fix(billing): guard syncJob lifecycle with a dedicated mutex

[AmanGIT07]

Summary

Synchronize access to the syncJob cron field across the four billing services, and make the blob resource cache read in GetAll race-safe.

Changes

• Add a dedicated syncJobMu (distinct from the sync-operation mutex mu) to the customer, checkout, subscription, and invoice services; guard syncJob reads/writes in Init and Close.
• Extract invoice's cron setup into initSyncJob so the lock uses defer while the credit-overdraft setup stays outside the lock.
• blob.ResourcesRepository.GetAll: re-read repo.cached under the mutex after refresh() instead of reading it unlocked.
• Add TestService_InitClose_Concurrent to each billing service.

Test Plan

• go test -race ./billing/subscription/ ./billing/checkout/ ./billing/customer/ ./billing/invoice/
• go build ./billing/... ./internal/store/blob/... and go vet pass

SQL Safety (if your PR touches *_repository.go or goqu.*)

• N/A — the resources_repository.go change is concurrency-only (mutex placement); no SQL or goqu query building touched.

🤖 Generated with Claude Code

[vercel]

The latest updates on your projects. Learn more about Vercel for GitHub.

Project	Deployment	Actions	Updated (UTC)
frontier	Ready	Preview, Comment	Jun 17, 2026 7:01pm

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Path: .coderabbit.yaml

Review profile: CHILL

Plan: Pro

Run ID: 37f2d69b-7b1b-458e-9540-9b568ac9d8a8

📥 Commits

Reviewing files that changed from the base of the PR and between e4d53c8 and 526225d.

📒 Files selected for processing (4)

• billing/checkout/service.go
• billing/customer/service.go
• billing/invoice/service.go
• billing/subscription/service.go

💤 Files with no reviewable changes (3)

• billing/subscription/service.go
• billing/checkout/service.go
• billing/customer/service.go

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

• billing/invoice/service.go

---

📝 Walkthrough

Summary by CodeRabbit

• Bug Fixes
  • Improved stability of billing service initialization and shutdown by serializing scheduled sync-job lifecycle handling across customer, checkout, invoice, and subscription.
  • Fixed thread-safety in cached resource reads to prevent potential unlocked access during refresh.
• Tests
  • Added concurrency-focused Init/Close tests to exercise race-prone billing service behavior under simultaneous calls.

Walkthrough

Four billing service structs (checkout, customer, invoice, subscription) each gain a syncJobMu sync.Mutex field; Init and Close in each service acquire this mutex to serialize cron sync-job lifecycle operations. The invoice service additionally extracts cron setup into a new initSyncJob helper. Concurrent race-detector tests are added for all four services. A separate fix in internal/store/blob/resources_repository.go makes GetAll re-read cached data under a mutex after refresh completes.

Changes

Billing Service syncJob Concurrency Fixes

Layer / File(s)	Summary
syncJobMu field additions across all four billing services billing/checkout/service.go, billing/customer/service.go, billing/invoice/service.go, billing/subscription/service.go	Each Service struct gains syncJobMu sync.Mutex field.
Init and Close mutex guards in checkout, customer, and subscription services billing/checkout/service.go, billing/customer/service.go, billing/subscription/service.go	Init and Close in each service acquire syncJobMu with defer unlock before any syncJob read or write; Close no longer returns syncJob.Stop().Err() and instead returns nil.
invoice service initSyncJob helper and syncJobMu guard billing/invoice/service.go	Init delegates cron setup to a new initSyncJob helper that locks syncJobMu, waits for any existing job to fully stop via Stop().Done(), then creates and starts a new cron; Close also acquires syncJobMu before stopping and returns nil.
Concurrent Init/Close race-detector tests billing/checkout/service_concurrent_test.go, billing/customer/service_concurrent_test.go, billing/invoice/service_concurrent_test.go, billing/subscription/service_concurrent_test.go	New TestService_InitClose_Concurrent tests for all four packages launch two goroutines calling Init concurrently via sync.WaitGroup, then call Close, asserting no errors and exposing races under go test -race.

Blob Resources Repository Cache Read Fix

Layer / File(s)	Summary
Mutex-protected cache read after refresh in GetAll internal/store/blob/resources_repository.go	After repo.refresh(ctx), GetAll now acquires repo.mu to read repo.cached before returning, replacing the prior unlocked direct field access. Import block is also reordered with no functional impact.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~10 minutes

🚥 Pre-merge checks | ✅ 2

✅ Passed checks (2 passed)

Check name	Status	Explanation
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

_{✏️ Tip: You can configure your own custom pre-merge checks in the settings.}

---

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 and usage tips.}

[coderabbitai]

Caution

Some comments are outside the diff and can’t be posted inline due to platform limitations.

⚠️ Outside diff range comments (1)

billing/checkout/service.go (1)

175-181: ⚠️ Potential issue | 🟠 Major

Use a single Stop() result in Close instead of stopping twice.

At Line 179 you already wait for shutdown completion, but Line 180 calls Stop() again and returns that second context's Err(). That return value is detached from the stop you actually awaited and can yield flaky/non-actionable close errors.

💡 Proposed fix

 func (s *Service) Close() error {
 	s.syncJobMu.Lock()
 	defer s.syncJobMu.Unlock()
 	if s.syncJob != nil {
-		<-s.syncJob.Stop().Done()
-		return s.syncJob.Stop().Err()
+		stopCtx := s.syncJob.Stop()
+		<-stopCtx.Done()
+		s.syncJob = nil
 	}
 	return nil
 }

Apply the same pattern in:

• billing/customer/service.go (Line 384-390)
• billing/subscription/service.go (Line 142-148)

Note: billing/invoice/service.go has a different issue—it calls Stop().Err() without awaiting completion and should also be fixed, but with a different approach.

---

ℹ️ Review info

⚙️ Run configuration

Configuration used: Path: .coderabbit.yaml

Review profile: CHILL

Plan: Pro

Run ID: 4313c410-b272-4223-9359-a21f45816dcb

📥 Commits

Reviewing files that changed from the base of the PR and between 9f793c1 and e4d53c8.

📒 Files selected for processing (9)

• billing/checkout/service.go
• billing/checkout/service_concurrent_test.go
• billing/customer/service.go
• billing/customer/service_concurrent_test.go
• billing/invoice/service.go
• billing/invoice/service_concurrent_test.go
• billing/subscription/service.go
• billing/subscription/service_concurrent_test.go
• internal/store/blob/resources_repository.go

[coveralls]

Coverage Report for CI Build 27712777114

Coverage increased (+0.2%) to 43.804%

Details

• Coverage increased (+0.2%) from the base build.
• Patch coverage: 13 uncovered changes across 2 files (30 of 43 lines covered, 69.77%).
• 1 coverage regression across 1 file.

Uncovered Changes

File	Changed	Covered	%
billing/invoice/service.go	27	18	66.67%
internal/store/blob/resources_repository.go	4	0	0.0%
Total (5 files)	43	30	69.77%

Coverage Regressions

1 previously-covered line in 1 file lost coverage.

File	Lines Losing Coverage	Coverage
billing/invoice/service.go	1	5.54%

---

Coverage Stats

Relevant Lines:	37058
Covered Lines:	16233
Line Coverage:	43.8%
Coverage Strength:	12.39 hits per line

---

💛 - Coveralls