refactor(country): improve country fetching logic #47
Conversation
- Introduce helper methods for fetching and caching event and headquarter countries - Use atomic assignment for _eventCountriesFuture and _headquarterCountriesFuture - Remove duplicate code and improve readability
fulleni
deleted the
Implement-Atomic-Cache-Assignment-and-Extract-Fetch-Logic-in-country-service
branch
![gemini-code-assist[bot]](https://avatars.githubusercontent.com/in/956858?s=60&v=4){kind=small}
There was a problem hiding this comment.
Summary of Changes
Hello @fulleni, 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 refactors the country fetching logic within the CountryService to enhance efficiency and prevent redundant data retrieval. It introduces dedicated helper methods for fetching and caching distinct event and headquarter countries, and streamlines the main retrieval methods to leverage an atomic assignment pattern. This ensures that only one fetch operation is initiated for a given country type at any time, improving performance and resource utilization.
Highlights
- Extraction of Fetching Logic: The core logic for fetching and caching distinct event and headquarter countries has been moved into new, dedicated private helper methods:
_fetchAndCacheEventCountriesand_fetchAndCacheHeadquarterCountries. - Improved Asynchronous Fetch Management: The main
_getEventCountriesand_getHeadquarterCountriesmethods now utilize a null-aware assignment (??=) to atomically assign and return the future for fetching countries. This pattern ensures that if a fetch is already in progress, the existing future is returned, preventing redundant API calls and potential cache stampedes. - Code Simplification and Readability: The refactoring simplifies the main country retrieval methods by centralizing the actual fetching and caching process into the new helper functions, leading to cleaner and more maintainable code.
Using Gemini Code Assist
The full guide for Gemini Code Assist can be found on our documentation page, here are some quick tips.
Invoking Gemini
You can request assistance from Gemini at any point in your pull request via creating an issue comment (i.e. comment on the pull request page) using either /gemini <command> or @gemini-code-assist <command>. Below is a summary of the supported commands.
| Feature | Command | Description |
|---|---|---|
| Code Review | /gemini review |
Performs a code review for the current pull request in its current state. |
| Pull Request Summary | /gemini summary |
Provides a summary of the current pull request in its current state. |
| Comment | @gemini-code-assist | Responds in comments when explicitly tagged, both in issue comments and review comments. |
| Help | /gemini help |
Displays a list of available commands. |
Customization
To customize Gemini Code Assist for GitHub experience, repository maintainers can create a configuration file and/or provide a custom code review style guide (such as PEP-8 for Python) by creating and adding files to a .gemini/ folder in the base of the repository. Detailed instructions can be found here.
Limitations & Feedback
Gemini Code Assist may make mistakes. Please leave feedback on any instances where its feedback is incorrect or counter productive. You can react with 👍 and 👎 on @gemini-code-assist comments. If you're interested in giving your feedback about your experience with Gemini Code Assist for Github and other Google products, sign up here.
You can also get AI-powered code generation, chat, as well as code reviews directly in the IDE at no cost with the Gemini Code Assist IDE Extension.
Footnotes
-
Review the Privacy Notices, Generative AI Prohibited Use Policy, Terms of Service, and learn how to configure Gemini Code Assist in GitHub here. Gemini can make mistakes, so double check it and use code with caution. ↩
There was a problem hiding this comment.
Code Review
This pull request effectively refactors the country fetching logic to improve cache stampede protection by using the ??= operator and extracting the fetch-and-cache logic into dedicated helper methods. This is a good simplification of the concurrency handling.
My review includes two high-severity comments that identify a subtle issue with the new implementation. The current approach of clearing the in-flight Future variable from within a finally block can be fragile. I've suggested a more robust pattern using Future.whenComplete to ensure the cleanup logic is executed safely after the asynchronous operation has fully completed for all listeners. Applying this suggestion will make the concurrency handling more reliable.
Status
READY
Type of Change