/**
*
* 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.hadoop.hbase.mapreduce;
import java.io.IOException;
import java.util.HashMap;
import java.util.Map;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.hbase.classification.InterfaceAudience;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.hbase.HBaseConfiguration;
import org.apache.hadoop.hbase.TableName;
import org.apache.hadoop.hbase.client.BufferedMutator;
import org.apache.hadoop.hbase.client.Connection;
import org.apache.hadoop.hbase.client.ConnectionFactory;
import org.apache.hadoop.hbase.client.Delete;
import org.apache.hadoop.hbase.client.Mutation;
import org.apache.hadoop.hbase.client.Put;
import org.apache.hadoop.hbase.client.Durability;
import org.apache.hadoop.hbase.io.ImmutableBytesWritable;
import org.apache.hadoop.hbase.util.Bytes;
import org.apache.hadoop.mapreduce.JobContext;
import org.apache.hadoop.mapreduce.OutputCommitter;
import org.apache.hadoop.mapreduce.OutputFormat;
import org.apache.hadoop.mapreduce.RecordWriter;
import org.apache.hadoop.mapreduce.TaskAttemptContext;
/**
* <p>
* Hadoop output format that writes to one or more HBase tables. The key is
* taken to be the table name while the output value <em>must</em> be either a
* {@link Put} or a {@link Delete} instance. All tables must already exist, and
* all Puts and Deletes must reference only valid column families.
* </p>
*
* <p>
* Write-ahead logging (WAL) for Puts can be disabled by setting
* {@link #WAL_PROPERTY} to {@link #WAL_OFF}. Default value is {@link #WAL_ON}.
* Note that disabling write-ahead logging is only appropriate for jobs where
* loss of data due to region server failure can be tolerated (for example,
* because it is easy to rerun a bulk import).
* </p>
*/
@InterfaceAudience.Public
public class MultiTableOutputFormat extends OutputFormat<ImmutableBytesWritable, Mutation> {
/** Set this to {@link #WAL_OFF} to turn off write-ahead logging (WAL) */
public static final String WAL_PROPERTY = "hbase.mapreduce.multitableoutputformat.wal";
/** Property value to use write-ahead logging */
public static final boolean WAL_ON = true;
/** Property value to disable write-ahead logging */
public static final boolean WAL_OFF = false;
/**
* Record writer for outputting to multiple HTables.
*/
protected static class MultiTableRecordWriter extends
RecordWriter<ImmutableBytesWritable, Mutation> {
private static final Log LOG = LogFactory.getLog(MultiTableRecordWriter.class);
Connection connection;
Map<ImmutableBytesWritable, BufferedMutator> mutatorMap = new HashMap<>();
Configuration conf;
boolean useWriteAheadLogging;
/**
* @param conf
* HBaseConfiguration to used
* @param useWriteAheadLogging
* whether to use write ahead logging. This can be turned off (
* <tt>false</tt>) to improve performance when bulk loading data.
*/
public MultiTableRecordWriter(Configuration conf,
boolean useWriteAheadLogging) throws IOException {
LOG.debug("Created new MultiTableRecordReader with WAL "
+ (useWriteAheadLogging ? "on" : "off"));
this.conf = conf;
this.useWriteAheadLogging = useWriteAheadLogging;
}
/**
* @param tableName
* the name of the table, as a string
* @return the named mutator
* @throws IOException
* if there is a problem opening a table
*/
BufferedMutator getBufferedMutator(ImmutableBytesWritable tableName) throws IOException {
if(this.connection == null){
this.connection = ConnectionFactory.createConnection(conf);
}
if (!mutatorMap.containsKey(tableName)) {
LOG.debug("Opening HTable \"" + Bytes.toString(tableName.get())+ "\" for writing");
BufferedMutator mutator =
connection.getBufferedMutator(TableName.valueOf(tableName.get()));
mutatorMap.put(tableName, mutator);
}
return mutatorMap.get(tableName);
}
@Override
public void close(TaskAttemptContext context) throws IOException {
for (BufferedMutator mutator : mutatorMap.values()) {
mutator.close();
}
if (connection != null) {
connection.close();
}
}
/**
* Writes an action (Put or Delete) to the specified table.
*
* @param tableName
* the table being updated.
* @param action
* the update, either a put or a delete.
* @throws IllegalArgumentException
* if the action is not a put or a delete.
*/
@Override
public void write(ImmutableBytesWritable tableName, Mutation action) throws IOException {
BufferedMutator mutator = getBufferedMutator(tableName);
// The actions are not immutable, so we defensively copy them
if (action instanceof Put) {
Put put = new Put((Put) action);
put.setDurability(useWriteAheadLogging ? Durability.SYNC_WAL
: Durability.SKIP_WAL);
mutator.mutate(put);
} else if (action instanceof Delete) {
Delete delete = new Delete((Delete) action);
mutator.mutate(delete);
} else
throw new IllegalArgumentException(
"action must be either Delete or Put");
}
}
@Override
public void checkOutputSpecs(JobContext context) throws IOException,
InterruptedException {
// we can't know ahead of time if it's going to blow up when the user
// passes a table name that doesn't exist, so nothing useful here.
}
@Override
public OutputCommitter getOutputCommitter(TaskAttemptContext context)
throws IOException, InterruptedException {
return new TableOutputCommitter();
}
@Override
public RecordWriter<ImmutableBytesWritable, Mutation> getRecordWriter(TaskAttemptContext context)
throws IOException, InterruptedException {
Configuration conf = context.getConfiguration();
return new MultiTableRecordWriter(HBaseConfiguration.create(conf),
conf.getBoolean(WAL_PROPERTY, WAL_ON));
}
}