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subscriber.py
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subscriber.py
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"""
This module provides a client subscription class that holds all the basic API
methods for subscribing to a data stream.
"""
import zmq
import sys
import json
import reciever
import multiprocessing
import requests
import logging
def sub_print(stream_id, data, state, log, ctrl):
"""!@brief Default stream data callback. Prints data.
@param stream_id data stream id
@param data data to be printed
@param log logging object
"""
log.info("[{}]: {}".format(stream_id, data))
return state
def poller_loop(sub_addr, queue):
log = logging.getLogger('poller')
log.setLevel(logging.DEBUG)
ch = logging.StreamHandler()
ch.setLevel(logging.DEBUG)
formatter = logging.Formatter('%(asctime)s - %(name)s - %(levelname)s - %(message)s')
ch.setFormatter(formatter)
log.addHandler(ch)
# a hash table (dict) of callbacks to perform when a message is recieved
# the hash is the data stream filter, the value is a list of callbacks
subscriptions = {}
#a dict shows which channel is subscribed and unsubscribed:
sub_list = {}
#subscription is a dict
context = zmq.Context()
sub_sock = context.socket(zmq.SUB)
# listen for one second, before doing housekeeping
sub_sock.setsockopt(zmq.RCVTIMEO, 1000)
sub_sock.connect(sub_addr)
# cmd = {
# 'action': 'SUBSCRIBE',
# 'stream_filter': stream_filter,
# 'callback': callback,
# 'kwargs': kwargs,
# }
while True:
try:
#get command from command queue
cmd = queue.get_nowait()
if cmd['action'] == 'SHUTDOWN':
break
if cmd['action'] == 'SUBSCRIBE':
msg = 'Subscribing with stream filter: [{}]'
stream_filter = cmd['stream_filter']
log.info(msg.format(stream_filter))
# add the callback to the list of things to do for the stream
if stream_filter not in subscriptions:
subscriptions[stream_filter] = []
#stream_filter is assigned as a key with an empty list
sub_sock.setsockopt_string(zmq.SUBSCRIBE, stream_filter)
subscriptions[stream_filter].append({
'callback': cmd['callback'],
'kwargs': cmd['kwargs'],
'state': {},
'control': {'alert': True, 'pause': False},
'id': cmd['id']
})
# add subscribed channel info to dict
#sub_list = {1:{'kwargs':{kwargs}, 'control':{control}}
sub_list[cmd['id']] = {
'kwargs': cmd['kwargs'],
'control': {'alert': True, 'pause': False}
}
log.info("subscriptions: {}".format(subscriptions[stream_filter]))
if cmd['action'] == 'UPDATE_KW':
msg = 'Updating channel...'
log.info(msg.format(cmd['stream_filter']))
for cb in subscriptions[stream_filter]:
if cb['id'] == cmd['id']:
cb['kwargs'] = cmd['kwargs']
#sub_list = {1:{'kwargs':{kwargs}, 'control':{control}}
sub_list[cmd['id']]={
'control': cb['control'],
'kwargs': cmd['kwargs']
}
log.info("subscriptions: {}".format(subscriptions[stream_filter]))
if (cmd['action'] == 'UNSUBSCRIBE' or
cmd['action'] == 'REMOVE_ALL_CBS'):
msg = 'Unsubscribing to stream filter: [{}]'
log.info(msg.format(cmd['stream_filter']))
sub_sock.setsockopt_string(zmq.UNSUBSCRIBE, stream_filter)
if (cmd['action'] == 'UNSUBSCRIBE_ALL'):
msg = 'Unsubscribing to all streams'
log.info(msg)
for stream_filter in subscriptions:
sub_sock.setsockopt_string(zmq.UNSUBSCRIBE, stream_filter)
subscriptions = {}
if cmd['action'] == 'REMOVE_ALL_CBS':
msg = 'Removing all callbacks for stream filter: [{}]'
log.info(msg.format(cmd['stream_filter']))
del subscriptions[cmd['stream_filter']]
if cmd['action'] == 'RESET':
msg = 'Resetting channel'
log.info(msg.format(cmd['stream_filter']))
for cb in subscriptions[stream_filter]:
#cb is a dict with all the info of each channel subscribed
#stream_filter is a list of all the cb dict.
if cb['id'] == cmd['id']:
cb['state']={}
log.info("subscriptions: {}".format(subscriptions[stream_filter]))
if cmd['action'] == 'RESET_ALL':
msg = 'Resetting all channels'
log.info(msg.format(cmd['stream_filter']))
for cb in subscriptions[stream_filter]:
#cb is a dict with all the info of each channel subscribed
#stream_filter is a list of all the cb dict.
