renderer: move waveform generation into worker and mutex the waveform

Addresses scheduling issues where a backend might be closed (or even
destroyed) before it processes a waveform signal from a worker. Requires
extra multithreading code.

app/node/output/track/track.h

@@ -199,6 +199,11 @@ public:
     return waveform_;
   }
 
+  QMutex* waveform_lock()
+  {
+    return &waveform_lock_;
+  }
+
 public slots:
   void SetTrackName(const QString& name);
 
@@ -276,6 +281,7 @@ private:
   rational queued_length_;
 
   AudioVisualWaveform waveform_;
+  QMutex waveform_lock_;
 
 private slots:
   void BlockConnected(NodeEdgePtr edge);

app/render/backend/renderbackend.cpp

@@ -34,7 +34,8 @@ OLIVE_NAMESPACE_ENTER
 RenderBackend::RenderBackend(QObject *parent) :
   QObject(parent),
   viewer_node_(nullptr),
-  update_with_graph_(false)
+  update_with_graph_(false),
+  preview_job_time_(0)
 {
 }
 
@@ -270,7 +271,6 @@ void RenderBackend::RunNextJob()
       RenderWorker* worker = CreateNewWorker();
 
       connect(worker, &RenderWorker::FinishedJob, this, &RenderBackend::WorkerFinished);
-      connect(worker, &RenderWorker::WaveformGenerated, this, &RenderBackend::WorkerGeneratedWaveform);
 
       workers_.replace(i, {worker, false});
     }
@@ -288,7 +288,9 @@ void RenderBackend::RunNextJob()
       worker->SetVideoParams(video_params_);
       worker->SetAudioParams(audio_params_);
       worker->SetVideoDownloadMatrix(video_download_matrix_);
-      worker->SetGeneratePreviews(generate_previews_);
+      if (preview_job_time_) {
+        worker->EnablePreviewGeneration(viewer_node_->audio_playback_cache(), preview_job_time_);
+      }
       worker->SetCopyMap(&copy_map_);
 
       RenderTicketPtr ticket = render_queue_.front();
@@ -351,37 +353,6 @@ void RenderBackend::WorkerFinished()
   }
 }
 
-void RenderBackend::WorkerGeneratedWaveform(const TrackOutput *copied_track, const AudioVisualWaveform& samples, const rational &r)
-{
-  if (!viewer_node_) {
-    return;
-  }
-
-  TrackOutput* track = nullptr;
-
-  /*
-  if (!viewer_node_->audio_playback_cache()->JobIsCurrent(r)) {
-    return;
-  }
-  */
-
-  QHash<Node*, Node*>::const_iterator i;
-  for (i=copy_map_.constBegin(); i!=copy_map_.constEnd(); i++) {
-    if (i.value() == copied_track) {
-      track = static_cast<TrackOutput*>(i.key());
-      break;
-    }
-  }
-
-  if (track) {
-    track->waveform().set_channel_count(audio_params_.channel_count());
-    track->waveform().OverwriteSums(samples, r);
-    emit track->PreviewChanged();
-  } else {
-    qDebug() << "Failed to find track";
-  }
-}
-
 void RenderBackend::CopyNodeInputValue(NodeInput *input)
 {
   // Find our copy of this parameter

app/render/backend/renderbackend.h

@@ -50,9 +50,9 @@ public:
     update_with_graph_ = e;
   }
 
-  void SetGeneratePreviews(bool e)
+  void EnablePreviewGeneration(qint64 job_time)
   {
-    generate_previews_ = e;
+    preview_job_time_ = job_time;
   }
 
   void ClearVideoQueue();
@@ -121,13 +121,11 @@ private:
 
   bool update_with_graph_;
 
-  bool generate_previews_;
+  qint64 preview_job_time_;
 
 private slots:
   void WorkerFinished();
 
-  void WorkerGeneratedWaveform(const OLIVE_NAMESPACE::TrackOutput* copied_track, const OLIVE_NAMESPACE::AudioVisualWaveform& samples, const OLIVE_NAMESPACE::rational& start);
-
 };
 
 OLIVE_NAMESPACE_EXIT

app/render/backend/renderworker.cpp

@@ -35,7 +35,7 @@ RenderWorker::RenderWorker(RenderBackend* parent) :
   parent_(parent),
   available_(true),
   audio_mode_is_preview_(false),
-  generate_previews_(false)
+  preview_cache_(nullptr)
 {
 }
 
