Make onNegotiationNeeded conform to spec

- Removes non-canon logic

operations.go

@@ -16,11 +16,19 @@ type operations struct {
 	mu   sync.Mutex
 	busy bool
 	ops  *list.List
+
+	updateNegotiationNeededFlagOnEmptyChain *atomicBool
+	onNegotiationNeeded                     func()
 }
 
-func newOperations() *operations {
+func newOperations(
+	updateNegotiationNeededFlagOnEmptyChain *atomicBool,
+	onNegotiationNeeded func(),
+) *operations {
 	return &operations{
 		ops:                                     list.New(),
+		updateNegotiationNeededFlagOnEmptyChain: updateNegotiationNeededFlagOnEmptyChain,
+		onNegotiationNeeded:                     onNegotiationNeeded,
 	}
 }
 
@@ -93,4 +101,9 @@ func (o *operations) start() {
 		fn()
 		fn = o.pop()
 	}
+	if !o.updateNegotiationNeededFlagOnEmptyChain.get() {
+		return
+	}
+	o.updateNegotiationNeededFlagOnEmptyChain.set(false)
+	o.onNegotiationNeeded()
 }

operations_test.go

@@ -4,19 +4,31 @@
 package webrtc
 
 import (
+	"sync"
 	"testing"
 
 	"github.com/stretchr/testify/assert"
 )
 
 func TestOperations_Enqueue(t *testing.T) {
-	ops := newOperations()
+	updateNegotiationNeededFlagOnEmptyChain := &atomicBool{}
-	for i := 0; i < 100; i++ {
+	onNegotiationNeededCalledCount := 0
+	var onNegotiationNeededCalledCountMu sync.Mutex
+	ops := newOperations(updateNegotiationNeededFlagOnEmptyChain, func() {
+		onNegotiationNeededCalledCountMu.Lock()
+		onNegotiationNeededCalledCount++
+		onNegotiationNeededCalledCountMu.Unlock()
+	})
+	for resultSet := 0; resultSet < 100; resultSet++ {
 		results := make([]int, 16)
+		resultSetCopy := resultSet
 		for i := range results {
 			func(j int) {
 				ops.Enqueue(func() {
 					results[j] = j * j
+					if resultSetCopy > 50 {
+						updateNegotiationNeededFlagOnEmptyChain.set(true)
+					}
 				})
 			}(i)
 		}
@@ -26,9 +38,13 @@ func TestOperations_Enqueue(t *testing.T) {
 		assert.Equal(t, len(expected), len(results))
 		assert.Equal(t, expected, results)
 	}
+	onNegotiationNeededCalledCountMu.Lock()
+	defer onNegotiationNeededCalledCountMu.Unlock()
+	assert.NotEqual(t, onNegotiationNeededCalledCount, 0)
 }
 
 func TestOperations_Done(*testing.T) {
-	ops := newOperations()
+	ops := newOperations(&atomicBool{}, func() {
+	})
 	ops.Done()
 }

peerconnection.go

@@ -57,7 +57,7 @@ type PeerConnection struct {
 
 	isClosed                                *atomicBool
 	isNegotiationNeeded                     *atomicBool
-	negotiationNeededState negotiationNeededState
+	updateNegotiationNeededFlagOnEmptyChain *atomicBool
 
 	lastOffer  string
 	lastAnswer string
@@ -115,6 +115,7 @@ func (api *API) NewPeerConnection(configuration Configuration) (*PeerConnection,
 	// https://w3c.github.io/webrtc-pc/#constructor (Step #2)
 	// Some variables defined explicitly despite their implicit zero values to
 	// allow better readability to understand what is happening.
+
 	pc := &PeerConnection{
 		statsID: fmt.Sprintf("PeerConnection-%d", time.Now().UnixNano()),
 		configuration: Configuration{
@@ -125,10 +126,9 @@ func (api *API) NewPeerConnection(configuration Configuration) (*PeerConnection,
 			Certificates:         []Certificate{},
 			ICECandidatePoolSize: 0,
 		},
-		ops:                    newOperations(),
 		isClosed:                                &atomicBool{},
 		isNegotiationNeeded:                     &atomicBool{},
-		negotiationNeededState: negotiationNeededStateEmpty,
+		updateNegotiationNeededFlagOnEmptyChain: &atomicBool{},
 		lastOffer:                               "",
 		lastAnswer:                              "",
 		greaterMid:                              -1,
@@ -137,6 +137,8 @@ func (api *API) NewPeerConnection(configuration Configuration) (*PeerConnection,
 		api: api,
 		log: api.settingEngine.LoggerFactory.NewLogger("pc"),
 	}
+	pc.ops = newOperations(pc.updateNegotiationNeededFlagOnEmptyChain, pc.onNegotiationNeeded)
+
 	pc.iceConnectionState.Store(ICEConnectionStateNew)
 	pc.connectionState.Store(PeerConnectionStateNew)
 
