Pathetically simplify retransmit timings.
This commit is contained in:
Dan Williams
parent
4dca6521aa
commit
96a90ca32c
@ -324,6 +324,7 @@ class Message(object):
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self._last_incoming_time = 0
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self._segments = {}
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self._complete = False
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self._dispatched_time = 0
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self._data = None
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self._data_sha = None
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self._src_addr = src_addr
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@ -359,20 +360,18 @@ class Message(object):
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return i
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return 0
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_DEF_RT_REQUEST_INTERVAL = 500
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_DEF_RT_REQUEST_INTERVAL = 0.09 # 70ms (in seconds)
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def update_rt_wait(self, now):
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"""now argument should be in seconds."""
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wait = self._DEF_RT_REQUEST_INTERVAL
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if self._last_incoming_time > now - 0.02:
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msg_completeness = float(len(self._segments)) / float(self._total_segments)
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next = self._DEF_RT_REQUEST_INTERVAL * (1.1 - msg_completeness)
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rt_penalty = 100
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first_missing = self.first_missing()
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if first_missing:
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rt_penalty = self._rt_tries[first_missing] * 100
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# print "** msg_comp: %s, next: %d, rt_penalty: %s, rt: %s" % (msg_completeness, next, rt_penalty, (float(next + rt_penalty) / 1000))
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next = next + rt_penalty
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self._next_rt_time = now + (float(next) * .001)
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wait = wait + (self._DEF_RT_REQUEST_INTERVAL * (1.0 - msg_completeness))
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self._next_rt_time = now + wait
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def add_segment(self, segment):
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if self.complete():
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return
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segno = segment.segment_number()
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if self._segments.has_key(segno):
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return
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@ -382,13 +381,15 @@ class Message(object):
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self._last_incoming_time = now
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num_segs = len(self._segments)
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if num_segs == segment.total_segments():
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if num_segs == self._total_segments:
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self._complete = True
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self._next_rt_time = 0
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self._data = ''
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for seg in self._segments.values():
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self._data = self._data + seg.data()
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self._data_sha = _sha_data(self._data)
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else:
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elif segno == num_segs or num_segs == 1:
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# If we're not missing segments, push back retransmit request
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self.update_rt_wait(now)
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def get_retransmit_message(self, msg_seq_num, segno):
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@ -403,6 +404,12 @@ class Message(object):
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def complete(self):
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return self._complete
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def dispatch_time(self):
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return self._dispatch_time
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def set_dispatch_time(self):
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self._dispatch_time = time.time()
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def data(self):
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return (self._data, self._data_sha)
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@ -441,6 +448,7 @@ class MostlyReliablePipe(object):
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self._sent = {}
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self._incoming = {} # (message sha, # of segments) -> [segment1, segment2, ...]
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self._dispatched = {}
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self._setup_listener()
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self._setup_sender()
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@ -483,18 +491,19 @@ class MostlyReliablePipe(object):
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# Watch the listener socket for data
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gobject.io_add_watch(self._listen_sock, gobject.IO_IN, self._handle_incoming_data)
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gobject.timeout_add(self._SEGMENT_TTL * 1000, self._segment_ttl_worker)
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gobject.timeout_add(250, self._retransmit_check_worker)
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gobject.timeout_add(50, self._retransmit_check_worker)
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self._started = True
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def _segment_ttl_worker(self):
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"""Cull already-sent message segments that are past their TTL."""
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now = time.time()
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for segment in self._sent[:]:
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for key in self._sent.keys()[:]:
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segment = self._sent[key]
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if segment.stime() < now - self._SEGMENT_TTL:
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if segment.userdata:
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gobject.source_remove(segment.userdata)
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self._sent.remove(segment)
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del self._sent[key]
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# Cull incomplete incoming segment chains that haven't gotten any data
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# for a long time either
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@ -502,11 +511,14 @@ class MostlyReliablePipe(object):
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message = self._incoming[msg_key]
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if message.last_incoming_time() < now - self._SEGMENT_TTL:
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del self._incoming[msg_key]
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return True
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def _dispatch_message(self, addr, message):
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"""Send complete message data to the owner's data callback."""
