class Thread(threading.Thread):
def __init__(self, tty=TTY, baud_rate=BAUD_RATE, logger=None, *args,
**kwargs):
if logger is None:
self.logger = logging.getLogger('blipper.thread')
else:
self.logger = logger
super(Thread, self).__init__(*args, **kwargs)
self.tty = tty
self.baud_rate = baud_rate
self.ser = Serial(self.tty, self.baud_rate)
self.ser.nonblocking()
self.daemon = True
self._handlers = defaultdict(list)
self._should_exit = False
self.waiting_for_packet = False
def on(self, packet_type, handler):
"""Register a handler for the given packet type.
If there are multiple handlers for a packet type, at most one
should return a response. If no handler returns a response, a
default OK response will be sent back.
"""
self._handlers[packet_type].append(handler)
def off(self, packet_type, handler):
packet_handlers = self._handlers.get(packet_type, [])
new_handlers = [h for h in packet_handlers if h != handler]
self._handlers[packet_type] = new_handlers
def send(self, packet):
self.ser.write(bytes(packet))
self.logger.debug('sent %r', packet)
def get_packet(self):
self.waiting_for_packet = True
data = self.ser.read(Header.length)
header = unpack_header(data)
body = self.ser.read(header.body_length)
cs = self.ser.read(1)
self.waiting_for_packet = False
cs_cmp = get_checksum(body)
if cs != cs_cmp:
raise PacketError("invalid body checksum")
packet = packet_types[header.cmd].from_body(body)
self.logger.debug('got %r', packet)
return packet
def run(self):
while True:
try:
packet = self.get_packet()
response = None
packet_handlers = self._handlers.get(type(packet), [])
for handler in packet_handlers:
handler_response = handler(packet)
if handler_response:
if response:
raise MultipleResponses
else:
response = handler_response
if response is None:
response = packet.default_response()
if response is not None:
self.ser.write(bytes(response))
except Exception as e:
if self._should_exit: # exception expected
break
else:
raise e
def join(self, timeout=None):
self._should_exit = True
self.ser.close()
super(Thread, self).join(timeout)
