[m3db-client] Circuit breaker: break only on timeout errors#4393
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arnav-chakraborty merged 1 commit intoMay 20, 2026
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Summary:
Context:
- Circuit breaker in M3DB client currently trips on all errors
- Per the ERD, it should only trip on timeout/transport errors (slow nodes)
- Application errors (bad request, partial batch) should not trip the breaker
Changes:
- Add ErrorFilter func(error) bool to middleware Params for error classification
- Modify withBreaker to only report filtered errors as CB failures
- Only store lastError for CB-relevant errors (so rejection message shows timeout)
- Add filteredFailures metric to distinguish CB failures from total failures
- Wire IsTimeoutError as the error filter in host_queue.go
- Add unit and integration tests for error filtering behavior
Test Plan:
go test ./src/dbnode/client/circuitbreaker/middleware/... -v
go test ./src/dbnode/client/ -run TestHostQueueCircuitBreaker -v
Revert Plan:
Revert the diff if it is not working as expected.
arnav-chakraborty
approved these changes
May 18, 2026
arnav-chakraborty
deleted the
prateek-sachan_UBER/circuit-breaker-timeout-filter
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What this PR does / why we need it:
Summary:
Context:
- Circuit breaker in M3DB client currently trips on all errors
- Application errors (bad request, partial batch) should not trip the breaker
Changes:
- Add ErrorFilter func(error) bool to middleware Params for error classification
- Modify withBreaker to only report filtered errors as CB failures
- Only store lastError for CB-relevant errors (so rejection message shows timeout)
- Add filteredFailures metric to distinguish CB failures from total failures
- Wire IsTimeoutError as the error filter in host_queue.go
- Add unit and integration tests for error filtering behavior
Test Plan:
go test ./src/dbnode/client/circuitbreaker/middleware/... -v
go test ./src/dbnode/client/ -run TestHostQueueCircuitBreaker -v
Fixes #
Special notes for your reviewer:
Does this PR introduce a user-facing and/or backwards incompatible change?:
Does this PR require updating code package or user-facing documentation?: