RFR: 8255248: NullPointerException in JFXPanel due to race condition in HostContainer [v3]

[Andy Goryachev]

On Mon, 24 Jul 2023 06:55:19 GMT, Prasanta Sadhukhan <psadhukhan at openjdk.org> wrote:

>> modules/javafx.swing/src/main/java/javafx/embed/swing/JFXPanel.java line 1069:
>> 
>>> 1067: 
>>> 1068:         @Override
>>> 1069:         public void setEmbeddedScene(EmbeddedSceneInterface embeddedScene) {
>> 
>> Same comment as with `setEmbeddedStage`; surrounding all accesses to `scenePeer` and `stagePeer` like this is not the way to do it, and looks incorrect.  I think this is more in the right direction:
>> 
>>         public void setEmbeddedScene(EmbeddedSceneInterface embeddedScene) {
>>             synchronized(LOCK) {
>>                 if (scenePeer == embeddedScene) {
>>                     return;
>>                 }
>>                 scenePeer = embeddedScene;
>>             }
>> 
>>             if (embeddedScene == null) {
>>                 invokeOnClientEDT(() -> {
>>                     if (dnd != null) {
>>                         dnd.removeNotify();
>>                         dnd = null;
>>                     }
>>                 });
>>                 return;
>>             }
>>             if (pWidth > 0 && pHeight > 0) {
>>                 embeddedScene.setSize(pWidth, pHeight);
>>             }
>>             embeddedScene.setPixelScaleFactors((float) scaleFactorX, (float) scaleFactorY);
>> 
>>             invokeOnClientEDT(() -> {
>>                 dnd = new SwingDnD(JFXPanel.this, scenePeer);
>>                 dnd.addNotify();
>>                 embeddedScene.setDragStartListener(dnd.getDragStartListener());
>>             });
>>         }
>
> ok

this code looks much better - eliminates TOC/TOU concern
https://en.wikipedia.org/wiki/Time-of-check_to_time-of-use

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PR Review Comment: https://git.openjdk.org/jfx/pull/1178#discussion_r1272372993