Add optional open-circuit fallback callable#105
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- Add asyncio.Lock (lazy, thread-safe) and async acall() on CircuitBreaker - Implement state.acall with awaitable support; reject sync/async generators - CircuitOpenState.acall delegates to half-open without re-entering acall - Tests: CircuitBreakerAsyncioTestCase (stdlib asyncio.run) - CHANGELOG: unreleased 1.5.0 note; .gitignore .venv-ci/ Made-with: Cursor
- Add __pybreaker_call_acall kwarg to decorator, wrapping async functions via acall - Raise ValueError when both __pybreaker_call_async and __pybreaker_call_acall are set - Add "Native asyncio (stdlib)" section to README with usage examples - Update features list in README - Tests: decorator wrapping, partial application, mutual exclusion guard Made-with: Cursor
Allow users to pass a `fallback` callable to CircuitBreaker that is invoked with the original arguments when the circuit is open, instead of raising CircuitBreakerError. Works for both sync `call` and async `acall` paths. The fallback is purely opt-in — omitting it preserves existing raise-on-open behaviour. Made-with: Cursor
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Summary
Adds an optional
fallbackparameter toCircuitBreaker. When the circuit is open and a fallback is provided, it is called with the original arguments instead of raisingCircuitBreakerError. Works for both sync (call) and async (acall) paths, including awaiting async fallbacks. Purely opt-in — omitting it preserves existing raise-on-open behaviour.Depends on #103 and the decorator/docs PR being merged first.
What changed
CircuitBreaker.__init__acceptsfallback: Callable | None._open_circuit_fallback_or_raise(sync) and_open_circuit_fallback_or_raise_asyncmethods.CircuitOpenState.before_callandCircuitOpenState.acalldelegate to fallback helpers when the timeout has not elapsed.fallbackread-only property.tests/typechecks.pyupdated for mypy coverage.Test plan