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HConnectionManager throwing runtime exceptions
/**
* Copyright 2010 The Apache Software Foundation
*
* 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.client;
import java.io.Closeable;
import java.io.IOException;
import java.lang.reflect.UndeclaredThrowableException;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.HashSet;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;
import java.util.Map.Entry;
import java.util.Set;
import java.util.TreeSet;
import java.util.concurrent.Callable;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.CopyOnWriteArraySet;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Future;
import java.util.concurrent.atomic.AtomicBoolean;
import java.util.concurrent.atomic.AtomicInteger;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.hbase.DoNotRetryIOException;
import org.apache.hadoop.hbase.HBaseConfiguration;
import org.apache.hadoop.hbase.HConstants;
import org.apache.hadoop.hbase.HRegionInfo;
import org.apache.hadoop.hbase.HRegionLocation;
import org.apache.hadoop.hbase.HServerAddress;
import org.apache.hadoop.hbase.HTableDescriptor;
import org.apache.hadoop.hbase.KeyValue;
import org.apache.hadoop.hbase.MasterAddressTracker;
import org.apache.hadoop.hbase.MasterNotRunningException;
import org.apache.hadoop.hbase.RemoteExceptionHandler;
import org.apache.hadoop.hbase.TableNotFoundException;
import org.apache.hadoop.hbase.ZooKeeperConnectionException;
import org.apache.hadoop.hbase.client.MetaScanner.MetaScannerVisitor;
import org.apache.hadoop.hbase.ipc.HBaseRPC;
import org.apache.hadoop.hbase.ipc.HBaseRPCProtocolVersion;
import org.apache.hadoop.hbase.ipc.HMasterInterface;
import org.apache.hadoop.hbase.ipc.HRegionInterface;
import org.apache.hadoop.hbase.util.Bytes;
import org.apache.hadoop.hbase.util.Pair;
import org.apache.hadoop.hbase.util.SoftValueSortedMap;
import org.apache.hadoop.hbase.util.Writables;
import org.apache.hadoop.hbase.zookeeper.RootRegionTracker;
import org.apache.hadoop.hbase.zookeeper.ZKTable;
import org.apache.hadoop.hbase.zookeeper.ZooKeeperWatcher;
import org.apache.hadoop.ipc.RemoteException;
import org.apache.zookeeper.KeeperException;
import com.google.common.collect.ImmutableMap;
/**
* A non-instantiable class that manages {@link HConnection}s.
* This class has a static Map of {@link HConnection} instances keyed by
* {@link Configuration}; all invocations of {@link #getConnection(Configuration)}
* that pass the same {@link Configuration} instance will be returned the same
* {@link HConnection} instance (Adding properties to a Configuration
* instance does not change its object identity). Sharing {@link HConnection}
* instances is usually what you want; all clients of the {@link HConnection}
* instances share the HConnections' cache of Region locations rather than each
* having to discover for itself the location of meta, root, etc. It makes
* sense for the likes of the pool of HTables class {@link HTablePool}, for
* instance (If concerned that a single {@link HConnection} is insufficient
* for sharing amongst clients in say an heavily-multithreaded environment,
* in practise its not proven to be an issue. Besides, {@link HConnection} is
* implemented atop Hadoop RPC and as of this writing, Hadoop RPC does a
* connection per cluster-member, exclusively).
*
* <p>But sharing connections
* makes clean up of {@link HConnection} instances a little awkward. Currently,
* clients cleanup by calling
* {@link #deleteConnection(Configuration, boolean)}. This will shutdown the
* zookeeper connection the HConnection was using and clean up all
* HConnection resources as well as stopping proxies to servers out on the
* cluster. Not running the cleanup will not end the world; it'll
* just stall the closeup some and spew some zookeeper connection failed
* messages into the log. Running the cleanup on a {@link HConnection} that is
* subsequently used by another will cause breakage so be careful running
* cleanup.
