test(gateway): pace qualification video source

gateway/qualification_contract_test.go

@@ -7,6 +7,7 @@ import (
 	"encoding/binary"
 	"errors"
 	"io"
+	"net"
 	"os"
 	"path/filepath"
 	"reflect"
@@ -67,6 +68,72 @@ func TestQualificationRecordsLinkedToolVersions(t *testing.T) {
 	}
 }
 
+func TestQualificationApolloFixturePacesSourceShapedVideo(t *testing.T) {
+	key := bytes.Repeat([]byte{0x3c}, 16)
+	encoded := make([]byte, 1000*apolloVideoShardPayloadSize-8)
+	packets := qualificationSourceVideoPackets(t, key, 1, encoded)
+	if len(packets) != 1000 || len(packets[0]) != 1072 {
+		t.Fatalf("source vector = %d packets of %d bytes, want 1000 packets of 1072 bytes", len(packets), len(packets[0]))
+	}
+	packetsPerMillisecond, batchSize := qualificationApolloVideoPacing(len(packets[0]))
+	if packetsPerMillisecond != 93 || batchSize != 61 {
+		t.Fatalf("Apollo pacing vector = %d packets/ms, batch %d; want 93 and 61", packetsPerMillisecond, batchSize)
+	}
+
+	receiver, err := net.ListenUDP("udp", &net.UDPAddr{IP: net.ParseIP("127.0.0.1")})
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer receiver.Close()
+	sender, err := net.ListenUDP("udp", &net.UDPAddr{IP: net.ParseIP("127.0.0.1")})
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer sender.Close()
+
+	fixture := &qualificationApolloFixture{video: sender, failures: make(chan error, 1)}
+	remote := *receiver.LocalAddr().(*net.UDPAddr)
+	fixture.videoRemote.Store(&remote)
+	drained := make(chan struct{})
+	go func() {
+		defer close(drained)
+		buffer := make([]byte, 2048)
+		for range len(packets) + 1 {
+			if _, _, readErr := receiver.ReadFromUDP(buffer); readErr != nil {
+				return
+			}
+		}
+	}()
+
+	started := time.Now()
+	if err := fixture.sendVideo(context.Background(), packets); err != nil {
+		t.Fatal(err)
+	}
+	if err := fixture.sendVideo(context.Background(), packets[:1]); err != nil {
+		t.Fatal(err)
+	}
+	elapsed := time.Since(started)
+	wantCarry := 10 * time.Millisecond // floor(1000 / 93) ms at Apollo's pinned 80%-of-1-Gbps rate.
+	if elapsed < wantCarry {
+		t.Fatalf("source fixture sent the next frame after %s, before Apollo pacing carry %s", elapsed, wantCarry)
+	}
+	select {
+	case <-drained:
+	case <-time.After(time.Second):
+		t.Fatal("source-shaped UDP receiver did not drain the fixed vector")
+	}
+	fixture.videoNext = time.Now().Add(time.Second)
+	beforeCancel := fixture.sentPackets.Load()
+	cancelled, cancel := context.WithCancel(context.Background())
+	cancel()
+	if err := fixture.sendVideo(cancelled, packets[:1]); !errors.Is(err, context.Canceled) {
+		t.Fatalf("cancelled pacing wait returned %v, want context.Canceled", err)
+	}
+	if fixture.sentPackets.Load() != beforeCancel {
+		t.Fatal("cancelled pacing wait emitted a UDP shard")
+	}
+}
+
 func TestQualificationOutputAndStatisticsFailClosed(t *testing.T) {
 	if err := validateQualificationOutputDir("relative/evidence"); err == nil {
 		t.Fatal("relative evidence directory was accepted")

gateway/qualification_harness_test.go

@@ -39,15 +39,18 @@ import (
 )
 
