/**
* 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.File;
import java.io.IOException;
import java.util.Iterator;
import java.util.Map;
import java.util.NavigableMap;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.FileUtil;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.hbase.*;
import org.apache.hadoop.hbase.client.HTable;
import org.apache.hadoop.hbase.client.Put;
import org.apache.hadoop.hbase.client.Result;
import org.apache.hadoop.hbase.client.ResultScanner;
import org.apache.hadoop.hbase.client.Scan;
import org.apache.hadoop.hbase.io.ImmutableBytesWritable;
import org.apache.hadoop.hbase.util.Bytes;
import org.apache.hadoop.mapreduce.Job;
import org.apache.hadoop.mapreduce.lib.output.FileOutputFormat;
import org.junit.AfterClass;
import org.junit.BeforeClass;
import org.junit.Test;
import org.junit.experimental.categories.Category;
import static org.junit.Assert.fail;
import static org.junit.Assert.assertTrue;
/**
* Test Map/Reduce job over HBase tables. The map/reduce process we're testing
* on our tables is simple - take every row in the table, reverse the value of
* a particular cell, and write it back to the table.
*/
@Category(LargeTests.class)
public class TestMultithreadedTableMapper {
private static final Log LOG = LogFactory.getLog(TestMultithreadedTableMapper.class);
private static final HBaseTestingUtility UTIL =
new HBaseTestingUtility();
static final byte[] MULTI_REGION_TABLE_NAME = Bytes.toBytes("mrtest");
static final byte[] INPUT_FAMILY = Bytes.toBytes("contents");
static final byte[] OUTPUT_FAMILY = Bytes.toBytes("text");
static final int NUMBER_OF_THREADS = 10;
@BeforeClass
public static void beforeClass() throws Exception {
UTIL.startMiniCluster();
HTable table = UTIL.createTable(MULTI_REGION_TABLE_NAME, new byte[][] {INPUT_FAMILY, OUTPUT_FAMILY});
UTIL.createMultiRegions(table, INPUT_FAMILY);
UTIL.loadTable(table, INPUT_FAMILY);
UTIL.startMiniMapReduceCluster();
}
@AfterClass
public static void afterClass() throws Exception {
UTIL.shutdownMiniMapReduceCluster();
UTIL.shutdownMiniCluster();
}
/**
* Pass the given key and processed record reduce
*/
public static class ProcessContentsMapper
extends TableMapper<ImmutableBytesWritable, Put> {
/**
* Pass the key, and reversed value to reduce
*
* @param key
* @param value
* @param context
* @throws IOException
*/
public void map(ImmutableBytesWritable key, Result value,
Context context)
throws IOException, InterruptedException {
if (value.size() != 1) {
throw new IOException("There should only be one input column");
}
Map<byte[], NavigableMap<byte[], NavigableMap<Long, byte[]>>>
cf = value.getMap();
if(!cf.containsKey(INPUT_FAMILY)) {
throw new IOException("Wrong input columns. Missing: '" +
Bytes.toString(INPUT_FAMILY) + "'.");
}
// Get the original value and reverse it
String originalValue = Bytes.toString(value.getValue(INPUT_FAMILY, null));
StringBuilder newValue = new StringBuilder(originalValue);
newValue.reverse();
// Now set the value to be collected
Put outval = new Put(key.get());
outval.add(OUTPUT_FAMILY, null, Bytes.toBytes(newValue.toString()));
context.write(key, outval);
}
}
/**
* Test multithreadedTableMappper map/reduce against a multi-region table
* @throws IOException
* @throws ClassNotFoundException
* @throws InterruptedException
*/
@Test
public void testMultithreadedTableMapper()
throws IOException, InterruptedException, ClassNotFoundException {
runTestOnTable(new HTable(new Configuration(UTIL.getConfiguration()),
MULTI_REGION_TABLE_NAME));
}
private void runTestOnTable(HTable table)
throws IOException, InterruptedException, ClassNotFoundException {
