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fawce
122 lines
3.7 KiB
Python
122 lines
3.7 KiB
Python
"""
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Commonly used messaging components.
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"""
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import json
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import uuid
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import zmq
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import util as qutil
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class ParallelBuffer(object):
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""" holds several queues of events by key, allows retrieval in date order
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or by merging"""
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def __init__(self, key_list):
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self.out_socket = None
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self.sent_count = 0
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self.received_count = 0
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self.draining = False
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self.data_buffer = {}
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for key in key_list:
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self.data_buffer[key] = []
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def __len__(self):
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return len(self.data_buffer)
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def append(self, key, value):
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self.data_buffer[key].append(value)
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self.received_count += 1
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def next(self):
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if(not(self.is_full() or self.draining)):
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return
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cur = None
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earliest = None
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for source, events in self.data_buffer.iteritems():
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if len(events) == 0:
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continue
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cur = events
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if(earliest == None) or (cur[0]['dt'] <= earliest[0]['dt']):
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earliest = cur
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if(earliest != None):
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return earliest.pop(0)
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def is_full(self):
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for source, events in self.data_buffer.iteritems():
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if (len(events) == 0):
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return False
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return True
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def pending_messages(self):
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total = 0
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for source, events in self.data_buffer.iteritems():
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total += len(events)
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return total
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def drain(self):
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self.draining = True
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while(self.pending_messages() > 0):
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self.send_next()
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def send_next(self):
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if(not(self.is_full() or self.draining)):
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return
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event = self.next()
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if(event != None):
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self.out_socket.send(json.dumps(event))
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self.sent_count += 1
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class MergedParallelBuffer(ParallelBuffer):
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"""
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Merges multiple streams of events into single messages.
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"""
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def __init__(self, keys):
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ParallelBuffer.__init__(self, keys)
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self.feed = []
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self.data_buffer["feed"] = self.feed
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def next(self):
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"""Get the next merged message from the feed buffer."""
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if(not(self.is_full() or self.draining)):
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return
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result = self.feed.pop(0)
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for source, events in self.data_buffer.iteritems():
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if(source == "feed"):
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continue
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if(len(events) > 0):
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cur = events.pop(0)
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result[source] = cur['value']
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return result
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class FeedSync(object):
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"""FeedSync instances register themselves with a DataFeed. Once the FeedSync
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is created, the DataFeed is guaranteed to block until confirm is called on this
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instance (and all others registered with the feed). Components can use instances
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to delay the start of the feed until initial setup is complete."""
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def __init__(self, feed, name):
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self.feed = feed
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self.id = "{name}-{id}".format(name=name, id=uuid.uuid1())
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self.feed.register_sync(self.id)
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#qutil.logger.info("registered {id} with feed".format(id=self.id))
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def confirm(self):
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"""Confirm readiness with the DataFeed."""
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context = zmq.Context()
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#synchronize with feed
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sync_socket = context.socket(zmq.REQ)
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sync_socket.connect(self.feed.sync_address)
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# send a synchronization request to the feed
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sync_socket.send(self.id)
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# wait for synchronization reply from the feed
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sync_socket.recv()
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sync_socket.close()
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context.term()
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qutil.logger.info("sync'd feed from {id}".format(id = self.id))
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