* <p>To create a {@link HConnection} that is not shared by others, you can
* create a new {@link Configuration} instance, pass this new instance to
* {@link #getConnection(Configuration)}, and then when done, close it up by
* doing something like the following:
* <pre>
* {@code
* Configuration newConfig = new Configuration(originalConf);
* HConnection connection = HConnectionManager.getConnection(newConfig);
* // Use the connection to your hearts' delight and then when done...
* HConnectionManager.deleteConnection(newConfig, true);
* }
* </pre>
* <p>Cleanup used to be done inside in a shutdown hook. On startup we'd
* register a shutdown hook that called {@link #deleteAllConnections(boolean)}
* on its way out but the order in which shutdown hooks run is not defined so
* were problematic for clients of HConnection that wanted to register their
* own shutdown hooks so we removed ours though this shifts the onus for
* cleanup to the client.
*/
@SuppressWarnings("serial")
public class HConnectionManager {
// A LRU Map of HConnectionKey -> HConnection (TableServer).
private static final Map<HConnectionKey, HConnectionImplementation> HBASE_INSTANCES;
public static final int MAX_CACHED_HBASE_INSTANCES;
static {
// We set instances to one more than the value specified for {@link
// HConstants#ZOOKEEPER_MAX_CLIENT_CNXNS}. By default, the zk default max
// connections to the ensemble from the one client is 30, so in that case we
// should run into zk issues before the LRU hit this value of 31.
MAX_CACHED_HBASE_INSTANCES = HBaseConfiguration.create().getInt(
HConstants.ZOOKEEPER_MAX_CLIENT_CNXNS,
HConstants.DEFAULT_ZOOKEPER_MAX_CLIENT_CNXNS) + 1;
HBASE_INSTANCES = new LinkedHashMap<HConnectionKey, HConnectionImplementation>(
(int) (MAX_CACHED_HBASE_INSTANCES / 0.75F) + 1, 0.75F, true) {
@Override
protected boolean removeEldestEntry(
Map.Entry<HConnectionKey, HConnectionImplementation> eldest) {
return size() > MAX_CACHED_HBASE_INSTANCES;
}
};
}
/*
* Non-instantiable.
*/
protected HConnectionManager() {
super();
}
/**
* Get the connection that goes with the passed <code>conf</code>
* configuration instance.
* If no current connection exists, method creates a new connection for the
* passed <code>conf</code> instance.
* @param conf configuration
* @return HConnection object for <code>conf</code>
* @throws ZooKeeperConnectionException
*/
public static HConnection getConnection(Configuration conf)
throws ZooKeeperConnectionException {
HConnectionKey connectionKey = new HConnectionKey(conf);
synchronized (HBASE_INSTANCES) {
HConnectionImplementation connection = HBASE_INSTANCES.get(connectionKey);
if (connection == null) {
connection = new HConnectionImplementation(conf);
HBASE_INSTANCES.put(connectionKey, connection);
}
connection.incCount();
return connection;
}
}
/**
* Delete connection information for the instance specified by configuration.
* If there are no more references to it, this will then close connection to
* the zookeeper ensemble and let go of all resources.
*
* @param conf
* configuration whose identity is used to find {@link HConnection}
* instance.
* @param stopProxy
* Shuts down all the proxy's put up to cluster members including to
* cluster HMaster. Calls
* {@link HBaseRPC#stopProxy(org.apache.hadoop.ipc.VersionedProtocol)}
* .
*/
public static void deleteConnection(Configuration conf, boolean stopProxy) {
deleteConnection(new HConnectionKey(conf), stopProxy);
}
/**
* Delete information for all connections.