Job job = null;
try {
LOG.info("Before map/reduce startup");
job = new Job(table.getConfiguration(), "process column contents");
job.setNumReduceTasks(1);
Scan scan = new Scan();
scan.addFamily(INPUT_FAMILY);
TableMapReduceUtil.initTableMapperJob(
Bytes.toString(table.getTableName()), scan,
MultithreadedTableMapper.class, ImmutableBytesWritable.class,
Put.class, job);
MultithreadedTableMapper.setMapperClass(job, ProcessContentsMapper.class);
MultithreadedTableMapper.setNumberOfThreads(job, NUMBER_OF_THREADS);
TableMapReduceUtil.initTableReducerJob(
Bytes.toString(table.getTableName()),
IdentityTableReducer.class, job);
FileOutputFormat.setOutputPath(job, new Path("test"));
LOG.info("Started " + Bytes.toString(table.getTableName()));
assertTrue(job.waitForCompletion(true));
LOG.info("After map/reduce completion");
// verify map-reduce results
verify(Bytes.toString(table.getTableName()));
} finally {
table.close();
if (job != null) {
FileUtil.fullyDelete(
new File(job.getConfiguration().get("hadoop.tmp.dir")));
}
}
}
private void verify(String tableName) throws IOException {
HTable table = new HTable(new Configuration(UTIL.getConfiguration()), tableName);
boolean verified = false;
long pause = UTIL.getConfiguration().getLong("hbase.client.pause", 5 * 1000);
int numRetries = UTIL.getConfiguration().getInt(HConstants.HBASE_CLIENT_RETRIES_NUMBER, 5);
for (int i = 0; i < numRetries; i++) {
try {
LOG.info("Verification attempt #" + i);
verifyAttempt(table);
verified = true;
break;
} catch (NullPointerException e) {
// If here, a cell was empty. Presume its because updates came in
// after the scanner had been opened. Wait a while and retry.
LOG.debug("Verification attempt failed: " + e.getMessage());
}
try {
Thread.sleep(pause);
} catch (InterruptedException e) {
// continue
}
}
assertTrue(verified);
table.close();
}
/**
* Looks at every value of the mapreduce output and verifies that indeed
* the values have been reversed.
*
* @param table Table to scan.
* @throws IOException
* @throws NullPointerException if we failed to find a cell value
*/
private void verifyAttempt(final HTable table)
throws IOException, NullPointerException {
Scan scan = new Scan();
scan.addFamily(INPUT_FAMILY);
scan.addFamily(OUTPUT_FAMILY);
ResultScanner scanner = table.getScanner(scan);
try {
Iterator<Result> itr = scanner.iterator();
assertTrue(itr.hasNext());
while(itr.hasNext()) {
Result r = itr.next();
if (LOG.isDebugEnabled()) {
if (r.size() > 2 ) {
throw new IOException("Too many results, expected 2 got " +
r.size());
}
}
byte[] firstValue = null;
byte[] secondValue = null;
int count = 0;
for(Cell kv : r.listCells()) {
if (count == 0) {
firstValue = CellUtil.cloneValue(kv);
}else if (count == 1) {
secondValue = CellUtil.cloneValue(kv);
}else if (count == 2) {
break;
}
count++;
}
String first = "";
if (firstValue == null) {
throw new NullPointerException(Bytes.toString(r.getRow()) +
": first value is null");
}
first = Bytes.toString(firstValue);
String second = "";
if (secondValue == null) {
throw new NullPointerException(Bytes.toString(r.getRow()) +
": second value is null");
}
byte[] secondReversed = new byte[secondValue.length];
for (int i = 0, j = secondValue.length - 1; j >= 0; j--, i++) {
secondReversed[i] = secondValue[j];
}
second = Bytes.toString(secondReversed);
if (first.compareTo(second) != 0) {
if (LOG.isDebugEnabled()) {
LOG.debug("second key is not the reverse of first. row=" +
Bytes.toStringBinary(r.getRow()) + ", first value=" + first +
", second value=" + second);
}
fail();
}
}
} finally {
scanner.close();
}
}
}