cache: warn user in UI when disk cache is full

app/core.cpp

@@ -87,7 +87,8 @@ Core::Core(const CoreParams& params) :
   addable_object_(Tool::kAddableEmpty),
   snapping_(true),
   core_params_(params),
-  pixel_sampling_users_(0)
+  pixel_sampling_users_(0),
+  shown_cache_full_warning_(false)
 {
   // Store reference to this object, making the assumption that Core will only ever be made in
   // main(). This will obviously break if not.
@@ -1297,6 +1298,22 @@ void Core::RequestPixelSamplingInViewers(bool e)
   }
 }
 
+void Core::WarnCacheFull()
+{
+  if (!shown_cache_full_warning_ && main_window_) {
+    shown_cache_full_warning_ = true;
+
+    QMessageBox::warning(main_window_, tr("Disk Cache Full"),
+                         tr("The disk cache is currently full and Olive is having to delete old "
+                            "frames to keep it within the limits set in the Disk preferences. This "
+                            "will result in SIGNIFICANTLY reduced cache performance.\n\n"
+                            "To remedy this, please do one of the following:\n\n"
+                            "1. Manually clear the disk cache in Disk preferences.\n"
+                            "2. Increase the maximum disk cache size in Disk preferences.\n"
+                            "3. Reduce usage of the disk cache (e.g. disable auto-cache or only cache specific sections of your sequence)."));
+  }
+}
+
 bool Core::SaveProjectAs(Project* p)
 {
   QFileDialog fd(main_window_, tr("Save Project As"));

app/core.h

@@ -441,6 +441,8 @@ public slots:
 
   void RequestPixelSamplingInViewers(bool e);
 
+  void WarnCacheFull();
+
 signals:
   /**
    * @brief Signal emitted when a project is opened
@@ -621,6 +623,8 @@ private:
    */
   int pixel_sampling_users_;
 
+  bool shown_cache_full_warning_;
+
 private slots:
   void SaveAutorecovery();
 

app/render/diskmanager.cpp

@@ -353,7 +353,16 @@ bool DiskCacheFolder::DeleteLeastRecent()
       }
     }
 
-  return DeleteFileInternal(hash_to_delete);
+    bool e = DeleteFileInternal(hash_to_delete);
+
+    if (e) {
+      Core::instance()->WarnCacheFull();
+    }
+
+    return e;
+  } else {
+    return false;
+  }
 }
 
 void DiskCacheFolder::CloseCacheFolder()