在asyncio.Protocol.data_received中调用协同程序

Question

我asyncio.Protocol.data_received在新的Python asyncio模块的回调中执行异步操作时遇到问题.

考虑以下服务器:

class MathServer(asyncio.Protocol):

   @asyncio.coroutine
   def slow_sqrt(self, x):
      yield from asyncio.sleep(1)
      return math.sqrt(x)

   def fast_sqrt(self, x):
      return math.sqrt(x)

   def connection_made(self, transport):
      self.transport = transport

   #@asyncio.coroutine
   def data_received(self, data):
      print('data received: {}'.format(data.decode()))
      x = json.loads(data.decode())
      #res = self.fast_sqrt(x)
      res = yield from self.slow_sqrt(x)
      self.transport.write(json.dumps(res).encode('utf8'))
      self.transport.close()

与以下客户一起使用:

class MathClient(asyncio.Protocol):

   def connection_made(self, transport):
      transport.write(json.dumps(2.).encode('utf8'))

   def data_received(self, data):
      print('data received: {}'.format(data.decode()))

   def connection_lost(self, exc):
      asyncio.get_event_loop().stop()

随着self.fast_sqrt被召唤,一切都按预期工作.

有self.slow_sqrt,它不起作用.

它也不适用self.fast_sqrt于@asyncio.coroutine装饰器data_received.

我觉得我在这里缺少一些基本的东西.

完整的代码在这里:

• 服务器
• 客户

经测试:

• Python 3.4.0b1(Windows)
• Python 3.3.3 + asyncio-0.2.1(FreeBSD)

两者的问题是相同的:在slow_sqrt,客户端/服务器只会挂起什么都不做.

Answer 1

看起来,这需要通过一个解耦Future- 尽管我仍然不确定这是否是正确的方法.

class MathServer(asyncio.Protocol):

   @asyncio.coroutine
   def slow_sqrt(self, x):
      yield from asyncio.sleep(2)
      return math.sqrt(x)

   def fast_sqrt(self, x):
      return math.sqrt(x)

   def consume(self):
      while True:
         self.waiter = asyncio.Future()
         yield from self.waiter
         while len(self.receive_queue):
            data = self.receive_queue.popleft()
            if self.transport:
               try:
                  res = self.process(data)
                  if isinstance(res, asyncio.Future) or \
                     inspect.isgenerator(res):
                     res = yield from res
               except Exception as e:
                  print(e)

   def connection_made(self, transport):
      self.transport = transport
      self.receive_queue = deque()
      asyncio.Task(self.consume())

   def data_received(self, data):
      self.receive_queue.append(data)
      if not self.waiter.done():
         self.waiter.set_result(None)
      print("data_received {} {}".format(len(data), len(self.receive_queue)))

   def process(self, data):
      x = json.loads(data.decode())
      #res = self.fast_sqrt(x)
      res = yield from self.slow_sqrt(x)
      self.transport.write(json.dumps(res).encode('utf8'))
      #self.transport.close()

   def connection_lost(self, exc):
      self.transport = None

以下是Guido van Rossum 的回答:

解决方案很简单:将该逻辑编写为标记为的单独方法@coroutine,并在data_received()使用时将 其触发async()(== Task()在本例中).之所以没有内置到协议中的原因是,如果是,则需要备用事件循环实现来处理协同程序.

def data_received(self, data):
    asyncio.ensure_future(self.process_data(data))

@asyncio.coroutine
def process_data(self, data):
    # ...stuff using yield from...

完整代码在这里: - 客户端 - 服务器