cb['state']={}
log.info("subscriptions: {}".format(subscriptions[stream_filter]))
if (cmd['action'] == 'MUTE' or
cmd['action'] == 'UNMUTE'):
msg = 'Muted channel alert'
log.info(msg.format(cmd['stream_filter']))
for cb in subscriptions[stream_filter]:
if cb['id'] == cmd['id']:
cb['control']['alert'] = (cmd['action'] == 'UNMUTE')
sub_list[cmd['id']]={
'control': cb['control'],
'kwargs': cb['kwargs']
}
if (cmd['action'] == 'MUTE_ALL' or
cmd['action'] == 'UNMUTE_ALL'):
msg = 'Muted/Unmuted all channel alert'
log.info(msg.format(cmd['stream_filter']))
for cb in subscriptions[stream_filter]:
cb['control']['alert'] = (cmd['action'] == 'UNMUTE_ALL')
sub_list[cb['id']]={
'control': cb['control'],
'kwargs': cb['kwargs']
}
if (cmd['action'] == 'PAUSE_ALL' or
cmd['action'] == 'RESTART_ALL'):
msg = 'Paused/ Restarted all channels'
log.info(msg.format(cmd['stream_filter']))
for cb in subscriptions[stream_filter]:
cb['control']['pause'] = (cmd['action'] == 'PAUSE_ALL')
sub_list[cb['id']]={
'control': cb['control'],
'kwargs': cb['kwargs']
}
if (cmd['action'] == 'PAUSE' or
cmd['action'] == 'RESTART'):
msg = 'Paused/Restarted this channel'
log.info(msg.format(cmd['stream_filter']))
for cb in subscriptions[stream_filter]:
if cb['id'] == cmd['id']:
cb['control']['pause'] = (cmd['action'] == 'PAUSE')
sub_list[cmd['id']]={
'control': cb['control'],
'kwargs': cb['kwargs']
}
sub_list_json = json.dumps(sub_list)
try:
requests.put('http://127.0.0.1:5000/monitor', json=sub_list_json)
except IOError:
log.error('no monitor port found')
except multiprocessing.queues.Empty:
pass
except IOError:
log.exception('IOError, probably a broken pipe. Exiting..')
sys.exit(1)
except:
log.exception("error encountered")
try:
[streamID, content] = sub_sock.recv_multipart()
#a change from python 2 to 3
try:
streamID = streamID.decode('utf-8')
except AttributeError:
#this will happen when the origin server gets converted to python 3
#i think, maybe
log.exception('streamID does not need to be decoded anymore')
try:
for cb in subscriptions[streamID]:
if cb['control']['pause'] == False:
cb['state'] = cb['callback'](
streamID, json.loads(content),
cb['state'], log, cb['control'], **cb['kwargs']
)
else:
pass
except KeyError:
msg = "An unrecognized streamID `{}` was encountered"
log.error(msg.format(streamID))
log.error(subscriptions)
except zmq.ZMQError as e:
if e.errno != zmq.EAGAIN:
log.exception("zmq error encountered")
except:
log.exception("error encountered")
log.info('Shutting down poller loop.')
sub_sock.close()
context.term()
class Subscriber(reciever.Reciever):
"""!@brief A class representing a data stream subscription to a data server
"""
def __init__(self, config, logger, loop=poller_loop):
"""!@brief Initialize the subscriber
@param config configuration object
@param logger python logging object
@param loop custom poller loop
"""
# call the parent class initialization
super(Subscriber, self).__init__(config, logger)
# we need the read socket for this class so we can get stream defs
self.connect(self.read_sock, self.read_port)
# request the available streams from the server
self.get_available_streams()
# set up queue for inter-process communication
self.queue = multiprocessing.Queue()
# start process
sub_addr = "tcp://{}:{}".format(self.ip, self.sub_port)
#setup a process as obj.loop for poller-loop
self.loop = multiprocessing.Process(
target=loop,
args=(sub_addr, self.queue)
)
#start loop process every time subscriber class is called
self.loop.start()
self.id_list=[]
self.last_index=0
def close(self):
super(Subscriber, self).close()
self.send_command({'action': 'SHUTDOWN'})
def subscribe(self, stream, callback=None, **kwargs):
"""!@brief Subscribe to a data stream and assign a callback
You can subscribe to multiple data streams simultaneously using the
same socket.
Just call subscribe again with a new filter.
You can also register multiple callbacks for the same stream, by
calling subscribe again.
The callback has to be a standalone function, not a class method or it
will throw an error.
