Example exponential backoff algorithm
- When a collision first occurs, send a "Jamming signal" to prevent further data from being sent.
- Resend a frame after either 0 seconds or 51.2 μs, chosen at random.
- If that fails, resend the frame after either 0 s, 51.2 μs, 102.4 μs, or 153.6 μs.
- If that still doesn't work, resend the frame after k · 51.2 μs, where k is a random integer between 0 and 23 − 1.
- In general, after the cth failed attempt, resend the frame after k · 51.2 μs, where k is a random integer between 0 and 2c − 1.
简单的 Python 实现，
import functools
import random
import time
def retry(tries, back_off=0.5):
def _retry(func):
@functools.wraps(func)
def wrapper(*args, **kwargs):
max_retries = tries
result = func(*args, **kwargs)
while max_retries > 0:
if result:
return result
max_retries -= 1
d = random.randint(0, (tries - max_retries) ** 2 - 1)
print(f"第{tries - max_retries}次重试,时间为{d}*0.5")
time.sleep(d * back_off)
result = func(*args, **kwargs)
return result
return wrapper
return _retry
@retry(5)
def get_response():
print("get http response")
if __name__ == '__main__':
get_response()
输出结果为
get http response
第1次重试,时间为0*0.5
get http response
第2次重试,时间为1*0.5
get http response
第3次重试,时间为7*0.5
get http response
第4次重试,时间为4*0.5
get http response
第5次重试,时间为10*0.5
get http response
设置的基本避退时间为 0.5 ，重试次数为 5