@@ -127,12 +127,41 @@ NodeValueTable RenderWorker::GenerateBlockTable(const TrackOutput *track, const
       NodeValueTable::Merge({merged_table, table});
     }
 
-    if (generate_previews_) {
-      // Generate visual waveform in this background thread
-      AudioVisualWaveform visual_waveform;
-      visual_waveform.set_channel_count(audio_params_.channel_count());
-      visual_waveform.AddSamples(block_range_buffer, audio_params_.sample_rate());
-      emit WaveformGenerated(track, visual_waveform, range.in());
+    if (preview_cache_) {
+      // Find original track object
+      TrackOutput* original_track = nullptr;
+
+      QList<TimeRange> valid_ranges = preview_cache_->GetValidRanges(range, preview_job_time_);
+      if (!valid_ranges.isEmpty()) {
+        qDebug() << "Worker generated valid waveform for" << range << preview_cache_;
+
+        QHash<Node*, Node*>::const_iterator i;
+        for (i=copy_map_->constBegin(); i!=copy_map_->constEnd(); i++) {
+          if (i.value() == track) {
+            original_track = static_cast<TrackOutput*>(i.key());
+            break;
+          }
+        }
+
+        // Generate visual waveform in this background thread
+        if (original_track) {
+          AudioVisualWaveform visual_waveform;
+          visual_waveform.set_channel_count(audio_params_.channel_count());
+          visual_waveform.AddSamples(block_range_buffer, audio_params_.sample_rate());
+
+          original_track->waveform_lock()->lock();
+
+          original_track->waveform().set_channel_count(audio_params_.channel_count());
+
+          foreach (const TimeRange& r, valid_ranges) {
+            original_track->waveform().OverwriteSums(visual_waveform, r.in(), r.in() - range.in(), r.length());
+          }
+
+          original_track->waveform_lock()->unlock();
+
+          emit original_track->PreviewChanged();
+        }
+      }
     }
 
     merged_table.Push(NodeParam::kSamples, QVariant::fromValue(block_range_buffer));

app/render/backend/renderworker.h

@@ -73,9 +73,10 @@ public:
     copy_map_ = copy_map;
   }
 
-  void SetGeneratePreviews(bool e)
+  void EnablePreviewGeneration(AudioPlaybackCache* cache, qint64 job_time)
   {
-    generate_previews_ = e;
+    preview_cache_ = cache;
+    preview_job_time_ = job_time;
   }
 
   /**
@@ -132,7 +133,7 @@ signals:
 
   void FinishedJob();
 
-  void WaveformGenerated(const OLIVE_NAMESPACE::TrackOutput* track, const OLIVE_NAMESPACE::AudioVisualWaveform& samples, const OLIVE_NAMESPACE::rational& start);
+  void WaveformGenerated(OLIVE_NAMESPACE::TrackOutput* track, OLIVE_NAMESPACE::AudioVisualWaveform samples, OLIVE_NAMESPACE::TimeRange start);
 
 private:
   NodeValue GetDataFromStream(StreamPtr stream, const TimeRange& input_time);
@@ -164,7 +165,8 @@ private:
 
   bool audio_mode_is_preview_;
 
-  bool generate_previews_;
+  AudioPlaybackCache* preview_cache_;
+  qint64 preview_job_time_;
 
   QHash<Node*, Node*>* copy_map_;
 

app/task/cache/cache.cpp

@@ -33,7 +33,7 @@ CacheTask::CacheTask(ViewerOutput* viewer, const VideoRenderingParams& vparams,
 {
   SetTitle(tr("Caching \"%1\"").arg(viewer->media_name()));
 
-  backend()->SetGeneratePreviews(true);
+  backend()->EnablePreviewGeneration(job_time());
 }
 
 bool CacheTask::Run()

app/widget/timelinewidget/view/timelineviewblockitem.cpp

@@ -99,6 +99,8 @@ void TimelineViewBlockItem::paint(QPainter *painter, const QStyleOptionGraphicsI
     painter->setPen(QColor(64, 64, 64));
     TrackOutput* track = TrackOutput::TrackFromBlock(block_);
     if (track) {
+      QMutexLocker locker(track->waveform_lock());
+
       AudioVisualWaveform::DrawWaveform(painter,
                                         rect().toRect(),
                                         this->GetScale(),