Your patches have been merged to master branch and they will be shipped with 3.9.0.
Thank you Enrico Il giorno sab 10 giu 2023 alle ore 18:13 Kezhu Wang <kez...@gmail.com> ha scritto: > > Hi all and committers, > > [ZOOKEEPER-4471][1] reported that `AddWatchMode.PERSISTENT` could be > partially removed by `WatcherType.Data` or `WatcherType.Children`. > > [ZOOKEEPER-4472][2] proposed to add `WatcherType.Persistent` and > `WatcherType.PersistentRecursive` to remove `AddWatchMode.PERSISTENT` > and `AddWatchMode.PERSISTENT_RECURSIVE` respectively. > > [ZOOKEEPER-4466][3] rescues us from conflict among different watch > types on the same path. So, clients can watch whatever paths in > whatever modes. They will not ruin each other. > > On the other hand, [ZOOKEEPER-4472][2] complements the removing part > of [ZOOKEEPER-4466][3]. If a client wants to remove a persistent > watch, it will issue a `removeWatches` `WatcherType.Persistent`. This > will not affect any other watcher types. Currently, clients have to > resort to `WatcherType.Any` to remove them. This could potentially > affect other ongoing watcher types. > > Ideally, ZOOKEEPER-4472 is independent of ZOOKEEPER-4471, but it would > be hard to ship only ZOOKEEPER-4472 without a fix to ZOOKEEPER-4471. > That will require particular attention to avoid trigger paths for > ZOOKEEPER-4471. That is why I delayed it until now. > > I saw discussions about [cut release for 3.9][4]. I really hope we can > merge [pr#1998][5] for ZOOKEEPER-4471 and [pr#2006][6] for > ZOOKEEPER-4472 in 3.9.0. It would be impossible for us to merge > ZOOKEEPER-4472 to patch versions of 3.9 series as it touches both > server logic and api side while ZOOKEEPER-4466 is shipped into 3.9. It > looks weird if we support different watcher types one same path in > watching but not all of them in removing. That is why I hope we can > ship them along with ZOOKEEPER-4466 in 3.9.0. > > I plan to reply with a short message about this possibility in the > release discussion thread to ref back this mail. Hope it won't bore > you in there or here. > > Anyway, please take your time to review pr#1998 and pr#2006 no matter > whether they will be included in 3.9.0. > > Last, if you are curious how ZOOKEEPER-4472 could affect a real > program. You can take a look at [try_remove_watcher][7] and > [dispatch_path_event][8] in [zookeeper-rust-client][9]. The > `try_remove_watcher` ignores dropping of persistent watches if there > are other watches remaining. But this will leak persistent watches on > the server side. `dispatch_path_event` handles this, it will issue > `removeWatches` with `WatcherType.Any` if it receives events to a path > with no watchers. For no persistent watches, the client will issue > corresponding `WatcherType`s if there are more watchers with them. But > it can't do the same for persistent watches due to leak of > `WatcherType.Persistent` and `WatcherType.PersistentRecursive`. Hope > this convinces you of ZOOKEEPER-4472. > > [1]: https://issues.apache.org/jira/browse/ZOOKEEPER-4471 > [2]: https://issues.apache.org/jira/browse/ZOOKEEPER-4472 > [3]: https://issues.apache.org/jira/browse/ZOOKEEPER-4466 > [4]: https://lists.apache.org/thread/dgnt1xnlf5n9tzt7m4otbodg2qdx3fz4 > [5]: https://github.com/apache/zookeeper/pull/1998 > [6]: https://github.com/apache/zookeeper/pull/2006 > [7]: > https://github.com/kezhuw/zookeeper-client-rust/blob/7466e867fb1b229d6b6ffb230e2e682c49ff494e/src/session/watch.rs#L368-L388 > [8]: > https://github.com/kezhuw/zookeeper-client-rust/blob/7466e867fb1b229d6b6ffb230e2e682c49ff494e/src/session/watch.rs#L341-L366 > [9]: https://github.com/kezhuw/zookeeper-client-rust > > Best, > Kezhu Wang
