134 lines
3.6 KiB
Python
134 lines
3.6 KiB
Python
from __future__ import annotations
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import time
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from enum import Enum
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class CircuitBreakerState(Enum):
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CLOSED = "closed"
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OPEN = "open"
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HALF_OPEN = "half_open"
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class CircuitBreaker:
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"""标准断路器，冷却后自动半开。"""
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def __init__(
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self,
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name: str,
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failure_threshold: int = 5,
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cooldown_seconds: float = 30.0,
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) -> None:
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self.name = name
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self.failure_threshold = failure_threshold
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self.cooldown_seconds = cooldown_seconds
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self._state = CircuitBreakerState.CLOSED
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self._failure_count = 0
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self._last_failure_time: float = 0.0
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@property
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def state(self) -> CircuitBreakerState:
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if (
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self._state == CircuitBreakerState.OPEN
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and time.monotonic() - self._last_failure_time >= self.cooldown_seconds
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):
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self._state = CircuitBreakerState.HALF_OPEN
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return self._state
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def record_success(self) -> None:
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self._failure_count = 0
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self._state = CircuitBreakerState.CLOSED
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def record_failure(self) -> None:
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self._failure_count += 1
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self._last_failure_time = time.monotonic()
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if self._failure_count >= self.failure_threshold:
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self._state = CircuitBreakerState.OPEN
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def allow_request(self) -> bool:
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return self.state != CircuitBreakerState.OPEN
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class RetryStrategy:
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"""指数退避重试。"""
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def __init__(
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self,
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max_retries: int = 3,
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base_delay: float = 1.0,
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max_delay: float = 60.0,
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multiplier: float = 2.0,
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) -> None:
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self.max_retries = max_retries
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self.base_delay = base_delay
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self.max_delay = max_delay
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self.multiplier = multiplier
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def should_retry(self, attempt_index: int) -> bool:
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return attempt_index < self.max_retries
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def get_delay(self, attempt_index: int) -> float:
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delay = self.base_delay * (self.multiplier**attempt_index)
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return min(delay, self.max_delay)
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class DowngradeAction:
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"""降级链中的一个步骤。"""
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def __init__(self, type: str, target: str) -> None: # noqa: A002
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self.type = type # "fallback_endpoint", "fallback_model", "cache", "degrade_quality"
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self.target = target
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class DowngradeChain:
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"""当模型/端点失败时的降级动作链。"""
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def __init__(self, actions: list[DowngradeAction]) -> None:
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self._actions = actions
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self._index = 0
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def next_action(self) -> tuple[str, str] | None:
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if self._index >= len(self._actions):
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return None
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action = self._actions[self._index]
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return (action.type, action.target)
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def advance(self) -> None:
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self._index += 1
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def is_exhausted(self) -> bool:
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return self._index >= len(self._actions)
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def reset(self) -> None:
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self._index = 0
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class ResilienceFactory:
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"""弹性组件工厂。"""
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@staticmethod
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def create_circuit_breaker(
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name: str,
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failure_threshold: int = 5,
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cooldown_seconds: float = 30.0,
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) -> CircuitBreaker:
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return CircuitBreaker(
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name=name,
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failure_threshold=failure_threshold,
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cooldown_seconds=cooldown_seconds,
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)
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@staticmethod
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def create_retry_strategy(
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max_retries: int = 3,
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base_delay: float = 1.0,
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max_delay: float = 60.0,
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multiplier: float = 2.0,
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) -> RetryStrategy:
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return RetryStrategy(
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max_retries=max_retries,
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base_delay=base_delay,
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max_delay=max_delay,
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multiplier=multiplier,
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)
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