fix: Fixes memiterator

[alpe]

Description

This PR contains 2 fixes to the MemIterator.

• Copy on write, see: [Bug]: server v2 - memIterator/ InitGenesis #21754 for more context (Thanks @fdymylja )
• Excluding end for keyInRange when in desc order

The first fix has side negative effects as described in #21754 that may have to be addressed before.
Not sure about the keyInRange fix. I was applying the rules defined in the constructor where end is ecluded.

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Summary by CodeRabbit

• New Features

  • Enhanced the iterator functionality to operate on a copy of the tree, improving accuracy and preventing unintended side effects.
  • Introduced refined key range validation for better identification of valid keys.

• Bug Fixes

  • Improved robustness of the memIterator through enhanced range checking logic.

• Tests

  • Renamed existing test for clarity and added a new test for comprehensive coverage of key range functionality.

[github-actions]

@alpe your pull request is missing a changelog!

[coderabbitai]

Walkthrough

Walkthrough

The changes introduced in this pull request enhance the functionality of the memIterator structure in the changeset.go file. The iterator is now initialized using a copy of the tree, and modifications to the keyInRange method improve the accuracy of key validation. Additionally, in the test file, the existing test function has been renamed for clarity, and a new test function has been added to evaluate the keyInRange method's behavior across various scenarios.

Changes

Files	Change Summary
server/v2/stf/branch/changeset.go	Modified memIterator initialization to use a copy of the tree; refined keyInRange logic.
server/v2/stf/branch/changeset_test.go	Renamed Test_memIterator to TestMemIteratorWithWriteToRebalance; added TestKeyInRange.

Possibly related PRs

• fix(stf/branch/memiter): Fix Iter validity #21556: The changes in this PR also involve modifications to the memIterator structure in changeset.go, specifically focusing on iterator validity and lifecycle management, which is closely related to the enhancements made in the main PR regarding the iterator's initialization and behavior.

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Recent review details

Configuration used: .coderabbit.yml
Review profile: CHILL

Commits

Files that changed from the base of the PR and between 081b90e and 2b30bd8.

Files selected for processing (2)

• server/v2/stf/branch/changeset.go (2 hunks)
• server/v2/stf/branch/changeset_test.go (2 hunks)

Additional context used

Path-based instructions (2)

server/v2/stf/branch/changeset_test.go (2)

Pattern **/*.go: Review the Golang code for conformity with the Uber Golang style guide, highlighting any deviations.

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Pattern **/*_test.go: "Assess the unit test code assessing sufficient code coverage for the changes associated in the pull request"

server/v2/stf/branch/changeset.go (1)

Pattern **/*.go: Review the Golang code for conformity with the Uber Golang style guide, highlighting any deviations.

Additional comments not posted (5)

server/v2/stf/branch/changeset_test.go (3)

Line range hint 7-28: LGTM!

The renaming of the test function to TestMemIteratorWithWriteToRebalance improves clarity about the specific scenario being tested. The test logic and assertions are correct and clear.

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30-87: Great job on adding comprehensive test coverage!

The new TestKeyInRange function provides thorough test coverage for the keyInRange method of the memIterator struct. The table-driven approach with various test cases covers different scenarios effectively, including edge cases and both ascending and descending order configurations.

The test structure is clear, and the assertions ensure that the keyInRange method behaves as expected in each scenario. This addition significantly improves the reliability and maintainability of the code.

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Line range hint 1-87: Unit test code provides sufficient coverage.

The unit test code in this file provides sufficient coverage for the changes associated with the pull request. The two test functions, TestMemIteratorWithWriteToRebalance and TestKeyInRange, cover the key aspects of the memIterator behavior and the functionality of the keyInRange method.

The TestKeyInRange function, in particular, includes a comprehensive set of test cases that cover various scenarios, edge cases, and both ascending and descending order configurations. The assertions in the tests ensure that the expected behavior is validated.

Overall, the unit tests demonstrate adequate coverage and contribute to the reliability and maintainability of the code changes introduced in this pull request.

server/v2/stf/branch/changeset.go (2)

114-114: Approved: Iterator now operates on a copy of the tree.

Creating a copy of the tree before iterating ensures that the iterator operates on a separate instance, preventing any unintended side effects on the original tree during iteration.

However, note that creating a copy might introduce some performance overhead compared to directly iterating over the original tree. Keep an eye on the performance impact of this change, especially if the tree size is large or if this function is called frequently.

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210-212: Approved: Improved key range validation in descending order.

The additional condition to check if the current key is greater than or equal to the end key when the iterator is in descending order improves the accuracy of the iterator in determining valid keys.

This change ensures that keys falling outside the specified range are correctly identified, enhancing the robustness of the keyInRange method.

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[tac0turtle]

can we add to the godoc that we create a copy here

[testinginprod]

llgtm