fixup! core: reuse remote transcoder for stream

core/orch_test.go

@@ -391,6 +391,7 @@ func TestRemoveFromRemoteTranscoders(t *testing.T) {
 	m := NewRemoteTranscoderManager()
 	strm := &StubTranscoderServer{manager: m}
 	strm2 := &StubTranscoderServer{manager: m}
+	strm3 := &StubTranscoderServer{manager: m}
 
 	// sanity check that transcoder is not in liveTranscoders or remoteTranscoders
 	assert := assert.New(t)
@@ -402,22 +403,63 @@ func TestRemoveFromRemoteTranscoders(t *testing.T) {
 	time.Sleep(1 * time.Millisecond) // allow time for first stream to register
 	go func() { m.Manage(strm2, 1) }()
 	time.Sleep(1 * time.Millisecond) // allow time for second stream to register
+	go func() { m.Manage(strm3, 1) }()
+	time.Sleep(1 * time.Millisecond) // allow time for second stream to register
 
-	// assert two transcoders added
-	assert.Len(m.remoteTranscoders, 2)
+	// assert three transcoders added
+	assert.Len(m.remoteTranscoders, 3)
 	t1 := m.liveTranscoders[strm]
 	t2 := m.liveTranscoders[strm2]
-
+	t3 := m.liveTranscoders[strm3]
 	assert.Equal(m.remoteTranscoders[0], t1)
 	assert.Equal(m.remoteTranscoders[1], t2)
+	assert.Equal(m.remoteTranscoders[2], t3)
 
-	// Remove transcoders and assert size reduces
+	// Remove transcoder froms head of the list
 	m.remoteTranscoders = removeFromRemoteTranscoders(t1, m.remoteTranscoders)
 	assert.Equal(m.remoteTranscoders[0], t2)
-	assert.Len(m.remoteTranscoders, 1)
+	assert.Equal(m.remoteTranscoders[1], t3)
+	assert.Len(m.remoteTranscoders, 2)
 
+	// add one back
+	go func() { m.Manage(strm, 1) }()
+	time.Sleep(1 * time.Millisecond) // allow time for first stream to register
+	t1 = m.liveTranscoders[strm]
+	assert.Equal(m.remoteTranscoders[0], t2)
+	assert.Equal(m.remoteTranscoders[1], t3)
+	assert.Equal(m.remoteTranscoders[2], t1)
+	assert.Len(m.remoteTranscoders, 3)
+
+	// Remove transcoder from the end of the list
+	m.remoteTranscoders = removeFromRemoteTranscoders(t3, m.remoteTranscoders)
+	assert.Equal(m.remoteTranscoders[0], t2)
+	assert.Equal(m.remoteTranscoders[1], t1)
+	assert.Len(m.remoteTranscoders, 2)
+
+	// add one back
+	go func() { m.Manage(strm, 1) }()
+	time.Sleep(1 * time.Millisecond) // allow time for first stream to register
+	t3 = m.liveTranscoders[strm]
+	assert.Equal(m.remoteTranscoders[0], t2)
+	assert.Equal(m.remoteTranscoders[1], t1)
+	assert.Equal(m.remoteTranscoders[2], t3)
+	assert.Len(m.remoteTranscoders, 3)
+
+	// Remove transcoder from the middle of the list
+	m.remoteTranscoders = removeFromRemoteTranscoders(t1, m.remoteTranscoders)
+	assert.Equal(m.remoteTranscoders[0], t2)
+	assert.Equal(m.remoteTranscoders[1], t3)
+	assert.Len(m.remoteTranscoders, 2)
+
+	// Remove all the remaining transcoders
 	m.remoteTranscoders = removeFromRemoteTranscoders(t2, m.remoteTranscoders)
+	m.remoteTranscoders = removeFromRemoteTranscoders(t3, m.remoteTranscoders)
 	assert.Len(m.remoteTranscoders, 0)
+
+	// Removing a transcoder when list is empty
+	m.remoteTranscoders = removeFromRemoteTranscoders(t3, m.remoteTranscoders)
+	emptyTList := []*RemoteTranscoder{}
+	assert.Equal(m.remoteTranscoders, emptyTList)
 }
 
 func TestTranscoderManagerTranscoding(t *testing.T) {

core/orchestrator.go

@@ -860,6 +860,11 @@ func (rtm *RemoteTranscoderManager) Manage(stream net.Transcoder_RegisterTransco
 }
 
 func removeFromRemoteTranscoders(rt *RemoteTranscoder, remoteTranscoders []*RemoteTranscoder) []*RemoteTranscoder {
+	if len(remoteTranscoders) == 0 {
+		// No transocerds to remove, return
+		return remoteTranscoders
+	}
+
 	lastIndex := len(remoteTranscoders) - 1
 	last := remoteTranscoders[lastIndex]
 	if rt == last {