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The Apache Cassandra Project develops a highly scalable second-generation distributed database, bringing together Dynamo's fully distributed design and Bigtable's ColumnFamily-based data model.
/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.cassandra.batchlog;
import java.io.IOException;
import java.nio.ByteBuffer;
import java.util.*;
import com.google.common.annotations.VisibleForTesting;
import org.apache.cassandra.db.Mutation;
import org.apache.cassandra.io.IVersionedSerializer;
import org.apache.cassandra.io.util.DataInputPlus;
import org.apache.cassandra.io.util.DataOutputPlus;
import org.apache.cassandra.net.MessagingService;
import org.apache.cassandra.utils.ByteBufferUtil;
import org.apache.cassandra.utils.UUIDSerializer;
import static org.apache.cassandra.db.TypeSizes.sizeof;
import static org.apache.cassandra.db.TypeSizes.sizeofUnsignedVInt;
public final class Batch
{
public static final Serializer serializer = new Serializer();
public final UUID id;
public final long creationTime; // time of batch creation (in microseconds)
// one of these will always be empty
final Collection decodedMutations;
final Collection encodedMutations;
private Batch(UUID id, long creationTime, Collection decodedMutations, Collection encodedMutations)
{
this.id = id;
this.creationTime = creationTime;
this.decodedMutations = decodedMutations;
this.encodedMutations = encodedMutations;
}
/**
* Creates a 'local' batch - with all enclosed mutations in decoded form (as Mutation instances)
*/
public static Batch createLocal(UUID id, long creationTime, Collection mutations)
{
return new Batch(id, creationTime, mutations, Collections.emptyList());
}
/**
* Creates a 'remote' batch - with all enclosed mutations in encoded form (as ByteBuffer instances)
*
* The mutations will always be encoded using the current messaging version.
*/
@SuppressWarnings("RedundantTypeArguments")
public static Batch createRemote(UUID id, long creationTime, Collection mutations)
{
return new Batch(id, creationTime, Collections.emptyList(), mutations);
}
/**
* Count of the mutations in the batch.
*/
public int size()
{
return decodedMutations.size() + encodedMutations.size();
}
@VisibleForTesting
public Collection getEncodedMutations()
{
return encodedMutations;
}
/**
* Local batches contain only already decoded {@link Mutation} instances. Unlike remote
* batches, which contain mutations encoded as {@link ByteBuffer} instances, local batches
* can be serialized and sent over the wire.
*
* @return {@code true} if there are no encoded mutations present, and {@code false} otherwise
*/
public boolean isLocal()
{
return encodedMutations.isEmpty();
}
public static final class Serializer implements IVersionedSerializer
{
public long serializedSize(Batch batch, int version)
{
assert batch.isLocal() : "attempted to serialize a 'remote' batch";
long size = UUIDSerializer.serializer.serializedSize(batch.id, version);
size += sizeof(batch.creationTime);
size += sizeofUnsignedVInt(batch.decodedMutations.size());
for (Mutation mutation : batch.decodedMutations)
{
int mutationSize = mutation.serializedSize(version);
size += sizeofUnsignedVInt(mutationSize);
size += mutationSize;
}
return size;
}
public void serialize(Batch batch, DataOutputPlus out, int version) throws IOException
{
assert batch.isLocal() : "attempted to serialize a 'remote' batch";
UUIDSerializer.serializer.serialize(batch.id, out, version);
out.writeLong(batch.creationTime);
out.writeUnsignedVInt(batch.decodedMutations.size());
for (Mutation mutation : batch.decodedMutations)
{
out.writeUnsignedVInt(mutation.serializedSize(version));
Mutation.serializer.serialize(mutation, out, version);
}
}
public Batch deserialize(DataInputPlus in, int version) throws IOException
{
UUID id = UUIDSerializer.serializer.deserialize(in, version);
long creationTime = in.readLong();
/*
* If version doesn't match the current one, we cannot not just read the encoded mutations verbatim,
* so we decode them instead, to deal with compatibility.
*/
return version == MessagingService.current_version
? createRemote(id, creationTime, readEncodedMutations(in))
: createLocal(id, creationTime, decodeMutations(in, version));
}
private static Collection readEncodedMutations(DataInputPlus in) throws IOException
{
int count = (int) in.readUnsignedVInt();
ArrayList mutations = new ArrayList<>(count);
for (int i = 0; i < count; i++)
mutations.add(ByteBufferUtil.readWithVIntLength(in));
return mutations;
}
private static Collection decodeMutations(DataInputPlus in, int version) throws IOException
{
int count = (int) in.readUnsignedVInt();
ArrayList mutations = new ArrayList<>(count);
for (int i = 0; i < count; i++)
{
in.readUnsignedVInt(); // skip mutation size
mutations.add(Mutation.serializer.deserialize(in, version));
}
return mutations;
}
}
}
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