add delivery tags for "near-first" msg deliveries

gossipsub.go

@@ -328,6 +328,9 @@ func (gs *GossipSubRouter) Attach(p *PubSub) {
 	// and the gossip tracing
 	gs.gossipTracer.Start(gs)
 
+	// and the tracer for connmgr tags
+	gs.tagTracer.Start(gs)
+
 	// start using the same msg ID function as PubSub for caching messages.
 	gs.mcache.SetMsgIdFn(p.msgID)
 

tag_tracer.go

@@ -1,6 +1,7 @@
 package pubsub
 
 import (
+	"context"
 	"fmt"
 	"sync"
 	"time"
@@ -55,9 +56,14 @@ type tagTracer struct {
 	sync.RWMutex
 
 	cmgr     connmgr.ConnManager
+	msgID    MsgIdFunction
 	decayer  connmgr.Decayer
 	decaying map[string]connmgr.DecayingTag
 	direct   map[peer.ID]struct{}
+
+	// track message deliveries to reward "near first" deliveries
+	// (a delivery that occurs while we're still validating the message)
+	deliveries *messageDeliveries
 }
 
 func newTagTracer(cmgr connmgr.ConnManager) *tagTracer {
@@ -66,12 +72,44 @@ func newTagTracer(cmgr connmgr.ConnManager) *tagTracer {
 		log.Warnf("connection manager does not support decaying tags, delivery tags will not be applied")
 	}
 	return &tagTracer{
-		cmgr:     cmgr,
-		decayer:  decayer,
-		decaying: make(map[string]connmgr.DecayingTag),
+		cmgr:       cmgr,
+		msgID:      DefaultMsgIdFn,
+		decayer:    decayer,
+		decaying:   make(map[string]connmgr.DecayingTag),
+		deliveries: &messageDeliveries{records: make(map[string]*deliveryRecord)},
 	}
 }
 
+func (t *tagTracer) Start(gs *GossipSubRouter) {
+	if t == nil {
+		return
+	}
+
+	t.msgID = gs.p.msgID
+	t.direct = gs.direct
+	go t.background(gs.p.ctx)
+}
+
+func (t *tagTracer) background(ctx context.Context) {
+	gcDeliveryRecords := time.NewTicker(time.Minute)
+	defer gcDeliveryRecords.Stop()
+
+	for {
+		select {
+		case <-gcDeliveryRecords.C:
+			t.gcDeliveryRecords()
+		case <-ctx.Done():
+			return
+		}
+	}
+}
+
+func (t *tagTracer) gcDeliveryRecords() {
+	t.Lock()
+	defer t.Unlock()
+	t.deliveries.gc()
+}
+
 func (t *tagTracer) tagPeerIfDirect(p peer.ID) {
 	if t.direct == nil {
 		return
@@ -163,6 +201,31 @@ func (t *tagTracer) bumpTagsForMessage(p peer.ID, msg *Message) {
 	}
 }
 
+// nearFirstPeers returns the peers who delivered the message while it was still validating
+func (t *tagTracer) nearFirstPeers(msg *Message) []peer.ID {
+	t.Lock()
+	defer t.Unlock()
+	drec := t.deliveries.getRecord(t.msgID(msg.Message))
+	nearFirstPeers := make([]peer.ID, 0, len(drec.peers))
+	// defensive check that this is the first delivery trace -- delivery status should be unknown
+	if drec.status != deliveryUnknown {
+		log.Warnf("unexpected delivery trace: message from %s was first seen %s ago and has delivery status %d", msg.ReceivedFrom, time.Now().Sub(drec.firstSeen), drec.status)
+		return nearFirstPeers
+	}
+
+	drec.status = deliveryValid
+	drec.validated = time.Now()
+
+	for p := range drec.peers {
+		// this check is to make sure a peer can't send us a message twice and get a double count
+		// if it is a first delivery.
+		if p != msg.ReceivedFrom {
+			nearFirstPeers = append(nearFirstPeers, p)
+		}
+	}
+	return nearFirstPeers
+}
+
 // -- internalTracer interface methods
 var _ internalTracer = (*tagTracer)(nil)
 
@@ -175,8 +238,12 @@ func (t *tagTracer) Join(topic string) {
 }
 
 func (t *tagTracer) DeliverMessage(msg *Message) {
-	// TODO: also give a bump to "near-first" message deliveries
+	nearFirst := t.nearFirstPeers(msg)
+
 	t.bumpTagsForMessage(msg.ReceivedFrom, msg)
+	for _, p := range nearFirst {
+		t.bumpTagsForMessage(p, msg)
+	}
 }
 
 func (t *tagTracer) Leave(topic string) {
@@ -191,7 +258,41 @@ func (t *tagTracer) Prune(p peer.ID, topic string) {
 	t.untagMeshPeer(p, topic)
 }
 
