Hi Zili,
There’s no such functionality in ZooKeeper as far as I’m concerned. I think
your multi example (zk.multi(Op.check(path), Op.setData(path, data))) is
already a usage pattern which multi is not designed to support.
Why do you need to do this in “transactions” (there’s no transaction in ZK)?
In Java you can do:
try {
zk.create();
} catch (NodeExistsException e) {
// swallow exception
}
zk.setData();
…
Regards,
Andor
> On 2019. Aug 6., at 14:44, Zili Chen <[email protected]> wrote:
>
> Hi Enrico,
>
> Thanks for your reply.
>
>> In this case usually you use conditional setData, using the 'version' of
>> thr znode
>
>
> what if the caller has no idea on whether the node exist?(see also
> my if-else pseudo-code above.)
>
> IIRC if we call `setData` on a non-exist path a NoNodeException
> will be thrown.
> Best,
> tison.
>
>
> Enrico Olivelli <[email protected]> 于2019年8月6日周二 下午8:27写道：
>
>> Il mar 6 ago 2019, 13:47 Zili Chen <[email protected]> ha scritto:
>>
>>> Any ideas?
>>>
>>>
>>> Zili Chen <[email protected]> 于2019年7月29日周一 上午11:12写道：
>>>
>>>> Hi ZooKeepers,
>>>>
>>>> Currently our transaction mechanism supports doing
>>>> create/setData/checkExist/delete in transaction. However, taking this
>>>> scenario into consideration, we want to put data in path "/path" but
>>>> don't know whether the znode exists or not. Let's say we program as
>>>> below
>>>>
>>>> if (zk.exist(path)) {
>>>> zk.setData(path, data);
>>>> } else {
>>>> zk.create(path, data);
>>>> }
>>>
>>
>> Do you need to perform other ops in the same transaction?
>> In this case usually you use conditional setData, using the 'version' of
>> thr znode
>>
>>
>> Enrico
>>
>>>
>>>> if we want to do the check and "put" in transaction, it would be like
>>>>
>>>> zk.multi(Op.check(path), Op.setData(path, data));
>>>>
>>>> but we cannot add a "else" branch. ZooKeeper's transaction would all
>>>> success or fail.
>>>>
>>>> Is there any way to do an "if-else" transaction?
>>>>
>>>> Best,
>>>> tison.
>>>>
>>>
>>
