renderer/decoder: clean up decoders after some time

app/render/rendermanager.cpp

@@ -36,6 +36,7 @@
 namespace olive {
 
 RenderManager* RenderManager::instance_ = nullptr;
+const int RenderManager::kDecoderMaximumInactivity = 10000;
 
 RenderManager::RenderManager(QObject *parent) :
   ThreadPool(QThread::IdlePriority, 0, parent),
@@ -56,6 +57,10 @@ RenderManager::RenderManager(QObject *parent) :
     decoder_cache_ = new DecoderCache();
     shader_cache_ = new ShaderCache();
     default_shader_ = context_->CreateNativeShader(ShaderCode(QString(), QString()));
+
+    decoder_clear_timer_.setInterval(kDecoderMaximumInactivity);
+    connect(&decoder_clear_timer_, &QTimer::timeout, this, &RenderManager::ClearOldDecoders);
+    decoder_clear_timer_.start();
   } else {
     qCritical() << "Tried to initialize unknown graphics backend";
     context_ = nullptr;
@@ -79,6 +84,24 @@ RenderManager::~RenderManager()
   }
 }
 
+void RenderManager::ClearOldDecoders()
+{
+  QMutexLocker locker(decoder_cache_->mutex());
+
+  qint64 min_age = QDateTime::currentMSecsSinceEpoch() - kDecoderMaximumInactivity;
+
+  for (auto it=decoder_cache_->begin(); it!=decoder_cache_->end(); ) {
+    DecoderPtr decoder = it.value();
+
+    if (decoder->GetLastAccessedTime() < min_age) {
+      decoder->Close();
+      it = decoder_cache_->erase(it);
+    } else {
+      it++;
+    }
+  }
+}
+
 QByteArray RenderManager::Hash(const Node *n, const QString& output, const VideoParams &params, const rational &time)
 {
   QCryptographicHash hasher(QCryptographicHash::Sha1);