2c4ae3b0a4
Содержимое пина, зафиксированного в go.mod sing-box-lx, одним коммитом без истории. Полная история SagerNet/gvisor — 1.45 ГБ и клонируется в каждой CI-джобе; наша дельта — одна вставка в одну функцию, история для неё не нужна. Module path github.com/sagernet/gvisor сохранён намеренно: на него опирается replace-директива суперпроекта. Патч поверх — отдельным коммитом, чтобы дельта читалась одним git show и переносилась на новый пин копированием. SPECS/TASKS/048-GVISOR_HANDSHAKE_NIL_CRASH
118 lines
3.5 KiB
Go
118 lines
3.5 KiB
Go
// Copyright 2018 The gVisor Authors.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package tcp
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import (
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"time"
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)
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// renoState stores the variables related to TCP New Reno congestion
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// control algorithm.
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//
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// +stateify savable
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type renoState struct {
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s *sender
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}
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// newRenoCC initializes the state for the NewReno congestion control algorithm.
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func newRenoCC(s *sender) *renoState {
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return &renoState{s: s}
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}
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// updateSlowStart will update the congestion window as per the slow-start
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// algorithm used by NewReno. If after adjusting the congestion window
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// we cross the SSthreshold then it will return the number of packets that
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// must be consumed in congestion avoidance mode.
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//
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// +checklocks:r.s.ep.mu
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func (r *renoState) updateSlowStart(packetsAcked int) int {
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// Don't let the congestion window cross into the congestion
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// avoidance range.
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newcwnd := r.s.SndCwnd + packetsAcked
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if newcwnd >= r.s.Ssthresh {
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newcwnd = r.s.Ssthresh
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r.s.SndCAAckCount = 0
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}
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packetsAcked -= newcwnd - r.s.SndCwnd
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r.s.SndCwnd = newcwnd
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return packetsAcked
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}
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// updateCongestionAvoidance will update congestion window in congestion
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// avoidance mode as described in RFC5681 section 3.1
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//
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// +checklocks:r.s.ep.mu
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func (r *renoState) updateCongestionAvoidance(packetsAcked int) {
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// Consume the packets in congestion avoidance mode.
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r.s.SndCAAckCount += packetsAcked
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if r.s.SndCAAckCount >= r.s.SndCwnd {
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r.s.SndCwnd += r.s.SndCAAckCount / r.s.SndCwnd
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r.s.SndCAAckCount = r.s.SndCAAckCount % r.s.SndCwnd
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}
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}
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// reduceSlowStartThreshold reduces the slow-start threshold per RFC 5681,
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// page 6, eq. 4. It is called when we detect congestion in the network.
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//
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// +checklocks:r.s.ep.mu
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func (r *renoState) reduceSlowStartThreshold() {
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r.s.Ssthresh = r.s.Outstanding / 2
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if r.s.Ssthresh < 2 {
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r.s.Ssthresh = 2
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}
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}
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// Update updates the congestion state based on the number of packets that
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// were acknowledged.
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// Update implements congestionControl.Update.
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//
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// +checklocks:r.s.ep.mu
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func (r *renoState) Update(packetsAcked int, _ time.Duration) {
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if r.s.SndCwnd < r.s.Ssthresh {
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packetsAcked = r.updateSlowStart(packetsAcked)
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if packetsAcked == 0 {
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return
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}
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}
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r.updateCongestionAvoidance(packetsAcked)
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}
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// HandleLossDetected implements congestionControl.HandleLossDetected.
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//
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// +checklocks:r.s.ep.mu
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func (r *renoState) HandleLossDetected() {
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// A retransmit was triggered due to nDupAckThreshold or when RACK
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// detected loss. Reduce our slow start threshold.
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r.reduceSlowStartThreshold()
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}
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// HandleRTOExpired implements congestionControl.HandleRTOExpired.
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//
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// +checklocks:r.s.ep.mu
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func (r *renoState) HandleRTOExpired() {
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// We lost a packet, so reduce ssthresh.
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r.reduceSlowStartThreshold()
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// Reduce the congestion window to 1, i.e., enter slow-start. Per
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// RFC 5681, page 7, we must use 1 regardless of the value of the
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// initial congestion window.
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r.s.SndCwnd = 1
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}
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// PostRecovery implements congestionControl.PostRecovery.
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func (r *renoState) PostRecovery() {
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// noop.
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}
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