On Tue, 15 Sep 2026 14:57:00 GMT, John Hendrikx <[email protected]> wrote:
>> This provides and uses a new implementation of `ExpressionHelper`, called
>> `ListenerManager` with improved semantics.
>>
>> See also #837 for a previous attempt which instead of triggering nested
>> emissions immediately (like this PR and `ExpressionHelper`) would wait until
>> the current emission finishes and then start a new (non-nested) emission.
>>
>> # Behavior
>>
>> |Listener...|ExpressionHelper|ListenerManager|
>> |---|---|---|
>> |Invocation Order|In order they were registered, invalidation listeners
>> always before change listeners|(unchanged)|
>> |Removal during Notification|All listeners present when notification started
>> are notified, but excluded for any nested changes|Listeners are removed
>> immediately regardless of nesting|
>> |Addition during Notification|Only listeners present when notification
>> started are notified, but included for any nested changes|New listeners are
>> never called during the current notification regardless of nesting|
>>
>> ## Nested notifications:
>>
>> | |ExpressionHelper|ListenerManager|
>> |---|---|---|
>> |Type|Depth first (call stack increases for each nested level)|(same)|
>> |# of Calls|Listeners * Depth (using incorrect old values)|Collapses nested
>> changes, skipping non-changes|
>> |Vetoing Possible?|No|Yes|
>> |Old Value correctness|Only for listeners called before listeners making
>> nested changes|Always|
>>
>> # Performance
>>
>> |Listener|ExpressionHelper|ListenerManager|
>> |---|---|---|
>> |Addition|Array based, append in empty slot, resize as needed|(same)|
>> |Removal|Array based, shift array, resize as needed|(same)|
>> |Addition during notification|Array is copied, removing collected
>> WeakListeners in the process|Appended when notification finishes|
>> |Removal during notification|As above|Entry is `null`ed (to avoid moving
>> elements in array that is being iterated)|
>> |Notification completion with changes|-|Null entries (and collected
>> WeakListeners) are removed|
>> |Notifying Invalidation Listeners|1 ns each|(same)|
>> |Notifying Change Listeners|1 ns each (*)|2-3 ns each|
>>
>> (*) a simple for loop is close to optimal, but unfortunately does not
>> provide correct old values
>>
>> # Memory Use
>>
>> Does not include alignment, and assumes a 32-bit VM or one that is using
>> compressed oops.
>>
>> |Listener|ExpressionHelper|ListenerManager|OldValueCaching ListenerManager|
>> |---|---|---|---|
>> |No Listeners|none|none|none|
>> |Single InvalidationListener|16 bytes overhead|none|none|
>> |Single ChangeListener|20 bytes overhead|none|16 bytes overhe...
>
> John Hendrikx has updated the pull request incrementally with one additional
> commit since the last revision:
>
> Implement notifying boolean
modules/javafx.base/src/main/java/javafx/beans/value/ObservableValue.java line
87:
> 85: * <li>Properties in the JavaFX library invalidate when the value
> they hold
> 86: * changes. Object properties compare the new value by reference,
> so they also
> 87: * invalidate when the new value is equal to the previous value
> but not the
"is equal" is a bit ambiguous here. I would use "`equals`" to clarify.
modules/javafx.base/src/main/java/javafx/beans/value/ObservableValue.java line
89:
> 87: * invalidate when the new value is equal to the previous value
> but not the
> 88: * same reference; primitive and {@code String} properties
> compare by value.
> 89: * Bindings invalidate when one of their dependencies is
> invalidated.
I think that you're resolving
[JDK-8334429](https://bugs.openjdk.org/browse/JDK-8334429) here.
modules/javafx.base/src/main/java/javafx/beans/value/ObservableValue.java line
100:
> 98: * to the value it last observed ({@code Object#equals(Object)}),
> so the
> 99: * {@code oldValue} and {@code newValue} it receives are never
> equal. The
> 100: * {@code newValue} is the current value of the {@code
> ObservableValue}; for
I'd mention that the current value is `get()` (or `getValue()`), even as a link
of "current value".
modules/javafx.base/src/test/java/test/com/sun/javafx/binding/SimpleObservableValue.java
line 85:
> 83: fireValueChanged.accept(this);
> 84: }
> 85: }
EOF newline.
-------------
PR Review Comment: https://git.openjdk.org/jfx/pull/1081#discussion_r4082361359
PR Review Comment: https://git.openjdk.org/jfx/pull/1081#discussion_r4082305242
PR Review Comment: https://git.openjdk.org/jfx/pull/1081#discussion_r4082383424
PR Review Comment: https://git.openjdk.org/jfx/pull/1081#discussion_r4082489652
