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https://issues.apache.org/jira/browse/ZOOKEEPER-965?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12975918#action_12975918
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Henry Robinson commented on ZOOKEEPER-965:
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Hi Ted -
You don't have to lose the idiomatic Java - I like the API. I'm just
distinguishing between the API provided by the Java client and the API that the
Java client calls in ZooKeeper, which should not be idiomatic. Currently that
API is defined by the serialisation (and this is true for most API calls, not
just multi(...)) rather than some abstract API signature which is realisable in
every implementing language - I want to make sure that the serialisation is not
the specification. Again, an Avro or Thrift or whatever IDL API would make
these issues go away.
However, the idiomatic changes here are so slight that having thought about it
overnight I'm not too concerned about separating it out. It would be different
if, e.g. the API was heavily object-oriented (for example a builder interface);
then I would mandate that such an API should wrap a simple procedural API. It's
pretty clear here what the multi(...) API means in all languages we're
interested in.
Thanks for listening :)
Henry
> 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
> Reporter: Ted Dunning
> Assignee: Ted Dunning
> Fix For: 3.4.0
>
>
> 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 include:
> - 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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