Fix MediaEngine Copy

Copy the entire API. Since the MediaEngine is a pointer that would
destroy the MediaEngine that is used by other PeerConnections

Relates to #1662

peerconnection.go

@@ -105,10 +105,6 @@ func NewPeerConnection(configuration Configuration) (*PeerConnection, error) {
 
 // NewPeerConnection creates a new PeerConnection with the provided configuration against the received API object
 func (api *API) NewPeerConnection(configuration Configuration) (*PeerConnection, error) {
-	if !api.settingEngine.disableMediaEngineCopy {
-		api.mediaEngine = api.mediaEngine.copy()
-	}
-
 	// 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.
@@ -137,7 +133,13 @@ func (api *API) NewPeerConnection(configuration Configuration) (*PeerConnection,
 		log: api.settingEngine.LoggerFactory.NewLogger("pc"),
 	}
 
-	pc.interceptorRTCPWriter = api.interceptor.BindRTCPWriter(interceptor.RTCPWriterFunc(pc.writeRTCP))
+	if !api.settingEngine.disableMediaEngineCopy {
+		pc.api = &API{
+			settingEngine: api.settingEngine,
+			mediaEngine:   api.mediaEngine.copy(),
+			interceptor:   api.interceptor,
+		}
+	}
 
 	var err error
 	if err = pc.initConfiguration(configuration); err != nil {
@@ -173,6 +175,8 @@ func (api *API) NewPeerConnection(configuration Configuration) (*PeerConnection,
 		}
 	})
 
+	pc.interceptorRTCPWriter = api.interceptor.BindRTCPWriter(interceptor.RTCPWriterFunc(pc.writeRTCP))
+
 	return pc, nil
 }
 

settingengine_test.go

@@ -145,19 +145,40 @@ func TestSettingEngine_SetDisableMediaEngineCopy(t *testing.T) {
 		m := &MediaEngine{}
 		assert.NoError(t, m.RegisterDefaultCodecs())
 
-		offerer, answerer, err := NewAPI(WithMediaEngine(m)).newPair(Configuration{})
+		api := NewAPI(WithMediaEngine(m))
+
+		offerer, answerer, err := api.newPair(Configuration{})
 		assert.NoError(t, err)
 
 		_, err = offerer.AddTransceiverFromKind(RTPCodecTypeVideo)
 		assert.NoError(t, err)
 
 		assert.NoError(t, signalPair(offerer, answerer))
 
+		// Assert that the MediaEngine the user created isn't modified
 		assert.False(t, m.negotiatedVideo)
 		assert.Empty(t, m.negotiatedVideoCodecs)
 
+		// Assert that the internal MediaEngine is modified
+		assert.True(t, offerer.api.mediaEngine.negotiatedVideo)
+		assert.NotEmpty(t, offerer.api.mediaEngine.negotiatedVideoCodecs)
+
 		assert.NoError(t, offerer.Close())
 		assert.NoError(t, answerer.Close())
+
+		newOfferer, newAnswerer, err := api.newPair(Configuration{})
+		assert.NoError(t, err)
+
+		// Assert that the first internal MediaEngine hasn't been cleared
+		assert.True(t, offerer.api.mediaEngine.negotiatedVideo)
+		assert.NotEmpty(t, offerer.api.mediaEngine.negotiatedVideoCodecs)
+
+		// Assert that the new internal MediaEngine isn't modified
+		assert.False(t, newOfferer.api.mediaEngine.negotiatedVideo)
+		assert.Empty(t, newAnswerer.api.mediaEngine.negotiatedVideoCodecs)
+
+		assert.NoError(t, newOfferer.Close())
+		assert.NoError(t, newAnswerer.Close())
 	})
 
 	t.Run("No Copy", func(t *testing.T) {
@@ -167,18 +188,31 @@ func TestSettingEngine_SetDisableMediaEngineCopy(t *testing.T) {
 		s := SettingEngine{}
 		s.DisableMediaEngineCopy(true)
 
-		offerer, answerer, err := NewAPI(WithMediaEngine(m), WithSettingEngine(s)).newPair(Configuration{})
+		api := NewAPI(WithMediaEngine(m), WithSettingEngine(s))
+
+		offerer, answerer, err := api.newPair(Configuration{})
 		assert.NoError(t, err)
 
 		_, err = offerer.AddTransceiverFromKind(RTPCodecTypeVideo)
 		assert.NoError(t, err)
 
 		assert.NoError(t, signalPair(offerer, answerer))
 
+		// Assert that the user MediaEngine was modified, so no copy happened
 		assert.True(t, m.negotiatedVideo)
 		assert.NotEmpty(t, m.negotiatedVideoCodecs)
 
 		assert.NoError(t, offerer.Close())
 		assert.NoError(t, answerer.Close())
+
+		offerer, answerer, err = api.newPair(Configuration{})
+		assert.NoError(t, err)
+
+		// Assert that the new internal MediaEngine was modified, so no copy happened
+		assert.True(t, offerer.api.mediaEngine.negotiatedVideo)
+		assert.NotEmpty(t, offerer.api.mediaEngine.negotiatedVideoCodecs)
+
+		assert.NoError(t, offerer.Close())
+		assert.NoError(t, answerer.Close())
 	})
 }