* @param stopProxy stop the proxy as well
* @throws IOException
*/
public static void deleteAllConnections(boolean stopProxy) {
synchronized (HBASE_INSTANCES) {
Set<HConnectionKey> connectionKeys = new HashSet<HConnectionKey>();
connectionKeys.addAll(HBASE_INSTANCES.keySet());
for (HConnectionKey connectionKey : connectionKeys) {
deleteConnection(connectionKey, stopProxy);
}
HBASE_INSTANCES.clear();
}
}
private static void deleteConnection(HConnection connection, boolean stopProxy) {
synchronized (HBASE_INSTANCES) {
for (Entry<HConnectionKey, HConnectionImplementation> connectionEntry : HBASE_INSTANCES
.entrySet()) {
if (connectionEntry.getValue() == connection) {
deleteConnection(connectionEntry.getKey(), stopProxy);
break;
}
}
}
}
private static void deleteConnection(HConnectionKey connectionKey, boolean stopProxy) {
synchronized (HBASE_INSTANCES) {
HConnectionImplementation connection = HBASE_INSTANCES
.get(connectionKey);
if (connection != null) {
connection.decCount();
if (connection.isZeroReference()) {
HBASE_INSTANCES.remove(connectionKey);
connection.close(stopProxy);
} else if (stopProxy) {
connection.stopProxyOnClose(stopProxy);
}
}
}
}
/**
* It is provided for unit test cases which verify the behavior of region
* location cache prefetch.
* @return Number of cached regions for the table.
* @throws ZooKeeperConnectionException
*/
static int getCachedRegionCount(Configuration conf,
final byte[] tableName)
throws IOException {
return execute(new HConnectable<Integer>(conf) {
@Override
public Integer connect(HConnection connection) {
return ((HConnectionImplementation) connection)
.getNumberOfCachedRegionLocations(tableName);
}
});
}
/**
* It's provided for unit test cases which verify the behavior of region
* location cache prefetch.
* @return true if the region where the table and row reside is cached.
* @throws ZooKeeperConnectionException
*/
static boolean isRegionCached(Configuration conf,
final byte[] tableName, final byte[] row) throws IOException {
return execute(new HConnectable<Boolean>(conf) {
@Override
public Boolean connect(HConnection connection) {
return ((HConnectionImplementation) connection).isRegionCached(tableName, row);
}
});
}
/**
* This class makes it convenient for one to execute a command in the context
* of a {@link HConnection} instance based on the given {@link Configuration}.
*
* <p>
* If you find yourself wanting to use a {@link Connection} for a relatively
* short duration of time, and do not want to deal with the hassle of creating
* and cleaning up that resource, then you should consider using this
* convenience class.
*
* @param <T>
* the return type of the {@link HConnectable#connect(HConnection)}
* method.
*/
public static abstract class HConnectable<T> {
public Configuration conf;
public HConnectable(Configuration conf) {
this.conf = conf;
}
public abstract T connect(HConnection connection) throws IOException;
}
/**
* This convenience method invokes the given {@link HConnectable#connect}
* implementation using a {@link HConnection} instance that lasts just for the
* duration of that invocation.
*
* @param <T> the return type of the connect method
* @param connectable the {@link HConnectable} instance
* @return the value returned by the connect method
* @throws IOException
*/
public static <T> T execute(HConnectable<T> connectable) throws IOException {
if (connectable == null || connectable.conf == null) {
return null;
}
Configuration conf = connectable.conf;
HConnection connection = HConnectionManager.getConnection(conf);
boolean connectSucceeded = false;
try {
T returnValue = connectable.connect(connection);
connectSucceeded = true;
return returnValue;
} finally {
try {
connection.close();
} catch (Exception e) {
if (connectSucceeded) {
throw new IOException("The connection to " + connection
+ " could not be deleted.", e);
}
}
}
}
/**
* Denotes a unique key to a {@link HConnection} instance.
*
* In essence, this class captures the properties in {@link Configuration}
* that may be used in the process of establishing a connection. In light of
* that, if any new such properties are introduced into the mix, they must be
* added to the {@link HConnectionKey#properties} list.
