为何心跳包必不可少？
...
import socket, threading, time
UDP_PORT = 43278; CHECK_PERIOD = 20; CHECK_TIMEOUT = 15
class Heartbeats(dict):
def _ _init_ _(self):
super(Heartbeats, self)._ _init_ _( )
self._lock = threading.Lock( )
def _ _setitem_ _(self, key, value):
self._lock.acquire( )
try:
super(Heartbeats, self)._ _setitem_ _(key, value)
finally:
self._lock.release( )
def getSilent(self):
limit = time.time( ) - CHECK_TIMEOUT
self._lock.acquire( )
try:
silent = [ip for (ip, ipTime) in self.items( ) if ipTime < limit]
finally:
self._lock.release( )
return silent
class Receiver(threading.Thread):
def _ _init_ _(self, goOnEvent, heartbeats):
super(Receiver, self)._ _init_ _( )
self.goOnEvent = goOnEvent
self.heartbeats = heartbeats
self.recSocket = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
self.recSocket.settimeout(CHECK_TIMEOUT)
self.recSocket.bind(('', UDP_PORT))
def run(self):
while self.goOnEvent.isSet( ):
try:
data, addr = self.recSocket.recvfrom(5)
if data == 'PyHB':
self.heartbeats[addr[0]] = time.time( )
except socket.timeout:
pass
def main(num_receivers=3):
receiverEvent = threading.Event( )
receiverEvent.set( )
heartbeats = Heartbeats( )
receivers = [ ]
for i in range(num_receivers):
receiver = Receiver(goOnEvent=receiverEvent, heartbeats=heartbeats)
receiver.start( )
receivers.append(receiver)
print 'Threaded heartbeat server listening on port %d' % UDP_PORT
print 'press Ctrl-C to stop'
try:
while True:
silent = heartbeats.getSilent( )
print 'Silent clients: %s' % silent
time.sleep(CHECK_PERIOD)
except KeyboardInterrupt:
print 'Exiting, please wait...'
receiverEvent.clear( )
for receiver in receivers:
receiver.join( )
print 'Finished.'
if _ _name_ _ == '_ _main_ _':
main( )