feat: concurrent engine execution with graceful degradation

- Run all local engines in parallel using goroutines + sync.WaitGroup
- Individual engine failures are captured as unresponsive_engines entries
  instead of aborting the entire search request
- Context cancellation is respected: cancelled engines report as unresponsive
- Upstream proxy failure is also gracefully handled (single unresponsive entry)
- Extract unresponsiveResponse() and emptyResponse() helpers for consistency
- Add comprehensive tests:
  - ConcurrentEngines: verifies parallelism (2x100ms engines complete in ~100ms)
  - GracefulDegradation: one engine fails, one succeeds, both represented
  - AllEnginesFail: no error returned, all engines in unresponsive_engines
  - ContextCancellation: engine respects context timeout, reports unresponsive
This commit is contained in:
Franz Kafka 2026-03-21 15:39:00 +00:00
parent 5181073a95
commit 385a7acab7
5 changed files with 355 additions and 35 deletions

2
go.sum
View file

@ -35,6 +35,8 @@ golang.org/x/sync v0.3.0/go.mod h1:FU7BRWz2tNW+3quACPkgCx/L+uEAv1htQ0V83Z9Rj+Y=
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golang.org/x/sync v0.10.0/go.mod h1:Czt+wKu1gCyEFDUtn0jG5QVvpJ6rzVqr5aXyt9drQfk=
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golang.org/x/sys v0.0.0-20201119102817-f84b799fce68/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
golang.org/x/sys v0.0.0-20210615035016-665e8c7367d1/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=