/**
*
* 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.io.InterruptedIOException;
import java.net.InetAddress;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import javax.naming.NamingException;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.classification.InterfaceAudience;
import org.apache.hadoop.classification.InterfaceStability;
import org.apache.hadoop.hbase.HConstants;
import org.apache.hadoop.hbase.HRegionLocation;
import org.apache.hadoop.hbase.HServerAddress;
import org.apache.hadoop.hbase.client.HTable;
import org.apache.hadoop.hbase.client.Result;
import org.apache.hadoop.hbase.client.Scan;
import org.apache.hadoop.hbase.io.ImmutableBytesWritable;
import org.apache.hadoop.hbase.util.Addressing;
import org.apache.hadoop.hbase.util.Bytes;
import org.apache.hadoop.hbase.util.Pair;
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.hadoop.net.DNS;
/**
* A base for {@link TableInputFormat}s. Receives a {@link HTable}, an
* {@link Scan} instance that defines the input columns etc. Subclasses may use
* other TableRecordReader implementations.
* <p>
* An example of a subclass:
* <pre>
* class ExampleTIF extends TableInputFormatBase implements JobConfigurable {
*
* public void configure(JobConf job) {
* HTable exampleTable = new HTable(HBaseConfiguration.create(job),
* Bytes.toBytes("exampleTable"));
* // mandatory
* setHTable(exampleTable);
* Text[] inputColumns = new byte [][] { Bytes.toBytes("columnA"),
* Bytes.toBytes("columnB") };
* // mandatory
* setInputColumns(inputColumns);
* RowFilterInterface exampleFilter = new RegExpRowFilter("keyPrefix.*");
* // optional
* setRowFilter(exampleFilter);
* }
*
* public void validateInput(JobConf job) throws IOException {
* }
* }
* </pre>
*/
@InterfaceAudience.Public
@InterfaceStability.Stable
public abstract class TableInputFormatBase
extends InputFormat<ImmutableBytesWritable, Result> {
final Log LOG = LogFactory.getLog(TableInputFormatBase.class);
/** Holds the details for the internal scanner. */
private Scan scan = null;
/** The table to scan. */
private HTable table = null;
/** The reader scanning the table, can be a custom one. */
private TableRecordReader tableRecordReader = null;
/** The reverse DNS lookup cache mapping: IPAddress => HostName */
private HashMap<InetAddress, String> reverseDNSCacheMap =
new HashMap<InetAddress, String>();
/** The NameServer address */
private String nameServer = null;
/**
* Builds a TableRecordReader. If no TableRecordReader was provided, uses
* the default.
*
* @param split The split to work with.
* @param context The current context.
* @return The newly created record reader.
* @throws IOException When creating the reader fails.
* @see org.apache.hadoop.mapreduce.InputFormat#createRecordReader(
* org.apache.hadoop.mapreduce.InputSplit,
* org.apache.hadoop.mapreduce.TaskAttemptContext)
*/
@Override
public RecordReader<ImmutableBytesWritable, Result> createRecordReader(
InputSplit split, TaskAttemptContext context)
throws IOException {
if (table == null) {
throw new IOException("Cannot create a record reader because of a" +
" previous error. Please look at the previous logs lines from" +
" the task's full log for more details.");
}
TableSplit tSplit = (TableSplit) split;
TableRecordReader trr = this.tableRecordReader;
// if no table record reader was provided use default
if (trr == null) {
trr = new TableRecordReader();
}
Scan sc = new Scan(this.scan);
sc.setStartRow(tSplit.getStartRow());
sc.setStopRow(tSplit.getEndRow());
trr.setScan(sc);
trr.setHTable(table);
try {
trr.initialize(tSplit, context);
} catch (InterruptedException e) {
throw new InterruptedIOException(e.getMessage());
}
return trr;
}
/**
* Calculates the splits that will serve as input for the map tasks. The
* number of splits matches the number of regions in a table.
*
* @param context The current job context.
* @return The list of input splits.
* @throws IOException When creating the list of splits fails.
