def start_streaming(self, timeout=10):
'''
Starts data streaming from the server, using the following algorithm:
1. Waits until start/data message arrives or timeout is over
2. If start message arrived, initializes buffer
3. Spawns a background process for data streaming
4. Releases
Parameters
----------
timeout : float, optional
time to wait for a start message (in seconds)
'''
if self.is_streaming:
raise Exception('already streaming')
self.logger.info('waiting for an rda start message...')
hdr = rdadefs.rda_msg_hdr_t()
then = time.time()
now = time.time()
while now - then < timeout:
n = self.sock.recv_into(hdr)
rdatools.check_received(n, hdr)
if not rdatools.validate_rda_guid(hdr):
self.logger.warning('packet with unknown GUID reveived')
if hdr.nType == rdadefs.RDA_START_MSG:
self.start_msg = rdatools.rda_read_start_msg(self.sock, hdr)
self.logger.info('start message received, ' + \
rdatools.startmsg2string(self.start_msg))
break
elif hdr.nType == rdadefs.RDA_FLOAT_MSG and self.start_msg:
self.sock.recv(hdr.nSize - c.sizeof(hdr))
self.logger.info('trying to resume previous session...')
break
else:
self.sock.recv(hdr.nSize - c.sizeof(hdr))
self.logger.info('skipped package (type = %s)' % hdr.nType)
now = time.time()
if not self.__buf.is_initialized:
self.logger.info('initializing buffer...')
self.__buf.initialize(int(self.start_msg.nChannels),
self.buffer_size,
self.buffer_window,
self.data_dtype)
self.logger.info('spawning a streamer process...')
self.__streamer = Streamer(self.q, self.sock.fileno(), self.__buf.raw)
self.__streamer._daemonic = True
self.__streamer.start()
def run(self):
'''
The main streaming loop.
'''
cmd = self.__get_cmd()
hdr = rdadefs.rda_msg_hdr_t()
self.logger.info('started streaming')
# Ignore Ctrl+C. The process is run in the daemonic mode, so if the
# Client terminates, the streamer will be terminated anyway. This
# ignoring however, allows for custom Ctrl+C handling in the
# Client process to gracefully stop both the Client and the Streamer
signal.signal(signal.SIGINT, signal.SIG_IGN)
# stream until there's a stop command
while cmd != 'stop':
n = self.sock.recv_into(hdr)
rdatools.check_received(n, hdr)
# check for a proper packet ID
if not rdatools.validate_rda_guid(hdr):
self.logger.warning('packet with unknown GUID reveived')
if hdr.nType == rdadefs.RDA_FLOAT_MSG:
msg = rdatools.rda_read_data_msg(self.sock, hdr, self.__buf.nChannels)
self.__put_datablock(msg)
# skip the weird undocumented package
elif hdr.nType == 10000:
self.sock.recv(hdr.nSize - c.sizeof(hdr))
elif hdr.nType == rdadefs.RDA_STOP_MSG:
self.logger.info('stop message received, stopping...')
self.q.put('stop')
time.sleep(.5)
else:
self.sock.recv(hdr.nSize - c.sizeof(hdr))
self.logger.info('skipped package (type = %s)' % hdr.nType)
cmd = self.__get_cmd()
self.logger.info('stopped streaming')
# execute the last command before exiting
cmd = self.__get_cmd()
self.__execute_cmd(cmd)
