sing-box/transport/hysteria/pacer.go
世界 d1c3dd0ee1
Add hysteria and acme TLS certificate issuer (#18)
* Add hysteria client/server
* Add acme TLS certificate issuer
2022-08-19 15:42:57 +08:00

87 lines
2.1 KiB
Go

package hysteria
import (
"math"
"time"
"github.com/sagernet/quic-go/congestion"
)
const (
maxBurstPackets = 10
minPacingDelay = time.Millisecond
)
// The pacer implements a token bucket pacing algorithm.
type pacer struct {
budgetAtLastSent congestion.ByteCount
maxDatagramSize congestion.ByteCount
lastSentTime time.Time
getBandwidth func() congestion.ByteCount // in bytes/s
}
func newPacer(getBandwidth func() congestion.ByteCount) *pacer {
p := &pacer{
budgetAtLastSent: maxBurstPackets * initMaxDatagramSize,
maxDatagramSize: initMaxDatagramSize,
getBandwidth: getBandwidth,
}
return p
}
func (p *pacer) SentPacket(sendTime time.Time, size congestion.ByteCount) {
budget := p.Budget(sendTime)
if size > budget {
p.budgetAtLastSent = 0
} else {
p.budgetAtLastSent = budget - size
}
p.lastSentTime = sendTime
}
func (p *pacer) Budget(now time.Time) congestion.ByteCount {
if p.lastSentTime.IsZero() {
return p.maxBurstSize()
}
budget := p.budgetAtLastSent + (p.getBandwidth()*congestion.ByteCount(now.Sub(p.lastSentTime).Nanoseconds()))/1e9
return minByteCount(p.maxBurstSize(), budget)
}
func (p *pacer) maxBurstSize() congestion.ByteCount {
return maxByteCount(
congestion.ByteCount((minPacingDelay+time.Millisecond).Nanoseconds())*p.getBandwidth()/1e9,
maxBurstPackets*p.maxDatagramSize,
)
}
// TimeUntilSend returns when the next packet should be sent.
// It returns the zero value of time.Time if a packet can be sent immediately.
func (p *pacer) TimeUntilSend() time.Time {
if p.budgetAtLastSent >= p.maxDatagramSize {
return time.Time{}
}
return p.lastSentTime.Add(maxDuration(
minPacingDelay,
time.Duration(math.Ceil(float64(p.maxDatagramSize-p.budgetAtLastSent)*1e9/
float64(p.getBandwidth())))*time.Nanosecond,
))
}
func (p *pacer) SetMaxDatagramSize(s congestion.ByteCount) {
p.maxDatagramSize = s
}
func maxByteCount(a, b congestion.ByteCount) congestion.ByteCount {
if a < b {
return b
}
return a
}
func minByteCount(a, b congestion.ByteCount) congestion.ByteCount {
if a < b {
return a
}
return b
}