*
*/
static class HConnectionKey {
public static String[] CONNECTION_PROPERTIES = new String[] {
HConstants.ZOOKEEPER_QUORUM, HConstants.ZOOKEEPER_ZNODE_PARENT,
HConstants.ZOOKEEPER_CLIENT_PORT,
HConstants.ZOOKEEPER_RECOVERABLE_WAITTIME,
HConstants.HBASE_CLIENT_PAUSE, HConstants.HBASE_CLIENT_RETRIES_NUMBER,
HConstants.HBASE_CLIENT_RPC_MAXATTEMPTS,
HConstants.HBASE_RPC_TIMEOUT_KEY,
HConstants.HBASE_CLIENT_PREFETCH_LIMIT,
HConstants.HBASE_META_SCANNER_CACHING,
HConstants.HBASE_CLIENT_INSTANCE_ID };
private Map<String, String> properties;
public HConnectionKey(Configuration conf) {
ImmutableMap.Builder<String, String> builder = ImmutableMap.builder();
if (conf != null) {
for (String property : CONNECTION_PROPERTIES) {
String value = conf.get(property);
if (value != null) {
builder.put(property, value);
}
}
}
this.properties = builder.build();
}
@Override
public int hashCode() {
final int prime = 31;
int result = 1;
for (String property : CONNECTION_PROPERTIES) {
String value = properties.get(property);
if (value != null) {
result = prime * result + value.hashCode();
}
}
return result;
}
@Override
public boolean equals(Object obj) {
if (this == obj)
return true;
if (obj == null)
return false;
if (getClass() != obj.getClass())
return false;
HConnectionKey that = (HConnectionKey) obj;
if (this.properties == null) {
if (that.properties != null) {
return false;
}
} else {
if (that.properties == null) {
return false;
}
for (String property : CONNECTION_PROPERTIES) {
String thisValue = this.properties.get(property);
String thatValue = that.properties.get(property);
if (thisValue == thatValue) {
continue;
}
if (thisValue == null || !thisValue.equals(thatValue)) {
return false;
}
}
}
return true;
}
}
/* Encapsulates connection to zookeeper and regionservers.*/
static class HConnectionImplementation implements HConnection, Closeable {
static final Log LOG = LogFactory.getLog(HConnectionImplementation.class);
private final Class<? extends HRegionInterface> serverInterfaceClass;
private final long pause;
private final int numRetries;
private final int maxRPCAttempts;
private final int rpcTimeout;
private final int prefetchRegionLimit;
private final Object masterLock = new Object();
private volatile boolean closed;
private volatile HMasterInterface master;
private volatile boolean masterChecked;
// ZooKeeper reference
private ZooKeeperWatcher zooKeeper;
// ZooKeeper-based master address tracker
private MasterAddressTracker masterAddressTracker;
private RootRegionTracker rootRegionTracker;
private final Object metaRegionLock = new Object();
private final Object userRegionLock = new Object();
private final Configuration conf;
// Known region HServerAddress.toString() -> HRegionInterface
private final Map<String, HRegionInterface> servers =
new ConcurrentHashMap<String, HRegionInterface>();
private final ConcurrentHashMap<String, String> connectionLock = new ConcurrentHashMap<String, String>();
/**
* Map of table to table {@link HRegionLocation}s. The table key is made
* by doing a {@link Bytes#mapKey(byte[])} of the table's name.
*/
private final Map<Integer, SoftValueSortedMap<byte [], HRegionLocation>>
cachedRegionLocations =
new HashMap<Integer, SoftValueSortedMap<byte [], HRegionLocation>>();
// region cache prefetch is enabled by default. this set contains all
// tables whose region cache prefetch are disabled.
