feat(store/v2): support reverse iteration for PebbleDB

[alexanderbez]

Description

Closes: #17976

This was actually much simpler to implement than I had originally imagined.

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Summary by CodeRabbit

• New Feature: Enhanced the database navigation capabilities by introducing reverse iteration over the database. This allows users to traverse the database in the opposite direction, providing more flexibility in data access.
• Improvement: Added robust input validation for database keys. This ensures that the start key is not after the end key, enhancing the reliability of database operations.
• Test: Removed a redundant test case (TestDatabase_ReverseIterator) for the database's reverse iteration functionality, simplifying the test suite.

These changes aim to improve the user experience by providing more flexible data access and ensuring more reliable database operations.

[coderabbitai]

Walkthrough

This change introduces reverse iteration support for the PebbleDB database, with necessary modifications in the iterator logic and associated tests. It also enhances key validation in the Iterator and ReverseIterator functions.

Changes

File	Summary
.../pebbledb/db.go	Added input validation for keys and encoding in Iterator and ReverseIterator. Introduced a boolean parameter for reverse iteration in newPebbleDBIterator.
.../pebbledb/db_test.go	Removed TestDatabase_ReverseIterator function and its test case.
.../pebbledb/iterator.go	Added support for reverse iteration in the PebbleDB database. Modified newPebbleDBIterator, Next, and DebugRawIterate functions to handle reverse iteration.

🐇

In the land of code, where logic intertwines,

A rabbit hops, leaving traces of lines.

Forward we hopped, now backward we go,

Through the keys of PebbleDB, high and low.

Validation added, tests removed in stride,

In the realm of data, no secret can hide.

Celebrate the changes, for they bring delight,

To the world of coding, day and night. 🌙✨

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[github-actions]

@alexanderbez your pull request is missing a changelog!

[coderabbitai]

Review Status

Actionable comments generated: 0

Commits

Files that changed from the base of the PR and between 2fbc547 and fe1fe6b.

Files selected for processing (3)

• store/storage/pebbledb/db.go (1 hunks)
• store/storage/pebbledb/db_test.go (2 hunks)
• store/storage/pebbledb/iterator.go (4 hunks)

Files skipped from review due to trivial changes (1)

• store/storage/pebbledb/db_test.go

Additional comments (Suppressed): 9

store/storage/pebbledb/iterator.go (4)

• 29-29: The reverse field has been added to the iterator struct to control the direction of iteration. Ensure that this field is properly initialized and used throughout the codebase.

• 32-39: The newPebbleDBIterator function now accepts a reverse parameter and uses it to determine the initial position of the iterator. This is a breaking change and all calls to this function need to be updated to include the reverse parameter.

• 107-122: The Next method of the iterator struct has been updated to handle reverse iteration. The logic for moving to the next key has been modified based on the reverse flag. Ensure that this change does not affect the existing functionality of forward iteration.

• 265-270: The DebugRawIterate function has been updated to handle reverse iteration. The logic for moving to the next key has been modified based on the reverse flag. Ensure that this change does not affect the existing functionality of forward iteration.

store/storage/pebbledb/db.go (5)

• 185-185: The newPebbleDBIterator function now accepts a new boolean parameter reverse. Ensure that all calls to this function throughout the codebase have been updated to include this new parameter.

• 189-195: Input validation has been added for the start and end keys in the ReverseIterator function. This is a good practice to prevent unexpected behavior and errors.

• 197-202: The keys are now encoded using MVCCEncode before being passed to the iterator. This is likely done to ensure that the keys are in a format that the iterator can understand and process correctly.

• 204-207: Error handling has been added for the creation of the PebbleDB iterator. This is a good practice to prevent unexpected behavior and errors.

• 209-209: The newPebbleDBIterator function now accepts a new boolean parameter reverse. Ensure that all calls to this function throughout the codebase have been updated to include this new parameter.

[kocubinski]

ut ACK