Move outline tree computation to background thread

[lwrage]

Summary

Outline tree computation is currently done in a foreground thread, which can block the UI. Xtext has support for updating the outline in the background.

See https://www.eclipse.org/forums/index.php/t/1103639/

related to #1832

Environment

• OSATE Version: 2.7.1
• Operating System: all

[lwrage]

There seems to be no official documentation. Get help on the TMF forum if needed.

[AaronGreenhouse]

So actually, are talking about the AADL textual outline or the AAXL instance model outline or both?

[AaronGreenhouse]

Okay comments on DefaultOutlineTreeProvider say this:

/**
 * The default implementation of an {@link IOutlineTreeProvider}.
 * If you would like to run your outline in Background, please have a look at {@link BackgroundOutlineTreeProvider}.
 * Please note that this would have implications to you LabelProvider implementation. Please read the JavaDoc in the mentioned class carefully.
 * 
 * @author Jan Koehnlein - Initial contribution and API
 */

and BackgroundOutlineTreeProvider says this:

 * It is essential that the {@link ILabelProvider} implements {@link ILabelProviderImageDescriptorExtension} and that
 * the method {@link ILabelProviderImageDescriptorExtension#getImageDescriptor(Object)} does not need to be executed in
 * the {@link Display} thread, e.g. does not create {@link Image} objects internally.

This matches up with the comments in https://www.eclipse.org/forums/index.php/t/1103639/ that stress the importance of using ImageDescriptor.

[lwrage]

Outline for the AADL text editor.

…

On Mon, Sep 21, 2020 at 4:33 PM AaronGreenhouse ***@***.***> wrote: So actually, are talking about the AADL textual outline or the AAXL instance model outline or both? — You are receiving this because you authored the thread. Reply to this email directly, view it on GitHub <#2320 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AAFXFZ5NSGLBDJEKJD6AVOTSG62CNANCNFSM4M4FLUIA> .

[AaronGreenhouse]

So need to change Aadl2OutlineTreeProvider to extend BackgroundOutlineTreeProvider, but first I need to fix Aadl2LabelProvider to also extend ILabelProviderImageDescriptorExtension.

[AaronGreenhouse]

Ugh. SO despite what the comments on DefaultOutlineTreeProvider suggest, you cannot just swap BackgroundOutlineTreeProvider for DefaultOutlineTreeProvider (modulo the image descriptor issue) because of this nonsense:

	protected PolymorphicDispatcher<Void> createChildrenDispatcher = PolymorphicDispatcher.createForSingleTarget(
			"_createChildren", 2, 2, this);

	protected PolymorphicDispatcher<Void> createNodeDispatcher = PolymorphicDispatcher.createForSingleTarget(
			"_createNode", 2, 2, this);

	protected PolymorphicDispatcher<Object> textDispatcher = PolymorphicDispatcher.createForSingleTarget("_text", 1, 1,
			this);

	protected PolymorphicDispatcher<Image> imageDispatcher = PolymorphicDispatcher.createForSingleTarget("_image", 1,
			1, this);

	protected PolymorphicDispatcher<Boolean> isLeafDispatcher = PolymorphicDispatcher.createForSingleTarget("_isLeaf",
			1, 1, this);

And the background tree wants to inject an OutlineNodeFactory

[AaronGreenhouse]

Good news: Aadl2LabelProvider already extends ILabelProviderImageDescriptorExtension!

[AaronGreenhouse]

I think I have this working. Certainly it doesn't seem to be breaking anything, but I'm having a hard time telling if it makes a difference.

Some strange stuff I noticed though: The original Aadl2OutlineTreeProvider has

	protected boolean _isLeaf(IntegerLiteral bpa) {

		if (bpa.eContainer() instanceof RecordValue) {
			return false;
		}
		return false;
	}

In particular this method always returns false. I am wondering if this is an error. Should the return value of the conditional really be true? There are two other methods that do:

	protected boolean _isLeaf(BasicPropertyAssociation bpa) {

		if (bpa.eContainer() instanceof RecordValue) {
			return true;
		}
		return false;
	}

	protected boolean _isLeaf(ReferenceValue bpa) {

		if (bpa.eContainer() instanceof RecordValue) {
			return true;
		}
		return false;
	}