private final Set<Integer> regionCachePrefetchDisabledTables =
new CopyOnWriteArraySet<Integer>();
private boolean stopProxy;
private int refCount;
/**
* constructor
* @param conf Configuration object
*/
@SuppressWarnings("unchecked")
public HConnectionImplementation(Configuration conf)
throws ZooKeeperConnectionException {
this.conf = conf;
String serverClassName = conf.get(HConstants.REGION_SERVER_CLASS,
HConstants.DEFAULT_REGION_SERVER_CLASS);
this.closed = false;
try {
this.serverInterfaceClass =
(Class<? extends HRegionInterface>) Class.forName(serverClassName);
} catch (ClassNotFoundException e) {
throw new UnsupportedOperationException(
"Unable to find region server interface " + serverClassName, e);
}
this.pause = conf.getLong(HConstants.HBASE_CLIENT_PAUSE,
HConstants.DEFAULT_HBASE_CLIENT_PAUSE);
this.numRetries = conf.getInt(HConstants.HBASE_CLIENT_RETRIES_NUMBER,
HConstants.DEFAULT_HBASE_CLIENT_RETRIES_NUMBER);
this.maxRPCAttempts = conf.getInt(
HConstants.HBASE_CLIENT_RPC_MAXATTEMPTS,
HConstants.DEFAULT_HBASE_CLIENT_RPC_MAXATTEMPTS);
this.rpcTimeout = conf.getInt(
HConstants.HBASE_RPC_TIMEOUT_KEY,
HConstants.DEFAULT_HBASE_RPC_TIMEOUT);
this.prefetchRegionLimit = conf.getInt(
HConstants.HBASE_CLIENT_PREFETCH_LIMIT,
HConstants.DEFAULT_HBASE_CLIENT_PREFETCH_LIMIT);
setupZookeeperTrackers();
this.master = null;
this.masterChecked = false;
}
private synchronized void setupZookeeperTrackers()
throws ZooKeeperConnectionException{
// initialize zookeeper and master address manager
this.zooKeeper = getZooKeeperWatcher();
masterAddressTracker = new MasterAddressTracker(this.zooKeeper, this);
masterAddressTracker.start();
this.rootRegionTracker = new RootRegionTracker(this.zooKeeper, this);
this.rootRegionTracker.start();
}
private synchronized void resetZooKeeperTrackers()
throws ZooKeeperConnectionException {
LOG.info("Trying to reconnect to zookeeper");
masterAddressTracker.stop();
masterAddressTracker = null;
rootRegionTracker.stop();
rootRegionTracker = null;
this.zooKeeper = null;
setupZookeeperTrackers();
}
public Configuration getConfiguration() {
return this.conf;
}
private long getPauseTime(int tries) {
int ntries = tries;
if (ntries >= HConstants.RETRY_BACKOFF.length) {
ntries = HConstants.RETRY_BACKOFF.length - 1;
}
return this.pause * HConstants.RETRY_BACKOFF[ntries];
}
public HMasterInterface getMaster()
throws MasterNotRunningException, ZooKeeperConnectionException {
// Check if we already have a good master connection
if (master != null) {
if (master.isMasterRunning()) {
return master;
}
}
HServerAddress masterLocation = null;
synchronized (this.masterLock) {
for (int tries = 0;
!this.closed &&
!this.masterChecked && this.master == null &&
tries < numRetries;
tries++) {
try {
masterLocation = masterAddressTracker.getMasterAddress();
if(masterLocation == null) {
LOG.info("ZooKeeper available but no active master location found");
throw new MasterNotRunningException();
}
HMasterInterface tryMaster = (HMasterInterface)HBaseRPC.getProxy(
HMasterInterface.class, HBaseRPCProtocolVersion.versionID,
masterLocation.getInetSocketAddress(), this.conf, this.rpcTimeout);
if (tryMaster.isMasterRunning()) {
this.master = tryMaster;
this.masterLock.notifyAll();
break;
}
} catch (IOException e) {
if (tries == numRetries - 1) {
// This was our last chance - don't bother sleeping
LOG.info("getMaster attempt " + tries + " of " + this.numRetries +
" failed; no more retrying.", e);
break;
}
LOG.info("getMaster attempt " + tries + " of " + this.numRetries +
" failed; retrying after sleep of " +
getPauseTime(tries), e);
}
// Cannot connect to master or it is not running. Sleep & retry
try {
this.masterLock.wait(getPauseTime(tries));
} catch (InterruptedException e) {
Thread.currentThread().interrupt();
throw new RuntimeException("Thread was interrupted while trying to connect to master.");
}
}
this.masterChecked = true;
}
if (this.master == null) {
if (masterLocation == null) {
throw new MasterNotRunningException();
}
throw new MasterNotRunningException(masterLocation.toString());
}
return this.master;
}
public boolean isMasterRunning()
