Limit image loading to one thread in async image loader

2 files changed, 102 insertions, 38 deletions

diff --git a/src/AsyncImageLoader.cpp b/src/AsyncImageLoader.cpp
index 762408c..4661960 100644
--- a/src/AsyncImageLoader.cpp
+++ b/src/AsyncImageLoader.cpp
@@ -147,29 +147,33 @@ namespace QuickMedia {
         return true;
     }
 
-    // Create thumbnail and load it. On failure load the original image
-    static void create_thumbnail(const Path &thumbnail_path, const Path &thumbnail_path_resized, ThumbnailData *thumbnail_data, sf::Vector2i resize_target_size) {
+    void AsyncImageLoader::load_create_thumbnail(const Path &thumbnail_path, const Path &thumbnail_path_resized, ThumbnailData *thumbnail_data, sf::Vector2i resize_target_size) {
         FileAnalyzer file_analyzer;
         if(!file_analyzer.load_file(thumbnail_path.data.c_str(), false)) {
-            fprintf(stderr, "Failed to convert %s to a thumbnail, using the original image\n", thumbnail_path.data.c_str());
+            fprintf(stderr, "Failed to convert %s to a thumbnail\n", thumbnail_path.data.c_str());
+            thumbnail_data->image = std::make_unique<sf::Image>();
             thumbnail_data->loading_state = LoadingState::FINISHED_LOADING;
             return;
         }
 
         if(is_content_type_video(file_analyzer.get_content_type())) {
-            if(video_get_first_frame(thumbnail_path.data.c_str(), thumbnail_path_resized.data.c_str(), resize_target_size.x, resize_target_size.y))
-                load_image_from_file(*thumbnail_data->image, thumbnail_path_resized.data);
-            thumbnail_data->loading_state = LoadingState::FINISHED_LOADING;
+            if(video_get_first_frame(thumbnail_path.data.c_str(), thumbnail_path_resized.data.c_str(), resize_target_size.x, resize_target_size.y)) {
+                thumbnail_data->loading_state = LoadingState::READY_TO_LOAD;
+            } else {
+                fprintf(stderr, "Failed to get first frame of %s\n", thumbnail_path.data.c_str());
+                thumbnail_data->image = std::make_unique<sf::Image>();
+                thumbnail_data->loading_state = LoadingState::FINISHED_LOADING;
+            }
             return;
         }
 
         if(create_thumbnail(thumbnail_path, thumbnail_path_resized, resize_target_size, file_analyzer.get_content_type(), true)) {
-            load_image_from_file(*thumbnail_data->image, thumbnail_path_resized.data);
+            thumbnail_data->loading_state = LoadingState::READY_TO_LOAD;
         } else {
-            load_image_from_file(*thumbnail_data->image, thumbnail_path.data);
-            fprintf(stderr, "Failed to convert %s to a thumbnail, using the original image\n", thumbnail_path.data.c_str());
+            fprintf(stderr, "Failed to convert %s to a thumbnail\n", thumbnail_path.data.c_str());
+            thumbnail_data->image = std::make_unique<sf::Image>();
+            thumbnail_data->loading_state = LoadingState::FINISHED_LOADING;
         }
-        thumbnail_data->loading_state = LoadingState::FINISHED_LOADING;
     }
 
     AsyncImageLoader& AsyncImageLoader::get_instance() {
@@ -179,7 +183,31 @@ namespace QuickMedia {
         return *instance;
     }
 
-    static void process_thumbnail(ThumbnailLoadData &thumbnail_load_data) {
+    void AsyncImageLoader::process_thumbnail(ThumbnailLoadData &thumbnail_load_data) {
+        Path thumbnail_path_resized = thumbnail_load_data.thumbnail_path;
+        if(thumbnail_load_data.resize_target_size.x != 0 && thumbnail_load_data.resize_target_size.y != 0)
+            thumbnail_path_resized.append("_" + std::to_string(thumbnail_load_data.resize_target_size.x) + "x" + std::to_string(thumbnail_load_data.resize_target_size.y));
+
+        if(get_file_type(thumbnail_path_resized) == FileType::REGULAR) {
+            fprintf(stderr, "Loaded %s from thumbnail cache\n", thumbnail_path_resized.data.c_str());
+            thumbnail_load_data.thumbnail_data->image = std::make_unique<sf::Image>();
+            thumbnail_load_data.thumbnail_data->loading_state = LoadingState::READY_TO_LOAD;
+            return;
+        }
+
+        Path thumbnail_original_path;
+        if(thumbnail_load_data.local)
+            thumbnail_original_path = thumbnail_load_data.path;
+        else
+            thumbnail_original_path = thumbnail_load_data.thumbnail_path;
+
+        if(thumbnail_load_data.resize_target_size.x != 0 && thumbnail_load_data.resize_target_size.y != 0)
+            load_create_thumbnail(thumbnail_original_path, thumbnail_path_resized, thumbnail_load_data.thumbnail_data.get(), thumbnail_load_data.resize_target_size);
+        else
+            thumbnail_load_data.thumbnail_data->loading_state = LoadingState::READY_TO_LOAD;
+    }
+
+    static void load_processed_thumbnail(ThumbnailLoadData &thumbnail_load_data) {
         thumbnail_load_data.thumbnail_data->image = std::make_unique<sf::Image>();
 
