fix(device-plugin): return error on failed Send in ListAndWatch

[AyushSrivastava1818]

What type of PR is this?

/kind bug

What this PR does / why we need it

ListAndWatch() (pkg/device-plugin/nvidiadevice/nvinternal/plugin/server.go) discarded the error returned by s.Send() at both call sites.

If the gRPC stream to kubelet becomes unavailable (for example, due to a client disconnect or stream cancellation), Send() returns an error. The current implementation ignored that error and continued running, causing subsequent device health updates to continue attempting writes on a failed stream.

This PR logs and returns the Send() error at both call sites, allowing the current ListAndWatch() RPC to terminate instead of silently ignoring stream failures. This follows the standard gRPC server-stream error handling pattern already used elsewhere in the codebase.

Which issue(s) this PR fixes

Fixes #2352

Special notes for your reviewer

• No behavioral changes to the successful (Send() succeeds) path.
• Added TestListAndWatch_SendError covering both Send() call sites:
  • Initial Send() failure.
  • Health-update Send() failure after an initial successful send.
• The tests verify that ListAndWatch() returns the propagated error and stops sending additional updates after the failure.
• Verified locally with:
  • go test ./pkg/device-plugin/nvidiadevice/nvinternal/plugin/... -v
  • make verify

AI assistance disclosure

I consulted ChatGPT and Claude to identify the issue and discuss the implementation approach. The implementation, tests, validation, commit message, and final code changes were completed and verified by me. I reviewed all generated suggestions, ran the relevant tests and make verify locally, and take full responsibility for the final contribution.

Does this PR introduce a user-facing change?

NONE

Summary by CodeRabbit

• Bug Fixes

  • Improved reliability of device status reporting by detecting communication failures with the cluster.
  • Prevented failed initial or health-update messages from being silently ignored.
  • Ensured device monitoring responds appropriately when status updates cannot be delivered.

• Tests

  • Added coverage for communication failures during initial and subsequent device status updates.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Pro Plus

Run ID: 64c30e71-2236-44a5-ad41-e4ff95fc4562

📥 Commits

Reviewing files that changed from the base of the PR and between 06e379d and 7ee96a8.

📒 Files selected for processing (2)

• pkg/device-plugin/nvidiadevice/nvinternal/plugin/server.go
• pkg/device-plugin/nvidiadevice/nvinternal/plugin/server_test.go

🚧 Files skipped from review as they are similar to previous changes (2)

• pkg/device-plugin/nvidiadevice/nvinternal/plugin/server.go
• pkg/device-plugin/nvidiadevice/nvinternal/plugin/server_test.go

---

📝 Walkthrough

Walkthrough

ListAndWatch now handles errors from initial and health-update gRPC response sends. Tests cover both send-failure paths with a mock server stream.

Changes

ListAndWatch stream error handling

Layer / File(s)	Summary
Propagate response send errors pkg/device-plugin/nvidiadevice/nvinternal/plugin/server.go, pkg/device-plugin/nvidiadevice/nvinternal/plugin/server_test.go	ListAndWatch logs failures from initial and health-update sends. The method returns after each failure path. Mock stream tests verify the initial-send error and the update-send error after two responses.

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

Possibly related PRs

• Project-HAMi/HAMi#2213: Both changes modify ListAndWatch, but that PR addresses unhealthy-device recovery.

Suggested reviewers: wawa0210

Poem

A rabbit watched the stream send,
Then found an error at the end.
Logs marked the break,
Tests checked each wake,
And updates stopped as planned.

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Linked Issues check	⚠️ Warning	Initial Send errors propagate, but health-update Send errors return nil instead of the Send error required by issue #2352.	Return the health-update Send error from ListAndWatch instead of returning nil after logging it.

✅ 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 describes the primary change to handle failed Send calls in ListAndWatch.
Out of Scope Changes check	✅ Passed	The changes are limited to ListAndWatch Send-error handling and focused tests for issue #2352.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

---

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.

Flag	Coverage Δ
unittests	62.44% <100.00%> (+1.42%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
...ce-plugin/nvidiadevice/nvinternal/plugin/server.go	42.15% <100.00%> (+2.82%)	⬆️

... and 21 files with indirect coverage changes

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[archlitchi]

/assign @Shouren

[Shouren]

/lgtm

[archlitchi]

/lgtm

[hami-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: archlitchi, AyushSrivastava1818, Shouren

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Needs approval from an approver in each of these files:

• OWNERS [Shouren,archlitchi]

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