com.bazaarvoice.emodb.databus.core.UpdateRefSerializer Maven / Gradle / Ivy

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package com.bazaarvoice.emodb.databus.core;

import com.bazaarvoice.emodb.sor.core.UpdateRef;
import com.google.common.collect.ImmutableList;
import com.google.common.collect.ImmutableSet;
import com.netflix.astyanax.Serializer;
import com.netflix.astyanax.model.Composite;
import com.netflix.astyanax.serializers.SetSerializer;
import com.netflix.astyanax.serializers.StringSerializer;
import com.netflix.astyanax.serializers.TimeUUIDSerializer;
import org.apache.cassandra.db.marshal.UTF8Type;

import java.nio.ByteBuffer;
import java.util.List;
import java.util.Set;
import java.util.UUID;

public class UpdateRefSerializer {
    private static final SetSerializer _setSerializer = new SetSerializer<>(UTF8Type.instance);

    private static final List> _serializers = ImmutableList.>of(
            StringSerializer.get(),
            StringSerializer.get(),
            TimeUUIDSerializer.get());
    private static final List _comparators = ImmutableList.of(
            StringSerializer.get().getComparatorType().getTypeName(),
            StringSerializer.get().getComparatorType().getTypeName(),
            TimeUUIDSerializer.get().getComparatorType().getTypeName());

    public static ByteBuffer toByteBuffer(UpdateRef ref) {
        Composite composite = newComposite();
        composite.add(ref.getTable());
        composite.add(ref.getKey());
        composite.add(ref.getChangeId());
        if (!ref.getTags().isEmpty()) {
            composite.add(_setSerializer.toByteBuffer(ref.getTags()).array());
        }
        return trim(composite.serialize());
    }

    public static UpdateRef fromByteBuffer(ByteBuffer buf) {
        Composite composite = newComposite();
        composite.deserialize(buf);

        String table = (String) composite.get(0);
        String key = (String) composite.get(1);
        UUID changeId = (UUID) composite.get(2);
        Set tags = ImmutableSet.of();
        if (composite.size() == 4) {
            tags = _setSerializer.fromByteBuffer((ByteBuffer) composite.get(3));
        }
        return new UpdateRef(table, key, changeId, tags);
    }

    private static Composite newComposite() {
        Composite composite = new Composite();
        composite.setSerializersByPosition(_serializers);
        composite.setComparatorsByPosition(_comparators);
        return composite;
    }

    /** Serialized Astyanax Composite objects use a lot of memory.  Trim it down. */
    private static ByteBuffer trim(ByteBuffer buf) {
        if (buf.capacity() <= 4 * buf.remaining()) {
            return buf;
        } else {
            ByteBuffer clone = ByteBuffer.allocate(buf.remaining());
            buf.get(clone.array());
            return clone;
        }
    }
}