refactor(inkless): SharedState to own StorageBackend lifecycle

[jeqo]

Summary

• SharedState now creates and manages 4 dedicated StorageBackend instances (fetchStorage, maybeLaggingFetchStorage, produceStorage, backgroundStorage) instead of exposing a buildStorage() factory method
• Centralizes resource lifecycle with proper cleanup on partial initialization failure and ordered shutdown
• Consumers (Reader, Writer, FileCleaner, FileMerger) no longer close storage backends — SharedState owns their lifecycle

Changes

• SharedState: private constructor, initialize() creates backends with try/catch cleanup, close() shuts down all backends in reverse creation order using Utils.closeQuietly
• FetchHandler/Reader: use fetchStorage() and maybeLaggingFetchStorage() (Optional) from SharedState
• AppendHandler/Writer: use produceStorage(), Writer no longer stores or closes a StorageBackend field
• FileCleaner/FileMerger: use backgroundStorage() (shared, thread-safe)
• New SharedStateTest: verifies close ordering, lagging-disabled path, and failure cleanup

Motivation

Previously each consumer called buildStorage() to create its own backend and was responsible for closing it. This led to:

• Distributed ownership making it hard to reason about lifecycle
• Risk of double-close or missed-close bugs
• No cleanup on partial initialization failure

Test plan

• All 900 inkless storage tests pass
• New SharedStateTest covers close ordering, disabled lagging path, and partial init failure cleanup
• CI passes

🤖 Generated with Claude Code

[Copilot]

Pull request overview

This PR refactors Inkless SharedState to centrally own the lifecycle of storage backends by eagerly creating dedicated StorageBackend instances for fetch/produce/background use, and updating consumers to stop creating/closing their own backends.

Changes:

• SharedState.initialize() now creates and stores 4 backend instances (fetchStorage, optional maybeLaggingFetchStorage, produceStorage, backgroundStorage) and close() shuts them down.
• Consumers (FetchHandler/Reader, AppendHandler/Writer, FileCleaner, FileMerger) are updated to use the new accessors and no longer close storage.
• Adds SharedStateTest and updates multiple tests to reflect the new constructor/lifecycle behavior.

Reviewed changes

Copilot reviewed 12 out of 12 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
storage/inkless/src/main/java/io/aiven/inkless/common/SharedState.java	Centralizes backend creation and lifecycle; adds dedicated backend accessors and new close behavior.
storage/inkless/src/main/java/io/aiven/inkless/consume/FetchHandler.java	Switches from buildStorage() to fetchStorage() / maybeLaggingFetchStorage().
storage/inkless/src/main/java/io/aiven/inkless/consume/Reader.java	Accepts optional lagging backend and stops closing storage backends on close().
storage/inkless/src/main/java/io/aiven/inkless/produce/AppendHandler.java	Uses produceStorage() instead of building a backend per consumer.
storage/inkless/src/main/java/io/aiven/inkless/produce/Writer.java	Removes direct storage ownership/closing; relies on SharedState lifecycle.
storage/inkless/src/main/java/io/aiven/inkless/delete/FileCleaner.java	Uses backgroundStorage() and stops closing storage in close().
storage/inkless/src/main/java/io/aiven/inkless/merge/FileMerger.java	Uses backgroundStorage() and stops closing storage in close().
storage/inkless/src/test/java/io/aiven/inkless/common/SharedStateTest.java	New tests for shutdown ordering, lagging-disabled path, and init-failure cleanup.
storage/inkless/src/test/java/io/aiven/inkless/delete/DeleteRecordsInterceptorTest.java	Updates test construction to avoid SharedState dependency.
storage/inkless/src/test/java/io/aiven/inkless/merge/FileMergerMockedTest.java	Adds config stubs needed for eager SharedState.initialize() backend creation.
storage/inkless/src/test/java/io/aiven/inkless/produce/WriterMockedTest.java	Updates Writer construction to reflect removed storage parameter in test ctor.
storage/inkless/src/test/java/io/aiven/inkless/produce/WriterPropertyTest.java	Updates Writer construction to reflect removed storage parameter in test ctor.

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Pull request overview

Copilot reviewed 13 out of 13 changed files in this pull request and generated 2 comments.

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Pull request overview

Copilot reviewed 13 out of 13 changed files in this pull request and generated 1 comment.

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Pull request overview

Copilot reviewed 13 out of 13 changed files in this pull request and generated no new comments.

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