如何在龍捲風中使用多個ioloop並在ioloop（s）之間共享數據？

Question

我有一個Beaglebone黑色連接到CAN總線設備：電池。

作爲GUI在Beaglebone Black上運行的龍捲風網頁。

CAN總線讀取循環不斷從CAN總線讀取數據更新電池例如

的狀態，但我怎樣才能使兩個IOLOOP攜手共進，共享電池組的實例？

龍捲風網絡：

class Battery(object): 
    status = {} 



class API_Handler(web.RequestHandler): 
    def get(self, dev, cmd): 
     if cmd == 'data': 
      self.write(self.application.battery0.status) 


class Application(web.Application): 
    def __init__(self): 

     self.battery0 = Battery('bat0')  

     routing = [ 
      (r'/api/battery/(data|)', API_Handler), 
     ] 

     settings = { 
      'template_path': os.path.join(os.path.dirname(__file__), "templates"), 
      'static_path': os.path.join(os.path.dirname(__file__), "static"), 
     } 

     web.Application.__init__(self, routing, debug=True, **settings) 


if __name__ == "__main__": 
    import tornado 

    app = Application() 
    app.listen(address='0.0.0.0', port=8888) 
    tornado.ioloop.IOLoop.instance().start() 

CAN總線讀取循環，代碼：

#!/usr/bin/env python 
# -*- coding: utf-8 -*- 
import errno 
import functools 
import tornado.ioloop 
import socket 
import struct 


can_frame_fmt = "=IB3x8s" 
can_frame_size = struct.calcsize(can_frame_fmt) 

def build_can_frame(can_id, data): 
    can_dlc = len(data) 
    data = data.ljust(8, b'\x00') 
    return struct.pack(can_frame_fmt, can_id, can_dlc, data) 

def dissect_can_frame(frame): 
    can_id, can_dlc, data = struct.unpack(can_frame_fmt, frame) 
    return (can_id, can_dlc, data[:can_dlc]) 

def connection_ready(sock, fd, events): 
    while True: 
     try: 
      cf, addr = sock.recvfrom(can_frame_size) 
     except socket.error as e: 
      if e.args[0] not in (errno.EWOULDBLOCK, errno.EAGAIN): 
       raise 
      return 
     dissect_can_frame(cf) 


if __name__ == '__main__': 
    sock = socket.socket(socket.AF_CAN, socket.SOCK_RAW, socket.CAN_RAW) 
    sock.bind(('can0',)) 
    sock.setblocking(0) 

    io_loop = tornado.ioloop.IOLoop.current() 
    callback = functools.partial(connection_ready, sock) 
    io_loop.add_handler(sock.fileno(), callback, io_loop.READ) 
    io_loop.start() 

Answer 1

，我可以看到你正在運行的應用程序，所以這將是難以共享電池實例。第一個解決方案 - 將一個應用程序中的所有功能組合在一起，以便Battery實例可以簡單使用，但是您將面臨一個挑戰，即在一個ioloop中服務HTTP請求和處理來自CAN的套接字事件。

所以這裏是另一個解決方案，保留兩個應用程序，但不嘗試共享一個Battery實例，只需從CAN監聽器向您的GUI應用程序發出http請求。

例如，在CAN文件：

from tornado.httpclient import AsyncHTTPClient 

... 

def connection_ready(sock, fd, events): 
    while True: 
     try: 
      cf, addr = sock.recvfrom(can_frame_size) 
     except socket.error as e: 
      if e.args[0] not in (errno.EWOULDBLOCK, errno.EAGAIN): 
       raise 
      return 
     http_client = AsyncHTTPClient() 
     http_client.fetch("http://localhost:8888/update-battery", 
          method="POST", 
          body="can_id={}&can_dlc={}&data={}".format(
           dissect_can_frame(cf))) 

會更好，如果你有數據字節使用進行urlencode從蟒蛇urllib to encode body。

在GUI文件：

class Battery_Update_Handler(web.RequestHandler): 
    def post(self): 
     self.application.battery0.status = dict(
      can_id=self.get_argument("can_id", None), 
      can_dlc=self.get_argument("can_dlc", None), 
      data=self.get_argument("data", None)) 


class Application(web.Application): 
    def __init__(self): 

     self.battery0 = Battery('bat0')  

     routing = [ 
      (r'/api/battery/(data|)', API_Handler), 
      (r'/update-battery', Battery_Update_Handler) 
     ] 

     settings = { 
      'template_path': os.path.join(os.path.dirname(__file__), "templates"), 
      'static_path': os.path.join(os.path.dirname(__file__), "static"), 
     } 

     web.Application.__init__(self, routing, debug=True, **settings)