/**
*
* 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.util;
import java.io.IOException;
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.conf.Configuration;
import org.apache.hadoop.conf.Configured;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.hbase.HBaseConfiguration;
import org.apache.hadoop.hbase.HConstants;
import org.apache.hadoop.hbase.HRegionInfo;
import org.apache.hadoop.hbase.HTableDescriptor;
import org.apache.hadoop.hbase.MasterNotRunningException;
import org.apache.hadoop.hbase.ZooKeeperConnectionException;
import org.apache.hadoop.hbase.client.Delete;
import org.apache.hadoop.hbase.client.Get;
import org.apache.hadoop.hbase.client.HBaseAdmin;
import org.apache.hadoop.hbase.client.Result;
import org.apache.hadoop.hbase.regionserver.HRegion;
import org.apache.hadoop.hbase.regionserver.wal.HLog;
import org.apache.hadoop.io.WritableComparator;
import org.apache.hadoop.util.GenericOptionsParser;
import org.apache.hadoop.util.Tool;
import org.apache.hadoop.util.ToolRunner;
import com.google.common.base.Preconditions;
/**
* Utility that can merge any two regions in the same table: adjacent,
* overlapping or disjoint.
*/
@InterfaceAudience.Public
@InterfaceStability.Evolving
public class Merge extends Configured implements Tool {
static final Log LOG = LogFactory.getLog(Merge.class);
private Path rootdir;
private volatile MetaUtils utils;
private byte [] tableName; // Name of table
private volatile byte [] region1; // Name of region 1
private volatile byte [] region2; // Name of region 2
private volatile boolean isMetaTable;
private volatile HRegionInfo mergeInfo;
/** default constructor */
public Merge() {
super();
}
/**
* @param conf configuration
*/
public Merge(Configuration conf) {
this.mergeInfo = null;
setConf(conf);
}
public int run(String[] args) throws Exception {
if (parseArgs(args) != 0) {
return -1;
}
// Verify file system is up.
FileSystem fs = FileSystem.get(getConf()); // get DFS handle
LOG.info("Verifying that file system is available...");
try {
FSUtils.checkFileSystemAvailable(fs);
} catch (IOException e) {
LOG.fatal("File system is not available", e);
return -1;
}
// Verify HBase is down
LOG.info("Verifying that HBase is not running...");
try {
HBaseAdmin.checkHBaseAvailable(getConf());
LOG.fatal("HBase cluster must be off-line, and is not. Aborting.");
return -1;
} catch (ZooKeeperConnectionException zkce) {
// If no zk, presume no master.
} catch (MasterNotRunningException e) {
// Expected. Ignore.
}
// Initialize MetaUtils and and get the root of the HBase installation
this.utils = new MetaUtils(getConf());
this.rootdir = FSUtils.getRootDir(getConf());
try {
if (isMetaTable) {
mergeTwoMetaRegions();
} else {
mergeTwoRegions();
}
return 0;
} catch (Exception e) {
LOG.fatal("Merge failed", e);
utils.scanMetaRegion(HRegionInfo.FIRST_META_REGIONINFO,
new MetaUtils.ScannerListener() {
public boolean processRow(HRegionInfo info) {
System.err.println(info.toString());
return true;
}
}
);
return -1;
} finally {
if (this.utils != null) {
this.utils.shutdown();
}
}
}
/** @return HRegionInfo for merge result */
HRegionInfo getMergedHRegionInfo() {
return this.mergeInfo;
}
/*
* Merge two meta regions. This is unlikely to be needed soon as we have only
* seend the meta table split once and that was with 64MB regions. With 256MB
* regions, it will be some time before someone has enough data in HBase to
* split the meta region and even less likely that a merge of two meta
* regions will be needed, but it is included for completeness.
