目標

解釋async關(guān)鍵字原理, 同時舉例說明協(xié)程中斷, 并交出控制權(quán)

例子說明

跟yield from的實現(xiàn)一樣, 每一行程序都是按順序一步一步執(zhí)行的，如果有程序不是按順序執(zhí)行，表示曾經(jīng)交出了控制權(quán)，以下的例子，本來應(yīng)該應(yīng)該順序輸出1,2，但是因為req1交出了控制權(quán)，所以，輸出了2,1

import time
from collections import deque

from asynciox.taskx import sleep

_delay = deque()


def sleep1():
def sleep01():
yield
return None
co = sleep01.__code__
sleep01.__code__ = co.replace(co_flags=co.co_flags | 0x100)
return sleep01()


def coroutine(func):
co = func.__code__
func.__code__ = co.replace(co_flags=co.co_flags | 0x100)
return func


@coroutine
def sleep0():
'''
裝飾器@：可以理解為 sleep0=coroutine(sleep0),意思就是sleep0函數(shù)執(zhí)行之前，
先調(diào)用coroutine方法執(zhí)行一段內(nèi)容之后，再把sleep0返回來
'''
yield
return None


async def req1():
b = await sleep0()
return 1


async def req2():
return 2


f1 = req1()
try:
result = f1.send(None)
except StopIteration as e:
print(f'正常打印 {e.value}')
pass
else:
_delay.append((f1, 1+time.time()))

f = req2()
try:
f.send(None)
except StopIteration as e:
print(f'正常打印 {e.value}')
pass

for i, v in _delay:
start = v
while True:
end = time.time()
if start < end:
try:
result = i.send(None)
except StopIteration as e:
print(f'延遲打印 {e.value}')
pass
break
pass

'''
結(jié)果:
正常打印 2
延遲打印 1
'''


審核編輯：劉清