renderer: implemented function to wait for workers in the main thread

The workers run in separate threads meaning if any significant change is made
(e.g. parameters changing, or even closing the program), these workers may still
be mid-render. This is particularly problematic when closing since the nodes a
worker is rendering may be deleted mid-render. Render backends now have a
function that pauses the main thread (but starts a second event loop so the UI
isn't frozen) until the worker threads are all finished. This way, massive
changes can be made safely without race conditions.

app/dialog/CMakeLists.txt

@@ -22,6 +22,7 @@ add_subdirectory(keyframeproperties)
 add_subdirectory(loadsave)
 add_subdirectory(preferences)
 add_subdirectory(projectproperties)
+add_subdirectory(rendercancel)
 add_subdirectory(sequence)
 add_subdirectory(speedduration)
 

app/dialog/preferences/tabs/preferencesaudiotab.cpp

@@ -105,13 +105,16 @@ void PreferencesAudioTab::Accept()
   // FIXME: Qt documentation states that QAudioDeviceInfo::deviceName() is a "unique identifiers", which would make them
   //        ideal for saving in preferences, but in practice they don't actually appear to be unique.
   //        See: https://bugreports.qt.io/browse/QTBUG-16841
+  if (Config::Current()["AudioOutput"] != selected_output_name) {
     Config::Current()["AudioOutput"] = selected_output_name;
-  Config::Current()["AudioInput"] = selected_input_name;
-
-  // Finally, set these as the current device
     AudioManager::instance()->SetOutputDevice(selected_output);
+  }
+
+  if (Config::Current()["AudioInput"] != selected_input_name) {
+    Config::Current()["AudioInput"] = selected_input_name;
     AudioManager::instance()->SetInputDevice(selected_input);
   }
+}
 
 void PreferencesAudioTab::RefreshDevices()
 {

app/dialog/rendercancel/CMakeLists.txt

@@ -0,0 +1,22 @@
+# Olive - Non-Linear Video Editor
+# Copyright (C) 2019 Olive Team
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+set(OLIVE_SOURCES
+  ${OLIVE_SOURCES}
+  dialog/rendercancel/rendercancel.h
+  dialog/rendercancel/rendercancel.cpp
+  PARENT_SCOPE
+)

app/dialog/rendercancel/rendercancel.cpp

@@ -0,0 +1,56 @@
+#include "rendercancel.h"
+
+RenderCancelDialog::RenderCancelDialog(QWidget *parent) :
+  LoadSaveDialog(tr("Waiting for workers to finish..."), tr("Renderer"), parent),
+  busy_workers_(0),
+  total_workers_(0)
+{
+}
+
+void RenderCancelDialog::RunIfWorkersAreBusy()
+{
+  if (busy_workers_ > 0) {
+    waiting_workers_ = busy_workers_;
+
+    exec();
+  }
+}
+
+void RenderCancelDialog::SetWorkerCount(int count)
+{
+  total_workers_ = count;
+
+  UpdateProgress();
+}
+
+void RenderCancelDialog::WorkerStarted()
+{
+  busy_workers_++;
+
+  UpdateProgress();
+}
+
+void RenderCancelDialog::WorkerDone()
+{
+  busy_workers_--;
+
+  UpdateProgress();
+}
+
+void RenderCancelDialog::showEvent(QShowEvent *event)
+{
+  UpdateProgress();
+}
+
+void RenderCancelDialog::UpdateProgress()
+{
+  if (!total_workers_ || !isVisible()) {
+    return;
+  }
+
+  SetProgress(qRound(100.0 * static_cast<double>(waiting_workers_ - busy_workers_) / static_cast<double>(waiting_workers_)));
+
+  if (busy_workers_ == 0) {
+    accept();
+  }
+}

