/*
* 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.util.HashMap;
import java.util.Map;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.apache.cassandra.auth.IAuthenticator;
import org.apache.cassandra.thrift.*;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.mapreduce.*;
import org.apache.thrift.protocol.TBinaryProtocol;
import org.apache.thrift.protocol.TProtocol;
import org.apache.thrift.transport.TTransport;
/**
* The <code>ColumnFamilyOutputFormat</code> acts as a Hadoop-specific
* OutputFormat that allows reduce tasks to store keys (and corresponding
* values) as Cassandra rows (and respective columns) in a given
* ColumnFamily.
*
* <p>
* As is the case with the {@link ColumnFamilyInputFormat}, you need to set the
* Keyspace and ColumnFamily in your
* Hadoop job Configuration. The {@link ConfigHelper} class, through its
* {@link ConfigHelper#setOutputColumnFamily} method, is provided to make this
* simple.
* </p>
*
* <p>
* For the sake of performance, this class employs a lazy write-back caching
* mechanism, where its record writer batches mutations created based on the
* reduce's inputs (in a task-specific map), and periodically makes the changes
* official by sending a batch mutate request to Cassandra.
* </p>
* @param <Y>
*/
public abstract class AbstractColumnFamilyOutputFormat<K, Y> extends OutputFormat<K, Y> implements org.apache.hadoop.mapred.OutputFormat<K, Y>
{
public static final String BATCH_THRESHOLD = "mapreduce.output.columnfamilyoutputformat.batch.threshold";
public static final String QUEUE_SIZE = "mapreduce.output.columnfamilyoutputformat.queue.size";
private static final Logger logger = LoggerFactory.getLogger(AbstractColumnFamilyOutputFormat.class);
/**
* Check for validity of the output-specification for the job.
*
* @param context
* information about the job
* @throws IOException
* when output should not be attempted
*/
public void checkOutputSpecs(JobContext context)
{
checkOutputSpecs(HadoopCompat.getConfiguration(context));
}
protected void checkOutputSpecs(Configuration conf)
{
if (ConfigHelper.getOutputKeyspace(conf) == null)
throw new UnsupportedOperationException("You must set the keyspace with setOutputKeyspace()");
if (ConfigHelper.getOutputPartitioner(conf) == null)
throw new UnsupportedOperationException("You must set the output partitioner to the one used by your Cassandra cluster");
if (ConfigHelper.getOutputInitialAddress(conf) == null)
throw new UnsupportedOperationException("You must set the initial output address to a Cassandra node");
}
/** Fills the deprecated OutputFormat interface for streaming. */
@Deprecated
public void checkOutputSpecs(org.apache.hadoop.fs.FileSystem filesystem, org.apache.hadoop.mapred.JobConf job) throws IOException
{
checkOutputSpecs(job);
}
/**
* The OutputCommitter for this format does not write any data to the DFS.
*
* @param context
* the task context
* @return an output committer
* @throws IOException
* @throws InterruptedException
*/
public OutputCommitter getOutputCommitter(TaskAttemptContext context) throws IOException, InterruptedException
{
return new NullOutputCommitter();
}
/**
* Connects to the given server:port and returns a client based on the given socket that points to the configured
* keyspace, and is logged in with the configured credentials.
*
* @param host fully qualified host name to connect to
* @param port RPC port of the server
* @param conf a job configuration
* @return a cassandra client
* @throws Exception set of thrown exceptions may be implementation defined,
* depending on the used transport factory
*/
public static Cassandra.Client createAuthenticatedClient(String host, int port, Configuration conf) throws Exception
{
logger.debug("Creating authenticated client for CF output format");
TTransport transport = ConfigHelper.getClientTransportFactory(conf).openTransport(host, port);
TProtocol binaryProtocol = new TBinaryProtocol(transport, true, true);
Cassandra.Client client = new Cassandra.Client(binaryProtocol);
client.set_keyspace(ConfigHelper.getOutputKeyspace(conf));
String user = ConfigHelper.getOutputKeyspaceUserName(conf);
String password = ConfigHelper.getOutputKeyspacePassword(conf);
if ((user != null) && (password != null))
login(user, password, client);
logger.debug("Authenticated client for CF output format created successfully");
return client;
}
public static void login(String user, String password, Cassandra.Client client) throws Exception
{
Map<String, String> creds = new HashMap<String, String>();
creds.put(IAuthenticator.USERNAME_KEY, user);
creds.put(IAuthenticator.PASSWORD_KEY, password);
AuthenticationRequest authRequest = new AuthenticationRequest(creds);
client.login(authRequest);
}
/**
* An {@link OutputCommitter} that does nothing.
*/
private static class NullOutputCommitter extends OutputCommitter
{
public void abortTask(TaskAttemptContext taskContext) { }
public void cleanupJob(JobContext jobContext) { }
public void commitTask(TaskAttemptContext taskContext) { }
public boolean needsTaskCommit(TaskAttemptContext taskContext)
{
return false;
}
public void setupJob(JobContext jobContext) { }
public void setupTask(TaskAttemptContext taskContext) { }
}
}