feat(simple reader): Adding support for short reads in Simple Reader

[abhishek10004]

Description

Adding support for short reads in Simple Reader

Link to the issue in case of a bug fix.

b/474070396

Testing details

1. Manual - NA
2. Unit tests - Done
3. Integration tests - NA

Any backward incompatible change? If so, please explain.

[abhishek10004]

/gemini review

[gemini-code-assist]

Summary of Changes

Hello @abhishek10004, 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 enhances the MrdSimpleReader by introducing robust handling for 'short reads.' When a read operation returns fewer bytes than expected but without a critical error, the system will now attempt to recover by recreating the underlying MultiRangeDownloader and retrying the read for the missing data. This change significantly improves the reliability and data integrity of read operations, ensuring that applications receive all requested data even under transient conditions that might cause partial reads.

Highlights

• Short Read Handling: Implemented a mechanism to detect and handle 'short reads' within the MrdSimpleReader, where a read operation returns fewer bytes than requested without a fatal error.
• New Helper Function: Introduced a new isShortRead helper function to precisely determine if a read operation resulted in an incomplete read, considering various error conditions like io.EOF.
• ReadAt Method Enhancement: Modified the ReadAt method to attempt recreating the MultiRangeDownloader (MRD) instance and retrying the read for the remaining bytes if a short read is detected. This improves robustness by ensuring full data retrieval.
• Comprehensive Testing: Added new unit tests to cover both successful retry scenarios after a short read and cases where the retry itself fails, ensuring correct error propagation and behavior.

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[gemini-code-assist]

Code Review

This pull request introduces support for handling short reads in MrdSimpleReader. When a short read occurs, the logic attempts to recreate the Multi-Range Downloader (MRD) instance and retries the read for the remaining bytes. This is a robust way to handle potentially stale connections or object generation changes. The implementation is sound and is accompanied by good unit tests covering both success and failure scenarios for the retry logic. I've added a couple of suggestions to improve code conciseness and enhance logging for better debuggability.

[gemini-code-assist]

Code Review

This pull request adds support for handling short reads in MrdSimpleReader by recreating the MRD pool and retrying the read. The overall approach is sound and the new logic is well-tested with unit tests for both success and failure scenarios of the retry mechanism. I've found one issue regarding error handling when RecreateMRD is called. The error is unintentionally suppressed, which could make debugging issues in production difficult. Please see my detailed comment.

[codecov]

Codecov Report

❌ Patch coverage is 88.23529% with 2 lines in your changes missing coverage. Please review.
✅ Project coverage is 83.04%. Comparing base (2cbaedd) to head (d1cb10f).
⚠️ Report is 3 commits behind head on master.

Files with missing lines	Patch %	Lines
internal/gcsx/mrd_simple_reader.go	88.23%	1 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #4261      +/-   ##
==========================================
- Coverage   83.06%   83.04%   -0.03%     
==========================================
  Files         156      156              
  Lines       19173    19188      +15     
==========================================
+ Hits        15926    15934       +8     
- Misses       2654     2659       +5     
- Partials      593      595       +2     

Flag	Coverage Δ
unittests	83.04% <88.23%> (-0.03%)	⬇️

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[github-actions]

Hi @raj-prince, @vadlakondaswetha, your feedback is needed to move this pull request forward. This automated reminder was triggered because there has been no activity for over 24 hours. Please provide your input when you have a moment. Thank you!