ZOOKEEPER-4466: Support different watch modes on same path by kezhuw · Pull Request #1859 · apache/zookeeper

kezhuw · 2022-04-09T07:52:36Z

Currently, in server side, there is only one watcher mode per path. This
will destroy and corrupt old watch when client watch a watching path.

eolivelli

This is a great work

@lvfangmin @Randgalt @breed please take a look carefully.

I am afraid that we could inadvertently change the semantics of watchers

eolivelli · 2022-04-09T11:04:23Z

We need more eyes on this patch

Currently, in server side, there is only one watcher mode per path. This will destroy and corrupt old watch when client watch a watching path.

kezhuw · 2023-02-27T13:23:03Z

Could you please take a look at this ? @tisonkun @eolivelli @Randgalt @symat @maoling @arshadmohammad @anmolnar @ztzg @lvfangmin @breed

eolivelli

+1

Unfortunately we need more eyes on this patch.

Signed-off-by: tison <wander4096@gmail.com>

tisonkun · 2023-03-04T02:44:56Z

-            }
-        }
-        return false;
+        Set<Watcher> list = watchTable.get(path);


@kezhuw Can you explain a bit why this change is correct?

It seems that previously, containsWatcher (path, watcher) will be true if any parent of the path has a persistent recursive watch.

It seems that previously, containsWatcher (path, watcher) will be true if any parent of the path has a persistent recursive watch.

It is no true though it might intend to do so. Two cases for old code:

If there is a watch for (watcher, path), the first return true will hold.

If there is no watch for (watcher, path), watcherMode will be WatcherMode.STANDARD, no return true will hold:

First return true will not hold as it only apply for leaf node where there is no such watch.

Second return true will not hold as WatcherMode.STANDARD is no recursive.

So my change has same behavior as old code and also same to when it was introduced. I think this behavior meets what OpCode.checkWatches expects which is the sole client visible call to this method. Disregard cheating behaviour of ZooKeeper.removeWatches, removing sub nodes from recursive watching sounds quirk as similar one I saw in ZOOKEEPER-4471.

Thanks for your explanation! I get it now :)

tisonkun

The rest looks good to me. One comment above.

Signed-off-by: tison <wander4096@gmail.com>

tisonkun

LGTM

tisonkun · 2023-03-04T04:22:27Z

-            }
-        }
-        return false;
+        Set<Watcher> list = watchTable.get(path);


Thanks for your explanation! I get it now :)

tisonkun · 2023-03-04T05:29:27Z

Cc @Randgalt @lvfangmin @breed if you can take a look also.

…st-with-same-path

kezhuw · 2023-04-27T10:52:10Z

Shall we merge this ? Or we need more eyeballs on this? @eolivelli @tisonkun @Randgalt @lvfangmin @breed @cnauroth @symat @maoling

I guess lazy consensus could apply here if no more comments.

tisonkun · 2023-05-05T07:57:50Z

Merging...

Thanks for your contribution @kezhuw!

PR apache#1950(ZOOKEEPER-4655) was created before apache#1859(ZOOKEEPER-4466) merged. It changes `assertEvent`'s signature which is depended by apache#1859.

…2012) PR #1950(ZOOKEEPER-4655) was created before #1859(ZOOKEEPER-4466) merged. It changes `assertEvent`'s signature which is depended by #1859.

PR #1950(ZOOKEEPER-4655) was created before #1859(ZOOKEEPER-4466) merged. It changes `assertEvent`'s signature which is depended by #1859.

Signed-off-by: Kezhu Wang <kezhuw@gmail.com> Co-authored-by: tison <wander4096@gmail.com>

…) (#49) Signed-off-by: Kezhu Wang <kezhuw@gmail.com> Co-authored-by: Kezhu Wang <kezhuw@gmail.com> Co-authored-by: tison <wander4096@gmail.com>

PR apache#1950(ZOOKEEPER-4655) was created before apache#1859(ZOOKEEPER-4466) merged. It changes `assertEvent`'s signature which is depended by apache#1859.

