On Sat, 1 Feb 2025 12:57:34 GMT, John Hendrikx <[email protected]> wrote:
>> This provides and uses a new implementation of `ExpressionHelper`, called
>> `ListenerManager` with improved semantics.
>>
>> # 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 overhead|
>> |Multiple listeners|57 + 4 per listener (excluding unused slots)|57 + 4 per
>> listener (excluding unused slots)|61 + 4 per listener (excluding unused
>> slots)|
>>
>> # About nested changes
>>
>> Nested changes are simply changes...
>
> John Hendrikx has updated the pull request incrementally with five additional
> commits since the last revision:
>
> - Clean-up and add tests
> - Pass in listener data directly for fireValueChanged calls
> - Fix documentation in a few places
> - Remove unused interface
> - Update copyrights and add missing
> ```java
> var property = new SimpleIntegerProperty(0);
>
> ChangeListener<? super Number> listenerA = (obs, ov, nv) -> {
> System.out.println("A got " + ov + "->" + nv + " (" +
> property.get() + ")");
> System.out.println("A set->5");
> property.set(5);
> };
>
> ChangeListener<? super Number> listenerB = (obs, ov, nv) -> {
> System.out.println("B got " + ov + "->" + nv + " (" +
> property.get() + ")");
> System.out.println("B removes A");
> property.removeListener(listenerA);
> System.out.println("B set->6");
> property.set(6);
> };
>
> property.addListener(listenerA);
> property.addListener(listenerB);
>
> property.set(1);
> ```
Thanks, I'm looking into this bug. You can remove the `property.set(5)` in
listenerA and it still fails.
-------------
PR Comment: https://git.openjdk.org/jfx/pull/1081#issuecomment-2663112914