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self._data_cb(addr, message, self._user_data)
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# Remove already dispatched messages after a while
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for msg_key in self._dispatched.keys()[:]:
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message = self._dispatched[msg_key]
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if message.dispatch_time() < now - (self._SEGMENT_TTL*2):
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del self._dispatched[msg_key]
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return True
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_MAX_SEGMENT_RETRIES = 10
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def _retransmit_request(self, message):
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@ -519,7 +531,7 @@ class MostlyReliablePipe(object):
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msg_seq = self._next_msg_seq()
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seg = message.get_retransmit_message(msg_seq, first_missing)
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if seg:
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print " Requesting retransmit of %d by %s" % (first_missing, message.source_address())
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print "(MRP): Requesting retransmit of %d by %s" % (first_missing, message.source_address())
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self._outgoing.append(seg)
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self._schedule_send_worker()
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return False
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@ -530,10 +542,14 @@ class MostlyReliablePipe(object):
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message = self._incoming[key]
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if message.complete():
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continue
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if message.next_rt_time() < now:
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next_rt = message.next_rt_time()
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if next_rt == 0 or next_rt > now:
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continue
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if self._retransmit_request(message):
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# Kill the message, too many retries
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print "Dropped message %s, exceeded retries." % _stringify_sha(message.sha())
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print "(MRP): Dropped message %s, exceeded retries." % _stringify_sha(message.sha())
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self._dispatched[key] = message
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message.set_dispatch_time()
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del self._incoming[key]
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return True
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@ -550,16 +566,13 @@ class MostlyReliablePipe(object):
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addr = segment.address()
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segno = segment.segment_number()
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# Short-circuit single-segment messages
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if segno == 1 and nsegs == 1:
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# Ensure the header's master sha actually equals the data's sha
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if msg_sha == _sha_data(segment.data()):
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self._dispatch_message(addr, segment.data())
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return
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# Otherwise, track the new segment
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msg_seq_num = segment.message_sequence_number()
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msg_key = (addr[0], msg_seq_num, msg_sha, nsegs)
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if self._dispatched.has_key(msg_key):
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# We already dispatched this message, this segment is useless
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return
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# First segment in the message
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if not self._incoming.has_key(msg_key):
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self._incoming[msg_key] = Message((addr[0], self._port), msg_seq_num, msg_sha, nsegs)
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@ -573,20 +586,12 @@ class MostlyReliablePipe(object):
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if message.complete():
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(msg_data, complete_data_sha) = message.data()
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if msg_sha == complete_data_sha:
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self._dispatch_message(addr, msg_data)
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self._data_cb(addr, msg_data, self._user_data)
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self._dispatched[msg_key] = message
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message.set_dispatch_time()
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del self._incoming[msg_key]
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return
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_STD_RETRANSMIT_INTERVAL = 150 # in milliseconds
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def _calc_next_retransmit(self, segment, now):
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"""Calculate the next time (in seconds) that a packet can be retransmitted."""
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num_retrans = segment.transmits() - 1
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interval = num_retrans * self._STD_RETRANSMIT_INTERVAL
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randomness = num_retrans * ((random.random() * 15) - 5)
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real_interval = max(self._STD_RETRANSMIT_INTERVAL, interval + randomness)
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# print "------ Interval %s" % (real_interval * .001)
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return max(now, segment.last_transmit() + (real_interval * .001))
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def _segment_retransmit_cb(self, key, segment):
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"""Add a segment ot the outgoing queue and schedule its transmission."""
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del self._sent[key]
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@ -594,22 +599,22 @@ class MostlyReliablePipe(object):
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self._schedule_send_worker()
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return False
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def _schedule_segment_retransmit(self, key, segment, when):
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def _schedule_segment_retransmit(self, key, segment, when, now):
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"""Schedule retransmission of a segment if one is not already scheduled."""
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if segment.userdata:
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# Already scheduled for retransmit
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return
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if when == 0:
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if when <= now:
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# Immediate retransmission
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segment.userdata = gobject.idle_add(self._segment_retransmit_cb, key, segment)
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self._segment_retransmit_cb(key, segment)
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else:
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# convert time to milliseconds
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timeout = int((when - time.time()) * 1000)
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print "RT timeout: %s" % timeout
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timeout = int((when - now) * 1000)
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segment.userdata = gobject.timeout_add(timeout, self._segment_retransmit_cb,
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key, segment)
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_STD_RETRANSMIT_INTERVAL = 0.05 # 50ms (in seconds)
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def _process_retransmit_request(self, segment):
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"""Validate and process a retransmission request."""
