JavaFX 9: Expose PlatformImpl.runAndWait() as Platform.runAndWait()

[Benjamin Gudehus]

I wonder, if it is possible to test JavaFX applications without blocking
the main thread. User interactions could be completely simulated by using
Event.fireEvent(...) and we could enqueue assertions in the JavaFX
application thread, in which case the assertion library needs to support
asynchronous assertions.

On Wed, Nov 2, 2016 at 9:02 PM, Stefan Fuchs <snfuchs at gmx.de> wrote:

> Hi,
>
> in my experience blocking your working thread for the JavaFX application
> thread is almost always a sign of bad application design.
> You can easily deadlock your application. In our quite complex JavaFX
> Application, we could eliminate almost all of its uses.
>
> However, in one case it is still needed: In a thread we sequentially
> prepare several images in the background, create a snapshot and save them
> as jpegs.
> Here we use java.util.concurrent.CountDownLatch to simulate
> PlatformImpl.runAndWait.
>
>         final WritableImage image = new WritableImage((int) targetWidth,
> (int) targetHeight);
>         final CountDownLatch countDownLatch = new CountDownLatch(1);
>         Platform.runLater(() -> {
>
>                  /* render  and snapshot image */
>
>                  countDownLatch.countDown();
>          });
>
>         boolean released = countDownLatch.await(10, TimeUnit.SECONDS);
>         if (!released) {
>             Logger.getLogger(getClass()).error("Timeout reached, while
> waiting for snapshot");
>             return null;
>         }
>
>         return image;
>
>
>
> What I would like to see implemented is a method, we call runNowOrLater.
>
> That is, if I'm on the JavaFX ApplicationThread execute the Runnable
> immediately, if not call Platform.runLater().
> With this method I have not to worry, if I'm on the JavaFX Application
> thread or not and I avoid flooding the event queue with calls to
> Platform.runLater, that could have been executed directly.
>
> So basically:
>
>     public static void runNowOrLater(final Runnable runnable) {
>         if (Platform.isFxApplicationThread()) {
>             runnable.run();
>         } else {
>             Platform.runLater(runnable);
>         }
>     }
>
> -- Stefan
>
>
>
>
> Hi, Kevin. Thanks for the info!
>>
>> On Wed, Nov 2, 2016 at 5:36 PM, Kevin Rushforth <
>> kevin.rushforth at oracle.com>
>> wrote:
>>
>> No. This isn't something we will do for JDK 9, which is feature complete
>>> (with an exception process for critical requests, especially relating to
>>> Jigsaw). I note in this case that it isn't clear whether we want to do
>>> this
>>> one at all.
>>>
>>> -- Kevin
>>>
>>>
>>>
>>> Benjamin Gudehus wrote:
>>>
>>> Hey!
>>>>
>>>> Are there plans to expose this API [1] in JavaFX 9?
>>>>
>>>> // NOTE: Add the following if we decide to expose it publicly
>>>> // public static void runAndWait(Runnable runnable) {
>>>> // PlatformImpl.runAndWait(runnable);
>>>> // }
>>>>
>>>> [1] http://hg.openjdk.java.net/openjfx/9-dev/rt/file/
>>>> 6edd0c3c01f4/modules/javafx.graphics/src/main/java/javafx/
>>>> application/Platform.java#l148
>>>>
>>>> --Benjamin
>>>>
>>>>
>>>>
>