qqeasonchen opened a new pull request, #5368:
URL: https://github.com/apache/eventmesh/pull/5368
## What this PR does
Closes #5357 — Phase 0 enforcement of the production-HA plan (#5354):
**`EventMeshFrame` becomes deeply immutable.** A frame that can be mutated
after publish lets two concurrent dispatchers race on the same instance; the
attribute map was also aliased from codec accumulators at construction.
### 1. `EventMeshFrame` changes
| Aspect | Before | After |
|---|---|---|
| Constructor | `this.attrs = attrs` — aliases the caller's map (codec
accumulators could mutate a live frame) | deep copy (`new
LinkedHashMap<>(attrs)`); null map/data normalized |
| `attributes()` | returns the internal mutable map |
`Collections.unmodifiableMap(attrs)` |
| Derivation | mutate the returned map | new `withAttribute(name, value)` —
derives a new frame with one attribute set (null removes); source unchanged |
### 2. Call-site migration
Verified by grep over **all 72 `attributes()` usages** — production code had
**zero** mutation sites; exactly 3 test files mutated the returned map:
- `RestartCursorAlignmentTest` / `MqCursorRecordingTest`: POP-cursor
stamping now chains `withAttribute`
- `FrameProtocolConversionTest.framePopCkStampedForDeferredAck`: converted
from a *mutability* test to an *immutability* test (asserts `withAttribute`
derives a stamped frame, source unchanged, `attributes().put` throws
`UnsupportedOperationException`)
### 3. ArchUnit guardrail (14 → 15 rules)
- **`ruleEventMeshFrameImmutable`** — only
`org.apache.eventmesh.common.wire..` may implement `EventMeshFrame*` types, so
no other class can grow frame-mutating APIs.
### Verification (full local CI parity, Temurin 21.0.11)
```
:eventmesh-architecture-guard:test + :eventmesh-common:test +
:eventmesh-runtime:test BUILD SUCCESSFUL
checkstyleMain/Test ×3 modules (maxWarnings=0)
BUILD SUCCESSFUL
./gradlew clean build dist jacocoTestReport (CI task set)
BUILD SUCCESSFUL (11m12s)
```
### Relations
- Closes #5357 (Phase 0, P0)
- Parent: #5354 · Plan: `docs/architecture-review/production-ha-plan.md` (PR
#5366)
- Blocks: #5361 (`FrameLimits` builds on the immutable API)
Co-authored-by: qqeasonchen <[email protected]>
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