*/
private void mergeTwoMetaRegions() throws IOException {
HRegion rootRegion = utils.getRootRegion();
Get get = new Get(region1);
get.addColumn(HConstants.CATALOG_FAMILY, HConstants.REGIONINFO_QUALIFIER);
Result result1 = rootRegion.get(get);
Preconditions.checkState(!result1.isEmpty(), "First region cells can not be null");
HRegionInfo info1 = HRegionInfo.getHRegionInfo(result1);
get = new Get(region2);
get.addColumn(HConstants.CATALOG_FAMILY, HConstants.REGIONINFO_QUALIFIER);
Result result2 = rootRegion.get(get);
Preconditions.checkState(!result2.isEmpty(), "Second region cells can not be null");
HRegionInfo info2 = HRegionInfo.getHRegionInfo(result2);
HRegion merged = merge(HTableDescriptor.META_TABLEDESC, info1, rootRegion, info2, rootRegion);
LOG.info("Adding " + merged.getRegionInfo() + " to " +
rootRegion.getRegionInfo());
HRegion.addRegionToMETA(rootRegion, merged);
merged.close();
}
private static class MetaScannerListener
implements MetaUtils.ScannerListener {
private final byte [] region1;
private final byte [] region2;
private HRegionInfo meta1 = null;
private HRegionInfo meta2 = null;
MetaScannerListener(final byte [] region1, final byte [] region2) {
this.region1 = region1;
this.region2 = region2;
}
public boolean processRow(HRegionInfo info) {
if (meta1 == null && HRegion.rowIsInRange(info, region1)) {
meta1 = info;
}
if (region2 != null && meta2 == null &&
HRegion.rowIsInRange(info, region2)) {
meta2 = info;
}
return meta1 == null || (region2 != null && meta2 == null);
}
HRegionInfo getMeta1() {
return meta1;
}
HRegionInfo getMeta2() {
return meta2;
}
}
/*
* Merges two regions from a user table.
*/
private void mergeTwoRegions() throws IOException {
LOG.info("Merging regions " + Bytes.toStringBinary(this.region1) + " and " +
Bytes.toStringBinary(this.region2) + " in table " + Bytes.toString(this.tableName));
// Scan the root region for all the meta regions that contain the regions
// we're merging.
MetaScannerListener listener = new MetaScannerListener(region1, region2);
this.utils.scanRootRegion(listener);
HRegionInfo meta1 = listener.getMeta1();
if (meta1 == null) {
throw new IOException("Could not find meta region for " + Bytes.toStringBinary(region1));
}
HRegionInfo meta2 = listener.getMeta2();
if (meta2 == null) {
throw new IOException("Could not find meta region for " + Bytes.toStringBinary(region2));
}
LOG.info("Found meta for region1 " + Bytes.toStringBinary(meta1.getRegionName()) +
", meta for region2 " + Bytes.toStringBinary(meta2.getRegionName()));
HRegion metaRegion1 = this.utils.getMetaRegion(meta1);
Get get = new Get(region1);
get.addColumn(HConstants.CATALOG_FAMILY, HConstants.REGIONINFO_QUALIFIER);
Result result1 = metaRegion1.get(get);
Preconditions.checkState(!result1.isEmpty(),
"First region cells can not be null");
HRegionInfo info1 = HRegionInfo.getHRegionInfo(result1);
if (info1 == null) {
throw new NullPointerException("info1 is null using key " +
Bytes.toStringBinary(region1) + " in " + meta1);
}
HRegion metaRegion2;
if (Bytes.equals(meta1.getRegionName(), meta2.getRegionName())) {
metaRegion2 = metaRegion1;
} else {
metaRegion2 = utils.getMetaRegion(meta2);
}
get = new Get(region2);
get.addColumn(HConstants.CATALOG_FAMILY, HConstants.REGIONINFO_QUALIFIER);
Result result2 = metaRegion2.get(get);
Preconditions.checkState(!result2.isEmpty(),
"Second region cells can not be null");
HRegionInfo info2 = HRegionInfo.getHRegionInfo(result2);
if (info2 == null) {
throw new NullPointerException("info2 is null using key " + meta2);
}
HTableDescriptor htd = FSTableDescriptors.getTableDescriptor(FileSystem.get(getConf()),
this.rootdir, this.tableName);
HRegion merged = merge(htd, info1, metaRegion1, info2, metaRegion2);
// Now find the meta region which will contain the newly merged region
listener = new MetaScannerListener(merged.getRegionName(), null);
utils.scanRootRegion(listener);
HRegionInfo mergedInfo = listener.getMeta1();
if (mergedInfo == null) {
throw new IOException("Could not find meta region for " +
