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A fork of the Apache Cassandra Project that uses Lucene indexes for providing near real time search such as ElasticSearch or Solr, including full text search capabilities, multi-dimensional queries, and relevance scoring.
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/*
* 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.hadoop;
import java.io.IOException;
import java.net.InetAddress;
import java.nio.ByteBuffer;
import java.util.*;
import org.apache.cassandra.dht.Range;
import org.apache.cassandra.dht.Token;
import org.apache.cassandra.thrift.*;
import org.apache.cassandra.utils.Pair;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.mapreduce.TaskAttemptContext;
import org.apache.thrift.TException;
import org.apache.hadoop.util.Progressable;
/**
* The ColumnFamilyRecordWriter maps the output <key, value>
* pairs to a Cassandra column family. In particular, it applies all mutations
* in the value, which it associates with the key, and in turn the responsible
* endpoint.
*
*
* Furthermore, this writer groups the mutations by the endpoint responsible for
* the rows being affected. This allows the mutations to be executed in parallel,
* directly to a responsible endpoint.
*
*
* @see ColumnFamilyOutputFormat
*/
final class ColumnFamilyRecordWriter extends AbstractColumnFamilyRecordWriter>
{
// handles for clients for each range running in the threadpool
private final Map clients;
/**
* Upon construction, obtain the map that this writer will use to collect
* mutations, and the ring cache for the given keyspace.
*
* @param context the task attempt context
* @throws IOException
*/
ColumnFamilyRecordWriter(TaskAttemptContext context)
{
this(HadoopCompat.getConfiguration(context));
this.context = context;
}
ColumnFamilyRecordWriter(Configuration conf, Progressable progressable)
{
this(conf);
this.progressable = progressable;
}
ColumnFamilyRecordWriter(Configuration conf)
{
super(conf);
this.clients = new HashMap();
}
@Override
public void close() throws IOException
{
// close all the clients before throwing anything
IOException clientException = null;
for (RangeClient client : clients.values())
{
try
{
client.close();
}
catch (IOException e)
{
clientException = e;
}
}
if (clientException != null)
throw clientException;
}
/**
* If the key is to be associated with a valid value, a mutation is created
* for it with the given column family and columns. In the event the value
* in the column is missing (i.e., null), then it is marked for
* {@link Deletion}. Similarly, if the entire value for a key is missing
* (i.e., null), then the entire key is marked for {@link Deletion}.
*
*
* @param keybuff
* the key to write.
* @param value
* the value to write.
* @throws IOException
*/
@Override
public void write(ByteBuffer keybuff, List value) throws IOException
{
Range range = ringCache.getRange(keybuff);
// get the client for the given range, or create a new one
RangeClient client = clients.get(range);
if (client == null)
{
// haven't seen keys for this range: create new client
client = new RangeClient(ringCache.getEndpoint(range));
client.start();
clients.put(range, client);
}
for (Mutation amut : value)
client.put(Pair.create(keybuff, amut));
if (progressable != null)
progressable.progress();
if (context != null)
HadoopCompat.progress(context);
}
/**
* A client that runs in a threadpool and connects to the list of endpoints for a particular
* range. Mutations for keys in that range are sent to this client via a queue.
*/
public class RangeClient extends AbstractRangeClient>
{
public final String columnFamily = ConfigHelper.getOutputColumnFamily(conf);
/**
* Constructs an {@link RangeClient} for the given endpoints.
* @param endpoints the possible endpoints to execute the mutations on
*/
public RangeClient(List endpoints)
{
super(endpoints);
}
/**
* Loops collecting mutations from the queue and sending to Cassandra
*/
public void run()
{
outer:
while (run || !queue.isEmpty())
{
Pair mutation;
try
{
mutation = queue.take();
}
catch (InterruptedException e)
{
// re-check loop condition after interrupt
continue;
}
Map>> batch = new HashMap>>();
while (mutation != null)
{
Map> subBatch = batch.get(mutation.left);
if (subBatch == null)
{
subBatch = Collections.singletonMap(columnFamily, (List) new ArrayList());
batch.put(mutation.left, subBatch);
}
subBatch.get(columnFamily).add(mutation.right);
if (batch.size() >= batchThreshold)
break;
mutation = queue.poll();
}
Iterator iter = endpoints.iterator();
while (true)
{
// send the mutation to the last-used endpoint. first time through, this will NPE harmlessly.
try
{
client.batch_mutate(batch, consistencyLevel);
break;
}
catch (Exception e)
{
closeInternal();
if (!iter.hasNext())
{
lastException = new IOException(e);
break outer;
}
}
// attempt to connect to a different endpoint
try
{
InetAddress address = iter.next();
String host = address.getHostName();
int port = ConfigHelper.getOutputRpcPort(conf);
client = ColumnFamilyOutputFormat.createAuthenticatedClient(host, port, conf);
}
catch (Exception e)
{
closeInternal();
// TException means something unexpected went wrong to that endpoint, so
// we should try again to another. Other exceptions (auth or invalid request) are fatal.
if ((!(e instanceof TException)) || !iter.hasNext())
{
lastException = new IOException(e);
break outer;
}
}
}
}
}
}
}