fix(storage): deadlock in event loop while coordinating channels

[cpriti-os]

No description provided.

[gemini-code-assist]

Summary of Changes

Hello @cpriti-os, 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 addresses a potential deadlock scenario in the MultiRangeDownloader's event loop by introducing an internal queue for outgoing requests. This change allows the event loop to process commands and session responses without blocking on sending requests, thereby improving the robustness and responsiveness of the multi-range download process. The implementation includes congestion control and prioritized handling for retried requests.

Highlights

• Request Queue Introduction: Introduced an unsentRequests queue (using container/list) within the multiRangeDownloaderManager to manage outgoing BidiReadObjectRequests, decoupling request generation from immediate sending.
• Asynchronous Request Sending: Refactored the eventLoop to asynchronously send requests from the unsentRequests queue to the current session's request channel, preventing potential deadlocks caused by blocking sends.
• Congestion Control: Implemented a congestion control mechanism that returns an error if the unsentRequests queue exceeds a predefined limit (10,000 requests), preventing unbounded memory growth and resource exhaustion.
• Prioritized Retries: Modified the retry logic in ensureSession to push retried requests to the front of the unsentRequests queue, giving them higher priority for re-transmission.
• Completion Logic Update: Updated the completion condition in the eventLoop to ensure all requests, including those currently residing in the unsentRequests queue, are processed before signaling overall completion.

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[gemini-code-assist]

Code Review

This pull request effectively resolves a potential deadlock in the event loop by introducing an internal queue for outgoing requests and using a non-blocking send pattern. This decouples command processing from network writes, preventing the event loop from blocking. The changes are logical and well-implemented, including a backpressure mechanism to handle congestion. I have one minor suggestion to improve maintainability by replacing a magic number with a named constant.

[tritone]

Minor suggestion, overall LGTM.