On Fri, 9 Oct 2026 04:15:48 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: > > Fix doc review comments I think this PR is about ready to go in now; I did some minor doc changes in my last commit (mostly Kevin's comments about inconsistent language) -- if there is anything I missed that any of you would really still like to see addressed that really can't wait for a later touch-up, then please point it out one more time (the PR has gotten so many comments, it is getting hard to keep track of what really must go in and what can wait). I will be starting on the CSR next week to finalize this. Thanks everyone for all the effort you put in, this was a long time in the making and raised lots of both old and new issues that I honestly didn't foresee for a simple "listener notification" system :) ------------- PR Comment: https://git.openjdk.org/jfx/pull/1081#issuecomment-6074220523