         Path thumbnail_path_resized = thumbnail_load_data.thumbnail_path;
@@ -189,7 +217,6 @@ namespace QuickMedia {
         if(get_file_type(thumbnail_path_resized) == FileType::REGULAR) {
             load_image_from_file(*thumbnail_load_data.thumbnail_data->image, thumbnail_path_resized.data);
             thumbnail_load_data.thumbnail_data->loading_state = LoadingState::FINISHED_LOADING;
-            fprintf(stderr, "Loaded %s from thumbnail cache\n", thumbnail_path_resized.data.c_str());
             return;
         }
 
@@ -199,12 +226,13 @@ namespace QuickMedia {
         else
             thumbnail_original_path = thumbnail_load_data.thumbnail_path;
 
-        if(thumbnail_load_data.resize_target_size.x != 0 && thumbnail_load_data.resize_target_size.y != 0)
-            create_thumbnail(thumbnail_original_path, thumbnail_path_resized, thumbnail_load_data.thumbnail_data.get(), thumbnail_load_data.resize_target_size);
-        else
+        if(thumbnail_load_data.resize_target_size.x != 0 && thumbnail_load_data.resize_target_size.y != 0) {
+            load_image_from_file(*thumbnail_load_data.thumbnail_data->image, thumbnail_path_resized.data);
+            thumbnail_load_data.thumbnail_data->loading_state = LoadingState::FINISHED_LOADING;
+        } else {
             load_image_from_file(*thumbnail_load_data.thumbnail_data->image, thumbnail_original_path.data);
-
-        thumbnail_load_data.thumbnail_data->loading_state = LoadingState::FINISHED_LOADING;
+            thumbnail_load_data.thumbnail_data->loading_state = LoadingState::FINISHED_LOADING;
+        }
     }
 
     AsyncImageLoader::AsyncImageLoader() {
@@ -215,10 +243,26 @@ namespace QuickMedia {
 
         load_thread = AsyncTask<void>([this]() mutable {
             std::optional<ThumbnailLoadData> thumbnail_load_data_opt;
-            while(image_load_queue.is_running()) {
-                thumbnail_load_data_opt = image_load_queue.pop_if_available();
-                if(thumbnail_load_data_opt)
+            while(image_thumbnail_create_queue.is_running()) {
+                ThumbnailLoadData load_image_data;
+                {
+                    std::lock_guard<std::mutex> lock(image_load_mutex);
+                    if(current_loading_image.thumbnail_data) {
+                        load_image_data = std::move(current_loading_image);
+                        current_loading_image = ThumbnailLoadData();
+                    }
+                }
+
+                if(load_image_data.thumbnail_data) {
+                    load_processed_thumbnail(load_image_data);
+                    load_image_data = ThumbnailLoadData();
+                }
+
+                thumbnail_load_data_opt = image_thumbnail_create_queue.pop_if_available();
+                if(thumbnail_load_data_opt) {
                     process_thumbnail(thumbnail_load_data_opt.value());
+                    thumbnail_load_data_opt = std::nullopt;
+                }
 
                 for(int i = 0; i < NUM_IMAGE_LOAD_PARALLEL; ++i) {
                     Download &download = downloads[i];
@@ -246,7 +290,7 @@ namespace QuickMedia {
     }
 
     AsyncImageLoader::~AsyncImageLoader() {
-        image_load_queue.close();
+        image_thumbnail_create_queue.close();
     }
 
     static bool download_file_async(const char *url, const char *save_filepath, ReadProgram *read_program) {
@@ -260,19 +304,16 @@ namespace QuickMedia {
         return exec_program_pipe(args, read_program) == 0;
     }
 
-    void AsyncImageLoader::load_thumbnail(const std::string &url, bool local, sf::Vector2i resize_target_size, std::shared_ptr<ThumbnailData> thumbnail_data) {
+    bool AsyncImageLoader::load_thumbnail(const std::string &url, bool local, sf::Vector2i resize_target_size, std::shared_ptr<ThumbnailData> thumbnail_data, Path &thumbnail_path) {
         if(thumbnail_data->loading_state != LoadingState::NOT_LOADED)
-            return;
+            return true;
 
         if(url.empty()) {
             thumbnail_data->image = std::make_unique<sf::Image>();
             thumbnail_data->loading_state = LoadingState::FINISHED_LOADING;
-            return;
+            return false;
         }
         