Bytes.toStringBinary(merged.getRegionName()));
}
HRegion mergeMeta;
if (Bytes.equals(mergedInfo.getRegionName(), meta1.getRegionName())) {
mergeMeta = metaRegion1;
} else if (Bytes.equals(mergedInfo.getRegionName(), meta2.getRegionName())) {
mergeMeta = metaRegion2;
} else {
mergeMeta = utils.getMetaRegion(mergedInfo);
}
LOG.info("Adding " + merged.getRegionInfo() + " to " +
mergeMeta.getRegionInfo());
HRegion.addRegionToMETA(mergeMeta, merged);
merged.close();
}
/*
* Actually merge two regions and update their info in the meta region(s)
* If the meta is split, meta1 may be different from meta2. (and we may have
* to scan the meta if the resulting merged region does not go in either)
* Returns HRegion object for newly merged region
*/
private HRegion merge(final HTableDescriptor htd, HRegionInfo info1,
HRegion meta1, HRegionInfo info2, HRegion meta2)
throws IOException {
if (info1 == null) {
throw new IOException("Could not find " + Bytes.toStringBinary(region1) + " in " +
Bytes.toStringBinary(meta1.getRegionName()));
}
if (info2 == null) {
throw new IOException("Cound not find " + Bytes.toStringBinary(region2) + " in " +
Bytes.toStringBinary(meta2.getRegionName()));
}
HRegion merged = null;
HLog log = utils.getLog();
HRegion r1 = HRegion.openHRegion(info1, htd, log, getConf());
try {
HRegion r2 = HRegion.openHRegion(info2, htd, log, getConf());
try {
merged = HRegion.merge(r1, r2);
} finally {
if (!r2.isClosed()) {
r2.close();
}
}
} finally {
if (!r1.isClosed()) {
r1.close();
}
}
// Remove the old regions from meta.
// HRegion.merge has already deleted their files
removeRegionFromMeta(meta1, info1);
removeRegionFromMeta(meta2, info2);
this.mergeInfo = merged.getRegionInfo();
return merged;
}
/*
* Removes a region's meta information from the passed <code>meta</code>
* region.
*
* @param meta META HRegion to be updated
* @param regioninfo HRegionInfo of region to remove from <code>meta</code>
*
* @throws IOException
*/
private void removeRegionFromMeta(HRegion meta, HRegionInfo regioninfo)
throws IOException {
if (LOG.isDebugEnabled()) {
LOG.debug("Removing region: " + regioninfo + " from " + meta);
}
Delete delete = new Delete(regioninfo.getRegionName(),
System.currentTimeMillis());
meta.delete(delete, true);
}
/*
* Adds a region's meta information from the passed <code>meta</code>
* region.
*
* @param metainfo META HRegionInfo to be updated
* @param region HRegion to add to <code>meta</code>
*
* @throws IOException
*/
private int parseArgs(String[] args) throws IOException {
GenericOptionsParser parser =
new GenericOptionsParser(getConf(), args);
String[] remainingArgs = parser.getRemainingArgs();
if (remainingArgs.length != 3) {
usage();
return -1;
}
tableName = Bytes.toBytes(remainingArgs[0]);
isMetaTable = Bytes.compareTo(tableName, HConstants.META_TABLE_NAME) == 0;
region1 = Bytes.toBytesBinary(remainingArgs[1]);
region2 = Bytes.toBytesBinary(remainingArgs[2]);
int status = 0;
if (notInTable(tableName, region1) || notInTable(tableName, region2)) {
status = -1;
} else if (Bytes.equals(region1, region2)) {
LOG.error("Can't merge a region with itself");
status = -1;
}
return status;
}
private boolean notInTable(final byte [] tn, final byte [] rn) {
if (WritableComparator.compareBytes(tn, 0, tn.length, rn, 0, tn.length) != 0) {
LOG.error("Region " + Bytes.toStringBinary(rn) + " does not belong to table " +
Bytes.toString(tn));
return true;
}
return false;
}
private void usage() {
System.err
.println("For hadoop 0.20, Usage: bin/hbase org.apache.hadoop.hbase.util.Merge "
+ "[-Dfs.default.name=hdfs://nn:port] <table-name> <region-1> <region-2>\n");
System.err
.println("For hadoop 0.21+, Usage: bin/hbase org.apache.hadoop.hbase.util.Merge "
+ "[-Dfs.defaultFS=hdfs://nn:port] <table-name> <region-1> <region-2>\n");
}
public static void main(String[] args) {
int status;
try {
status = ToolRunner.run(HBaseConfiguration.create(), new Merge(), args);
} catch (Exception e) {
LOG.error("exiting due to error", e);
status = -1;
}
System.exit(status);
}
}