forked from quic-go/quic-go
42b198b8d1
* utils: initialize the {Smoothed, Latest, Min}RTT to 100ms
* utils: use time.Duration.Nanoseconds instead of uint64
No functional change expected.
* congestion: better check to avoid division by zero
243 lines
7.4 KiB
Go
243 lines
7.4 KiB
Go
package quic
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import (
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"fmt"
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"math/rand/v2"
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"testing"
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"time"
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"github.com/quic-go/quic-go/internal/monotime"
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"github.com/quic-go/quic-go/internal/protocol"
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"github.com/quic-go/quic-go/internal/utils"
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"github.com/quic-go/quic-go/qlog"
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"github.com/quic-go/quic-go/testutils/events"
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"github.com/stretchr/testify/require"
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)
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func TestMTUDiscovererTiming(t *testing.T) {
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const rtt = 100 * time.Millisecond
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rttStats := utils.NewRTTStats()
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rttStats.UpdateRTT(rtt, 0)
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d := newMTUDiscoverer(rttStats, 1000, 2000, nil)
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now := monotime.Now()
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require.False(t, d.ShouldSendProbe(now))
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d.Start(now)
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require.False(t, d.ShouldSendProbe(now))
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require.False(t, d.ShouldSendProbe(now.Add(rtt*9/2)))
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now = now.Add(5 * rtt)
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require.True(t, d.ShouldSendProbe(now))
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// only a single outstanding probe packet is permitted
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ping, _ := d.GetPing(now)
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require.False(t, d.ShouldSendProbe(now))
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now = now.Add(5 * rtt)
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require.False(t, d.ShouldSendProbe(now))
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ping.Handler.OnLost(ping.Frame)
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require.True(t, d.ShouldSendProbe(now))
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}
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func TestMTUDiscovererAckAndLoss(t *testing.T) {
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const rtt = 200 * time.Millisecond
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rttStats := utils.NewRTTStats()
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rttStats.UpdateRTT(rtt, 0)
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d := newMTUDiscoverer(rttStats, 1000, 2000, nil)
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now := monotime.Now()
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ping, size := d.GetPing(now)
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require.Equal(t, protocol.ByteCount(1500), size)
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// the MTU is reduced if the frame is lost
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ping.Handler.OnLost(ping.Frame)
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require.Equal(t, protocol.ByteCount(1000), d.CurrentSize()) // no change to the MTU yet
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now = now.Add(5 * rtt)
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require.True(t, d.ShouldSendProbe(now))
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ping, size = d.GetPing(now)
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require.Equal(t, protocol.ByteCount(1250), size)
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ping.Handler.OnAcked(ping.Frame)
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require.Equal(t, protocol.ByteCount(1250), d.CurrentSize()) // the MTU is increased
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// Even though the 1500 byte MTU probe packet was lost, we try again with a higher MTU.
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// This protects against regular (non-MTU-related) packet loss.
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now = now.Add(5 * rtt)
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require.True(t, d.ShouldSendProbe(now))
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ping, size = d.GetPing(now)
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require.Greater(t, size, protocol.ByteCount(1500))
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ping.Handler.OnAcked(ping.Frame)
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require.Equal(t, size, d.CurrentSize())
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// We continue probing until the MTU is close to the maximum.
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var steps int
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oldSize := size
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now = now.Add(5 * rtt)
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for d.ShouldSendProbe(now) {
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ping, size = d.GetPing(now)
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require.Greater(t, size, oldSize)
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oldSize = size
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ping.Handler.OnAcked(ping.Frame)
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steps++
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require.Less(t, steps, 10)
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now = now.Add(5 * rtt)
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}
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require.Less(t, 2000-maxMTUDiff, size)
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}
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func TestMTUDiscovererMTUDiscovery(t *testing.T) {
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for i := range 5 {
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t.Run(fmt.Sprintf("test %d", i), func(t *testing.T) {
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testMTUDiscovererMTUDiscovery(t)
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})
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}
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}
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func testMTUDiscovererMTUDiscovery(t *testing.T) {
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const rtt = 100 * time.Millisecond
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const startMTU protocol.ByteCount = 1000
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rttStats := utils.NewRTTStats()
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rttStats.UpdateRTT(rtt, 0)
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maxMTU := protocol.ByteCount(rand.IntN(int(3000-startMTU))) + startMTU + 1
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var eventRecorder events.Recorder
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d := newMTUDiscoverer(rttStats, startMTU, maxMTU, &eventRecorder)
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now := monotime.Now()
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d.Start(now)
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realMTU := protocol.ByteCount(rand.IntN(int(maxMTU-startMTU))) + startMTU
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t.Logf("MTU: %d, max: %d", realMTU, maxMTU)
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now = now.Add(mtuProbeDelay * rtt)
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var probes []protocol.ByteCount
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for d.ShouldSendProbe(now) {
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require.Less(t, len(probes), 25, fmt.Sprintf("too many iterations: %v", probes))
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ping, size := d.GetPing(now)
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probes = append(probes, size)
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if size <= realMTU {
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ping.Handler.OnAcked(ping.Frame)
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} else {
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ping.Handler.OnLost(ping.Frame)
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}
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now = now.Add(mtuProbeDelay * rtt)
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}
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currentMTU := d.CurrentSize()
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diff := realMTU - currentMTU