-        SHA256 sha256;
-        sha256.add(url.data(), url.size());
-        Path thumbnail_path = get_cache_dir().join("thumbnails").join(sha256.getHash());
         if(local) {
             struct stat file_stat;
             memset(&file_stat, 0, sizeof(file_stat));
@@ -280,24 +321,24 @@ namespace QuickMedia {
                 fprintf(stderr, "Failed to load thumbnail %s: no such file\n", url.c_str());
                 thumbnail_data->image = std::make_unique<sf::Image>();
                 thumbnail_data->loading_state = LoadingState::FINISHED_LOADING;
-                return;
+                return false;
             }
 
             thumbnail_path.append("_" + std::to_string(file_stat.st_mtim.tv_sec));
             thumbnail_data->loading_state = LoadingState::LOADING;
-            image_load_queue.push({ url, std::move(thumbnail_path), true, thumbnail_data, resize_target_size });
-            return;
+            image_thumbnail_create_queue.push({ url, thumbnail_path, true, thumbnail_data, resize_target_size });
+            return true;
         }
 
         if(get_file_type(thumbnail_path) == FileType::REGULAR) {
             thumbnail_data->loading_state = LoadingState::LOADING;
-            image_load_queue.push({ url, std::move(thumbnail_path), false, thumbnail_data, resize_target_size });
-            return;
+            image_thumbnail_create_queue.push({ url, thumbnail_path, false, thumbnail_data, resize_target_size });
+            return true;
         }
 
         int free_index = get_free_load_index();
         if(free_index == -1)
-            return;
+            return false;
 
         std::lock_guard<std::mutex> lock(download_mutex);
         thumbnail_data->loading_state = LoadingState::LOADING;
@@ -305,14 +346,15 @@ namespace QuickMedia {
         tmp_thumbnail_path.append(".tmp");
         if(!download_file_async(url.c_str(), tmp_thumbnail_path.data.c_str(), &downloads[free_index].read_program)) {
             fprintf(stderr, "Failed to start download of %s\n", url.c_str());
-            return;
+            return false;
         }
 
         downloads[free_index].download_start = get_boottime_milliseconds();
-        downloads[free_index].thumbnail_path = std::move(thumbnail_path);
+        downloads[free_index].thumbnail_path = thumbnail_path;
         downloads[free_index].thumbnail_data = thumbnail_data;
         downloads[free_index].resize_target_size = resize_target_size;
         downloads[free_index].url = url;
+        return true;
     }
 
     std::shared_ptr<ThumbnailData> AsyncImageLoader::get_thumbnail(const std::string &url, bool local, sf::Vector2i resize_target_size) {
@@ -321,7 +363,22 @@ namespace QuickMedia {
         if(!thumbnail_data)
             thumbnail_data = std::make_shared<ThumbnailData>();
         thumbnail_data->counter = counter;
-        load_thumbnail(url, local, resize_target_size, thumbnail_data);
+
+        if(thumbnail_data->thumbnail_path.data.empty()) {
+            SHA256 sha256;
+            sha256.add(url.data(), url.size());
+            thumbnail_data->thumbnail_path = get_cache_dir().join("thumbnails").join(sha256.getHash());
+        }
+
+        if(!load_thumbnail(url, local, resize_target_size, thumbnail_data, thumbnail_data->thumbnail_path))
+            return thumbnail_data;
+
+        if(thumbnail_data->loading_state == LoadingState::READY_TO_LOAD) {
+            std::lock_guard<std::mutex> lock(image_load_mutex);
+            if(!current_loading_image.thumbnail_data)
+                current_loading_image = { url, thumbnail_data->thumbnail_path, local, thumbnail_data, resize_target_size };
+        }
+
         return thumbnail_data;
     }
 
@@ -342,9 +399,16 @@ namespace QuickMedia {
                     }
                 }
 
-                image_load_queue.erase_if([&it](ThumbnailLoadData &load_data) {
+                image_thumbnail_create_queue.erase_if([&it](ThumbnailLoadData &load_data) {
                     return load_data.path.data == it->first;
                 });
+
+                {
+                    std::lock_guard<std::mutex> lock(image_load_mutex);
+                    if(current_loading_image.thumbnail_data == it->second)
+                        current_loading_image = ThumbnailLoadData();
+                }
+
                 it = thumbnails.erase(it);
                 loaded_textures_changed = true;
             } else {
diff --git a/src/Body.cpp b/src/Body.cpp
index d4b6c5c..eb7a1be 100644
--- a/src/Body.cpp
+++ b/src/Body.cpp
@@ -1070,7 +1070,7 @@ namespace QuickMedia {
             std::shared_ptr<BodyItem> &item = items[index];
             assert(item->visible);
 
-            int prev_index;
+            int prev_index = 0;
             if(attach_side == AttachSide::BOTTOM) {
                 prev_index = get_previous_visible_item(index);
                 if(prev_index == -1)