Don't create new threads for files we couldn't generate a thumbnail for

src/app/file_system.cpp

@@ -1,5 +1,5 @@
 // Aseprite
-// Copyright (C) 2019-2021  Igara Studio S.A.
+// Copyright (C) 2019-2022  Igara Studio S.A.
 // Copyright (C) 2001-2018  David Capello
 //
 // This program is distributed under the terms of
@@ -71,7 +71,7 @@ unsigned int current_file_system_version = 0;
 #endif
 
 // a position in the file-system
-class FileItem : public IFileItem {
+class FileItem final : public IFileItem {
 public:
   // TODO make all these fields private
   std::string m_keyname;
@@ -123,6 +123,13 @@ public:
     m_thumbnailProgress = progress;
   }
 
+  bool needThumbnail() const override {
+    return
+      !isBrowsable() &&
+      m_thumbnail == nullptr &&
+      m_thumbnailProgress < 1.0;
+  }
+
   os::SurfaceRef getThumbnail() override;
   void setThumbnail(const os::SurfaceRef& thumbnail) override;
 
@@ -593,6 +600,8 @@ os::SurfaceRef FileItem::getThumbnail()
 
 void FileItem::setThumbnail(const os::SurfaceRef& newThumbnail)
 {
+  m_thumbnailProgress = 1.0;
+
   if (newThumbnail)
     newThumbnail->ref();
   auto old = m_thumbnail.exchange(newThumbnail.get());

src/app/file_system.h

@@ -1,5 +1,5 @@
 // Aseprite
-// Copyright (C) 2019-2020  Igara Studio S.A.
+// Copyright (C) 2019-2022  Igara Studio S.A.
 // Copyright (C) 2001-2018  David Capello
 //
 // This program is distributed under the terms of
@@ -87,8 +87,10 @@ namespace app {
     virtual double getThumbnailProgress() = 0;
     virtual void setThumbnailProgress(double progress) = 0;
 
+    virtual bool needThumbnail() const = 0;
     virtual os::SurfaceRef getThumbnail() = 0;
     virtual void setThumbnail(const os::SurfaceRef& thumbnail) = 0;
+
   };
 
 } // namespace app

src/app/thumbnail_generator.cpp

@@ -176,17 +176,26 @@ private:
       THUMB_TRACE("FOP done with thumbnail: %s %s\n",
                   m_item.fileitem->fileName().c_str(),
                   (m_fop->isStop() ? " (stop)": ""));
-
-      // Reset the m_item (first the fileitem so this worker is not
-      // associated to this fileitem anymore, and then the FileOp).
-      {
-        std::lock_guard<std::mutex> lock(m_mutex);
-        m_item.fileitem = nullptr;
-      }
     }
     catch (const std::exception& e) {
       m_fop->setError("Error loading file:\n%s", e.what());
     }
+
+    if (!m_fop->isStop()) {
+      // Set a nullptr thumbnail if we failed loading the given file,
+      // in this way we're not going to re-try generating this same
+      // thumbnail.
+      if (m_item.fileitem->needThumbnail())
+        m_item.fileitem->setThumbnail(nullptr);
+    }
+
+    // Reset the m_item (first the fileitem so this worker is not
+    // associated to this fileitem anymore, and then the FileOp).
+    {
+      std::lock_guard<std::mutex> lock(m_mutex);
+      m_item.fileitem = nullptr;
+    }
+
     m_fop->done();
     {
       std::lock_guard<std::mutex> lock(m_mutex);
@@ -262,8 +271,7 @@ bool ThumbnailGenerator::checkWorkers()
 
 void ThumbnailGenerator::generateThumbnail(IFileItem* fileitem)
 {
-  if (fileitem->isBrowsable() ||
-      fileitem->getThumbnail())
+  if (!fileitem->needThumbnail())
     return;
 
   if (fileitem->getThumbnailProgress() > 0.0) {
@@ -302,11 +310,12 @@ void ThumbnailGenerator::generateThumbnail(IFileItem* fileitem)
       fileitem->fileName().c_str(),
       FILE_LOAD_SEQUENCE_NONE |
       FILE_LOAD_ONE_FRAME));
-  if (!fop)
-    return;
-
-  if (fop->hasError())
+  if (!fop || fop->hasError()) {
+    // Set a nullptr thumbnail so we don't try to generate a thumbnail
+    // for this fileitem again.
+    fileitem->setThumbnail(nullptr);
     return;
+  }
 
   m_remainingItems.push(Item(fileitem, fop.get()));
   fop.release();

src/app/ui/file_list.cpp

@@ -885,7 +885,7 @@ void FileList::selectIndex(int index)
 
 void FileList::generateThumbnailForFileItem(IFileItem* fi)
 {
-  if (fi && animation() == ANI_NONE) {
+  if (fi && fi->needThumbnail() && animation() == ANI_NONE) {
     auto it = std::find(m_generateThumbnailsForTheseItems.begin(),
                         m_generateThumbnailsForTheseItems.end(), fi);
     if (it != m_generateThumbnailsForTheseItems.end())