@param stream A string holding the stream name
@param callback A callback function that expects a python dict with
data
@return success True if the data stream subscription was successful,
False otherwise
"""
try:
stream_filter = self.get_stream_filter(stream)
self.id = self.get_id()
except KeyError:
msg = "No stream matching string: `{}` found."
self.log.error(msg.format(stream))
return False
msg = "Subscribing to stream: {} [{}]"
self.log.info(msg.format(stream, stream_filter))
# default is a function that just prints the data as it comes in
if callback is None:
callback = sub_print
# send subscription info to the poller loop
#kwargs is a dict including all the keyword parameters needed
cmd = {
'action': 'SUBSCRIBE',
'stream_filter': stream_filter,
'callback': callback,
'kwargs': kwargs,
'id' : self.get_id(),
}
self.log.info('sending cmd to process: {}'.format(cmd))
self.send_command(cmd)
def get_stream_filter(self, stream):
"""!@brief Make the appropriate stream filter to subscribe to a stream
@param stream A string holding the stream name
@return stream_filter A string holding the filter to subscribe to the
resquested data stream
"""
stream_id = str(self.known_streams[stream]['id'])
# ascii to unicode str
stream_id = stream_id.zfill(self.filter_len)
self.log.info(stream_id)
return stream_id
def remove_callbacks(self, stream):
"""Remove all callbacks associate with the given stream.
Calling this leaves the callbacks associated with the data stream.
Call remove_callbacks if you want to remove the callbacks.
@param stream A string holding the stream name
"""
stream_filter = self.get_stream_filter(stream)
self.send_command({
'action': 'REMOVE_ALL_CBS',
'stream_filter': stream_filter,
})
def unsubscribe(self, stream, i):
"""Unsubscribe from stream at the publisher.
Calling this leaves the callbacks associated with the data stream.
Call remove_callbacks if you want to remove the callbacks.
@param stream A string holding the stream name
"""
stream_filter = self.get_stream_filter(stream)
self.send_command({
'action': 'UNSUBSCRIBE',
'stream_filter': stream_filter,
})
def unsubscribe_all(self):
"""Unsubscribe from stream at the publisher.
Calling this leaves the callbacks associated with the data stream.
Call remove_callbacks if you want to remove the callbacks.
@param stream A string holding the stream name
"""
self.send_command({
'action': 'UNSUBSCRIBE_ALL',
'stream_filter': None,
})
def reset(self, stream, id):
stream_filter = self.get_stream_filter(stream)
self.send_command({
'action': 'RESET',
'stream_filter': stream_filter,
'id': id
})
def reset_all(self, stream):
stream_filter = self.get_stream_filter(stream)
self.send_command({
'action': 'RESET_ALL',
'stream_filter': stream_filter,
})
def update(self, stream, id, **kwargs):
stream_filter = self.get_stream_filter(stream)
self.send_command({
'action': 'UPDATE_KW',
'stream_filter': stream_filter,
'kwargs': kwargs,
'id': id
})
def mute(self, stream, id):
stream_filter = self.get_stream_filter(stream)
self.send_command({
'action': 'MUTE',
'stream_filter': stream_filter,
'id': id
})
def unmute(self, stream, id):
stream_filter = self.get_stream_filter(stream)
self.send_command({
'action': 'UNMUTE',
'stream_filter': stream_filter,
'id': id,
})
def mute_all(self, stream):
stream_filter = self.get_stream_filter(stream)
self.send_command({
'action': 'MUTE_ALL',
'stream_filter': stream_filter,
})
def unmute_all(self, stream):
stream_filter = self.get_stream_filter(stream)
self.send_command({
'action': 'UNMUTE_ALL',
'stream_filter': stream_filter,
})
def pause(self, stream, id):
stream_filter = self.get_stream_filter(stream)
self.send_command({
'action': 'PAUSE',
'stream_filter': stream_filter,
'id': id,
})
def pause_all(self, stream):
stream_filter = self.get_stream_filter(stream)
self.send_command({
'action': 'PAUSE_ALL',
'stream_filter': stream_filter,
})
def restart(self, stream, id):
stream_filter = self.get_stream_filter(stream)
self.send_command({
'action': 'RESTART',
'stream_filter': stream_filter,
'id': id,
})
def restart_all(self, stream):
stream_filter = self.get_stream_filter(stream)
self.send_command({
'action': 'RESTART_ALL',
'stream_filter': stream_filter,
})
def send_command(self, cmd):
#function/method to put command into a queue
self.queue.put(cmd)
def get_id(self):
#function to assign unique id index to each subscribed channel
while self.last_index in self.id_list:
self.last_index+=1
self.id_list.append(self.last_index)
return self.id_list[-1]