/**
* 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.master.balancer;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Collection;
import java.util.HashMap;
import java.util.List;
import java.util.Set;
import java.util.concurrent.Callable;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.hbase.ClusterStatus;
import org.apache.hadoop.hbase.HDFSBlocksDistribution;
import org.apache.hadoop.hbase.HRegionInfo;
import org.apache.hadoop.hbase.HTableDescriptor;
import org.apache.hadoop.hbase.ServerName;
import org.apache.hadoop.hbase.TableName;
import org.apache.hadoop.hbase.classification.InterfaceAudience;
import org.apache.hadoop.hbase.master.AssignmentManager;
import org.apache.hadoop.hbase.master.MasterServices;
import org.apache.hadoop.hbase.master.RegionStates;
import org.apache.hadoop.hbase.regionserver.HRegion;
import org.apache.hadoop.hbase.util.EnvironmentEdgeManager;
import com.google.common.cache.CacheBuilder;
import com.google.common.cache.CacheLoader;
import com.google.common.cache.LoadingCache;
import com.google.common.collect.Lists;
import com.google.common.util.concurrent.Futures;
import com.google.common.util.concurrent.ListenableFuture;
import com.google.common.util.concurrent.ListeningExecutorService;
import com.google.common.util.concurrent.MoreExecutors;
import com.google.common.util.concurrent.ThreadFactoryBuilder;
/**
* This will find where data for a region is located in HDFS. It ranks
* {@link ServerName}'s by the size of the store files they are holding for a
* given region.
*
*/
@InterfaceAudience.Private
class RegionLocationFinder {
private static final Log LOG = LogFactory.getLog(RegionLocationFinder.class);
private static final long CACHE_TIME = 240 * 60 * 1000;
private static final HDFSBlocksDistribution EMPTY_BLOCK_DISTRIBUTION = new HDFSBlocksDistribution();
private Configuration conf;
private volatile ClusterStatus status;
private MasterServices services;
private final ListeningExecutorService executor;
// Do not scheduleFullRefresh at master startup
private long lastFullRefresh = EnvironmentEdgeManager.currentTime();
private CacheLoader<HRegionInfo, HDFSBlocksDistribution> loader =
new CacheLoader<HRegionInfo, HDFSBlocksDistribution>() {
public ListenableFuture<HDFSBlocksDistribution> reload(final HRegionInfo hri,
HDFSBlocksDistribution oldValue) throws Exception {
return executor.submit(new Callable<HDFSBlocksDistribution>() {
@Override
public HDFSBlocksDistribution call() throws Exception {
return internalGetTopBlockLocation(hri);
}
});
}
@Override
public HDFSBlocksDistribution load(HRegionInfo key) throws Exception {
return internalGetTopBlockLocation(key);
}
};
// The cache for where regions are located.
private LoadingCache<HRegionInfo, HDFSBlocksDistribution> cache = null;
RegionLocationFinder() {
this.cache = createCache();
executor = MoreExecutors.listeningDecorator(
Executors.newScheduledThreadPool(
5,
new ThreadFactoryBuilder().
setDaemon(true)
.setNameFormat("region-location-%d")
.build()));
}
/**
* Create a cache for region to list of servers
* @param time time to cache the locations
* @return A new Cache.
*/
private LoadingCache<HRegionInfo, HDFSBlocksDistribution> createCache() {
return CacheBuilder.newBuilder()
.expireAfterWrite(CACHE_TIME, TimeUnit.MILLISECONDS)
.build(loader);
}
public Configuration getConf() {
return conf;
}
public void setConf(Configuration conf) {
this.conf = conf;
}
public void setServices(MasterServices services) {
this.services = services;
}
public void setClusterStatus(ClusterStatus status) {
long currentTime = EnvironmentEdgeManager.currentTime();
this.status = status;
if (currentTime > lastFullRefresh + (CACHE_TIME / 2)) {
// Only count the refresh if it includes user tables ( eg more than meta and namespace ).
lastFullRefresh = scheduleFullRefresh()?currentTime:lastFullRefresh;
}
}
/**
* Refresh all the region locations.
*
* @return true if user created regions got refreshed.
*/
private boolean scheduleFullRefresh() {
// Protect from anything being null while starting up.
if (services == null) {
return false;
}
AssignmentManager am = services.getAssignmentManager();
if (am == null) {
return false;
}
RegionStates regionStates = am.getRegionStates();
if (regionStates == null) {
return false;
}
Set<HRegionInfo> regions = regionStates.getRegionAssignments().keySet();
boolean includesUserTables = false;
for (final HRegionInfo hri : regions) {
cache.refresh(hri);
includesUserTables = includesUserTables || !hri.isSystemTable();
}
return includesUserTables;
}
protected List<ServerName> getTopBlockLocations(HRegionInfo region) {
List<String> topHosts = getBlockDistribution(region).getTopHosts();
return mapHostNameToServerName(topHosts);
}
/**
* Returns an ordered list of hosts which have better locality for this region
* than the current host.