 const (
-	qualificationToolVersion                   = "versevdi-gateway-qualification/v6"
-	qualificationImpairmentQueuePackets        = nativeApolloVideoQueuePackets
-	qualificationImpairmentMaxPackets          = 100_000
-	qualificationImpairmentPacketCount         = 10_000
-	qualificationProcessingLimit               = 5 * time.Millisecond
-	qualificationImpairmentSeed         uint64 = 0x3c6a11ce
-	qualificationClockOverheadMethod           = "median of 1000 batches of 100 monotonic time reads"
-	qualificationGatewayCPUScope               = "isolated gateway subprocess; bounded recorder/control included, fixture and client driver excluded"
-	qualificationResourceMethod                = "RUSAGE_SELF user+system CPU; runtime/metrics heap objects, allocated objects/bytes, and live goroutines sampled once per second"
+	qualificationToolVersion                         = "versevdi-gateway-qualification/v7"
+	qualificationImpairmentQueuePackets              = nativeApolloVideoQueuePackets
+	qualificationImpairmentMaxPackets                = 100_000
+	qualificationImpairmentPacketCount               = 10_000
+	qualificationProcessingLimit                     = 5 * time.Millisecond
+	qualificationImpairmentSeed               uint64 = 0x3c6a11ce
+	qualificationClockOverheadMethod                 = "median of 1000 batches of 100 monotonic time reads"
+	qualificationGatewayCPUScope                     = "isolated gateway subprocess; bounded recorder/control included, fixture and client driver excluded"
+	qualificationResourceMethod                      = "RUSAGE_SELF user+system CPU; runtime/metrics heap objects, allocated objects/bytes, and live goroutines sampled once per second"
+	qualificationApolloVideoRateBitsPerSecond        = 1_000_000_000 * 80 / 100
+	qualificationApolloVideoBatchBytes               = 64 * 1024
+	qualificationApolloVideoBatchPackets             = 64
 )
 
 type qualificationMediaProfile struct {
@@ -425,6 +428,8 @@ type qualificationApolloFixture struct {
 	closeOnce   sync.Once
 	sentPackets atomic.Uint64
 	work        protocol.ProviderSessionWork
+	videoPaceMu sync.Mutex
+	videoNext   time.Time
 
 	controlImpairmentMu sync.Mutex
 	controlRTT          time.Duration
@@ -754,15 +759,76 @@ func (f *qualificationApolloFixture) sendVideo(ctx context.Context, packets [][]
 		}
 	}
 	remote := f.videoRemote.Load()
-	for _, packet := range packets {
-		if _, err := f.video.WriteToUDP(packet, remote); err != nil {
-			return err
-		}
-		f.sentPackets.Add(1)
+	if len(packets) == 0 {
+		return nil
 	}
+	packetsPerMillisecond, batchSize := qualificationApolloVideoPacing(len(packets[0]))
+	if packetsPerMillisecond == 0 || batchSize == 0 {
+		return ErrProviderMalformed
+	}
+
+	f.videoPaceMu.Lock()
+	defer f.videoPaceMu.Unlock()
+	frameStart := time.Now()
+	if f.videoNext.After(frameStart) {
+		frameStart = f.videoNext
+	}
+	framePackets, groupPackets := 0, 0
+	for batchStart := 0; batchStart < len(packets); batchStart += batchSize {
+		if framePackets == 0 || groupPackets >= packetsPerMillisecond {
+			due := frameStart.Add(time.Millisecond * time.Duration(framePackets) / time.Duration(packetsPerMillisecond))
+			if err := qualificationWaitContext(ctx, due); err != nil {
+				return err
+			}
+			groupPackets = 0
+		}
+		batchEnd := min(batchStart+batchSize, len(packets))
+		for _, packet := range packets[batchStart:batchEnd] {
+			if len(packet) != len(packets[0]) {
+				return ErrProviderMalformed
+			}
+			if _, err := f.video.WriteToUDP(packet, remote); err != nil {
+				return err
+			}
+			f.sentPackets.Add(1)
+		}
+		currentBatch := batchEnd - batchStart
+		framePackets += currentBatch
+		groupPackets += currentBatch
+	}
+	f.videoNext = frameStart.Add(time.Millisecond * time.Duration(framePackets) / time.Duration(packetsPerMillisecond))
 	return nil
 }
 
+func qualificationApolloVideoPacing(packetBytes int) (packetsPerMillisecond, batchSize int) {
+	if packetBytes <= 0 {
+		return 0, 0
+	}
+	packetsPerMillisecond = qualificationApolloVideoRateBitsPerSecond / 1000 / packetBytes / 8
+	batchSize = min(qualificationApolloVideoBatchBytes/packetBytes, qualificationApolloVideoBatchPackets)
+	return packetsPerMillisecond, batchSize
+}
+
+func qualificationWaitContext(ctx context.Context, due time.Time) error {
+	delay := time.Until(due)
+	if delay <= 0 {
+		select {
+		case <-ctx.Done():
+			return ctx.Err()
+		default:
+			return nil
+		}
+	}
+	timer := time.NewTimer(delay)
+	defer timer.Stop()
+	select {
+	case <-ctx.Done():
+		return ctx.Err()
+	case <-timer.C:
+		return nil
+	}
+}
+
 func (f *qualificationApolloFixture) streamKey() ([]byte, error) {
 	key := f.key.Load()
 	if key == nil || len(*key) != 16 {