如何检查asyncio循环是否有任何关联的套接字

Question

asyncio.Task.all_tasks（）给出了一个事件循环的所有任务的列表，但我找不到任何类似的套接字，特别是与数据报关联的套接字一个循环？

没有插座&任务然后可以表示循环的“生命结束”。

的问题是，在下面的例子中，要放什么loop_not_empty()，使得它返回False当任务设置为空和没有关联的插座（即两秒钟后）

例子：

import asyncio 
import socket 
import threading 

class Handler(asyncio.Protocol): 
    def connection_made(self, transport): 
     self.transport = transport 
     print("connection made") 

    def datagram_received(self, data, addr): 
     if data == b'die': 
      print("shutting down") 
      self.transport.abort() 

@asyncio.coroutine 
def sometask(): 
    yield from asyncio.sleep(1) 
    print("task done") 

def loop_not_empty(l): 
    # if asyncio.Task.all_tasks() == set() and WHAT_GOES_HERE 
    # return False 
    return True 

def main(): 
    a,b = socket.socketpair(socket.AF_UNIX, socket.SOCK_DGRAM) 

    l = asyncio.get_event_loop() 

    asyncio.ensure_future(sometask(), loop=l) 
    asyncio.ensure_future(l.create_datagram_endpoint(Handler, sock=a), loop=l) 

    threading.Timer(2, lambda: b.send(b'die')).start() 

    while loop_not_empty(l): 
     l.run_until_complete(asyncio.sleep(1, loop=l)) 

main() 

Answer 1

下面是一个使用一个简单的类和asyncio.Event()计数活动作业的数量和信号回路停止时，所有的工作都做了一个解决方案：

import asyncio 

import random 


class UseCounter: 
    def __init__(self, loop=None): 
     self.loop = loop 
     self.event = asyncio.Event(loop=loop) 
     self.n = 0 # The number of active jobs 

    def __enter__(self): 
     self.enter() 

    def __exit__(self, exc_type, exc_val, exc_tb): 
     self.exit() 

    def enter(self): 
     self.n += 1 

    def exit(self): 
     self.n -= 1 
     if self.n == 0: 
      self.event.set() 

    async def wait(self): 
     return await self.event.wait() 


async def my_coroutine(counter, term): 
    with counter: 
     print("start", term) 
     n = random.uniform(0.2, 1.5) 
     await asyncio.sleep(n) 
     print("end", term) 


loop = asyncio.get_event_loop() 
counter = UseCounter(loop) 
terms = ["apple", "banana", "melon"] 
for term in terms: 
    asyncio.ensure_future(my_coroutine(counter, term)) 

loop.run_until_complete(counter.wait()) 

loop.close() 

对于上述示例，请将.enter()添加到connection_made()和.exit()到connection_lost()。