Hello @lidezhu, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request introduces internal modifications to the event store, streamlining its operation by removing an explicit data cleanup step for obsolete subscriptions. Concurrently, it significantly improves the system's testability and debuggability by integrating a failpoint mechanism that enables the dynamic unregistration of dispatchers, allowing developers to simulate and test various operational states more effectively.

Highlights

• Subscription Data Cleanup Refinement: The direct deletion of event data for obsolete subscriptions has been removed from the cleanObsoleteSubscriptions function, suggesting a potential change in how this data lifecycle is managed.
• Enhanced Testability with Failpoints: A new failpoint, EventStoreDeleteDispatcher, has been introduced. This allows for the controlled unregistration of dispatchers during testing or debugging scenarios.
• New Dispatcher Unregistration Helper: A private helper function, unregisterDispatcherByString, was added to facilitate the unregistration of dispatchers by their string ID, primarily for use with the new failpoint.

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Changelog

• logservice/eventstore/event_store.go
  • Removed the import of the math package as math.MaxUint64 is no longer utilized.
  • Added the github.com/pingcap/failpoint package import to support new debugging capabilities.
  • Eliminated the direct call to deleteDataRange within the cleanObsoleteSubscriptions function.
  • Implemented a failpoint.Inject block named EventStoreDeleteDispatcher within runMetricsCollector to enable conditional dispatcher unregistration.
  • Introduced a new private method unregisterDispatcherByString to locate and unregister dispatchers based on a provided string identifier.

Activity

• The pull request is marked as [DNM] (Do Not Merge), indicating it is a draft or work in progress.
• The PR description contains placeholder comments, suggesting it is in an early stage of development and awaiting further details.

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Code Review

This pull request introduces a failpoint for testing dispatcher unregistration and removes an unused import. However, it critically removes the garbage collection logic for obsolete subscriptions in the event store. This will lead to unbounded disk usage as data for old subscriptions will never be deleted. I've added a comment to restore this functionality with a fix for what seems to be the original issue in the removed code.

[gemini-code-assist]

The logic to delete data for an obsolete subscription has been removed. This will cause data to accumulate in the event store, leading to a potential disk space leak. The data for an obsolete subscription should be garbage collected.

Please re-add the data deletion logic. Note that deleteDataRange is a method on eventStore, so it should be called as e.deleteDataRange. Also, you'll need to re-import the math package to use math.MaxUint64.

						e.subClient.Unsubscribe(subID)
						db := e.dbs[subStat.dbIndex]
						if err := e.deleteDataRange(db, uint64(subID), subStat.tableSpan.TableID, 0, math.MaxUint64); err != nil {
							log.Warn("fail to delete events", zap.Error(err))
						}