signal address change

p2p/host/basic/basic_host.go

@@ -90,6 +90,8 @@ type BasicHost struct {
 		evtLocalProtocolsUpdated event.Emitter
 		evtLocalAddrsUpdated     event.Emitter
 	}
+
+	addrChangeChan chan struct{}
 }
 
 var _ host.Host = (*BasicHost)(nil)
@@ -136,6 +138,7 @@ func NewHost(ctx context.Context, net network.Network, opts *HostOpts) (*BasicHo
 		AddrsFactory:   DefaultAddrsFactory,
 		maResolver:     madns.DefaultResolver,
 		eventbus:       eventbus.NewBus(),
+		addrChangeChan: make(chan struct{}, 1),
 	}
 
 	var err error
@@ -230,6 +233,7 @@ func New(net network.Network, opts ...interface{}) *BasicHost {
 	}
 
 	h, err := NewHost(context.Background(), net, hostopts)
+	h.Start()
 	if err != nil {
 		// this cannot happen with legacy options
 		// plus we want to keep the (deprecated) legacy interface unchanged
@@ -300,24 +304,13 @@ func (h *BasicHost) newStreamHandler(s network.Stream) {
 	go handle(protoID, s)
 }
 
-// CheckForAddressChanges determines whether our listen addresses have recently
-// changed and emits an EvtLocalAddressesUpdatedEvent & a Push Identify if so.
+// SignalAddressChange signals to the host that it needs to determine whether our listen addresses have recently
+// changed.
 // Warning: this interface is unstable and may disappear in the future.
-func (h *BasicHost) CheckForAddressChanges() {
-	h.mx.Lock()
-	addrs := h.Addrs()
-	changeEvt := makeUpdatedAddrEvent(h.lastAddrs, addrs)
-	if changeEvt != nil {
-		h.lastAddrs = addrs
-	}
-	h.mx.Unlock()
-
-	if changeEvt != nil {
-		err := h.emitters.evtLocalAddrsUpdated.Emit(*changeEvt)
-		if err != nil {
-			log.Warnf("error emitting event for updated addrs: %s", err)
-		}
-		h.ids.Push()
+func (h *BasicHost) SignalAddressChange() {
+	select {
+	case h.addrChangeChan <- struct{}{}:
+	default:
 	}
 }
 
@@ -366,10 +359,36 @@ func (h *BasicHost) background(p goprocess.Process) {
 	}
 	h.mx.Unlock()
 
+	//  emit an EvtLocalAddressesUpdatedEvent & a Push Identify if our listen addresses have changed.
+	go func() {
+		for {
+			select {
+			case <-h.addrChangeChan:
+				h.mx.Lock()
+				addrs := h.Addrs()
+				changeEvt := makeUpdatedAddrEvent(h.lastAddrs, addrs)
+				if changeEvt != nil {
+					h.lastAddrs = addrs
+				}
+				h.mx.Unlock()
+
+				if changeEvt != nil {
+					err := h.emitters.evtLocalAddrsUpdated.Emit(*changeEvt)
+					if err != nil {
+						log.Warnf("error emitting event for updated addrs: %s", err)
+					}
+					h.ids.Push()
+				}
+			case <-p.Closing():
+				return
+			}
+		}
+	}()
+
 	for {
 		select {
 		case <-ticker.C:
-			h.CheckForAddressChanges()
+			h.SignalAddressChange()
 
 		case <-p.Closing():
 			return

p2p/host/basic/basic_host_test.go

@@ -6,6 +6,7 @@ import (
 	"io"
 	"reflect"
 	"sort"
+	"sync"
 	"testing"
 	"time"
 
@@ -518,7 +519,7 @@ func TestHostAddrChangeDetection(t *testing.T) {
 		{ma.StringCast("/ip4/2.3.4.5/tcp/1234"), ma.StringCast("/ip4/3.4.5.6/tcp/4321")},
 	}
 
-	// The events we expect the host to emit when CheckForAddressChanges is called
+	// The events we expect the host to emit when SignalAddressChange is called
 	// and the changes between addr sets are detected
 	expectedEvents := []event.EvtLocalAddressesUpdated{
 		{
@@ -548,8 +549,11 @@ func TestHostAddrChangeDetection(t *testing.T) {
 		},
 	}
 
+	var lk sync.Mutex
 	currentAddrSet := 0
 	addrsFactory := func(addrs []ma.Multiaddr) []ma.Multiaddr {
+		lk.Lock()
+		defer lk.Unlock()
 		return addrSets[currentAddrSet]
 	}
 
@@ -563,46 +567,40 @@ func TestHostAddrChangeDetection(t *testing.T) {
 	}
 	defer sub.Close()
 
+	// wait for the host background thread to start
+	time.Sleep(1 * time.Second)
 	// host should start with no addrs (addrSet 0)
 	addrs := h.Addrs()
 	if len(addrs) != 0 {
 		t.Fatalf("expected 0 addrs, got %d", len(addrs))
 	}
 
-	// Advance between addrSets
+	// change addr, signal and assert event
 	for i := 1; i < len(addrSets); i++ {
+		lk.Lock()
 		currentAddrSet = i
-		h.CheckForAddressChanges() // forces the host to check for changes now, instead of waiting for background update
+		lk.Unlock()
+		h.SignalAddressChange()
+		evt := waitForAddrChangeEvent(ctx, sub, t)
+		if !updatedAddrEventsEqual(expectedEvents[i-1], evt) {
+			t.Errorf("change events not equal: \n\texpected: %v \n\tactual: %v", expectedEvents[i], evt)
 		}
 
-	// drain events from the subscription
-	var receivedEvents []event.EvtLocalAddressesUpdated
-readEvents:
+	}
+}
+
+func waitForAddrChangeEvent(ctx context.Context, sub event.Subscription, t *testing.T) event.EvtLocalAddressesUpdated {
 	for {
 		select {
 		case evt, more := <-sub.Out():
 			if !more {
-				break readEvents
-			}
-			receivedEvents = append(receivedEvents, evt.(event.EvtLocalAddressesUpdated))
-			if len(receivedEvents) == len(expectedEvents) {
-				break readEvents
+				t.Fatal("channel should not be closed")
 			}
+			return evt.(event.EvtLocalAddressesUpdated)
 		case <-ctx.Done():
-			break readEvents
-		case <-time.After(1 * time.Second):
-			break readEvents
-		}
-	}
-
-	// assert that we received the events we expected
-	if len(receivedEvents) != len(expectedEvents) {
-		t.Errorf("expected to receive %d addr change events, got %d", len(expectedEvents), len(receivedEvents))
-	}
-	for i, expected := range expectedEvents {
-		actual := receivedEvents[i]
-		if !updatedAddrEventsEqual(expected, actual) {
-			t.Errorf("change events not equal: \n\texpected: %v \n\tactual: %v", expected, actual)
+			t.Fatal("context should not have cancelled")
+		case <-time.After(2 * time.Second):
+			t.Fatal("timed out waiting for address change event")
 		}
 	}
 }

p2p/host/relay/autorelay.go

@@ -119,7 +119,7 @@ func (ar *AutoRelay) background(ctx context.Context) {
 			ar.cachedAddrs = nil
 			ar.mx.Unlock()
 			push = false
-			ar.host.CheckForAddressChanges()
+			ar.host.SignalAddressChange()
 		}
 	}
 }