[jira] [Commented] (ZOOKEEPER-2163) Introduce new ZNode type: container

["ASF GitHub Bot (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/ZOOKEEPER-2163?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14494742#comment-14494742 ] 

ASF GitHub Bot commented on ZOOKEEPER-2163:
-------------------------------------------

GitHub user Randgalt opened a pull request:

    https://github.com/apache/zookeeper/pull/29

    ZOOKEEPER-2163 - Introduce new ZNode type: container

    Major changes:
    
    * New APIs to create container nodes (in ZooKeeper.java)
    * New OpCode for createContainer, deleteContainer (deleteContainer is used internally only)
    * New class ContainerManager which processes empty containers using a timer. This is meant to operate only in the leader
    * DataTree - overload the meaning of ephemeralOwner. When its value is DataTree.CONTAINER_EPHEMERAL_OWNER, it's a container node
    * PrepRequestProcessor - code to create containers and process deleteContainer requests
    * zookeeper.jute - CreateContainerRequest, and CreateContainerTxn

You can merge this pull request into a Git repository by running:

    $ git pull https://github.com/Randgalt/zookeeper ZOOKEEPER-2163

Alternatively you can review and apply these changes as the patch at:

    https://github.com/apache/zookeeper/pull/29.patch

To close this pull request, make a commit to your master/trunk branch
with (at least) the following in the commit message:

    This closes #29
    
----
commit 508b2758afae9c8a84a0c00703c28e664c11016e
Author: randgalt <jo...@jordanzimmerman.com>
Date:   2015-04-13T20:12:35Z

    ZOOKEEPER-2163 intial work at defining createContainer API and a few tests

commit 77677e40d1b90fe2c0e795095ba2a84c9c763b91
Author: randgalt <jo...@jordanzimmerman.com>
Date:   2015-04-14T15:45:29Z

    ZOOKEEPER-2163 - wip

commit 19e466eb3b193bc4dd84c68ab59c4e4d4ba0708a
Author: randgalt <jo...@jordanzimmerman.com>
Date:   2015-04-14T17:14:16Z

    ZOOKEEPER-2163 - basic workings complete. We now have a checkContainers() method that will delete candidate containers

commit d386c5ab458065e8cdd93c8b59eef3829e973da9
Author: randgalt <jo...@jordanzimmerman.com>
Date:   2015-04-14T17:53:48Z

    ZOOKEEPER-2163 more testing

commit 88cd089456c0d66d37b4d6be33b9989866100d14
Author: randgalt <jo...@jordanzimmerman.com>
Date:   2015-04-14T17:55:16Z

    ZOOKEEPER-2163 added back ACLs to containers

commit 1346587ff474636fbff238242245594a1fdf10a9
Author: randgalt <jo...@jordanzimmerman.com>
Date:   2015-04-14T19:18:17Z

    ZOOKEEPER-2163 first pass now complete.

commit 301af7707398bf9a9eb1722cfd93d2599396cc16
Author: randgalt <jo...@jordanzimmerman.com>
Date:   2015-04-14T19:40:56Z

    ZOOKEEPER-2163 some refactoring, doc, etc.

----


> Introduce new ZNode type: container
> -----------------------------------
>
>                 Key: ZOOKEEPER-2163
>                 URL: https://issues.apache.org/jira/browse/ZOOKEEPER-2163
>             Project: ZooKeeper
>          Issue Type: New Feature
>          Components: c client, java client, server
>    Affects Versions: 3.5.0
>            Reporter: Jordan Zimmerman
>
> BACKGROUND
> ============
> A recurring problem for ZooKeeper users is garbage collection of parent nodes. Many recipes (e.g. locks, leaders, etc.) call for the creation of a parent node under which participants create sequential nodes. When the participant is done, it deletes its node. In practice, the ZooKeeper tree begins to fill up with orphaned parent nodes that are no longer needed. The ZooKeeper APIs don’t provide a way to clean these. Over time, ZooKeeper can become unstable due to the number of these nodes.
> CURRENT SOLUTIONS
> ===================
> Apache Curator has a workaround solution for this by providing the Reaper class which runs in the background looking for orphaned parent nodes and deleting them. This isn’t ideal and it would be better if ZooKeeper supported this directly.
> PROPOSAL
> =========
> ZOOKEEPER-723 and ZOOKEEPER-834 have been proposed to allow EPHEMERAL nodes to contain child nodes. This is not optimum as EPHEMERALs are tied to a session and the general use case of parent nodes is for PERSISTENT nodes. This proposal adds a new node type, CONTAINER. A CONTAINER node is the same as a PERSISTENT node with the additional property that when its last child is deleted, it is deleted (and CONTAINER nodes recursively up the tree are deleted if empty).



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