[codex] Fix driver error monitoring

[Alb3e3]

Summary

• add a shared driver monitor that polls driver tasks by completion order
• use it from both serve and daemon so driver failures are observed promptly
• add a regression test for a later failing driver sitting behind an earlier long-running driver

Root cause

serve and daemon collected driver join handles in a FuturesUnordered, but then awaited each join handle from the collection iterator. That made failures depend on insertion order rather than completion order. If an earlier driver kept running and a later Ouroboros Unix socket driver failed to bind, the bind error could remain unread until shutdown.

Fixes #293.

Bounty note

I linked Githoney bounty 64 from #293 with /githoney link-bounty --bountyId 64. The issue bot comment shows a 2025-01-26 deadline, so please confirm whether it is still claimable.

Verification

• cargo test monitor_drivers_observes_later_failures_before_waiting_for_earlier_drivers --no-default-features
• cargo test --no-default-features
• git diff --check

I also tried cargo fmt --check, but this checkout has pre-existing rustfmt drift outside this PR on stable rustfmt, so I left those unrelated files untouched.

Summary by CodeRabbit

• Bug Fixes

  • Improved driver failure detection so errors trigger prompt shutdown without waiting for unrelated tasks to complete.
  • Continued monitoring remaining drivers after a failure to ensure additional errors are detected and reported.

• Refactor

  • Unified driver monitoring and error handling across service configurations, providing more consistent shutdown behavior.

[Alb3e3]

/githoney link-bounty --bountyId 64

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro Plus

Run ID: da858b46-8b18-4a9a-93e2-be3b38a10560

📥 Commits

Reviewing files that changed from the base of the PR and between ba00b6c and 3c982c8.

📒 Files selected for processing (1)

• src/bin/dolos/common.rs

🚧 Files skipped from review as they are similar to previous changes (1)

• src/bin/dolos/common.rs

---

📝 Walkthrough

Walkthrough

Centralizes driver task monitoring for daemon and serve entry points. The shared monitor_drivers function detects driver and join failures, logs them, cancels the exit token, and continues monitoring remaining tasks. A Tokio test validates prompt failure detection.

Changes

Driver monitoring refactor

Layer / File(s)	Summary
monitor_drivers implementation and test src/bin/dolos/common.rs	Adds monitor_drivers with completion-order task monitoring, failure logging, exit-token cancellation, and a test for later-driver failure detection.
daemon.rs integration src/bin/dolos/daemon.rs	Replaces local driver handling with a call to monitor_drivers.
serve.rs integration src/bin/dolos/serve.rs	Replaces local driver handling with a call to monitor_drivers.

Estimated code review effort: 2 (Simple) | ~10 minutes

Suggested reviewers: scarmuega

Sequence Diagram(s)

sequenceDiagram
  participant DaemonOrServe
  participant monitor_drivers
  participant DriverTasks
  participant ExitToken
  DaemonOrServe->>monitor_drivers: pass driver tasks and exit token
  monitor_drivers->>DriverTasks: await completed task
  DriverTasks-->>monitor_drivers: return success or failure
  monitor_drivers->>ExitToken: cancel when a failure occurs
  monitor_drivers->>DriverTasks: monitor remaining tasks

Loading

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 50.00% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly identifies the main change: fixing driver error monitoring.
Linked Issues check	✅ Passed	The monitor observes drivers by completion order and surfaces early socket bind failures, addressing issue #293.
Out of Scope Changes check	✅ Passed	The changes remain focused on shared driver monitoring, error reporting, cancellation, and regression coverage.

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

---

Thanks for using CodeRabbit! It's free for OSS, and your support helps us grow. If you like it, consider giving us a shout-out.

❤️ Share

• X
• Mastodon
• Reddit
• LinkedIn

_{Comment @coderabbitai help to get the list of available commands.}