Avoid overriding finalize()

[bt90]

Is your feature request related to a problem? Please describe.

The current implementation to make Resource.setNonDisposehandler(Consumer) work, uses finalize() under the hood:

eclipse.platform.swt/bundles/org.eclipse.swt/Eclipse SWT/common/org/eclipse/swt/graphics/Resource.java

Lines 74 to 81 in 4d68329

	protected void finalize() {
	if (ignoreMe) return;
	if (nonDisposedReporter == null) return;
	// If the Resource is GC'ed before it was disposed, this is a leak.
	if (!resource.isDisposed())
	nonDisposedReporter.accept(allocationStack);
	}

This method is deprecated for removal since Java 18 as described in JEP 421.

Describe the solution you'd like

We should rewrite this functionality using PhantomReferences and a daemon thread polling from the shared ReferenceQueue.

Describe alternatives you've considered

The cleaner API might also work:

https://docs.oracle.com/en/java/javase/17/docs/api/java.base/java/lang/ref/Cleaner.html

[laeubi]

I already made some PO to use Cleaner API instead:

• [gtk] Make Fonts GC disposable #1054

this has the advantage that one still can use dispose() to clear early, wait for the GC (and probably log), support clearing of Weak/SoftReference and so on.

[jukzi]

here is a working commit that was rejected:
https://git.eclipse.org/r/c/platform/eclipse.platform.swt/+/185578/24/bundles/org.eclipse.swt/Eclipse+SWT/common/org/eclipse/swt/graphics/Resource.java#b74

[bt90]

Is there any reason why we can't let the Cleaner do the disposal, effectively making dispose() a best practice instead of a necessity?

[jukzi]

Aa cleaner depends on GC, which has literally no guaranties to run. Resources are OS objects which need to be released otherwise the OS runs in out of resource; and- a cleaner does not run in swt thread.

[otbutz]

My proposed solution: #1702