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From Bryan Bende <bbe...@gmail.com>
Subject Re: Adding HBase Support for AtomicDistributedMapCacheClient
Date Thu, 25 Apr 2019 21:25:46 GMT
Thanks, I'm following now...

I think adding the new method to the interface and throwing
UnsupportedOperationException for 1_1_2, or using the original
checkAndPut and implementing it in both services, would both be fine
solutions.

I guess another variation might be to introduce the new method in the
interface, but in the 1_1_2 implementation just delegate back to the
original checkAndPut and ignore the timestamp, and document that it
isn't used in that implementation. I don't love this, but it does
allow both services to implement the functionality and still leverage
the better solution for 2_x.


On Thu, Apr 25, 2019 at 3:54 PM Shawn Weeks <sweeks@weeksconsulting.us> wrote:
>
> Here is what I think the new checkAndPut or checkAndMutate method would look like. This
also shows what the new mutate api looks like.
>
>     @Override
>     public boolean checkAndPut(String tableName, byte[] rowId, byte[] family, byte[]
qualifier, byte[] value, long timestamp, PutColumn column) throws IOException {
>         try (final Table table = connection.getTable(TableName.valueOf(tableName))) {
>             Put put = new Put(rowId);
>             put.addColumn(
>                     column.getColumnFamily(),
>                     column.getColumnQualifier(),
>                     column.getBuffer());
>             return table.checkAndMutate(rowId, family).qualifier(qualifier).ifEquals(value).timeRange(TimeRange.at(timestamp)).thenPut(put);
>         }
>     }
>
> If the atomic guarantee for the original checkAndPut is good enough then there is no
reason I can't implement the atomic map cache for both versions of HBase.
>
> Thanks
> Shawn
>
> -----Original Message-----
> From: Bryan Bende <bbende@gmail.com>
> Sent: Thursday, April 25, 2019 12:39 PM
> To: dev@nifi.apache.org
> Subject: Re: Adding HBase Support for AtomicDistributedMapCacheClient
>
> I'm not totally if would matter if there were changes in between, as long as the current
value is what we thought it was then the changes we are sending back should be accurate as
a replacement. As a simplified scenario, if the current value is 1 and thread-A retrieves
that value, thread-B then changes it to 2 and back to 1 before thread-A can do anything, then
thread-A sends in 2 with a previous of 1, that is still the correct replacement.
>
> I can see the argument for using the timestamp though... can you show the method signature
of the new checkAndMutate method that would need to be added to the client service, and also
which method of the HBase client it needs to call?
>
> Just so I can get an idea of the differences between 1.x and 2.x.
>
> On Thu, Apr 25, 2019 at 1:00 PM Shawn Weeks <sweeks@weeksconsulting.us> wrote:
> >
> > While checkAndPut is atomic as it's built now it doesn't support also checking the
timestamp range which is included in the new checkAndMutate API. I had planned on using the
cell's timestamp as the revision along with the value to ensure not only that the value hadn't
been changed but that there hadn't been changes in between that just happened to put the value
back.
> >
> > As I was looking at everything I had another question. Why is the cache currently
using a scan instead of a get to fetch values from HBase. It seems like that would be much
less performant considering we know the row key we're looking for.
> >
> >
> > Thanks
> > Shawn
> >
> > -----Original Message-----
> > From: Bryan Bende <bbende@gmail.com>
> > Sent: Thursday, April 25, 2019 11:56 AM
> > To: dev@nifi.apache.org
> > Subject: Re: Adding HBase Support for AtomicDistributedMapCacheClient
> >
> > Can it not be done with the existing checkAndPut method? [1]
> >
> > I think if you use the value as the revision it should work. Would be similar to
how the Redis implementation works [2].
> >
> > [1]
> > https://github.com/apache/nifi/blob/master/nifi-nar-bundles/nifi-stand
> > ard-services/nifi-hbase-client-service-api/src/main/java/org/apache/ni
> > fi/hbase/HBaseClientService.java#L65
> > [2]
> > https://github.com/apache/nifi/blob/master/nifi-nar-bundles/nifi-redis
> > -bundle/nifi-redis-extensions/src/main/java/org/apache/nifi/redis/serv
> > ice/RedisDistributedMapCacheClientService.java#L271
> >
> > On Thu, Apr 25, 2019 at 12:38 PM Shawn Weeks <sweeks@weeksconsulting.us> wrote:
> > >
> > > I'll need to add a check and mutate method to the HBaseClientService Interface,
should I just extend with a HBase2ClientService or add checkAndMutate to the existing interface
and just make it raise an exception if you try and use it against hbase 1? While Hbase 1.x
supports checkAndMutate it doesn't provide a way to filter on timestamp which is part of how
I was going to implement the revision requirement for AtomicMapCache.
> > >
> > > Thanks
> > > Shawn
> > >
> > > -----Original Message-----
> > > From: Bryan Bende <bbende@gmail.com>
> > > Sent: Thursday, April 25, 2019 9:11 AM
> > > To: dev@nifi.apache.org
> > > Subject: Re: Adding HBase Support for
> > > AtomicDistributedMapCacheClient
> > >
> > > I'm not aware of a JIRA, so I'd say go for it.
> > >
> > > On Wed, Apr 24, 2019 at 9:27 PM Shawn Weeks <sweeks@weeksconsulting.us>
wrote:
> > > >
> > > > Seems like this should be fairly easy for HBase 2.x with the checkAndMutate
functionality and I was wondering if there is already a Jira for this. Otherwise I might make
an attempt at it. It would be good to be able to support Wait/Notify and other things that
need AtomicDistributedMapCacheClient using an Apache developed product commonly found in a
Hadoop Cluster.
> > > >
> > > > Thanks
> > > > Shawn

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