Add a cluster-scoped convergence status API - #275
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PranaviAncha wants to merge 6 commits into
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Extract the external view comparison from StrictMatchExternalViewVerifier into a reusable evaluation and report it through Helix REST, so a caller that only wants to observe convergence does not have to run a verifier, hold a connection open or wait on a callback. The verifier delegates to the same evaluation, so the two cannot disagree. Converged, pending and failed are reported separately, the observation time is returned, and a failed read is an error rather than an empty converged result. Loading the metadata for the read leaves participant history untouched, which the controller refresh writes. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
A command parameter on the existing cluster read is answered by an older server with the ordinary cluster payload and HTTP 200, so a caller that reaches a node without this change during a rolling deployment receives a successful response carrying no status. A dedicated path answers 404 there instead, which cannot be mistaken for convergence, and leaves the existing cluster read untouched. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
Unknown resources are reported by their own field, so the reason that was never attached to one is removed rather than left as a second way to say the same thing. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
Describe the invariant the test protects rather than how it relates to a change. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
A requested resource that uses the task state model exists, so reporting it as one Helix does not know about was wrong. Unknown resources are now decided before anything is filtered out, and a resource that exists but is not compared is reported as skipped instead of counted as evaluated, so a caller can see what the answer rests on. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
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Issues
No linked GitHub issue.
Description
Add
GET /clusters/{clusterId}/convergence-statusso a caller can obtain Helix's convergence decision without hosting a cluster verifier.The calculation is shared with
StrictMatchExternalViewVerifier. Requests support STRICT or LENIENT matching and an optional resource scope. The response distinguishes CONVERGED, PENDING, and FAILED, with exact counts and bounded diagnostic detail.The read borrows the server's accessor, creates no verifier or background worker, and does not write participant history or trigger rebalance. Missing metadata cannot become an empty successful result. Observation time does not imply an atomic controller snapshot.
Task resources without external views are reported as skipped. A leftover task external view is compared against an empty ideal state and counted as evaluated.
Tests
The selected Maven suites ran on JDK 11. The final follow-up changes only documentation.
Changes that Break Backward Compatibility (Optional)
The REST route is additive. Existing verifier matching behavior is retained through the shared evaluator.
Deploy the provider to every serving REST node before enabling callers to depend on the new route. An older server returns 404, which must not be interpreted as convergence.
Documentation (Optional)
The README documents the request, response, scope, failure semantics, and observation limits. Public API Javadocs describe the shared evaluator and result.
Commits
The commits are additive, use the repository's personal GitHub identity, and do not rewrite shared history.
Code Quality
The implementation follows the surrounding Java conventions and keeps evaluation separate from caller retry policy.
Generated with GitHub Copilot CLI