Fix initial freeze when downloading files

src/main/java/org/jabref/gui/externalfiles/FileDownloadTask.java

@@ -11,7 +11,7 @@
 
 import org.fxmisc.easybind.EasyBind;
 
-public class FileDownloadTask extends BackgroundTask<Void> {
+public class FileDownloadTask extends BackgroundTask<Path> {
 
  private final URL source;
  private final Path destination;
@@ -22,7 +22,7 @@ public FileDownloadTask(URL source, Path destination) {
  }
 
  @Override
- protected Void call() throws Exception {
+ protected Path call() throws Exception {
  URLDownload download = new URLDownload(source);
  try (ProgressInputStream inputStream = download.asInputStream()) {
  EasyBind.subscribe(
@@ -35,6 +35,6 @@ protected Void call() throws Exception {
  Files.copy(inputStream, destination, StandardCopyOption.REPLACE_EXISTING);
  }
 
- return null;
+ return destination;
  }
 }

src/main/java/org/jabref/gui/fieldeditors/LinkedFileViewModel.java

@@ -356,26 +356,30 @@ public void download() {
  }
 
  try {
- URLDownload urlDownload = new URLDownload(linkedFile.getLink());
- Optional<ExternalFileType> suggestedType = inferFileType(urlDownload);
- String suggestedTypeName = suggestedType.map(ExternalFileType::getName).orElse("");
- linkedFile.setFileType(suggestedTypeName);
-
  Optional<Path> targetDirectory = databaseContext.getFirstExistingFileDir(fileDirectoryPreferences);
  if (!targetDirectory.isPresent()) {
  dialogService.showErrorDialogAndWait(Localization.lang("Download file"), Localization.lang("File directory is not set or does not exist!"));
  return;
  }
- String suffix = suggestedType.map(ExternalFileType::getExtension).orElse("");
- String suggestedName = getSuggestedFileName(suffix);
- Path destination = targetDirectory.get().resolve(suggestedName);
 
- BackgroundTask<Void> downloadTask = new FileDownloadTask(urlDownload.getSource(), destination)
- .onSuccess(event -> {
- LinkedFile newLinkedFile = LinkedFilesEditorViewModel.fromFile(destination, databaseContext.getFileDirectoriesAsPaths(fileDirectoryPreferences));
- linkedFile.setLink(newLinkedFile.getLink());
- linkedFile.setFileType(newLinkedFile.getFileType());
- }).onFailure(ex -> dialogService.showErrorDialogAndWait("Download failed", ex));
+ URLDownload urlDownload = new URLDownload(linkedFile.getLink());
+ BackgroundTask<Path> downloadTask = BackgroundTask
+ .wrap(() -> {
+ Optional<ExternalFileType> suggestedType = inferFileType(urlDownload);
+ String suggestedTypeName = suggestedType.map(ExternalFileType::getName).orElse("");
+ linkedFile.setFileType(suggestedTypeName);
+
+ String suffix = suggestedType.map(ExternalFileType::getExtension).orElse("");
+ String suggestedName = getSuggestedFileName(suffix);
+ return targetDirectory.get().resolve(suggestedName);
+ })
+ .then(destination -> new FileDownloadTask(urlDownload.getSource(), destination))
+ .onSuccess(destination -> {
+ LinkedFile newLinkedFile = LinkedFilesEditorViewModel.fromFile(destination, databaseContext.getFileDirectoriesAsPaths(fileDirectoryPreferences));
+ linkedFile.setLink(newLinkedFile.getLink());
+ linkedFile.setFileType(newLinkedFile.getFileType());
+ })
+ .onFailure(exception -> dialogService.showErrorDialogAndWait("Download failed", exception));
 
  downloadProgress.bind(downloadTask.workDonePercentageProperty());
  taskExecutor.execute(downloadTask);
@@ -395,7 +399,6 @@ private Optional<ExternalFileType> inferFileType(URLDownload urlDownload) {
  }
 
  private Optional<ExternalFileType> inferFileTypeFromMimeType(URLDownload urlDownload) {
- // TODO: what if this takes long time?
  String mimeType = urlDownload.getMimeType();
 
  if (mimeType != null) {

src/main/java/org/jabref/gui/util/BackgroundTask.java

@@ -3,6 +3,7 @@
 import java.util.concurrent.Callable;
 import java.util.concurrent.Future;
 import java.util.function.Consumer;
+import java.util.function.Function;
 
 import javafx.beans.property.DoubleProperty;
 import javafx.beans.property.ObjectProperty;
@@ -120,11 +121,33 @@ public BackgroundTask<V> onFinished(Runnable onFinished) {
  return this;
  }
 
+ /**
+ * Creates a {@link BackgroundTask} that first runs this task and based on the result runs a second task.
+ *
+ * @param nextTaskFactory the function that creates the new task
+ * @param <T> type of the return value of the second task
+ */
+ public <T> BackgroundTask<T> then(Function<V, BackgroundTask<T>> nextTaskFactory) {
+ return new BackgroundTask<T>() {
+ @Override
+ protected T call() throws Exception {
+ V result = BackgroundTask.this.call();
+ BackgroundTask<T> nextTask = nextTaskFactory.apply(result);
+ EasyBind.subscribe(nextTask.progressProperty(), this::updateProgress);
+ return nextTask.call();
+ }
+ };
+ }
+
+ protected void updateProgress(BackgroundProgress newProgress) {
+ progress.setValue(newProgress);
+ }
+
  protected void updateProgress(double workDone, double max) {
- progress.setValue(new BackgroundProgress(workDone, max));
+ updateProgress(new BackgroundProgress(workDone, max));
  }
 
- public class BackgroundProgress {
+ class BackgroundProgress {
 
  private final double workDone;
  private final double max;