throws MasterNotRunningException, ZooKeeperConnectionException {
if (this.master == null) {
getMaster();
}
boolean isRunning = master.isMasterRunning();
if(isRunning) {
return true;
}
throw new MasterNotRunningException();
}
public HRegionLocation getRegionLocation(final byte [] name,
final byte [] row, boolean reload)
throws IOException {
return reload? relocateRegion(name, row): locateRegion(name, row);
}
public HTableDescriptor[] listTables() throws IOException {
final TreeSet<HTableDescriptor> uniqueTables =
new TreeSet<HTableDescriptor>();
MetaScannerVisitor visitor = new MetaScannerVisitor() {
public boolean processRow(Result result) throws IOException {
try {
byte[] value = result.getValue(HConstants.CATALOG_FAMILY,
HConstants.REGIONINFO_QUALIFIER);
HRegionInfo info = null;
if (value != null) {
info = Writables.getHRegionInfo(value);
}
// Only examine the rows where the startKey is zero length
if (info != null && info.getStartKey().length == 0) {
uniqueTables.add(info.getTableDesc());
}
return true;
} catch (RuntimeException e) {
LOG.error("Result=" + result);
throw e;
}
}
};
MetaScanner.metaScan(conf, visitor);
return uniqueTables.toArray(new HTableDescriptor[uniqueTables.size()]);
}
public boolean isTableEnabled(byte[] tableName) throws IOException {
return testTableOnlineState(tableName, true);
}
public boolean isTableDisabled(byte[] tableName) throws IOException {
return testTableOnlineState(tableName, false);
}
public boolean isTableAvailable(final byte[] tableName) throws IOException {
final AtomicBoolean available = new AtomicBoolean(true);
final AtomicInteger regionCount = new AtomicInteger(0);
MetaScannerVisitor visitor = new MetaScannerVisitor() {
@Override
public boolean processRow(Result row) throws IOException {
byte[] value = row.getValue(HConstants.CATALOG_FAMILY,
HConstants.REGIONINFO_QUALIFIER);
HRegionInfo info = Writables.getHRegionInfoOrNull(value);
if (info != null) {
if (Bytes.equals(tableName, info.getTableDesc().getName())) {
value = row.getValue(HConstants.CATALOG_FAMILY,
HConstants.SERVER_QUALIFIER);
if (value == null) {
available.set(false);
return false;
}
regionCount.incrementAndGet();
}
}
return true;
}
};
MetaScanner.metaScan(conf, visitor);
return available.get() && (regionCount.get() > 0);
}
/*
* @param True if table is online
*/
private boolean testTableOnlineState(byte [] tableName, boolean online)
throws IOException {
if (Bytes.equals(tableName, HConstants.ROOT_TABLE_NAME)) {
// The root region is always enabled
return online;
}
String tableNameStr = Bytes.toString(tableName);
try {
if (online) {
return ZKTable.isEnabledTable(this.zooKeeper, tableNameStr);
}
return ZKTable.isDisabledTable(this.zooKeeper, tableNameStr);
} catch (KeeperException e) {
throw new IOException("Enable/Disable failed", e);
}
}
private static class HTableDescriptorFinder
implements MetaScanner.MetaScannerVisitor {
byte[] tableName;
HTableDescriptor result;
protected HTableDescriptorFinder(byte[] tableName) {
this.tableName = tableName;
}
public boolean processRow(Result rowResult) throws IOException {
HRegionInfo info = Writables.getHRegionInfoOrNull(
rowResult.getValue(HConstants.CATALOG_FAMILY,
HConstants.REGIONINFO_QUALIFIER));
if (info == null) return true;
HTableDescriptor desc = info.getTableDesc();
if (Bytes.compareTo(desc.getName(), tableName) == 0) {
result = desc;
return false;
}
return true;
}
HTableDescriptor getResult() {
return result;
}
}
public HTableDescriptor getHTableDescriptor(final byte[] tableName)
throws IOException {
if (Bytes.equals(tableName, HConstants.ROOT_TABLE_NAME)) {
return new UnmodifyableHTableDescriptor(HTableDescriptor.ROOT_TABLEDESC);
}
if (Bytes.equals(tableName, HConstants.META_TABLE_NAME)) {
return HTableDescriptor.META_TABLEDESC;
}
HTableDescriptorFinder finder = new HTableDescriptorFinder(tableName);
MetaScanner.metaScan(conf, finder, tableName);
HTableDescriptor result = finder.getResult();
if (result == null) {
throw new TableNotFoundException(Bytes.toString(tableName));
}
return result;
}
@Override
public HRegionLocation locateRegion(final byte [] regionName)
throws IOException {
// TODO implement. use old stuff or new stuff?
