breakers 0.1.0

Usable Circuit Breaker pattern implementation

Usable Circuit Breaker pattern implementation.

Install

$ pip install breakers

Usage

import functools
from breakers import Breaker

def circuit_breaker(time_span=20000, unit=1000, calls_limit=10,
                    error_limit=0.5, retry_time=10000):
    def deco(func):
        # Create breaker
        if not hasattr(func, '__breaker__'):
            func.__breaker__ = Breaker(time_span, unit, calls_limit,
                                       error_limit, retry_time)
        breaker = func.__breaker__

        @functools.wraps(func)
        def wraps(*args, **kwargs):
            if not breaker.is_allow():
                raise RuntimeError('Circuit breaker')

            exc = None
            try:
                return func(*args, **kwargs)
            except Exception as e:
                exc = e
                raise
            finally:
                if exc:
                    breaker.add_failure(1)
                else:
                    breaker.add_success(1)
        return wraps
    return deco

@circuit_breaker()
def f():
    import random
    if random.randint(1, 4) in (1, 2):
        raise ValueError
    return 'succeed'