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#!/usr/bin/env python
import asyncio
import json
import logging
from websockets.asyncio.server import broadcast, serve
logging.basicConfig()
USERS = set()
VALUE = 0
def users_event():
return json.dumps({"type": "users", "count": len(USERS)})
def value_event():
return json.dumps({"type": "value", "value": VALUE})
async def counter(websocket):
global USERS, VALUE
try:
# Register user
USERS.add(websocket)
broadcast(USERS, users_event())
# Send current state to user
await websocket.send(value_event())
# Manage state changes
async for message in websocket:
event = json.loads(message)
if event["action"] == "minus":
VALUE -= 1
broadcast(USERS, value_event())
elif event["action"] == "plus":
VALUE += 1
broadcast(USERS, value_event())
else:
logging.error("unsupported event: %s", event)
finally:
# Unregister user
USERS.remove(websocket)
broadcast(USERS, users_event())
async def main():
async with serve(counter, "localhost", 6789) as server:
await server.serve_forever()
if __name__ == "__main__":
asyncio.run(main())
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