Language: Python · Sphere: system-administration · Category: Wave 6 · Resource guards & quotas
Signature: (failure_threshold: int, recovery_timeout: float) → ?
Circuit breaker that stops calling a failing dependency.
Wraps a callable (as decorator or via call()) and tracks failures: after the threshold trips it opens and fails fast without invoking the callable, then after a recovery timeout enters half-open to probe once — a success closes and resets, a failure re-opens. Use it to prevent cascading failures against a flaky downstream service. Guarantees (self-test oracle): the threshold count opens the circuit, an open breaker does not call the wrapped function, a half-open failure re-opens while a success closes and zeroes the count, and exceptions outside the expected type pass through without tripping it.
When it runs, circuit breaker guarantees breaker.state == 'open'; short_circuits >= 80; breaker.failure_count >= 10 (weak-grade: directional, proven by run).
Checkable constraints:
breaker.state == 'open'short_circuits >= 80breaker.failure_count >= 10
- Green-run: ✓ passes (re-run under the extractor's gate)
- Constraint strength: weak (directional)
- Independent oracle: ✓ hard — positive, xlang (validator v1.9)
- Peer review: unreviewed
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