feat: RetryHelper to report all previous exceptions

[AbgarSim]

Thank you for opening a Pull Request! Before submitting your PR, there are a few things you can do to make sure it goes smoothly:

• Make sure to open an issue as a bug/issue before writing your code! That way we can discuss the change, evaluate designs, and agree on the general idea
• Ensure the tests and linter pass
• Code coverage does not decrease (if any source code was changed)
• Appropriate docs were updated (if necessary)

Fixes #3951 ☕️

If you write sample code, please follow the samples format.

[gemini-code-assist]

Summary of Changes

Hello @AbgarSim, 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 significantly improves the debuggability of retriable operations within the BigQuery client library. By capturing and reporting all intermediate exceptions that occur during retry attempts, developers will gain a clearer understanding of the sequence of failures leading to a final exception. This change ensures that transient issues are easier to diagnose by providing a full context of what went wrong across all retries.

Highlights

• Enhanced Exception Reporting: The BigQueryRetryHelper now collects all exceptions encountered during failed retry attempts and attaches them as suppressed exceptions to the final exception thrown. This provides a complete history of failures for improved debugging.
• Preservation of Suppressed Exceptions: When an IOException is wrapped into a BigQueryException, any suppressed exceptions from the original IOException are now correctly preserved and transferred to the new BigQueryException.
• New Unit Tests: Comprehensive unit tests have been added to validate the new exception reporting behavior, covering scenarios from successful retries to multiple failures where suppressed exceptions are expected.

🧠 New Feature in Public Preview: You can now enable Memory to help Gemini Code Assist learn from your team's feedback. This makes future code reviews more consistent and personalized to your project's style. Click here to enable Memory in your admin console.

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 by creating a comment using either /gemini <command> or @gemini-code-assist <command>. Below is a summary of the supported commands on the current page.

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 pull request 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

1. 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. ↩

[gemini-code-assist]

Code Review

This pull request enhances the RetryHelper to report all previous exceptions from failed attempts by adding them as suppressed exceptions to the final exception. This is a valuable improvement for debugging failed operations that involve retries. The implementation is solid, wrapping the user-provided Callable to record failures and then attaching them in the final catch block. The changes are well-supported by a new test suite that covers various scenarios, including multiple failures before success and exhausting all retry attempts. My only feedback is a minor clarification in a code comment to ensure it accurately reflects the implementation's behavior regarding duplicate exceptions.

[lqiu96]

Thanks for the PR @AbgarSim! I will take a look at this over the coming days/ week. I did a quick pas over this and the changes generally look fine. I just want to double check the behavior with Gax's RetryingExecutor and ensure there isn't anything unexpected.

The lint issue look like it's complaining about a missing header in the newly added test. We just need to add that with the year :)