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From "Sam Baskinger (JIRA)" <j...@apache.org>
Subject [jira] Commented: (ZOOKEEPER-767) Submitting Demo/Recipe Shared / Exclusive Lock Code
Date Thu, 03 Jun 2010 22:38:05 GMT

    [ https://issues.apache.org/jira/browse/ZOOKEEPER-767?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12875334#action_12875334

Sam Baskinger commented on ZOOKEEPER-767:

Thanks for the feedback Benjamin,

Perhaps I misread the recipe or am missing the philosophy of ZK's atomicity. It wouldn't be
the first time. :) To your points:

We do the create to ensure that we, at some point, will hold a lock. I do want to do the create,
ensuring my turn, and then wait until I'm at the front of the line (front being defined in
the exclusive or shared way).

There should be a unit test that ensure that this does indeed happen, semantically. Exclusive
locks block all shared access, if I take your meaning correctly.

I thought the API guaranteed that in the event of a connection loss the EPHEMERAL creation
property would guarantee that when the session timed out the file would be removed and watchers
would be signaled.

All but those behind me in the line of locks. This could certainly be optimized and is something
I thought about, but moved past to get the rough implementation in flight.

If the above 4 points hold, then extending the other implementation may be better for the
community. :) I hope you'll include the code, but if not, we're very happy with it and appreciate
ZooKeeper! Keep up the fine work. :)

What do you think? What did I miss? :)

Sam Baskinger


> Submitting Demo/Recipe Shared / Exclusive Lock Code
> ---------------------------------------------------
>                 Key: ZOOKEEPER-767
>                 URL: https://issues.apache.org/jira/browse/ZOOKEEPER-767
>             Project: Zookeeper
>          Issue Type: Improvement
>          Components: recipes
>    Affects Versions: 3.3.0
>            Reporter: Sam Baskinger
>            Assignee: Sam Baskinger
>            Priority: Minor
>             Fix For: 3.4.0
>         Attachments: ZOOKEEPER-767.patch, ZOOKEEPER-767.patch
> Networked Insights would like to share-back some code for shared/exclusive locking that
we are using in our labs.

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