decoder/renderer: no longer index automatically as part of the retrieve

functions

Indexing is a lengthy process and had a high chance of getting RenderWorkers
stuck doing it rather than being responsive to cache requests. This commit
introduces a system where workers never index media, but instead signal that
media is not ready to their RenderBackends which ensure that the media gets
indexed and re-queues the affected frames when those indexes are ready.

app/render/backend/renderworker.h

@@ -24,24 +24,26 @@ public:
 public slots:
   void Close();
 
-  void Render(NodeDependency path, qint64 job_time);
+  void Render(NodeDependency CurrentPath, qint64 job_time);
 
 signals:
   void CompletedCache(NodeDependency dep, NodeValueTable data, qint64 job_time);
 
+  void FootageUnavailable(StreamPtr stream, Decoder::RetrieveState state, const TimeRange& range, const rational& stream_time);
+
 protected:
   virtual bool InitInternal() = 0;
 
   virtual void CloseInternal() = 0;
 
-  virtual NodeValueTable RenderInternal(const NodeDependency& path, const qint64& job_time);
+  virtual NodeValueTable RenderInternal(const NodeDependency& CurrentPath, const qint64& job_time);
 
   virtual void RunNodeAccelerated(const Node *node, const TimeRange& range, const NodeValueDatabase &input_params, NodeValueTable* output_params);
 
   StreamPtr ResolveStreamFromInput(NodeInput* input);
   DecoderPtr ResolveDecoderFromInput(StreamPtr stream);
 
-  virtual FramePtr RetrieveFromDecoder(DecoderPtr decoder, const TimeRange& range, const QAtomicInt* cancelled) = 0;
+  virtual FramePtr RetrieveFromDecoder(DecoderPtr decoder, const TimeRange& range) = 0;
 
   virtual void FrameToValue(StreamPtr stream, FramePtr frame, NodeValueTable* table) = 0;
 
@@ -51,6 +53,10 @@ protected:
 
   NodeValueTable ProcessInput(const NodeInput* input, const TimeRange &range);
 
+  virtual void ReportUnavailableFootage(StreamPtr stream, Decoder::RetrieveState state, const rational& stream_time);
+
+  const NodeDependency& CurrentPath() const;
+
 private:
   NodeValueDatabase GenerateDatabase(const Node *node, const TimeRange &range);
 
@@ -58,6 +64,8 @@ private:
 
   DecoderCache decoder_cache_;
 
+  NodeDependency path_;
+
 };
 
 #endif // RENDERWORKER_H