[英]In a no-coroutine function, how do you get a return value from coroutine function of Tornado TCP?
I wrote 3 sections of code with Tornado TCP. 我用Tornado TCP编写了3部分代码。 I've encountered some difficulties.
我遇到了一些困难。
My code is following: 我的代码如下:
client.py client.py
'''tcp client'''
from socket import socket, AF_INET, SOCK_STREAM
s = socket(AF_INET, SOCK_STREAM)
s.connect(('localhost', 20000))
resp = s.recv(8192)
print('Response:', resp)
s.send(b'Hello\n')
s.close()
server.py server.py
'''tcp server'''
#! /usr/bin/env python
#coding=utf-8
from tornado.tcpserver import TCPServer
from tornado.ioloop import IOLoop
from tornado.gen import *
clientDict=dict() #save infomation of client
class TcpConnection(object):
def __init__(self,stream,address):
self._stream=stream
self._address=address
self._stream.set_close_callback(self.on_close)
@coroutine
def send_messages(self):
yield self.send_message(b'world \n')
response = yield self.read_message()
return response
def read_message(self):
return self._stream.read_until(b'\n')
def send_message(self,data):
return self._stream.write(data)
def on_close(self):
global clientDict
clientDict.pop(self._address)
print("the monitored %d has left",self._address)
class MonitorServer(TCPServer):
@coroutine
def handle_stream(self,stream,address):
global clientDict
print("new connection",address,stream)
clientDict.setdefault(address, TcpConnection(stream,address))
if __name__=='__main__':
print('server start .....')
server=MonitorServer()
server.listen(20000)
IOLoop.instance().start()
main.py main.py
import time
from threading import Thread
import copy
from server import *
def watchClient():
'''call the "send" function when a new client connect''
global clientDict
print('start watch')
lastClientList=list()
while True:
currentClientList=copy.deepcopy([key for key in clientDict.keys()])
difference=list(set(currentClientList).difference(set(lastClientList)))
if len(difference)>0:
send(difference)
lastClientList=copy.deepcopy(currentClientList)
time.sleep(5)
else:
time.sleep(5)
continue
def send(addressList):
'''send message to a new client and get response'''
global clientDict
for address in addressList:
response=clientDict[address].send_messages()
print(address," response :",response)
def listen():
server=MonitorServer()
server.listen(20000)
IOLoop.instance().start()
if __name__=='__main__':
listenThread=Thread(target=listen)
watchThead=Thread(target=watchClient)
watchThead.start()
listenThread.start()
I want to get the "print information" when the main.py is run--- address,response:b'hello\\n' 我想在main.py运行时获取“打印信息” --- 地址,响应:b'hello \\ n'
But in fact I get the "print information" as ---- 但实际上我得到的“打印信息”为----
('127.0.0.1', 41233) response :<tornado.concurrent.Future object at 0x7f2894d30518>
It can't return the b'hello\\n' . 它无法返回b'hello \\ n' 。
Then I guess it can't get the response reasonably in the no-coroutine function( def send(addressList) ) from the coroutine function( @coroutine def send_messages(self) ). 然后我猜想它不能从协程函数( @coroutine def send_messages(self) )在no-协程函数( def send(addressList) )中合理地获得响应。
How to solve this? 如何解决呢?
By the way, I want to know how to make the clientDict to be a property of the class MonitorServer ,not a global property. 顺便说一句,我想知道如何使clientDict成为MonitorServer类的属性,而不是全局属性。 Please help me!
请帮我! Thank you.
谢谢。
In general, anything that calls a coroutine should be a coroutine itself. 通常,任何称为协程的东西都应该是协程本身。 Mixing threads and coroutines can be very tricky;
混合线程和协程可能非常棘手。 most coroutine-based code is deliberately not thread-safe.
大多数基于协程的代码故意不是线程安全的。
The correct way to call a coroutine from a non-coroutine function on a different thread is something like this: 从不同线程上的非协程函数调用协程的正确方法是这样的:
def call_coro_from_thread(f, *args, **kwargs):
q = queue.Queue()
def wrapper():
fut = f(*args, **kwargs)
fut.add_done_callback(q.put)
IOLoop.instance().add_callback(wrapper)
fut = q.get()
return fut.result()
IOLoop.add_callback
is necessary to safely transfer control to the IOLoop thread, and then the Queue is used to transfer the result back. IOLoop.add_callback
是将控制安全地传输到IOLoop线程所必需的,然后使用Queue来将结果传输回去。
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