fix(fc2): fix double cancellation on quality upgrade

cmd/download/download_command.go

@@ -273,7 +273,14 @@ Available format options:
 		if loop {
 			for {
 				_, err := downloader.Watch(ctx)
-				if errors.Is(err, context.Canceled) || errors.Is(err, fc2.ErrWebSocketStreamEnded) {
+				if errors.Is(err, context.Canceled) {
+					select {
+					case <-ctx.Done():
+					default:
+						log.Panic().
+							Err(err).
+							Msg("a channel was cancelled, but the parent context was not")
+					}
 					log.Info().Str("channelID", channelID).Msg("abort watching channel")
 					break
 				}

fc2/fc2.go

@@ -677,35 +677,33 @@ playlistLoop:
 			doneChan = make(chan struct{}, 1)
 
 			// Download thread.
-			go func() {
+			go func(ctx context.Context) {
+				log.Info().Msg("downloader thread started")
 				defer func() {
 					close(doneChan)
 				}()
 				span.AddEvent("downloading")
-				end := metrics.TimeStartRecording(currentCtx, metrics.Downloads.CompletionTime, time.Second, metric.WithAttributes(
+				end := metrics.TimeStartRecording(ctx, metrics.Downloads.CompletionTime, time.Second, metric.WithAttributes(
 					attribute.String("channel_id", f.channelID),
 				),
 				)
 				defer end()
-				metrics.Downloads.Runs.Add(currentCtx, 1, metric.WithAttributes(
+				metrics.Downloads.Runs.Add(ctx, 1, metric.WithAttributes(
 					attribute.String("channel_id", f.channelID),
 				))
 
 				// Actually download. It will block until the download is finished.
 				checkpointMu.Lock()
-				checkpoint, err = downloader.Read(currentCtx, file, checkpoint)
+				checkpoint, err = downloader.Read(ctx, file, checkpoint)
 				checkpointMu.Unlock()
 
 				if err != nil {
 					errChan <- err
 				}
-			}()
+				f.log.Info().Msg("downloader thread finished")
+			}(currentCtx)
 
 		case err := <-errChan:
-			if currentCancel != nil {
-				currentCancel()
-			}
-
 			if err == nil {
 				f.log.Panic().Msg(
 					"undefined behavior, downloader finished with nil, the download MUST finish with io.EOF",
@@ -714,13 +712,24 @@ playlistLoop:
 			if err == io.EOF {
 				f.log.Info().Msg("downloader finished reading")
 			} else if errors.Is(err, context.Canceled) {
-				f.log.Info().Msg("downloader canceled")
+				select {
+				case <-ctx.Done():
+					f.log.Info().Msg("downloader cancelled by parent context")
+					// Parent context was cancelled, we should return.
+				default:
+					// Parent context was not cancelled, we should continue.
+					f.log.Info().Msg("downloader cancelled")
+					continue
+				}
 			} else {
 				span.RecordError(err)
 				span.SetStatus(codes.Error, err.Error())
 				f.log.Error().Err(err).Msg("downloader failed with error")
 			}
 
+			if currentCancel != nil {
+				currentCancel()
+			}
 			return err
 		}
 	}

fc2/fc2_websocket.go

@@ -157,16 +157,21 @@ func (w *WebSocket) Listen(
 				}
 				switch arguments.Code {
 				case 4101:
+					w.log.Info().Msg("ws paid program")
 					return ErrWebSocketPaidProgram
 				case 4507:
+					w.log.Info().Msg("ws login required")
 					return ErrWebSocketLoginRequired
 				case 4512:
+					w.log.Info().Msg("ws multiple connection")
 					return ErrWebSocketMultipleConnection
 				default:
+					w.log.Error().Msg("ws server disconnection")
 					return ErrWebSocketServerDisconnection
 				}
 
 			case "publish_stop":
+				w.log.Info().Msg("ws stream ended")
 				return ErrWebSocketStreamEnded
 			case "comment":
 				var arguments CommentArguments

hls/hls_downloader.go

@@ -345,7 +345,7 @@ func (hls *Downloader) Read(
 	writer io.Writer,
 	checkpoint Checkpoint,
 ) (newCheckpoint Checkpoint, err error) {
-	hls.log.Debug().Msg("started to read stream")
+	hls.log.Info().Msg("hls downloader started")
 	ctx, span := otel.Tracer(tracerName).Start(ctx, "hls.Read", trace.WithAttributes(
 		attribute.String("last_fragment_name", checkpoint.LastFragmentName),
 		attribute.String("last_fragment_time", checkpoint.LastFragmentTime.String()),