Firebase Storage: cancel a task / download

[casaucao]

As you probably know, method getFile() in Firebase Storage returns StorageTask<FileDownloadTask.TaskSnapshot> which extends from CancellableTask. Both classes are cancellable, which means we could cancel the current download.

More info here.

Sample code:

StorageTask fileDownloadTask = someFileStorageRef.getFile(someFile).addOnSuccessListener(taskSnapshot -> {
                doStuff();
              });

// Somewhere in your project a user wants to cancel this download.
fileDownloadTask.cancel();

This feature would be quite interesting in order to let a user cancel the download.

[FrangSierra]

You are totally right, I'm gonna change the implementation for all the storage calls which can be canceled to something like :

 @NonNull
   public static Maybe<FileDownloadTask.TaskSnapshot> getFile(@NonNull final StorageReference storageRef, 
                                                              @NonNull final Uri destinationUri) {
      return Maybe.create(new MaybeOnSubscribe<FileDownloadTask.TaskSnapshot>() {
         public void subscribe(final MaybeEmitter<FileDownloadTask.TaskSnapshot> emitter) throws Exception {
            final StorageTask<FileDownloadTask.TaskSnapshot> taskSnapshotStorageTask =
               storageRef.getFile(destinationUri).addOnCompleteListener(new OnCompleteListener<FileDownloadTask.TaskSnapshot>() {
                  @Override
                  public void onComplete(@NonNull Task<FileDownloadTask.TaskSnapshot> task) {
                     if (task.isComplete()) {
                        emitter.onSuccess(task.getResult());
                     } else {
                        emitter.onError(task.getException());
                     }
                     emitter.onComplete();
                  }
               });
            emitter.setCancellable(new Cancellable() {
               @Override public void cancel() throws Exception {
                  taskSnapshotStorageTask.cancel();
               }
            });
         }
      });
   }

I will fix it this weekend and upload a new version.Thanks for your feedback!

[FrangSierra]

This change is already on production with the last release(1.4.0) Enjoy it!