package org.apache.cassandra.hadoop;
/*
*
* 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
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import java.io.IOException;
import java.net.InetAddress;
import java.nio.ByteBuffer;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.Random;
import java.util.SortedMap;
import java.util.concurrent.Callable;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.Future;
import org.apache.cassandra.db.IColumn;
import org.apache.cassandra.service.StorageService;
import org.apache.cassandra.thrift.Cassandra;
import org.apache.cassandra.thrift.InvalidRequestException;
import org.apache.cassandra.thrift.TokenRange;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.mapreduce.InputFormat;
import org.apache.hadoop.mapreduce.InputSplit;
import org.apache.hadoop.mapreduce.JobContext;
import org.apache.hadoop.mapreduce.RecordReader;
import org.apache.hadoop.mapreduce.TaskAttemptContext;
import org.apache.thrift.TException;
import org.apache.thrift.protocol.TBinaryProtocol;
import org.apache.thrift.transport.TFramedTransport;
import org.apache.thrift.transport.TSocket;
import org.apache.thrift.transport.TTransport;
import org.apache.thrift.transport.TTransportException;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
/**
* Hadoop InputFormat allowing map/reduce against Cassandra rows within one ColumnFamily.
*
* At minimum, you need to set the CF and predicate (description of columns to extract from each row)
* in your Hadoop job Configuration. The ConfigHelper class is provided to make this
* simple:
* ConfigHelper.setColumnFamily
* ConfigHelper.setSlicePredicate
*
* You can also configure the number of rows per InputSplit with
* ConfigHelper.setInputSplitSize
* This should be "as big as possible, but no bigger." Each InputSplit is read from Cassandra
* with multiple get_slice_range queries, and the per-call overhead of get_slice_range is high,
* so larger split sizes are better -- but if it is too large, you will run out of memory.
*
* The default split size is 64k rows.
*/
public class ColumnFamilyInputFormat extends InputFormat<ByteBuffer, SortedMap<ByteBuffer, IColumn>>
{
private static final Logger logger = LoggerFactory.getLogger(ColumnFamilyInputFormat.class);
private String keyspace;
private String cfName;
private static void validateConfiguration(Configuration conf)
{
if (ConfigHelper.getInputKeyspace(conf) == null || ConfigHelper.getInputColumnFamily(conf) == null)
{
throw new UnsupportedOperationException("you must set the keyspace and columnfamily with setColumnFamily()");
}
if (ConfigHelper.getInputSlicePredicate(conf) == null)
{
throw new UnsupportedOperationException("you must set the predicate with setPredicate");
}
}
public List<InputSplit> getSplits(JobContext context) throws IOException
{
Configuration conf = context.getConfiguration();
validateConfiguration(conf);
// cannonical ranges and nodes holding replicas
List<TokenRange> masterRangeNodes = getRangeMap(conf);
keyspace = ConfigHelper.getInputKeyspace(context.getConfiguration());
cfName = ConfigHelper.getInputColumnFamily(context.getConfiguration());
// cannonical ranges, split into pieces, fetching the splits in parallel
ExecutorService executor = Executors.newCachedThreadPool();
List<InputSplit> splits = new ArrayList<InputSplit>();
try
{
List<Future<List<InputSplit>>> splitfutures = new ArrayList<Future<List<InputSplit>>>();
for (TokenRange range : masterRangeNodes)
{
// for each range, pick a live owner and ask it to compute bite-sized splits
splitfutures.add(executor.submit(new SplitCallable(range, conf)));
}
// wait until we have all the results back
for (Future<List<InputSplit>> futureInputSplits : splitfutures)
{
try
{
splits.addAll(futureInputSplits.get());
}
catch (Exception e)
{
throw new IOException("Could not get input splits", e);
}
}
}
finally
{
executor.shutdownNow();
}
assert splits.size() > 0;
Collections.shuffle(splits, new Random(System.nanoTime()));
return splits;
}
/**
* Gets a token range and splits it up according to the suggested
* size into input splits that Hadoop can use.
*/
class SplitCallable implements Callable<List<InputSplit>>
{
private final TokenRange range;
private final Configuration conf;
public SplitCallable(TokenRange tr, Configuration conf)
{
this.range = tr;
this.conf = conf;
}
public List<InputSplit> call() throws Exception
{
ArrayList<InputSplit> splits = new ArrayList<InputSplit>();
List<String> tokens = getSubSplits(keyspace, cfName, range, conf);
// turn the sub-ranges into InputSplits
String[] endpoints = range.endpoints.toArray(new String[range.endpoints.size()]);
// hadoop needs hostname, not ip
for (int i = 0; i < endpoints.length; i++)
{
endpoints[i] = InetAddress.getByName(endpoints[i]).getHostName();
}
for (int i = 1; i < tokens.size(); i++)
{
ColumnFamilySplit split = new ColumnFamilySplit(tokens.get(i - 1), tokens.get(i), endpoints);
logger.debug("adding " + split);
splits.add(split);
}
return splits;
}
}
private List<String> getSubSplits(String keyspace, String cfName, TokenRange range, Configuration conf) throws IOException
{
// TODO handle failure of range replicas & retry
List<String> splits;
int splitsize = ConfigHelper.getInputSplitSize(conf);
try
{
Cassandra.Client client = createConnection(range.endpoints.get(0), ConfigHelper.getRpcPort(conf), true);
client.set_keyspace(keyspace);
splits = client.describe_splits(cfName, range.start_token, range.end_token, splitsize);
}
catch (TException e)
{
throw new RuntimeException(e);
}
catch (InvalidRequestException e)
{
throw new RuntimeException(e);
}
return splits;
}
private static Cassandra.Client createConnection(String host, Integer port, boolean framed) throws IOException
{
TSocket socket = new TSocket(host, port);
TTransport trans = framed ? new TFramedTransport(socket) : socket;
try
{
trans.open();
}
catch (TTransportException e)
{
throw new IOException("unable to connect to server", e);
}
return new Cassandra.Client(new TBinaryProtocol(trans));
}
private List<TokenRange> getRangeMap(Configuration conf) throws IOException
{
Cassandra.Client client = createConnection(ConfigHelper.getInitialAddress(conf), ConfigHelper.getRpcPort(conf), true);
List<TokenRange> map;
try
{
map = client.describe_ring(ConfigHelper.getInputKeyspace(conf));
}
catch (TException e)
{
throw new RuntimeException(e);
}
catch (InvalidRequestException e)
{
throw new RuntimeException(e);
}
return map;
}
public RecordReader<ByteBuffer, SortedMap<ByteBuffer, IColumn>> createRecordReader(InputSplit inputSplit, TaskAttemptContext taskAttemptContext) throws IOException, InterruptedException
{
return new ColumnFamilyRecordReader();
}
}