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https://issues.apache.org/jira/browse/CURATOR-549?focusedWorklogId=411670&page=com.atlassian.jira.plugin.system.issuetabpanels:worklog-tabpanel#worklog-411670
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ASF GitHub Bot logged work on CURATOR-549:
------------------------------------------
Author: ASF GitHub Bot
Created on: 28/Mar/20 10:49
Start Date: 28/Mar/20 10:49
Worklog Time Spent: 10m
Work Description: shayshim commented on pull request #335: [CURATOR-549]
Recipes based on Persistent Recursive Watchers
URL: https://github.com/apache/curator/pull/335#discussion_r399259021
##########
File path:
curator-recipes/src/main/java/org/apache/curator/framework/recipes/cache/CuratorCache.java
##########
@@ -0,0 +1,127 @@
+/**
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements. See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied. See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+package org.apache.curator.framework.recipes.cache;
+
+import org.apache.curator.framework.CuratorFramework;
+import org.apache.curator.framework.listen.Listenable;
+import java.io.Closeable;
+import java.util.Optional;
+import java.util.stream.Stream;
+
+/**
+ * <p>
+ * A utility that attempts to keep the data from a node locally cached.
Optionally the entire
+ * tree of children below the node can also be cached. Will respond to
update/create/delete events, pull
+ * down the data, etc. You can register listeners that will get notified
when changes occur.
+ * </p>
+ *
+ * <p>
+ * <b>IMPORTANT</b> - it's not possible to stay transactionally in sync.
Users of this class must
Review comment:
This comment was never very clear to me, and if it is not only me, maybe it
is good opportunity to rephrase it or give more details.
By "false positive" here do you mean that we might get events that do not
reflect anymore the latest state of the zknode?
These events are still true, just a bit late. Soon there should follow the
subsequent events until latest state is reflected. This behavior is general in
ZK clients, not just the cache.
By "false negative" do you mean that we can miss events because ZK only
sends the latest event (e.g. while cache might have been disconnected for a
while, missing some zknode events)? Again, I feel like it is true for any ZK
client, not just the cache. Though in Persistent Watchers I guess we
potentially miss less momentarily events, because the Watcher is always there.
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Issue Time Tracking
-------------------
Worklog Id: (was: 411670)
Time Spent: 13h (was: 12h 50m)
> ZooKeeper 3.6 will add support for Persistent Recursive Watchers - Add
> Curator support
> --------------------------------------------------------------------------------------
>
> Key: CURATOR-549
> URL: https://issues.apache.org/jira/browse/CURATOR-549
> Project: Apache Curator
> Issue Type: Improvement
> Components: Client, Documentation, Framework, Recipes, Tests
> Affects Versions: 4.2.0
> Reporter: Jordan Zimmerman
> Assignee: Jordan Zimmerman
> Priority: Major
> Fix For: 5.0.0
>
> Time Spent: 13h
> Remaining Estimate: 0h
>
> ZOOKEEPER-1416 will add support for Persistent Recursive Watchers. This
> feature allows Curator to re-think/re-write the various cache recipes so that
> they're simpler, use less resources and more stable.
> * Change Curator to depend on ZooKeeper 3.6.x
> * Add a new module so that backward compatibility with 3.5 is ensured
> * Add new methods corresponding to {{ZooKeeper.addWatch()}}
> * Add a new recipe that enables a fully managed Persistent watch
> * Create new Cache recipes that use the new Persistent watch recipe
> * Replace internal usages of TreeCache/PathChildrenCache/NodeCache with new
> cache recipe
> * Deprecate TreeCache/PathChildrenCache/NodeCache
> * Updated docs/tests/etc
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