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Mini Shell
Mini Shell
from typing import Iterable
from ..packet_builder import QuicSentPacket
from .base import (
K_MINIMUM_WINDOW,
QuicCongestionControl,
QuicRttMonitor,
register_congestion_control,
)
K_LOSS_REDUCTION_FACTOR = 0.5
class RenoCongestionControl(QuicCongestionControl):
"""
New Reno congestion control.
"""
def __init__(self, *, max_datagram_size: int) -> None:
super().__init__(max_datagram_size=max_datagram_size)
self._max_datagram_size = max_datagram_size
self._congestion_recovery_start_time = 0.0
self._congestion_stash = 0
self._rtt_monitor = QuicRttMonitor()
def on_packet_acked(self, *, now: float, packet: QuicSentPacket) -> None:
self.bytes_in_flight -= packet.sent_bytes
# don't increase window in congestion recovery
if packet.sent_time <= self._congestion_recovery_start_time:
return
if self.ssthresh is None or self.congestion_window < self.ssthresh:
# slow start
self.congestion_window += packet.sent_bytes
else:
# congestion avoidance
self._congestion_stash += packet.sent_bytes
count = self._congestion_stash // self.congestion_window
if count:
self._congestion_stash -= count * self.congestion_window
self.congestion_window += count * self._max_datagram_size
def on_packet_sent(self, *, packet: QuicSentPacket) -> None:
self.bytes_in_flight += packet.sent_bytes
def on_packets_expired(self, *, packets: Iterable[QuicSentPacket]) -> None:
for packet in packets:
self.bytes_in_flight -= packet.sent_bytes
def on_packets_lost(self, *, now: float, packets: Iterable[QuicSentPacket]) -> None:
lost_largest_time = 0.0
for packet in packets:
self.bytes_in_flight -= packet.sent_bytes
lost_largest_time = packet.sent_time
# start a new congestion event if packet was sent after the
# start of the previous congestion recovery period.
if lost_largest_time > self._congestion_recovery_start_time:
self._congestion_recovery_start_time = now
self.congestion_window = max(
int(self.congestion_window * K_LOSS_REDUCTION_FACTOR),
K_MINIMUM_WINDOW * self._max_datagram_size,
)
self.ssthresh = self.congestion_window
# TODO : collapse congestion window if persistent congestion
def on_rtt_measurement(self, *, now: float, rtt: float) -> None:
# check whether we should exit slow start
if self.ssthresh is None and self._rtt_monitor.is_rtt_increasing(
now=now, rtt=rtt
):
self.ssthresh = self.congestion_window
register_congestion_control("reno", RenoCongestionControl)
Zerion Mini Shell 1.0