Add X-Request-ID header to member publisher messages by hmchangw · Pull Request #268 · hmchangw/chat

hmchangw · 2026-06-03T05:56:42Z

Summary

Propagate correlation IDs as X-Request-ID headers in both canonical and frontdoor member publisher messages to enable end-to-end request tracing across the pipeline.

Changes

canonicalMemberPublisher.Publish: Now uses PublishMsg with a nats.Msg that includes the X-Request-ID header set to the corrID parameter. Previously the corrID was ignored.
frontdoorMemberPublisher.Publish: Now uses PublishMsg with a nats.Msg that includes the X-Request-ID header set to the corrID parameter. Previously used PublishRequest without headers.
Test coverage: Added two new tests:
- TestCanonicalMemberPublisher_SetsRequestIDHeader: Verifies canonical publishes carry the correlation ID as the X-Request-ID header
- TestFrontdoorMemberPublisher_SetsRequestIDHeader: Verifies frontdoor publishes carry the correlation ID as the X-Request-ID header
Imports: Added "github.com/hmchangw/chat/pkg/natsutil" to both files to access RequestIDHeader constant

Implementation Details

Both publishers now construct a nats.Msg with headers before publishing, allowing the correlation ID to flow through downstream services (room-worker and room-service) that require or validate the X-Request-ID header. This ensures request tracing is consistent across the entire member addition pipeline.

https://claude.ai/code/session_014eeLP8ENEQxFhC4SjaAY27

Summary by CodeRabbit

Bug Fixes
- Correlation IDs are now propagated in request headers for published member messages (canonical and frontdoor).
New Features
- Sustained-members workload now performs a preflight capacity check and will refuse to start if requested rate/duration exceeds capacity, reporting achievable limits.
Documentation
- Updated members workload docs and adjusted the members-medium candidate pool size.
Tests
- Added tests for request-ID headers and sustained-capacity validation.

coderabbitai · 2026-06-03T05:56:53Z

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ℹ️ Review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro

Run ID: fdb59330-0a86-45fc-8766-505c7fc9bd81

📥 Commits

Reviewing files that changed from the base of the PR and between 045542d and 785e8bd.

📒 Files selected for processing (8)

tools/loadgen/README.md
tools/loadgen/main.go
tools/loadgen/members.go
tools/loadgen/members_capacity_test.go
tools/loadgen/members_generator.go
tools/loadgen/members_publisher.go
tools/loadgen/members_publisher_test.go
tools/loadgen/members_test.go

📝 Walkthrough

Walkthrough

Adds NATS request-id header propagation to canonical and frontdoor member publishers and tests that verify the header; introduces sustained-capacity helpers and a preflight validation that runs before NATS setup, updates the members-medium preset and README, and adds unit/integration tests for capacity logic.

Changes

Member Publisher Request ID Headers

Layer / File(s)	Summary
Request ID header propagation in publishers `tools/loadgen/members_publisher.go`	Imports `natsutil` and updates canonical and frontdoor publishers to build `nats.Msg` with `natsutil.RequestIDHeader` set to `corrID`; frontdoor messages set `Reply` and both use `PublishMsg`.
Request ID header verification tests `tools/loadgen/members_publisher_test.go`	Adds tests `TestCanonicalMemberPublisher_SetsRequestIDHeader` and `TestFrontdoorMemberPublisher_SetsRequestIDHeader` that subscribe, publish with a correlation ID, and assert the received message header matches.

Sustained Capacity Preflight

Layer / File(s)	Summary
Capacity contract & helpers `tools/loadgen/members_generator.go`	Add `ErrInsufficientPool`, `SustainableOps`, and `ValidateSustainedCapacity` to compute sustained add-member capacity and return wrapped, actionable errors when insufficient.
Preflight wiring in CLI/runtime `tools/loadgen/main.go`	Build sustained fixtures/pools before connecting to NATS, call `ValidateSustainedCapacity(...)`, and abort with exit code 2 on failure; remove duplicate later fixture build.
Preset & README updates `tools/loadgen/members.go`, `tools/loadgen/README.md`	Increase `members-medium` `CandidatePool` to 900 and update README to document new pool sizing and the changed sustained-mode behavior (refuse to start and report achievable max).
Capacity unit & preset tests `tools/loadgen/members_capacity_test.go`	Add tests for `SustainableOps` and `ValidateSustainedCapacity` (within budget, at boundary, oversubscribed, too small, zero usersPerAdd) and a preset integration test verifying `members-medium` default invocation is satisfiable.

Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~20 minutes

Possibly related PRs

hmchangw/chat#203: Adds the original loadgen member-add publishers with frontdoor request/reply correlation; this PR extends those publishers with request-id header propagation.

Suggested reviewers

mliu33
Joey0538

Poem

🐰 I hopped through headers, small and spry,
I set corrIDs for messages flying by.
I checked the pools before the run began,
Now publishers and tests all follow the plan.
Hip-hop hooray — payloads and IDs align!

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 25.00% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ 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 and accurately describes the main change: adding the X-Request-ID header to member publisher messages, which is the primary focus of the code modifications.
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.

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Commit unit tests in branch claude/zealous-mccarthy-Wt1vU

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The members-sustained (and members-capacity) generators mint a corrID via idgen.GenerateRequestID() but the canonical and frontdoor member publishers never put it on the NATS message. Backend services require the header: room-worker rejects canonical events with no X-Request-ID as a permanent error, and room-service requires it on the frontdoor request. Stamp corrID as the X-Request-ID header on both publish paths so requests are accepted and trace end-to-end, matching the daily scenario's pattern. https://claude.ai/code/session_014eeLP8ENEQxFhC4SjaAY27

…nfig Candidate accounts are single-use (once added they're room members and can't be re-added; baseline+pool is capped at MAX_ROOM_SIZE), so a sustained run can make at most rooms × floor(pool/usersPerAdd) publishes. The default invocation (rate=100, duration=60s, users-per-add=10 = 6000 ops) exceeded every preset's budget, so the run always aborted with ErrPoolsExhausted — members-medium ran ~50s before failing, smaller presets exhausted during warmup. - Add a preflight capacity guard (SustainableOps + ValidateSustainedCapacity) that fails fast with exit 2 before any NATS/store work, printing the achievable max --rate/--duration for the preset (or steering to a larger preset when it's too small to sustain any sensible run). - Right-size members-medium's candidate pool 500 -> 900 (baseline 100 + 900 = 1000 = MAX_ROOM_SIZE) so the documented default command completes with margin (9000-op budget vs 6000-op demand). - Update README preset table and the over-capacity guidance. https://claude.ai/code/session_014eeLP8ENEQxFhC4SjaAY27

700 rooms x baseline 10 x candidate pool 990 yields 69,300 add-member ops, enough to sustain rate=1000/60s (60,000 ops) at the default users-per-add=10. Pool stays capped at MAX_ROOM_SIZE; capacity scales via room count. https://claude.ai/code/session_014eeLP8ENEQxFhC4SjaAY27

Capacity mode grows each room to --target-size from its single-use pool and never sends a partial batch, so a room with pool P reaches at most baseline + floor(P/users-per-add)*users-per-add. ValidateCapacityTarget rejects an unreachable target before any NATS/store work, naming how many rooms fall short and the reachable ceiling, instead of silently under-filling rooms. https://claude.ai/code/session_014eeLP8ENEQxFhC4SjaAY27

mliu33

Thanks

claude added 4 commits June 4, 2026 05:12

hmchangw force-pushed the claude/zealous-mccarthy-Wt1vU branch from f4afb27 to 785e8bd Compare June 4, 2026 05:12

mliu33 approved these changes Jun 4, 2026

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mliu33 merged commit c8048eb into main Jun 4, 2026
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Add X-Request-ID header to member publisher messages#268

Add X-Request-ID header to member publisher messages#268
mliu33 merged 4 commits into
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hmchangw commented Jun 3, 2026 •

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