jfjoch_viewer: Handle image buffer counter to stop updating

reader/JFJochHttpReader.cpp

@@ -14,14 +14,11 @@ void JFJochHttpReader::Close() {
     std::unique_lock ul(http_mutex);
     addr = "";
     SetStartMessage({});
+    last_image_buffer_counter = {};
+    last_op_http_sync = false;
 }
 
-uint64_t JFJochHttpReader::GetNumberOfImages() const {
-    std::unique_lock ul(http_mutex);
-
-    if (addr.empty())
-        return 0;
-
+ImageBufferStatus JFJochHttpReader::GetImageBufferStatus() const {
     httplib::Client cli_cmd(addr);
 
     auto res = cli_cmd.Get("/image_buffer/status");
@@ -31,13 +28,30 @@ uint64_t JFJochHttpReader::GetNumberOfImages() const {
 
     try {
         org::openapitools::server::model::Image_buffer_status status = nlohmann::json::parse(res->body);
-        return status.getMaxImageNumber() + 1;
+        ImageBufferStatus ret{};
+        ret.max_image_number = status.getMaxImageNumber();
+        ret.min_image_number = status.getMinImageNumber();
+        ret.available_slots = status.getAvailableSlots();
+        ret.total_slots = status.getTotalSlots();
+        ret.images_in_the_buffer = status.getImageNumbers();
+        if (status.currentCounterIsSet())
+            ret.current_counter = status.getCurrentCounter();
+        return ret;
     } catch (std::exception &e) {
         throw JFJochException(JFJochExceptionCategory::InputParameterInvalid,
                               "Could not parse image buffer status");
     }
 }
 
+uint64_t JFJochHttpReader::GetNumberOfImages() const {
+    std::unique_lock ul(http_mutex);
+
+    if (addr.empty())
+        return 0;
+    auto status = GetImageBufferStatus();
+    return status.max_image_number + 1;
+}
+
 std::shared_ptr<JFJochReaderDataset> JFJochHttpReader::UpdateDataset_i() {
     httplib::Client cli_cmd(addr);
 
@@ -153,8 +167,26 @@ bool JFJochHttpReader::LoadImage_i(std::shared_ptr<JFJochReaderDataset> &dataset
 
     httplib::Client cli_cmd(addr);
 
+    bool buffer_changed = false;
+
+    // For autoupdate - if buffer didn't change don't update dataset
+    auto status = GetImageBufferStatus();
+    if (!last_image_buffer_counter.has_value() // No information on the previous buffer state - always assume it changed
+        || !status.current_counter.has_value() // No information on the current buffer state - e.g. old version of software
+        || last_image_buffer_counter.value() != status.current_counter.value()) // current counter value different from previous
+        buffer_changed = true;
+    last_image_buffer_counter = status.current_counter;
+
+    if (image_number == -1) {
+        if (last_op_http_sync && !buffer_changed)
+            return false;
+        last_op_http_sync = true;
+    } else {
+        last_op_http_sync = false;
+    }
+
     // Always update dataset, as it might have changed from the last time
-    if (update_dataset)
+    if (buffer_changed && update_dataset)
         dataset = UpdateDataset_i();
     if (!dataset)
         return false;