refactoring work to improve issues with new rendering pipeline

app/render/backend/renderbackend.cpp

@@ -1,7 +1,11 @@
 #include "renderbackend.h"
 
+#include <QDateTime>
+#include <QThread>
+
 RenderBackend::RenderBackend(QObject *parent) :
   QObject(parent),
+  started_(false),
   viewer_node_(nullptr)
 {
 
@@ -11,6 +15,50 @@ RenderBackend::~RenderBackend()
 {
 }
 
+bool RenderBackend::Init()
+{
+  if (started_) {
+    return true;
+  }
+
+  threads_.resize(QThread::idealThreadCount());
+
+  for (int i=0;i<threads_.size();i++) {
+    QThread* thread = new QThread(this);
+    threads_.replace(i, thread);
+
+    // We use low priority to keep the app responsive at all times (GUI thread should always prioritize over this one)
+    thread->start(QThread::LowPriority);
+  }
+
+  started_ = InitInternal();
+
+  if (!started_) {
+    Close();
+  }
+
+  return started_;
+}
+
+void RenderBackend::Close()
+{
+  if (!started_) {
+    return;
+  }
+
+  started_ = false;
+
+  CloseInternal();
+
+  decoder_cache_.Clear();
+
+  foreach (QThread* thread, threads_) {
+    thread->quit();
+    thread->wait(); // FIXME: Maximum time in case a thread is stuck?
+  }
+  threads_.clear();
+}
+
 const QString &RenderBackend::GetError() const
 {
   return error_;
@@ -20,6 +68,8 @@ void RenderBackend::SetViewerNode(ViewerOutput *viewer_node)
 {
   if (viewer_node_ != nullptr) {
     disconnect(viewer_node_, SIGNAL(TextureChangedBetween(const rational&, const rational&)), this, SLOT(InvalidateCache(const rational&, const rational&)));
+
+    Decompile();
   }
 
   viewer_node_ = viewer_node;
@@ -29,8 +79,61 @@ void RenderBackend::SetViewerNode(ViewerOutput *viewer_node)
   }
 
   ViewerNodeChangedEvent(viewer_node_);
+}
 
-  Decompile();
+void RenderBackend::SetCacheName(const QString &s)
+{
+  cache_name_ = s;
+  cache_time_ = QDateTime::currentMSecsSinceEpoch();
+
+  RegenerateCacheID();
+}
+
+bool RenderBackend::IsInitiated()
+{
+  return started_;
+}
+
+bool RenderBackend::Compile()
+{
+  if (compiled_) {
+    return true;
+  }
+
+  compiled_ = CompileInternal();
+
+  if (!compiled_) {
+    Decompile();
+  }
+
+  return compiled_;
+}
+
+void RenderBackend::Decompile()
+{
+  if (!compiled_) {
+    return;
+  }
+
+  DecompileInternal();
+}
+
+void RenderBackend::RegenerateCacheID()
+{
+  QCryptographicHash hash(QCryptographicHash::Sha1);
+
+  if (cache_name_.isEmpty()
+      || !cache_time_
+      || !GenerateCacheIDInternal(hash)) {
+    cache_id_.clear();
+    return;
+  }
+
+  hash.addData(cache_name_.toUtf8());
+  hash.addData(QString::number(cache_time_).toUtf8());
+
+  QByteArray bytes = hash.result();
+  cache_id_ = bytes.toHex();
 }
 
 void RenderBackend::SetError(const QString &error)
@@ -47,3 +150,8 @@ ViewerOutput *RenderBackend::viewer_node() const
 {
   return viewer_node_;
 }
+
+const QVector<QThread *> &RenderBackend::threads()
+{
+  return threads_;
+}