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key = (segment.rt_msg_seq_num(), segment.rt_master_sha(), segment.rt_segment_number())
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@ -619,9 +624,10 @@ class MostlyReliablePipe(object):
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# Calculate next retransmission time and schedule packet for retransmit
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segment = self._sent[key]
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# only retransmit segments every 150ms or more
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now = time.time()
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next_retrans = self._calc_next_retransmit(segment, now)
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self._schedule_segment_retransmit(key, segment, next_retrans - now)
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next_transmit = max(now, segment.last_transmit() + self._STD_RETRANSMIT_INTERVAL)
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self._schedule_segment_retransmit(key, segment, next_transmit, now)
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def set_drop_probability(self, prob=4):
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"""Debugging function to randomly drop incoming packets.
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@ -645,7 +651,7 @@ class MostlyReliablePipe(object):
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try:
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segment = SegmentBase.new_from_data(addr, data)
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if should_drop:
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print "Dropped segment %d (p (%s) < %s)." % (segment.segment_number(), p, self._drop_prob)
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print "(MRP): Dropped segment %d." % segment.segment_number()
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else:
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stype = segment.segment_type()
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if stype == SegmentBase.type_data():
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@ -653,7 +659,7 @@ class MostlyReliablePipe(object):
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elif stype == SegmentBase.type_retransmit():
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self._process_retransmit_request(segment)
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except ValueError, exc:
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print "Bad segment: %s" % exc
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print "(MRP): Bad segment: %s" % exc
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return True
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def _next_msg_seq(self):
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@ -692,11 +698,12 @@ class MostlyReliablePipe(object):
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def _schedule_send_worker(self):
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if len(self._outgoing) > 0 and self._send_worker == 0:
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self._send_worker = gobject.idle_add(self._send_worker_cb)
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self._send_worker = gobject.timeout_add(50, self._send_worker_cb)
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def _send_worker_cb(self):
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"""Send all queued segments that have yet to be transmitted."""
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self._send_worker = 0
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nsent = 0
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for segment in self._outgoing:
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packet = segment.packetize()
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segment.inc_transmits()
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@ -709,7 +716,12 @@ class MostlyReliablePipe(object):
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segment.userdata = None # Retransmission GSource
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key = (segment.message_sequence_number(), segment.master_sha(), segment.segment_number())
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self._sent[key] = segment
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self._outgoing = []
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nsent = nsent + 1
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if nsent > 10:
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break
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self._outgoing = self._outgoing[nsent:]
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if len(self._outgoing):
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self._schedule_send_worker()
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return False
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@ -1036,7 +1048,7 @@ class SHAUtilsTestCase(unittest.TestCase):
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def main():
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def foobar():
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suite = unittest.TestSuite()
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SegmentBaseInitTestCase.addToSuite(suite)
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DataSegmentTestCase.addToSuite(suite)
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@ -1049,12 +1061,19 @@ def main():
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def got_data(addr, data, user_data=None):
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print "Data (%s): %s" % (addr, data)
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print "Got data from %s, writing to %s." % (addr, user_data)
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fl = open(user_data, "w+")
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fl.write(data)
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fl.close()
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def retry_test():
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pipe = MostlyReliablePipe('', '224.0.0.222', 2293, got_data)
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pipe.set_drop_probability(3)
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def main():
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import sys
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pipe = MostlyReliablePipe('', '224.0.0.222', 2293, got_data, sys.argv[2])
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# pipe.set_drop_probability(4)
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pipe.start()
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fl = open(sys.argv[1], "r")
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data = fl.read()
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fl.close()
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msg = """The said Eliza, John, and Georgiana were now clustered round their mama in the drawing-room:
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she lay reclined on a sofa by the fireside, and with her darlings about her (for the time neither
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quarrelling nor crying) looked perfectly happy. Me, she had dispensed from joining the group; saying,
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@ -1063,7 +1082,7 @@ Bessie, and could discover by her own observation, that I was endeavouring in go
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a more sociable and childlike disposition, a more attractive and sprightly manner -- something lighter,
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franker, more natural, as it were -- she really must exclude me from privileges intended only for
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contented, happy, little children.'"""
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pipe.send(msg)
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pipe.send(data)
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try:
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gtk.main()
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except KeyboardInterrupt:
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