def new_timestamp_group(self, timestamp: int, arrival_time: int) -> bool:
if self.belongs_to_burst(timestamp, arrival_time):
return False
else:
timestamp_delta = uint32_add(timestamp,
-self.current_group.first_timestamp)
return timestamp_delta > self.group_length
def compute_deltas(self, timestamp: int, arrival_time: int,
packet_size: int) -> Optional[InterArrivalDelta]:
deltas = None
if self.current_group is None:
self.current_group = TimestampGroup(timestamp)
elif self.packet_out_of_order(timestamp):
return deltas
elif self.new_timestamp_group(timestamp, arrival_time):
if self.previous_group is not None:
deltas = InterArrivalDelta(
timestamp=uint32_add(
self.current_group.last_timestamp,
-self.previous_group.last_timestamp,
),
arrival_time=(self.current_group.arrival_time -
self.previous_group.arrival_time),
size=self.current_group.size - self.previous_group.size,
)
# shift groups
self.previous_group = self.current_group
self.current_group = TimestampGroup(timestamp=timestamp)
elif uint32_gt(timestamp, self.current_group.last_timestamp):
self.current_group.last_timestamp = timestamp
self.current_group.size += packet_size
self.current_group.arrival_time = arrival_time
return deltas
def belongs_to_burst(self, timestamp: int, arrival_time: int) -> bool:
timestamp_delta = uint32_add(timestamp,
-self.current_group.last_timestamp)
timestamp_delta_ms = round(self.timestamp_to_ms * timestamp_delta)
arrival_time_delta = arrival_time - self.current_group.arrival_time
return timestamp_delta_ms == 0 or (
(arrival_time_delta - timestamp_delta_ms) < 0
and arrival_time_delta <= BURST_DELTA_THRESHOLD_MS)
def test_uint32_add(self):
self.assertEqual(uint32_add(0, 1), 1)
self.assertEqual(uint32_add(1, 1), 2)
self.assertEqual(uint32_add(1, 2), 3)
self.assertEqual(uint32_add(4294967294, 1), 4294967295)
self.assertEqual(uint32_add(4294967295, 1), 0)
self.assertEqual(uint32_add(4294967295, 3), 2)
def packet_out_of_order(self, timestamp: int) -> bool:
timestamp_delta = uint32_add(timestamp,
-self.current_group.first_timestamp)
return timestamp_delta >= 0x80000000