@@ -293,66 +295,54 @@ func (pc *PeerConnection) OnNegotiationNeeded(f func()) {
 
 // onNegotiationNeeded enqueues negotiationNeededOp if necessary
 // caller of this method should hold `pc.mu` lock
+// https://www.w3.org/TR/webrtc/#dfn-update-the-negotiation-needed-flag
 func (pc *PeerConnection) onNegotiationNeeded() {
-	// https://w3c.github.io/webrtc-pc/#updating-the-negotiation-needed-flag
+	// 4.7.3.1 If the length of connection.[[Operations]] is not 0, then set
-	// non-canon step 1
+	// connection.[[UpdateNegotiationNeededFlagOnEmptyChain]] to true, and abort these steps.
-	if pc.negotiationNeededState == negotiationNeededStateRun {
+	if !pc.ops.IsEmpty() {
-		pc.negotiationNeededState = negotiationNeededStateQueue
+		pc.updateNegotiationNeededFlagOnEmptyChain.set(true)
-		return
-	} else if pc.negotiationNeededState == negotiationNeededStateQueue {
 		return
 	}
-	pc.negotiationNeededState = negotiationNeededStateRun
 	pc.ops.Enqueue(pc.negotiationNeededOp)
 }
 
+// https://www.w3.org/TR/webrtc/#dfn-update-the-negotiation-needed-flag
 func (pc *PeerConnection) negotiationNeededOp() {
-	// non-canon, reset needed state machine and run again if there was a request
+	// 4.7.3.2.1 If connection.[[IsClosed]] is true, abort these steps.
-	defer func() {
-		pc.mu.Lock()
-		defer pc.mu.Unlock()
-		if pc.negotiationNeededState == negotiationNeededStateQueue {
-			defer pc.onNegotiationNeeded()
-		}
-		pc.negotiationNeededState = negotiationNeededStateEmpty
-	}()
-
-	// Don't run NegotiatedNeeded checks if OnNegotiationNeeded is not set
-	if handler, ok := pc.onNegotiationNeededHandler.Load().(func()); !ok || handler == nil {
-		return
-	}
-
-	// https://www.w3.org/TR/webrtc/#updating-the-negotiation-needed-flag
-	// Step 2.1
 	if pc.isClosed.get() {
 		return
 	}
-	// non-canon step 2.2
+
+	// 4.7.3.2.2 If the length of connection.[[Operations]] is not 0,
+	// then set connection.[[UpdateNegotiationNeededFlagOnEmptyChain]] to
+	// true, and abort these steps.
 	if !pc.ops.IsEmpty() {
-		pc.ops.Enqueue(pc.negotiationNeededOp)
+		pc.updateNegotiationNeededFlagOnEmptyChain.set(true)
 		return
 	}
 
-	// Step 2.3
+	// 4.7.3.2.3 If connection's signaling state is not "stable", abort these steps.
 	if pc.SignalingState() != SignalingStateStable {
 		return
 	}
 
-	// Step 2.4
+	// 4.7.3.2.4 If the result of checking if negotiation is needed is false,
+	// clear the negotiation-needed flag by setting connection.[[NegotiationNeeded]]
+	// to false, and abort these steps.
 	if !pc.checkNegotiationNeeded() {
 		pc.isNegotiationNeeded.set(false)
 		return
 	}
 
-	// Step 2.5
+	// 4.7.3.2.5 If connection.[[NegotiationNeeded]] is already true, abort these steps.
 	if pc.isNegotiationNeeded.get() {
 		return
 	}
 
-	// Step 2.6
+	// 4.7.3.2.6 Set connection.[[NegotiationNeeded]] to true.
 	pc.isNegotiationNeeded.set(true)
 
-	// Step 2.7
+	// 4.7.3.2.7 Fire an event named negotiationneeded at connection.
 	if handler, ok := pc.onNegotiationNeededHandler.Load().(func()); ok && handler != nil {
 		handler()
 	}

peerconnection_go_test.go

@@ -1623,41 +1623,3 @@ func TestPeerConnectionState(t *testing.T) {
 	assert.NoError(t, pc.Close())
 	assert.Equal(t, PeerConnectionStateClosed, pc.ConnectionState())
 }
-
-// See https://github.com/pion/webrtc/issues/2774
-func TestNegotiationNeededAddedAfterOpQueueDone(t *testing.T) {
-	lim := test.TimeOut(time.Second * 30)
-	defer lim.Stop()
-
-	report := test.CheckRoutines(t)
-	defer report()
-
-	pc, err := NewPeerConnection(Configuration{})
-	if err != nil {
-		t.Error(err.Error())
-	}
-
-	var wg sync.WaitGroup
-	wg.Add(1)
-
-	_, err = pc.CreateDataChannel("initial_data_channel", nil)
-	assert.NoError(t, err)
-
-	// after there are no ops left in the queue, a previously faulty version
-	// of negotiationNeededOp would keep the negotiation needed state in
-	// negotiationNeededStateQueue which will cause all subsequent
-	// onNegotiationNeeded calls to never queue again, only if
-	// OnNegotiationNeeded has not been set yet.
-	for !pc.ops.IsEmpty() {
-		time.Sleep(time.Millisecond)
-	}
-
-	pc.OnNegotiationNeeded(wg.Done)
-
-	_, err = pc.CreateDataChannel("another_data_channel", nil)
-	assert.NoError(t, err)
-
-	wg.Wait()
-
-	assert.NoError(t, pc.Close())
-}

peerconnectionstate.go

@@ -84,14 +84,3 @@ func (t PeerConnectionState) String() string {
 		return ErrUnknownType.Error()
 	}
 }
-
-type negotiationNeededState int
-
-const (
-	// NegotiationNeededStateEmpty not running and queue is empty
-	negotiationNeededStateEmpty = iota
-	// NegotiationNeededStateEmpty running and queue is empty
-	negotiationNeededStateRun
-	// NegotiationNeededStateEmpty running and queue
-	negotiationNeededStateQueue
-)