This patch removes the `finalize` methods from the `Property` classes in the
`javafx.base` module.
The `{Boolean,Double,Float,Int,Long}Property` classes each have a pair of
methods -- `asObject` and `xxxxxProperty` -- that create a `Property<Xxxxx>`
object from a primitive `XxxxxProperty` object and vice versa. Each of the
methods bidirectionally binds the original property object to the created
property object. All of the bidirectional bindings in question use
`WeakReference`s to refer to the pair of objects being bound to each other, so
that they won't cause a memory leak.
The `finalize` methods were added in an attempt to cleanup the bidirectional
bindings when the created object goes away. I say attempt, because it is
entirely ineffective in doing so. The logic that removes the binding creates a
new one from the same pair of objects, but fails to match the original binding
because the referent to the created property object has been garbage collected
before the `finalize` method is called; the `WeakReference` in the binding is
cleared and no longer matches. Fortunately, the only impact of this ineffective
logic is that it can delay the removal of the binding (which is a small object
that just contains the two weak references) from the original property object
until it (the original property) is either garbage collected or modified (the
binding logic already looks for a referent that has been GCed and removes the
binding).
Given that the `finalize` methods don't do anything useful today, and that
there is no memory leak in the first place, the proposed fix is to just remove
the `finalize` methods entirely with no replacement needed. There will be no
changes in behavior as a result of this.
Existing tests of the methods in question are sufficient to ensure no
functional regressions, although there is no existing test for leaks, so I
created new tests to verify that there is no leak. Since there is no existing
leak, those tests will pass both with and without this fix.
-------------
Commits:
- e90abed6: 8196586: Remove use of deprecated finalize methods from javafx
property objects
Changes: https://git.openjdk.java.net/jfx/pull/113/files
Webrev: https://webrevs.openjdk.java.net/jfx/113/webrev.00
Issue: https://bugs.openjdk.java.net/browse/JDK-8196586
Stats: 433 lines in 6 files changed: 278 ins; 155 del; 0 mod
Patch: https://git.openjdk.java.net/jfx/pull/113.diff
Fetch: git fetch https://git.openjdk.java.net/jfx pull/113/head:pull/113
PR: https://git.openjdk.java.net/jfx/pull/113
