fix(sync): synchronize readiness state

[Baltsat]

This PR

• synchronizes gRPC and HTTP readiness state with atomic.Bool
• preserves blob sync's existing mutex synchronization from feat: improve ETag and body hash support to blob/http sync #1991
• avoids copying atomic.Bool values in HTTP tests
• adds production-path race regressions for both sync implementations

Related Issues

Fixes #2004

Notes

The issue's blob item is already synchronized by #1991, so this PR leaves it unchanged.

How to test

• cd core && go test -race -short ./pkg/sync/grpc ./pkg/sync/http
• cd core && go test -race -count=3 -run "TestIsReadyRaceFreeDuring" ./pkg/sync/grpc ./pkg/sync/http
• cd core && go vet ./...
• cd core && go test -short ./...
• git diff --check

[netlify]

✅ Deploy Preview for polite-licorice-3db33c canceled.

Name	Link
🔨 Latest commit	e67f001
🔍 Latest deploy log	https://app.netlify.com/projects/polite-licorice-3db33c/deploys/6a67584706e10600088a3005

[Copilot]

Copilot was unable to review this pull request because the user who requested the review has reached their quota limit.

[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: df06f2e6-9bf1-4d7e-af18-584e753de4f6

📥 Commits

Reviewing files that changed from the base of the PR and between 30ef582 and e67f001.

📒 Files selected for processing (4)

• core/pkg/sync/grpc/grpc_sync.go
• core/pkg/sync/grpc/grpc_sync_test.go
• core/pkg/sync/http/http_sync.go
• core/pkg/sync/http/http_sync_test.go

🚧 Files skipped from review as they are similar to previous changes (3)

• core/pkg/sync/http/http_sync.go
• core/pkg/sync/grpc/grpc_sync_test.go
• core/pkg/sync/http/http_sync_test.go

---

📝 Walkthrough

Walkthrough

The gRPC and HTTP sync implementations now use atomic readiness flags. New concurrency tests exercise readiness checks during startup, and HTTP tests update callbacks to use *Sync.

Changes

Sync readiness concurrency

Layer / File(s)	Summary
gRPC atomic readiness core/pkg/sync/grpc/grpc_sync.go, core/pkg/sync/grpc/grpc_sync_test.go	The gRPC readiness flag now uses atomic.Bool, with concurrent stream-start coverage and an EOF client stub.
HTTP atomic readiness and test updates core/pkg/sync/http/http_sync.go, core/pkg/sync/http/http_sync_test.go	The HTTP readiness flag now uses atomic operations, startup concurrency is tested, and response callbacks receive *Sync.

Estimated code review effort: 3 (Moderate) | ~20 minutes

Possibly related PRs

• open-feature/flagd#1985: Related gRPC readiness tracking and startup changes.

Suggested reviewers: toddbaert, anxkhn

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly summarizes the main change: making sync readiness state concurrent-safe.
Description check	✅ Passed	The description matches the code changes and mentions the atomic.Bool race fix and tests.
Linked Issues check	✅ Passed	The PR fixes the unsynchronized ready reads/writes in gRPC and HTTP, and leaves blob unchanged as noted in #1991.
Out of Scope Changes check	✅ Passed	The added tests and minor formatting updates support the readiness race fix and stay within scope.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.

Warning

There were issues while running some tools. Please review the errors and either fix the tool's configuration or disable the tool if it's a critical failure.

🔧 golangci-lint (2.12.2)

level=error msg="[linters_context] typechecking error: pattern ./...: directory prefix . does not contain main module or its selected dependencies"

---

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.}

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud