Determine Location of RiakObject during conflict resolution

Question

I am in the process of migrating my Java code from Riak Client 1.4 to Riak Client 2.0.

I'm storing a BinaryValue in Riak 2.0, encapsulated in a RiakObject. I need to provide my own ConflictResolver to deal with siblings, but in order to do that I need to pull in other data. This data is derived from the key of the stored object.

In Riak 1.4, I used IRiakObject, which exposed getKey(). RiakObject of Riak 2.0 does not offer this.

How is it possible to determine the Location (specifically the key) of the object during ConflictResolver.resolve(List<RiakObject> siblings)?

score 2 · Accepted Answer · answered Apr 15 '15 at 11:11

Not sure if this is the best approach, but it seems to work:

Create a POJO as a container for the binary data. Annotate a String field with @RiakKey:

public class Chunk {

    @RiakKey
    public String   chunkId;

    public byte[]   data;
}

Create a custom converter:

import com.basho.riak.client.api.convert.ConversionException;
import com.basho.riak.client.api.convert.Converter;
import com.basho.riak.client.core.util.BinaryValue;
public class ChunkConverter extends Converter<Chunk> {

    public ChunkConverter() {
        super(Chunk.class);
    }

    public Chunk toDomain(BinaryValue val, String contentType) throws ConversionException {
        Chunk chunk = newDomainInstance();
        chunk.data = val.getValue();
    }

    public ContentAndType fromDomain(Chunk chunk) throws ConversionException {
        return new ContentAndType(BinaryValue.unsafeCreate(chunk.data), "application/octet-stream");
    }
}

Register the converter from #2 for the class from #1:

ConverterFactory.getInstance().registerConverterForClass(Chunk.class, new ChunkConverter());

Create a conflict resolver for the class from #1:

public class ChunkConflictResolver implements ConflictResolver<Chunk> {

    public Chunk resolve(List<Chunk> siblings) throws UnresolvedConflictException {
        if (siblings == null) {
            return null;
        }
        Chunk oneChunk = siblings.get(0);
        // finally, the key!
        String key = oneChunk.chunkId;
        ...
    }
}

Register the new conflict resolver from #4 for the class from #1:

ConflictResolverFactory.getInstance().registerConflictResolver(Chunk.class, new ChunkResolver());

When fetching the object from Riak, specify the class from #1 as type of value:

Location loc = new Location(...);
FetchValue op = new FetchValue.Builder(loc).build();
Chunk chunk = riakClient.execute(op).getValue(Chunk.class);

During the conversion, the context of the object is transferred, observing the annotations. The custom converter only needs to transfer the value-part of the data.

Determine Location of RiakObject during conflict resolution

1 Answers1