熔断机制的实战：高并发下怎么优雅“断电”保命？

import time
import random

class CircuitBreaker:
    def __init__(self, failure_threshold=3, recovery_timeout=5):
        self.failure_count = 0
        self.failure_threshold = failure_threshold
        self.last_failure_time = None
        self.state = 'CLOSED'  # CLOSED, OPEN, HALF-OPEN
        self.recovery_timeout = recovery_timeout

    def call(self, func, *args, **kwargs):
        current_time = time.time()

        # OPEN 状态，检查是否可以转 HALF-OPEN
        if self.state == 'OPEN':
            if current_time - self.last_failure_time >= self.recovery_timeout:
                self.state = 'HALF-OPEN'
            else:
                raise Exception('CircuitBreaker is OPEN')

        try:
            result = func(*args, **kwargs)
        except Exception:
            self.failure_count += 1
            self.last_failure_time = current_time
            if self.failure_count >= self.failure_threshold:
                self.state = 'OPEN'
            raise
        else:
            if self.state == 'HALF-OPEN':
                self.state = 'CLOSED'
                self.failure_count = 0
            return result

# 模拟一个有概率失败的外部服务
def slow_service():
    if random.random() < 0.5:
        raise Exception("Service failed")
    return "Success"

cb = CircuitBreaker()

for i in range(10):
    try:
        print(f"Attempt {i+1}: {cb.call(slow_service)}")
    except Exception as e:
        print(f"Attempt {i+1} Failed: {e}")
    time.sleep(1)