app/dialog/rendercancel/rendercancel.h

@@ -0,0 +1,35 @@
+#ifndef RENDERCANCELDIALOG_H
+#define RENDERCANCELDIALOG_H
+
+#include "dialog/loadsave/loadsave.h"
+
+class RenderCancelDialog : public LoadSaveDialog
+{
+  Q_OBJECT
+public:
+  RenderCancelDialog(QWidget* parent = nullptr);
+
+  void RunIfWorkersAreBusy();
+
+  void SetWorkerCount(int count);
+
+  void WorkerStarted();
+
+public slots:
+  void WorkerDone();
+
+protected:
+  virtual void showEvent(QShowEvent* event) override;
+
+private:
+  void UpdateProgress();
+
+  int busy_workers_;
+
+  int total_workers_;
+
+  int waiting_workers_;
+
+};
+
+#endif // RENDERCANCELDIALOG_H

app/panel/panelmanager.h

@@ -87,8 +87,6 @@ public:
   template<class T>
   /**
    * @brief Create a panel
-   * @param parent
-   * @return
    */
   T* CreatePanel(QWidget* parent);
 
@@ -114,6 +112,12 @@ public:
    */
   static PanelManager* instance();
 
+  template<class T>
+  /**
+   * @brief Get a list of panels of a certain type
+   */
+  QList<T*> GetPanelsOfType();
+
 public slots:
   /**
    * @brief Connect this to a QApplication's SIGNAL(focusChanged())
@@ -173,4 +177,22 @@ T* PanelManager::MostRecentlyFocused()
   return nullptr;
 }
 
+template<class T>
+QList<T*> PanelManager::GetPanelsOfType()
+{
+  QList<T*> panels;
+
+  T* cast_test;
+
+  foreach (PanelWidget* panel, focus_history_) {
+    cast_test = dynamic_cast<T*>(panel);
+
+    if (cast_test) {
+      panels.append(cast_test);
+    }
+  }
+
+  return panels;
+}
+
 #endif // PANELFOCUSMANAGER_H

app/render/backend/opengl/openglbackend.cpp

@@ -39,7 +39,10 @@ bool OpenGLBackend::InitInternal()
 
   // Create master texture (the one sent to the viewer)
   master_texture_ = std::make_shared<OpenGLTexture>();
-  master_texture_->Create(share_ctx, params().effective_width(), params().effective_height(), params().format());
+  master_texture_->Create(share_ctx,
+                          params().effective_width(),
+                          params().effective_height(),
+                          params().format());
 
   // Create copy buffer/pipeline
   copy_buffer_.Create(share_ctx);
@@ -156,11 +159,13 @@ void OpenGLBackend::EmitCachedFrameReady(const rational &time, const QVariant &v
 
 void OpenGLBackend::ParamsChangedEvent()
 {
-  // Assume if the texture is allocated, it needs to be changed. Otherwise the texture should be created through
-  // InitInternal() with the correct parameters
-  if (master_texture_) {
+  // If we're initiated, we need to recreate the texture. Otherwise this backend isn't active so it doesn't matter.
+  if (IsInitiated()) {
     master_texture_->Destroy();
-    master_texture_->Create(QOpenGLContext::currentContext(), params().effective_width(), params().effective_height(), params().format());
+    master_texture_->Create(QOpenGLContext::currentContext(),
+                            params().effective_width(),
+                            params().effective_height(),
+                            params().format());
   }
 }
 

app/render/backend/renderbackend.cpp

@@ -3,6 +3,9 @@
 #include <QDateTime>
 #include <QThread>
 
+#include "core.h"
+#include "window/mainwindow/mainwindow.h"
+
 RenderBackend::RenderBackend(QObject *parent) :
   QObject(parent),
   compiled_(false),
@@ -12,6 +15,8 @@ RenderBackend::RenderBackend(QObject *parent) :
   recompile_queued_(false),
   input_update_queued_(false)
 {
+  // FIXME: Don't create in CLI mode
+  cancel_dialog_ = new RenderCancelDialog(Core::instance()->main_window());
 }
 
 bool RenderBackend::Init()
@@ -30,6 +35,8 @@ bool RenderBackend::Init()
     thread->start(QThread::LowPriority);
   }
 
+  cancel_dialog_->SetWorkerCount(threads_.size());
+
   started_ = InitInternal();
 