*/
protected List<ServerName> getTopBlockLocations(HRegionInfo region, String currentHost) {
HDFSBlocksDistribution blocksDistribution = getBlockDistribution(region);
List<String> topHosts = new ArrayList<>();
for (String host : blocksDistribution.getTopHosts()) {
if (host.equals(currentHost)) {
break;
}
topHosts.add(host);
}
return mapHostNameToServerName(topHosts);
}
/**
* Returns an ordered list of hosts that are hosting the blocks for this
* region. The weight of each host is the sum of the block lengths of all
* files on that host, so the first host in the list is the server which holds
* the most bytes of the given region's HFiles.
*
* @param region region
* @return ordered list of hosts holding blocks of the specified region
*/
protected HDFSBlocksDistribution internalGetTopBlockLocation(HRegionInfo region) {
try {
HTableDescriptor tableDescriptor = getTableDescriptor(region.getTable());
if (tableDescriptor != null) {
HDFSBlocksDistribution blocksDistribution =
HRegion.computeHDFSBlocksDistribution(getConf(), tableDescriptor, region);
return blocksDistribution;
}
} catch (IOException ioe) {
LOG.warn("IOException during HDFSBlocksDistribution computation. for " + "region = "
+ region.getEncodedName(), ioe);
}
return EMPTY_BLOCK_DISTRIBUTION;
}
/**
* return HTableDescriptor for a given tableName
*
* @param tableName the table name
* @return HTableDescriptor
* @throws IOException
*/
protected HTableDescriptor getTableDescriptor(TableName tableName) throws IOException {
HTableDescriptor tableDescriptor = null;
try {
if (this.services != null && this.services.getTableDescriptors() != null) {
tableDescriptor = this.services.getTableDescriptors().get(tableName);
}
} catch (FileNotFoundException fnfe) {
LOG.debug("FileNotFoundException during getTableDescriptors." + " Current table name = "
+ tableName, fnfe);
}
return tableDescriptor;
}
/**
* Map hostname to ServerName, The output ServerName list will have the same
* order as input hosts.
*
* @param hosts the list of hosts
* @return ServerName list
*/
protected List<ServerName> mapHostNameToServerName(List<String> hosts) {
if (hosts == null || status == null) {
if (hosts == null) {
LOG.warn("RegionLocationFinder top hosts is null");
}
return Lists.newArrayList();
}
List<ServerName> topServerNames = new ArrayList<>();
Collection<ServerName> regionServers = status.getServers();
// create a mapping from hostname to ServerName for fast lookup
HashMap<String, List<ServerName>> hostToServerName = new HashMap<>();
for (ServerName sn : regionServers) {
String host = sn.getHostname();
if (!hostToServerName.containsKey(host)) {
hostToServerName.put(host, new ArrayList<>());
}
hostToServerName.get(host).add(sn);
}
for (String host : hosts) {
if (!hostToServerName.containsKey(host)) {
continue;
}
for (ServerName sn : hostToServerName.get(host)) {
// it is possible that HDFS is up ( thus host is valid ),
// but RS is down ( thus sn is null )
if (sn != null) {
topServerNames.add(sn);
}
}
}
return topServerNames;
}
public HDFSBlocksDistribution getBlockDistribution(HRegionInfo hri) {
HDFSBlocksDistribution blockDistbn = null;
try {
if (cache.asMap().containsKey(hri)) {
blockDistbn = cache.get(hri);
return blockDistbn;
} else {
LOG.debug("HDFSBlocksDistribution not found in cache for region "
+ hri.getRegionNameAsString());
blockDistbn = internalGetTopBlockLocation(hri);
cache.put(hri, blockDistbn);
return blockDistbn;
}
} catch (ExecutionException e) {
LOG.warn("Error while fetching cache entry ", e);
blockDistbn = internalGetTopBlockLocation(hri);
cache.put(hri, blockDistbn);
return blockDistbn;
}
}
private ListenableFuture<HDFSBlocksDistribution> asyncGetBlockDistribution(
HRegionInfo hri) {
try {
return loader.reload(hri, EMPTY_BLOCK_DISTRIBUTION);
} catch (Exception e) {
return Futures.immediateFuture(EMPTY_BLOCK_DISTRIBUTION);
}
}
public void refreshAndWait(Collection<HRegionInfo> hris) {
ArrayList<ListenableFuture<HDFSBlocksDistribution>> regionLocationFutures = new ArrayList<>(hris.size());
for (HRegionInfo hregionInfo : hris) {
regionLocationFutures.add(asyncGetBlockDistribution(hregionInfo));
}
int index = 0;
for (HRegionInfo hregionInfo : hris) {
ListenableFuture<HDFSBlocksDistribution> future = regionLocationFutures
.get(index);
try {
cache.put(hregionInfo, future.get());
} catch (InterruptedException ite) {
Thread.currentThread().interrupt();
} catch (ExecutionException ee) {
LOG.debug(
"ExecutionException during HDFSBlocksDistribution computation. for region = "
+ hregionInfo.getEncodedName(), ee);
}
index++;
}
}
// For test
LoadingCache<HRegionInfo, HDFSBlocksDistribution> getCache() {
return cache;
}
}