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#!/usr/bin/env python
#
# Copyright 2009 Facebook
#
# Licensed under the Apache License, Version 2.0 (the "License"); you may
# not use this file except in compliance with the License. You may obtain
# a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
# License for the specific language governing permissions and limitations
# under the License.
"""Simplified chat demo for websockets.
Authentication, error handling, etc are left as an exercise for the reader :)
"""
import asyncio
import logging
import tornado.escape
import tornado.options
import tornado.web
import tornado.websocket
import os.path
import uuid
from tornado.options import define, options
define("port", default=8888, help="run on the given port", type=int)
class Application(tornado.web.Application):
def __init__(self):
handlers = [(r"/", MainHandler), (r"/chatsocket", ChatSocketHandler)]
settings = dict(
cookie_secret="__TODO:_GENERATE_YOUR_OWN_RANDOM_VALUE_HERE__",
template_path=os.path.join(os.path.dirname(__file__), "templates"),
static_path=os.path.join(os.path.dirname(__file__), "static"),
xsrf_cookies=True,
)
super().__init__(handlers, **settings)
class MainHandler(tornado.web.RequestHandler):
def get(self):
self.render("index.html", messages=ChatSocketHandler.cache)
class ChatSocketHandler(tornado.websocket.WebSocketHandler):
waiters = set()
cache = []
cache_size = 200
def get_compression_options(self):
# Non-None enables compression with default options.
return {}
def open(self):
ChatSocketHandler.waiters.add(self)
def on_close(self):
ChatSocketHandler.waiters.remove(self)
@classmethod
def update_cache(cls, chat):
cls.cache.append(chat)
if len(cls.cache) > cls.cache_size:
cls.cache = cls.cache[-cls.cache_size :]
@classmethod
def send_updates(cls, chat):
logging.info("sending message to %d waiters", len(cls.waiters))
for waiter in cls.waiters:
try:
waiter.write_message(chat)
except:
logging.error("Error sending message", exc_info=True)
def on_message(self, message):
logging.info("got message %r", message)
parsed = tornado.escape.json_decode(message)
chat = {"id": str(uuid.uuid4()), "body": parsed["body"]}
chat["html"] = tornado.escape.to_basestring(
self.render_string("message.html", message=chat)
)
ChatSocketHandler.update_cache(chat)
ChatSocketHandler.send_updates(chat)
async def main():
tornado.options.parse_command_line()
app = Application()
app.listen(options.port)
await asyncio.Event().wait()
if __name__ == "__main__":
asyncio.run(main())
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