Add support for list storage and operations

[bootjp]

No description provided.

[gemini-code-assist]

Summary of Changes

Hello @bootjp, 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 robust support for list data types, allowing for their storage and manipulation within the key-value system. It establishes a dedicated ListStore for managing list elements and metadata, seamlessly integrates this functionality into the Redis adapter to support standard list commands like RPUSH and LRANGE, and updates the DynamoDB transcoder to correctly interpret and store list attributes. The changes ensure that list operations are handled transactionally and that internal list keys are properly managed, providing a more complete and versatile data storage solution.

Highlights

• New ListStore Implementation: A new ListStore has been introduced in store/list_store.go to manage list data. This store uses a 'wide-column' approach, storing list metadata and individual list items as separate key-value pairs, enabling efficient range scans and transactional operations.
• Redis Adapter Integration: The adapter/redis.go file has been significantly updated to integrate the new ListStore. This includes adding a ListStore instance to the RedisServer, modifying existing commands (SET, GET, DEL, EXISTS) to handle list keys appropriately (e.g., returning WRONGTYPE errors or performing list-specific deletions), and implementing RPUSH and LRANGE commands using the new list storage.
• Transactional List Operations: The transactional context (txnContext) in adapter/redis.go has been enhanced to support list operations. It now tracks listTxnState separately, allowing RPUSH and LRANGE to be part of multi-command transactions, ensuring atomicity and consistency for list modifications.
• DynamoDB Transcoder Updates: The adapter/dynamodb_transcoder.go has been updated to recognize and handle list attributes (L field) in DynamoDB attributeValue structures. It now translates these into multiple kv.Operation elements for the underlying key-value store, representing both list metadata and individual list items.
• Key Management Refinements: The localKeys functionality in adapter/redis.go has been refactored to correctly identify and return only user-facing keys, filtering out the internal list metadata and item keys used by the ListStore.

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[gemini-code-assist]

Code Review

This pull request introduces significant new functionality by adding support for list data structures, backed by a scalable wide-column storage model. The changes are extensive, touching the DynamoDB and Redis adapters and introducing a new store package for list operations. While the overall approach is sound, the review has identified several critical issues related to data integrity, particularly in the list deletion logic, which can lead to orphaned data. There are also deviations from standard Redis API behavior and potential bugs in key formatting that could affect range scans. These issues should be addressed to ensure the reliability and correctness of the new list functionality.