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require.GreaterOrEqual(t, diff, protocol.ByteCount(0))
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if maxMTU > currentMTU+maxMTU {
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events := eventRecorder.Events(qlog.MTUUpdated{})
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require.NotEmpty(t, events)
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require.Equal(t, qlog.MTUUpdated{Value: int(currentMTU), Done: true}, events[0])
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}
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t.Logf("MTU discovered: %d (diff: %d)", currentMTU, diff)
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t.Logf("probes sent (%d): %v", len(probes), probes)
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require.LessOrEqual(t, diff, maxMTUDiff)
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}
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func TestMTUDiscovererWithRandomLoss(t *testing.T) {
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for i := range 5 {
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t.Run(fmt.Sprintf("test %d", i), func(t *testing.T) {
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testMTUDiscovererWithRandomLoss(t)
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})
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}
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}
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func testMTUDiscovererWithRandomLoss(t *testing.T) {
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const rtt = 100 * time.Millisecond
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const startMTU protocol.ByteCount = 1000
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const maxRandomLoss = maxLostMTUProbes - 1
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rttStats := utils.NewRTTStats()
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rttStats.SetInitialRTT(rtt)
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require.Equal(t, rtt, rttStats.SmoothedRTT())
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maxMTU := protocol.ByteCount(rand.IntN(int(3000-startMTU))) + startMTU + 1
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var eventRecorder events.Recorder
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d := newMTUDiscoverer(rttStats, startMTU, maxMTU, &eventRecorder)
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d.Start(monotime.Now())
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now := monotime.Now()
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realMTU := protocol.ByteCount(rand.IntN(int(maxMTU-startMTU))) + startMTU
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t.Logf("MTU: %d, max: %d", realMTU, maxMTU)
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now = now.Add(mtuProbeDelay * rtt)
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var probes, randomLosses []protocol.ByteCount
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for d.ShouldSendProbe(now) {
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require.Less(t, len(probes), 32, fmt.Sprintf("too many iterations: %v", probes))
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ping, size := d.GetPing(now)
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probes = append(probes, size)
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packetFits := size <= realMTU
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var acked bool
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if packetFits {
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randomLoss := rand.IntN(maxLostMTUProbes) == 0 && len(randomLosses) < maxRandomLoss
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if randomLoss {
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randomLosses = append(randomLosses, size)
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} else {
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ping.Handler.OnAcked(ping.Frame)
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acked = true
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}
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}
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if !acked {
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ping.Handler.OnLost(ping.Frame)
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}
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now = now.Add(mtuProbeDelay * rtt)
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}
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currentMTU := d.CurrentSize()
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diff := realMTU - currentMTU
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require.GreaterOrEqual(t, diff, protocol.ByteCount(0))
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if maxMTU > currentMTU+maxMTU {
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events := eventRecorder.Events(qlog.MTUUpdated{})
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require.NotEmpty(t, events)
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require.Equal(t, qlog.MTUUpdated{Value: int(currentMTU), Done: true}, events[0])
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}
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t.Logf("MTU discovered with random losses %v: %d (diff: %d)", randomLosses, currentMTU, diff)
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t.Logf("probes sent (%d): %v", len(probes), probes)
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require.LessOrEqual(t, diff, maxMTUDiff)
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}
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func TestMTUDiscovererReset(t *testing.T) {
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t.Run("probe on old path acknowledged", func(t *testing.T) {
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testMTUDiscovererReset(t, true)
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})
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t.Run("probe on old path lost", func(t *testing.T) {
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testMTUDiscovererReset(t, false)
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})
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}
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func testMTUDiscovererReset(t *testing.T, ackLastProbe bool) {
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const startMTU protocol.ByteCount = 1000
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const maxMTU = 1400
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const rtt = 100 * time.Millisecond
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rttStats := utils.NewRTTStats()
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rttStats.SetInitialRTT(rtt)
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now := monotime.Now()
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d := newMTUDiscoverer(rttStats, startMTU, maxMTU, nil)
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d.Start(now)
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ping, _ := d.GetPing(now.Add(5 * rtt))
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ping.Handler.OnAcked(ping.Frame)
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require.Greater(t, d.CurrentSize(), startMTU)
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now = now.Add(5 * rtt)
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// send another probe packet, but neither acknowledge nor lose it before resetting
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ping, _ = d.GetPing(now.Add(5 * rtt))
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now = now.Add(2 * rtt) // advance the timer by an arbitrary amount
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const newStartMTU protocol.ByteCount = 900
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const newMaxMTU = 1500
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d.Reset(now, newStartMTU, newMaxMTU)
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require.Equal(t, d.CurrentSize(), newStartMTU)
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// Now acknowledge / lose the probe packet.
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// This should be ignored, since it's on the old path.
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if ackLastProbe {
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ping.Handler.OnAcked(ping.Frame)
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} else {
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ping.Handler.OnLost(ping.Frame)
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}
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// the MTU should not have changed
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require.Equal(t, d.CurrentSize(), newStartMTU)
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// the next probe should be sent after 5 RTTs
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require.False(t, d.ShouldSendProbe(now.Add(5*rtt).Add(-time.Microsecond)))
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require.True(t, d.ShouldSendProbe(now.Add(5*rtt)))
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}
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