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From "Marshall McMullen (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (ZOOKEEPER-965) Need a multi-update command to allow multiple znodes to be updated safely
Date Tue, 03 May 2011 23:50:03 GMT

    [ https://issues.apache.org/jira/browse/ZOOKEEPER-965?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13028510#comment-13028510

Marshall McMullen commented on ZOOKEEPER-965:

I've just committed a rewrite of the C API:

>From my commit message:

commit dcd7ea9233314ce96c8913b8b0659a8f7d02e93b
Author: Marshall McMullen <marshall@solidfire.com>
Date:   Tue May 3 17:45:00 2011 -0600

    ZOOKEEPER-965 - Rewrite of the C API for multi op support.
    This is a rewrite of my earlier C API support for multi op support.
    My earlier version didn't work correctly due to a lack of understanding
    of the completion mechanism and how it interacted with sync and async
    mechanisms. This version correctly works in both sync and async
    I've also gotten rid of the horrid variadic zoo_multi/zoo_amulti interfaces
    in favor of a simpler, stricter/safer, and actually more succinct and
    easier to use syntax. See test cases in TestClient.cc for examples.
    I've also added a couple of more tests cases to test the async
    interface and to test error code propagation.
    Removed no-longer-necessary cruft from my last version.

> Need a multi-update command to allow multiple znodes to be updated safely
> -------------------------------------------------------------------------
>                 Key: ZOOKEEPER-965
>                 URL: https://issues.apache.org/jira/browse/ZOOKEEPER-965
>             Project: ZooKeeper
>          Issue Type: Bug
>    Affects Versions: 3.3.3
>            Reporter: Ted Dunning
>            Assignee: Ted Dunning
>             Fix For: 3.4.0
>         Attachments: ZOOKEEPER-965.patch
> The basic idea is to have a single method called "multi" that will accept a list of create,
delete, update or check objects each of which has a desired version or file state in the case
of create.  If all of the version and existence constraints can be satisfied, then all updates
will be done atomically.
> Two API styles have been suggested.  One has a list as above and the other style has
a "Transaction" that allows builder-like methods to build a set of updates and a commit method
to finalize the transaction.  This can trivially be reduced to the first kind of API so the
list based API style should be considered the primitive and the builder style should be implemented
as syntactic sugar.
> The total size of all the data in all updates and creates in a single transaction should
be limited to 1MB.
> Implementation-wise this capability can be done using standard ZK internals.  The changes
> - update to ZK clients to all the new call
> - additional wire level request
> - on the server, in the code that converts transactions to idempotent form, the code
should be slightly extended to convert a list of operations to idempotent form.
> - on the client, a down-rev server that rejects the multi-update should be detected gracefully
and an informative exception should be thrown.
> To facilitate shared development, I have established a github repository at https://github.com/tdunning/zookeeper
 and am happy to extend committer status to anyone who agrees to donate their code back to
Apache.  The final patch will be attached to this bug as normal.

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