feat(experimental): integrate writes strategy and appendable object writer

[Pulkit0110]

Integrate all the components required for bidi writes retries

[gemini-code-assist]

Summary of Changes

Hello @Pulkit0110, 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 robustness of asynchronous object operations in Google Cloud Storage by implementing a sophisticated retry and resumption system for bidirectional streaming. It introduces dedicated strategies to manage the state of ongoing read and write operations, automatically re-establishing streams and continuing data transfer from the last known good state in the event of transient network issues or server-side redirects. This ensures that applications using these experimental APIs can handle intermittent failures gracefully, leading to more reliable data transfers.

Highlights

• Bidirectional Stream Retry Mechanism: Introduced a comprehensive retry mechanism for asynchronous bidirectional (bidi) streaming operations, specifically for object reads and writes, to enhance resilience against transient errors and redirects.
• New Retry Strategies and Manager: Implemented a generic _BidiStreamRetryManager and specific _ReadResumptionStrategy and _WriteResumptionStrategy classes to manage the state, generate requests, and recover from failures during bidi stream retries.
• Integration into Async Writers/Readers: Refactored AsyncAppendableObjectWriter and AsyncMultiRangeDownloader to integrate the new retry logic, allowing their open, append, and download_ranges methods to automatically handle retries and stream re-establishment.
• Error Handling and State Recovery: Added predicates (_is_write_retryable, _is_read_retryable) to identify retryable exceptions and _on_open_error methods to extract routing tokens and handles from redirect errors, enabling intelligent state recovery.
• Extensive Testing: Included new conformance tests for bidi reads to validate retry behavior under various fault injection scenarios, alongside new unit tests for the retry manager and both read/write resumption strategies.

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[gemini-code-assist]

Code Review

This pull request introduces a significant and well-designed refactoring to integrate retry strategies for bidirectional reads and writes, enhancing the robustness of experimental asyncio features. The abstraction of retry logic into a _BidiStreamRetryManager and specific _WriteResumptionStrategy and _ReadResumptionStrategy classes is a solid architectural choice. The accompanying unit and conformance tests are comprehensive and provide good coverage for the new functionality. My review comments focus on improving error handling by replacing broad except Exception blocks with more specific ones and avoiding print() statements in library code.

[Pulkit0110]

/gcbrun

[Pulkit0110]

/gcbrun

[Pulkit0110]

/gcbrun