   // Connects workers and moves them to their respective threads
@@ -50,6 +57,8 @@ void RenderBackend::Close()
 
   started_ = false;
 
+  CancelQueue();
+
   Decompile();
 
   CloseInternal();
@@ -81,6 +90,8 @@ const QString &RenderBackend::GetError() const
 void RenderBackend::SetViewerNode(ViewerOutput *viewer_node)
 {
   if (viewer_node_ != nullptr) {
+    CancelQueue();
+
     DisconnectViewer(viewer_node_);
 
     Decompile();
@@ -297,6 +308,7 @@ void RenderBackend::CacheNext()
       render_job_info_.insert(cache_frame, job_time);
 
       SetWorkerBusyState(worker, true);
+      cancel_dialog_->WorkerStarted();
 
       QMetaObject::invokeMethod(worker,
                                 "Render",
@@ -312,6 +324,20 @@ ViewerOutput *RenderBackend::viewer_node() const
   return copied_viewer_node_;
 }
 
+void RenderBackend::CancelQueue()
+{
+  cache_queue_.clear();
+
+  int busy = 0;
+  for (int i=0;i<processor_busy_state_.size();i++) {
+    if (processor_busy_state_.at(i))
+      busy++;
+  }
+  qDebug() << this << "has" << busy << "busy workers";
+
+  cancel_dialog_->RunIfWorkersAreBusy();
+}
+
 bool RenderBackend::ViewerIsConnected() const
 {
   return viewer_node_ != nullptr;
@@ -375,6 +401,9 @@ void RenderBackend::InitWorkers()
     // Connect to it
     ConnectWorkerToThis(processor);
 
+    // Connect cancel dialog to it
+    connect(processor, &RenderWorker::CompletedCache, cancel_dialog_, &RenderCancelDialog::WorkerDone, Qt::QueuedConnection);
+
     // Finally, we can move it to its own thread
     processor->moveToThread(thread);
 

app/render/backend/renderbackend.h

@@ -4,6 +4,7 @@
 #include <QLinkedList>
 
 #include "common/constructors.h"
+#include "dialog/rendercancel/rendercancel.h"
 #include "decodercache.h"
 #include "node/graph.h"
 #include "node/output/viewer/viewer.h"
@@ -15,8 +16,6 @@ class RenderBackend : public QObject
 public:
   RenderBackend(QObject* parent = nullptr);
 
-  DISABLE_COPY_MOVE(RenderBackend)
-
   bool Init();
 
   void Close();
@@ -29,6 +28,8 @@ public:
 
   ViewerOutput* viewer_node() const;
 
+  void CancelQueue();
+
 public slots:
   void InvalidateCache(const rational &start_range, const rational &end_range);
 
@@ -142,6 +143,8 @@ private:
 
   QVector<bool> processor_busy_state_;
 
+  RenderCancelDialog* cancel_dialog_;
+
 };
 
 #endif // RENDERBACKEND_H

app/render/backend/videorenderbackend.cpp

@@ -76,10 +76,7 @@ const VideoRenderingParams &VideoRenderBackend::params() const
 
 void VideoRenderBackend::SetParameters(const VideoRenderingParams& params)
 {
-  if (!AllProcessorsAreAvailable()) {
-    qCritical() << "Attempted to set parameters on a backend whose workers are still busy";
-    return;
-  }
+  CancelQueue();
 
   // Set new parameters
   params_ = params;

app/window/mainwindow/mainwindow.cpp

@@ -145,10 +145,14 @@ void MainWindow::ProjectOpen(Project* p)
 
 void MainWindow::closeEvent(QCloseEvent *e)
 {
+  // Close viewers first since we don't want to delete any nodes while they might be mid-render
+  QList<ViewerPanel*> viewers = PanelManager::instance()->GetPanelsOfType<ViewerPanel>();
+  foreach (ViewerPanel* viewer, viewers) {
+    viewer->ConnectViewerNode(nullptr);
+  }
+
   PanelManager::instance()->DeleteAllPanels();
 
-
-
   QMainWindow::closeEvent(e);
 }