fix(events): synchronize drainer status reads

[chenrui333]

What

Protect drainer status snapshots with the existing mutex and add concurrent polling coverage.

Why

Status requests and shutdown logging can read operation counts while commands update them.

Testing

Drainer regression fails under -race before the fix; 20 repetitions and the events package pass.

[Copilot]

🟡 Changes recommended

The new TestDrainer_ConcurrentStatus uses sync.WaitGroup.Go, which doesn’t exist and will not compile.

Once you've addressed the issues Copilot identified, you can request another Copilot review.

Pull request overview

This PR hardens the events.Drainer concurrency model by ensuring status snapshots are read under the same mutex used for updates, and it updates tests to better exercise shutdown and concurrent status polling.

Changes:

• Synchronize Drainer.GetStatus() by locking the existing mutex before returning the status snapshot.
• Replace the shutdown test’s timing-based coordination with testing/synctest to deterministically wait for shutdown blocking.
• Add a concurrent status polling test intended to catch races between operation updates and status reads.

File summaries

File	Description
server/events/drainer.go	Locks around GetStatus() to prevent concurrent reads of status racing with updates.
server/events/drainer_test.go	Updates shutdown test to use synctest; adds concurrent status polling coverage (currently has a compile issue).

Review details

Suppressed comments (1)

server/events/drainer_test.go:92

• sync.WaitGroup does not have a Go method; this goroutine should be started with go + wg.Add/Done, otherwise the test won't compile.

	wg.Go(func() {
		<-start
		for range 1000 {
			status := d.GetStatus()
			if status.ShuttingDown || status.InProgressOps < 0 || status.InProgressOps > workers {

• Files reviewed: 2/2 changed files
• Comments generated: 1
• Review effort level: Lite

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[github-code-quality]

Code Coverage Overview

Languages: Go

Go / code-coverage/go

The overall line coverage in commit b302208 in the fix/drainer-status-r... branch is 73%. Line coverage data for the main branch is not yet available.

Show a line coverage summary of the most covered files.

File	main	fix/drainer-status-r... b302208	+/-
server/events/v...ithub/client.go	—	88%	—
server/core/ter...aform_client.go	—	88%	—
server/controll...i_controller.go	—	83%	—
server/events/p...mand_builder.go	—	83%	—
server/events/v...itlab/client.go	—	80%	—
server/events/p...mmand_runner.go	—	76%	—
server/events/event_parser.go	—	76%	—
server/events/working_dir.go	—	73%	—
server/server.go	—	70%	—
server/controll...s_controller.go	—	64%	—

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_{Updated September 07, 2026 23:47 UTC}