-func (t *tagTracer) RemovePeer(peer.ID)             {}
-func (t *tagTracer) ValidateMessage(*Message)       {}
-func (t *tagTracer) RejectMessage(*Message, string) {}
-func (t *tagTracer) DuplicateMessage(*Message)      {}
+func (t *tagTracer) ValidateMessage(msg *Message) {
+	t.Lock()
+	defer t.Unlock()
+
+	// create a delivery record for the message
+	_ = t.deliveries.getRecord(t.msgID(msg.Message))
+}
+
+func (t *tagTracer) DuplicateMessage(msg *Message) {
+	t.Lock()
+	defer t.Unlock()
+
+	drec := t.deliveries.getRecord(t.msgID(msg.Message))
+	if drec.status == deliveryUnknown {
+		// the message is being validated; track the peer delivery and wait for
+		// the Deliver/Reject notification.
+		drec.peers[msg.ReceivedFrom] = struct{}{}
+	}
+}
+
+func (t *tagTracer) RejectMessage(msg *Message, reason string) {
+	t.Lock()
+	defer t.Unlock()
+
+	// mark message as invalid and release tracking info
+	drec := t.deliveries.getRecord(t.msgID(msg.Message))
+
+	// defensive check that this is the first rejection trace -- delivery status should be unknown
+	if drec.status != deliveryUnknown {
+		log.Warnf("unexpected rejection trace: message from %s was first seen %s ago and has delivery status %d", msg.ReceivedFrom, time.Now().Sub(drec.firstSeen), drec.status)
+		return
+	}
+
+	drec.status = deliveryInvalid
+	drec.peers = nil
+}
+
+func (t *tagTracer) RemovePeer(peer.ID) {}

tag_tracer_test.go

@@ -1,6 +1,7 @@
 package pubsub
 
 import (
+	"fmt"
 	"github.com/benbjohnson/clock"
 	connmgr "github.com/libp2p/go-libp2p-connmgr"
 	connmgri "github.com/libp2p/go-libp2p-core/connmgr"
@@ -139,6 +140,76 @@ func TestTagTracerDeliveryTags(t *testing.T) {
 	}
 }
 
+func TestTagTracerDeliveryTagsNearFirst(t *testing.T) {
+	// use fake time to test the tag decay
+	clk := clock.NewMock()
+	decayCfg := &connmgr.DecayerCfg{
+		Clock:      clk,
+		Resolution: time.Minute,
+	}
+	cmgr := connmgr.NewConnManager(5, 10, time.Minute, connmgr.DecayerConfig(decayCfg))
+
+	tt := newTagTracer(cmgr)
+
+	topic := "test"
+
+	p := peer.ID("a-peer")
+	p2 := peer.ID("another-peer")
+	p3 := peer.ID("slow-peer")
+
+	tt.Join(topic)
+
+	for i := 0; i < GossipSubConnTagMessageDeliveryCap+5; i++ {
+		topics := []string{topic}
+		msg := &Message{
+			ReceivedFrom: p,
+			Message: &pb.Message{
+				From:     []byte(p),
+				Data:     []byte(fmt.Sprintf("msg-%d", i)),
+				TopicIDs: topics,
+				Seqno:    []byte(fmt.Sprintf("%d", i)),
+			},
+		}
+
+		// a duplicate of the message, received from p2
+		dup := &Message{
+			ReceivedFrom: p2,
+			Message:      msg.Message,
+		}
+
+		// the message starts validating as soon as we receive it from p
+		tt.ValidateMessage(msg)
+		// p2 should get near-first credit for the duplicate message that arrives before
+		// validation is complete
+		tt.DuplicateMessage(dup)
+		// DeliverMessage gets called when validation is complete
+		tt.DeliverMessage(msg)
+
+		// p3 delivers a duplicate after validation completes & gets no credit
+		dup.ReceivedFrom = p3
+		tt.DuplicateMessage(dup)
+	}
+
+	clk.Add(time.Minute)
+
+	// both p and p2 should get delivery tags equal to the cap
+	tag := "pubsub-deliveries:test"
+	val := getTagValue(cmgr, p, tag)
+	if val != GossipSubConnTagMessageDeliveryCap {
+		t.Errorf("expected tag %s to have val %d, was %d", tag, GossipSubConnTagMessageDeliveryCap, val)
+	}
+	val = getTagValue(cmgr, p2, tag)
+	if val != GossipSubConnTagMessageDeliveryCap {
+		t.Errorf("expected tag %s for near-first peer to have val %d, was %d", tag, GossipSubConnTagMessageDeliveryCap, val)
+	}
+
+	// p3 should have no delivery tag credit
+	val = getTagValue(cmgr, p3, tag)
+	if val != 0 {
+		t.Errorf("expected tag %s for slow peer to have val %d, was %d", tag, 0, val)
+	}
+}
+
 func getTagValue(mgr connmgri.ConnManager, p peer.ID, tag string) int {
 	info := mgr.GetTagInfo(p)
 	if info == nil {