* @see org.apache.hadoop.mapreduce.InputFormat#getSplits(
* org.apache.hadoop.mapreduce.JobContext)
*/
@Override
public List<InputSplit> getSplits(JobContext context) throws IOException {
if (table == null) {
throw new IOException("No table was provided.");
}
// Get the name server address and the default value is null.
this.nameServer =
context.getConfiguration().get("hbase.nameserver.address", null);
Pair<byte[][], byte[][]> keys = table.getStartEndKeys();
if (keys == null || keys.getFirst() == null ||
keys.getFirst().length == 0) {
HRegionLocation regLoc = table.getRegionLocation(
HConstants.EMPTY_BYTE_ARRAY, false);
if (null == regLoc) {
throw new IOException("Expecting at least one region.");
}
List<InputSplit> splits = new ArrayList<InputSplit>(1);
InputSplit split = new TableSplit(table.getTableName(),
HConstants.EMPTY_BYTE_ARRAY, HConstants.EMPTY_BYTE_ARRAY, regLoc
.getHostnamePort().split(Addressing.HOSTNAME_PORT_SEPARATOR)[0]);
splits.add(split);
return splits;
}
List<InputSplit> splits = new ArrayList<InputSplit>(keys.getFirst().length);
for (int i = 0; i < keys.getFirst().length; i++) {
if ( !includeRegionInSplit(keys.getFirst()[i], keys.getSecond()[i])) {
continue;
}
HServerAddress regionServerAddress =
table.getRegionLocation(keys.getFirst()[i]).getServerAddress();
InetAddress regionAddress =
regionServerAddress.getInetSocketAddress().getAddress();
String regionLocation;
try {
regionLocation = reverseDNS(regionAddress);
} catch (NamingException e) {
LOG.error("Cannot resolve the host name for " + regionAddress +
" because of " + e);
regionLocation = regionServerAddress.getHostname();
}
byte[] startRow = scan.getStartRow();
byte[] stopRow = scan.getStopRow();
// determine if the given start an stop key fall into the region
if ((startRow.length == 0 || keys.getSecond()[i].length == 0 ||
Bytes.compareTo(startRow, keys.getSecond()[i]) < 0) &&
(stopRow.length == 0 ||
Bytes.compareTo(stopRow, keys.getFirst()[i]) > 0)) {
byte[] splitStart = startRow.length == 0 ||
Bytes.compareTo(keys.getFirst()[i], startRow) >= 0 ?
keys.getFirst()[i] : startRow;
byte[] splitStop = (stopRow.length == 0 ||
Bytes.compareTo(keys.getSecond()[i], stopRow) <= 0) &&
keys.getSecond()[i].length > 0 ?
keys.getSecond()[i] : stopRow;
InputSplit split = new TableSplit(table.getTableName(),
splitStart, splitStop, regionLocation);
splits.add(split);
if (LOG.isDebugEnabled()) {
LOG.debug("getSplits: split -> " + i + " -> " + split);
}
}
}
return splits;
}
private String reverseDNS(InetAddress ipAddress) throws NamingException {
String hostName = this.reverseDNSCacheMap.get(ipAddress);
if (hostName == null) {
hostName = DNS.reverseDns(ipAddress, this.nameServer);
this.reverseDNSCacheMap.put(ipAddress, hostName);
}
return hostName;
}
/**
*
*
* Test if the given region is to be included in the InputSplit while splitting
* the regions of a table.
* <p>
* This optimization is effective when there is a specific reasoning to exclude an entire region from the M-R job,
* (and hence, not contributing to the InputSplit), given the start and end keys of the same. <br>
* Useful when we need to remember the last-processed top record and revisit the [last, current) interval for M-R processing,
* continuously. In addition to reducing InputSplits, reduces the load on the region server as well, due to the ordering of the keys.
* <br>
* <br>
* Note: It is possible that <code>endKey.length() == 0 </code> , for the last (recent) region.
* <br>
* Override this method, if you want to bulk exclude regions altogether from M-R. By default, no region is excluded( i.e. all regions are included).
*
*
* @param startKey Start key of the region
* @param endKey End key of the region
* @return true, if this region needs to be included as part of the input (default).
*
*/
protected boolean includeRegionInSplit(final byte[] startKey, final byte [] endKey) {
return true;
}
/**
* Allows subclasses to get the {@link HTable}.
*/
protected HTable getHTable() {
return this.table;
}
/**
* Allows subclasses to set the {@link HTable}.
*
* @param table The table to get the data from.
*/
protected void setHTable(HTable table) {
this.table = table;
}
/**
* Gets the scan defining the actual details like columns etc.
*
* @return The internal scan instance.
*/
public Scan getScan() {
if (this.scan == null) this.scan = new Scan();
return scan;
}
/**
* Sets the scan defining the actual details like columns etc.
*
* @param scan The scan to set.
*/
public void setScan(Scan scan) {
this.scan = scan;
}
/**
* Allows subclasses to set the {@link TableRecordReader}.
*
* @param tableRecordReader A different {@link TableRecordReader}
* implementation.
*/
protected void setTableRecordReader(TableRecordReader tableRecordReader) {
this.tableRecordReader = tableRecordReader;
}
}