PyHeartBeat example

pyheartbeat_client.py

import sys
import time
import socket
import asyncio

DEFAULT_IP   = '127.0.0.1' # local host, just for testing
DEFAULT_PORT = 43278       # an arbitrary UDP port
BEATWAIT     = 1           # number of seconds between heartbeats

async def main():
    ip = sys.argv[1] if len(sys.argv) > 1 else DEFAULT_IP
    port = sys.argv[2] if len(sys.argv) > 2 else DEFAULT_PORT

    print(f'PyHeartBeat client sending to IP {ip}, port {port}\n')
    print('*** Press Ctrl-C to terminate ***\n')

    s = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
    while True:
        s.sendto(b'Thump!', (ip, port))
        print('Time:', time.ctime(time.time()))
        await asyncio.sleep(BEATWAIT)

if __name__ == '__main__':
    try: asyncio.run(main())
    except KeyboardInterrupt: pass

pyheartbeat_server.py

import sys
import time
import socket
import threading

DEFAULT_PORT = 43278 # an arbitrary UDP port
DEFAULT_WAIT = 10    # number of seconds between heartbeats

class BeatReceiver(threading.Thread):
    "Receive UDP packets, log them in heartbeat dictionary"

    def __init__(self, port, expiry):
        super().__init__()
        self._expiry = expiry
        self._dict = dict()
        self._lock = threading.Lock()
        self._socket = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
        self._socket.bind(('', port))

    def __repr__(self):
        when = time.time() - self._expiry
        msg = 'IP address: {} - Last time: {}'
        with self._lock:
            items = filter(lambda x: x[1] >= when, self._dict.items())
            return '\n'.join(msg.format(k, time.ctime(v)) for k, v in items)

    def run(self):
        while True:
            try:
                _, addr = self._socket.recvfrom(6)
            except:
                return
            with self._lock:
                self._dict[addr[0]] = time.time()

    def stop(self):
        self._socket.shutdown(socket.SHUT_WR)
        self._socket.close()


def main():
    port = sys.argv[1] if len(sys.argv) > 1 else DEFAULT_PORT
    checkwait = sys.argv[2] if len(sys.argv) > 2 else DEFAULT_WAIT

    print(f'PyHeartBeat server listening on port {port}\n')
    print('*** Press Ctrl-C to stop ***\n')

    receiver = BeatReceiver(port, checkwait)
    receiver.start()
    while receiver.is_alive():
        try:
            time.sleep(checkwait)
            print('Active clients:')
            print(receiver)
        except KeyboardInterrupt:
            print('Exiting')
            receiver.stop()


if __name__ == '__main__':
    main()