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 <[email protected]>
Sent: Thursday, April 25, 2019 12:39 PM
To: [email protected]
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 <[email protected]> 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 <[email protected]>
> Sent: Thursday, April 25, 2019 11:56 AM
> To: [email protected]
> 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 <[email protected]>
> 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 <[email protected]>
> > Sent: Thursday, April 25, 2019 9:11 AM
> > To: [email protected]
> > 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 <[email protected]>
> > 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
