add a method to get the pubsub peers list

floodsub.go

@@ -36,6 +36,9 @@ type PubSub struct {
 	//
 	getTopics chan *topicReq
 
+	//
+	getPeers chan chan []peer.ID
+
 	// a notification channel for incoming streams from other peers
 	newPeers chan inet.Stream
 
@@ -77,6 +80,7 @@ func NewFloodSub(ctx context.Context, h host.Host) *PubSub {
 		publish:      make(chan *Message),
 		newPeers:     make(chan inet.Stream),
 		peerDead:     make(chan peer.ID),
+		getPeers:     make(chan chan []peer.ID),
 		addSub:       make(chan *addSub),
 		getTopics:    make(chan *topicReq),
 		myTopics:     make(map[string]chan *Message),
@@ -124,6 +128,12 @@ func (p *PubSub) processLoop(ctx context.Context) {
 			treq.resp <- out
 		case sub := <-p.addSub:
 			p.handleSubscriptionChange(sub)
+		case pch := <-p.getPeers:
+			var peers []peer.ID
+			for p := range p.peers {
+				peers = append(peers, p)
+			}
+			pch <- peers
 		case rpc := <-p.incoming:
 			err := p.handleIncomingRPC(rpc)
 			if err != nil {
@@ -341,3 +351,9 @@ func (p *PubSub) Publish(topic string, data []byte) error {
 	}
 	return nil
 }
+
+func (p *PubSub) ListPeers() []peer.ID {
+	out := make(chan []peer.ID)
+	p.getPeers <- out
+	return <-out
+}

floodsub_test.go

@@ -9,6 +9,7 @@ import (
 	"testing"
 	"time"
 
+	peer "github.com/ipfs/go-libp2p-peer"
 	host "github.com/libp2p/go-libp2p/p2p/host"
 	netutil "github.com/libp2p/go-libp2p/p2p/test/util"
 )
@@ -320,6 +321,20 @@ func TestOneToOne(t *testing.T) {
 	checkMessageRouting(t, "foobar", psubs, []<-chan *Message{ch})
 }
 
+func assertPeerLists(t *testing.T, hosts []host.Host, ps *PubSub, has ...int) {
+	peers := ps.ListPeers()
+	set := make(map[peer.ID]struct{})
+	for _, p := range peers {
+		set[p] = struct{}{}
+	}
+
+	for _, h := range has {
+		if _, ok := set[hosts[h].ID()]; !ok {
+			t.Fatal("expected to have connection to peer: ", h)
+		}
+	}
+}
+
 func TestTreeTopology(t *testing.T) {
 	ctx, cancel := context.WithCancel(context.Background())
 	defer cancel()
@@ -359,6 +374,10 @@ func TestTreeTopology(t *testing.T) {
 
 	time.Sleep(time.Millisecond * 50)
 
+	assertPeerLists(t, hosts, psubs[0], 1, 5)
+	assertPeerLists(t, hosts, psubs[1], 0, 2, 4)
+	assertPeerLists(t, hosts, psubs[2], 1, 3)
+
 	checkMessageRouting(t, "fizzbuzz", []*PubSub{psubs[9], psubs[3]}, chs)
 }