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package ackhandler
import (
"fmt"
"math"
"github.com/quic-go/quic-go/internal/protocol"
. "github.com/onsi/ginkgo/v2"
. "github.com/onsi/gomega"
)
var _ = Describe("Sequential Packet Number Generator", func() {
It("generates sequential packet numbers", func() {
const initialPN protocol.PacketNumber = 123
png := newSequentialPacketNumberGenerator(initialPN)
for i := initialPN; i < initialPN+1000; i++ {
Expect(png.Peek()).To(Equal(i))
Expect(png.Peek()).To(Equal(i))
skipNext, pn := png.Pop()
Expect(skipNext).To(BeFalse())
Expect(pn).To(Equal(i))
}
})
})
var _ = Describe("Skipping Packet Number Generator", func() {
const initialPN protocol.PacketNumber = 8
const initialPeriod protocol.PacketNumber = 25
const maxPeriod protocol.PacketNumber = 300
It("uses a maximum period that is sufficiently small such that using a 32-bit random number is ok", func() {
Expect(2 * protocol.SkipPacketMaxPeriod).To(BeNumerically("<", math.MaxInt32))
})
It("can be initialized to return any first packet number", func() {
png := newSkippingPacketNumberGenerator(12345, initialPeriod, maxPeriod)
_, pn := png.Pop()
Expect(pn).To(Equal(protocol.PacketNumber(12345)))
})
It("allows peeking", func() {
png := newSkippingPacketNumberGenerator(initialPN, initialPeriod, maxPeriod).(*skippingPacketNumberGenerator)
Expect(png.Peek()).To(Equal(initialPN))
Expect(png.Peek()).To(Equal(initialPN))
skipped, pn := png.Pop()
Expect(pn).To(Equal(initialPN))
next := initialPN + 1
if skipped {
next++
}
Expect(png.Peek()).To(Equal(next))
Expect(png.Peek()).To(Equal(next))
})
It("skips a packet number", func() {
png := newSkippingPacketNumberGenerator(initialPN, initialPeriod, maxPeriod)
var last protocol.PacketNumber
var skipped bool
for i := 0; i < int(maxPeriod); i++ {
didSkip, num := png.Pop()
if didSkip {
skipped = true
_, nextNum := png.Pop()
Expect(nextNum).To(Equal(num + 1))
break
}
if i != 0 {
Expect(num).To(Equal(last + 1))
}
last = num
}
Expect(skipped).To(BeTrue())
})
It("generates a new packet number to skip", func() {
const rep = 2500
periods := make([][]protocol.PacketNumber, rep)
expectedPeriods := []protocol.PacketNumber{25, 50, 100, 200, 300, 300, 300}
for i := 0; i < rep; i++ {
png := newSkippingPacketNumberGenerator(initialPN, initialPeriod, maxPeriod)
lastSkip := initialPN
for len(periods[i]) < len(expectedPeriods) {
skipNext, next := png.Pop()
if skipNext {
skipped := next + 1
Expect(skipped).To(BeNumerically(">", lastSkip+1))
periods[i] = append(periods[i], skipped-lastSkip-1)
lastSkip = skipped
}
}
}
for j := 0; j < len(expectedPeriods); j++ {
var average float64
for i := 0; i < rep; i++ {
average += float64(periods[i][j]) / float64(len(periods))
}
fmt.Fprintf(GinkgoWriter, "Period %d: %.2f (expected %d)\n", j, average, expectedPeriods[j])
tolerance := protocol.PacketNumber(5)
if t := expectedPeriods[j] / 10; t > tolerance {
tolerance = t
}
Expect(average).To(BeNumerically("~", expectedPeriods[j]+1 /* we never skip two packet numbers at the same time */, tolerance))
}
})
})
|
