Geek Answers Handbook

Python Tornado updates shared data between requests

I have a Python Tornado application. The application contains request handlers for which I pass data (for example, the code below is not complete and just illustrates what I want):

configs = {'some_data': 1, # etc.
          }

class Application(tornado.web.Application):
    def __init__(self):
        handlers = [('/pageone', PageOneHandler, configs),
                    ('/pagetwo', PageTwoHandler, configs)]
        settings = dict(template_path='/templates',
                    static_path='/static', debug=False)
        tornado.web.Application.__init__(self, handlers, **settings)

# Run the instance
# ... code goes here ...
application = Application()
http_server = tornado.httpserver.HTTPServer(application)
# ... other code (bind to port, etc.)

# Callback function to update configs
some_time_period = 1000 # Once an second
tornado.ioloop.PeriodicCallback(update_configs, some_time_period).start()
tornado.ioloop.IOLoop.instance().start()

I want the function to update_configsupdate the variable configsdefined above, and this transmission is propagated through the handlers. For example (I know this does not work):

def update_configs():
    configs['some_data'] += 1

# Now, assuming PageOneHandler just prints out configs['some_data'], I'd expect
# the output to be: "1" on the first load, "2" if I load the page a second
# later, "4" if I load the page two seconds after that, etc.

The problem is that the variable configsis passed along with the handlers during creation in the class constructor Application. How to update configs['some_data']in periodic callback function?

My actual use case for this mechanism is to update the data stored in the dictionary configsfrom the database so often.

, application.handlers ( )?

+4
2

, config dict , dict. dicts , , dict, :

import tornado.web
import tornado.httpserver

configs = {'some_data': 1, # etc.
          }

def update_configs():
    print("updating")
    configs['some_data'] += 1

class PageOneHandler(tornado.web.RequestHandler):
    def initialize(self, configs):
        self.configs = configs
    def get(self):
        self.write(str(self.configs) + "\n")


class PageTwoHandler(tornado.web.RequestHandler):
    def initialize(self, configs):
        self.configs = configs

    def get(self):
        self.write(str(self.configs) + "\n")


class Application(tornado.web.Application):
    def __init__(self):
        handlers = [('/pageone', PageOneHandler, {'configs' : configs}),
                ('/pagetwo', PageTwoHandler, {'configs': configs})]
        settings = dict(template_path='/templates',
                    static_path='/static', debug=False)
        tornado.web.Application.__init__(self, handlers, **settings)

# Run the instance
application = Application()
http_server = tornado.httpserver.HTTPServer(application)
http_server.listen(8888)

# Callback function to update configs
some_time_period = 1000 # Once an second
tornado.ioloop.PeriodicCallback(update_configs, some_time_period).start()
tornado.ioloop.IOLoop.instance().start()

:

dan@dantop:~> curl localhost:8888/pageone
{'some_data': 2}
dan@dantop:~> curl localhost:8888/pageone
{'some_data': 3}
dan@dantop:~> curl localhost:8888/pagetwo
{'some_data': 4}
dan@dantop:~> curl localhost:8888/pageone
{'some_data': 4}

; , configs, RequestHandler, , RequsetHandlers, PeriodicCallback. , X , . , , dict, .

+2

, , , Application.

class MyApplication(tornado.web.Application):

    def __init__(self):

       self.shared_attribute = foo;

        handlers = [#your handlers here]        
        settings = dict(#your application settings here)
        super().__init__(handlers, **settings)


server = tornado.httpserver.HTTPServer(MyApplication())
server.listen(8888)
tornado.ioloop.IOLoop.instance().start()

shared_attribute, , request handlers, self.application.shared_attribute.

.

+3

More articles:


All Articles