userver.py

# userver.py Demo of simple uasyncio-based echo server

# Released under the MIT licence
# Copyright (c) Peter Hinch 2019-2020

import usocket as socket
import asyncio
import uselect as select
import ujson
from heartbeat import heartbeat  # Optional LED flash


class Server:
    def __init__(self, host="0.0.0.0", port=8123, backlog=5, timeout=20):
        self.host = host
        self.port = port
        self.backlog = backlog
        self.timeout = timeout

    async def run(self):
        print("Awaiting client connection.")
        self.cid = 0
        asyncio.create_task(heartbeat(100))
        self.server = await asyncio.start_server(
            self.run_client, self.host, self.port, self.backlog
        )
        while True:
            await asyncio.sleep(100)

    async def run_client(self, sreader, swriter):
        self.cid += 1
        print("Got connection from client", self.cid)
        try:
            while True:
                try:
                    res = await asyncio.wait_for(sreader.readline(), self.timeout)
                except asyncio.TimeoutError:
                    res = b""
                if res == b"":
                    raise OSError
                print("Received {} from client {}".format(ujson.loads(res.rstrip()), self.cid))
                swriter.write(res)
                await swriter.drain()  # Echo back
        except OSError:
            pass
        print("Client {} disconnect.".format(self.cid))
        await sreader.wait_closed()
        print("Client {} socket closed.".format(self.cid))

    async def close(self):
        print("Closing server")
        self.server.close()
        await self.server.wait_closed()
        print("Server closed.")


server = Server()
try:
    asyncio.run(server.run())
except KeyboardInterrupt:
    print("Interrupted")  # This mechanism doesn't work on Unix build.
finally:
    asyncio.run(server.close())
    _ = asyncio.new_event_loop()