PR apache#1950(ZOOKEEPER-4655) was created before apache#1859(ZOOKEEPER-4466) merged. It changes `assertEvent`'s signature which is depended by apache#1859. Co-authored-by: Kezhu Wang <kezhuw@gmail.com>

PR apache#1950(ZOOKEEPER-4655) was created before apache#1859(ZOOKEEPER-4466) merged. It changes `assertEvent`'s signature which is depended by apache#1859.

sonatype-lift Bot reviewed Apr 9, 2022

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Comment thread zookeeper-server/src/main/java/org/apache/zookeeper/server/watch/WatchManager.java

eolivelli requested changes Apr 9, 2022

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kezhuw force-pushed the ZOOKEEPER-4466-different-watch-modes-coexist-with-same-path branch 2 times, most recently from 1722faa to c8557af Compare July 1, 2022 03:24

kezhuw mentioned this pull request Jul 4, 2022

ZOOKEEPER-4475: Fix NodeChildrenChanged delivered to recursive watcher #1820

Merged

kezhuw force-pushed the ZOOKEEPER-4466-different-watch-modes-coexist-with-same-path branch from c8557af to 4bdd355 Compare February 23, 2023 04:08

ZOOKEEPER-4466: Support different watch modes on same path

b65852e

Currently, in server side, there is only one watcher mode per path. This will destroy and corrupt old watch when client watch a watching path.

kezhuw force-pushed the ZOOKEEPER-4466-different-watch-modes-coexist-with-same-path branch from 4bdd355 to b65852e Compare February 27, 2023 04:12

tisonkun self-requested a review February 27, 2023 14:31

eolivelli approved these changes Feb 27, 2023

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tisonkun reviewed Feb 28, 2023

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Comment thread zookeeper-server/src/main/java/org/apache/zookeeper/server/DataTree.java

refactor WatchStats internals

cc74acd

Signed-off-by: tison <wander4096@gmail.com>

tisonkun reviewed Mar 4, 2023

View reviewed changes

try fix CI

5355029

Signed-off-by: tison <wander4096@gmail.com>

tisonkun approved these changes Mar 4, 2023

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Merge branch 'master' into ZOOKEEPER-4466-different-watch-modes-coexi…

6e8cd81

…st-with-same-path

kezhuw mentioned this pull request May 4, 2023

ZOOKEEPER-4541 Ephemeral znode owned by closed session visible in 1 of 3 servers #1925

Closed

tisonkun merged commit a64dbf5 into apache:master May 5, 2023

kezhuw mentioned this pull request May 8, 2023

ZOOKEEPER-4471: Match removing WatcherType to standard, persistent modes #1998

Merged

kezhuw mentioned this pull request Jun 16, 2023

ZOOKEEPER-4655: [ADDENDUM] fix build error #2012

Merged

anmolnar pushed a commit that referenced this pull request Jun 16, 2023

ZOOKEEPER-4655: [ADDENDUM] fix build error (#2012)

6254f33

PR #1950(ZOOKEEPER-4655) was created before #1859(ZOOKEEPER-4466) merged. It changes `assertEvent`'s signature which is depended by #1859.

anurag-harness pushed a commit to anurag-harness/zookeeper that referenced this pull request Aug 31, 2023

ZOOKEEPER-4466: Support different watch modes on same path (apache#1859)

ef711d1

Signed-off-by: Kezhu Wang <kezhuw@gmail.com> Co-authored-by: tison <wander4096@gmail.com>

anurag-harness mentioned this pull request Aug 31, 2023

ZOOKEEPER-4655: [ADDENDUM] fix build error (#2012) anurag-harness/zookeeper#56

Merged

kezhuw deleted the ZOOKEEPER-4466-different-watch-modes-coexist-with-same-path branch September 24, 2023 15:08

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