return null;
}
@Override
public List<HRegionLocation> locateRegions(final byte [] tableName)
throws IOException {
// TODO implement. use old stuff or new stuff?
return null;
}
public HRegionLocation locateRegion(final byte [] tableName,
final byte [] row)
throws IOException{
return locateRegion(tableName, row, true);
}
public HRegionLocation relocateRegion(final byte [] tableName,
final byte [] row)
throws IOException{
return locateRegion(tableName, row, false);
}
private HRegionLocation locateRegion(final byte [] tableName,
final byte [] row, boolean useCache)
throws IOException {
if (this.closed) throw new IOException(toString() + " closed");
if (tableName == null || tableName.length == 0) {
throw new IllegalArgumentException(
"table name cannot be null or zero length");
}
if (Bytes.equals(tableName, HConstants.ROOT_TABLE_NAME)) {
try {
HServerAddress hsa =
this.rootRegionTracker.waitRootRegionLocation(this.rpcTimeout);
LOG.debug("Lookedup root region location, connection=" + this +
"; hsa=" + hsa);
if (hsa == null) return null;
return new HRegionLocation(HRegionInfo.ROOT_REGIONINFO, hsa);
} catch (InterruptedException e) {
Thread.currentThread().interrupt();
return null;
}
} else if (Bytes.equals(tableName, HConstants.META_TABLE_NAME)) {
return locateRegionInMeta(HConstants.ROOT_TABLE_NAME, tableName, row,
useCache, metaRegionLock);
} else {
// Region not in the cache - have to go to the meta RS
return locateRegionInMeta(HConstants.META_TABLE_NAME, tableName, row,
useCache, userRegionLock);
}
}
/*
* Search .META. for the HRegionLocation info that contains the table and
* row we're seeking. It will prefetch certain number of regions info and
* save them to the global region cache.
*/
private void prefetchRegionCache(final byte[] tableName,
final byte[] row) {
// Implement a new visitor for MetaScanner, and use it to walk through
// the .META.
MetaScannerVisitor visitor = new MetaScannerVisitor() {
public boolean processRow(Result result) throws IOException {
try {
byte[] value = result.getValue(HConstants.CATALOG_FAMILY,
HConstants.REGIONINFO_QUALIFIER);
HRegionInfo regionInfo = null;
if (value != null) {
// convert the row result into the HRegionLocation we need!
regionInfo = Writables.getHRegionInfo(value);
// possible we got a region of a different table...
if (!Bytes.equals(regionInfo.getTableDesc().getName(),
tableName)) {
return false; // stop scanning
}
if (regionInfo.isOffline()) {
// don't cache offline regions
return true;
}
value = result.getValue(HConstants.CATALOG_FAMILY,
HConstants.SERVER_QUALIFIER);
if (value == null) {
return true; // don't cache it
}
final String serverAddress = Bytes.toString(value);
// instantiate the location
HRegionLocation loc = new HRegionLocation(regionInfo,
new HServerAddress(serverAddress));
// cache this meta entry
cacheLocation(tableName, loc);
}
return true;
} catch (RuntimeException e) {
throw new IOException(e);
}
}
};
try {
// pre-fetch certain number of regions info at region cache.
MetaScanner.metaScan(conf, visitor, tableName, row,
this.prefetchRegionLimit);
} catch (IOException e) {
LOG.warn("Encountered problems when prefetch META table: ", e);
}
}
/*
* Search one of the meta tables (-ROOT- or .META.) for the HRegionLocation
* info that contains the table and row we're seeking.
*/
private HRegionLocation locateRegionInMeta(final byte [] parentTable,
final byte [] tableName, final byte [] row, boolean useCache,
Object regionLockObject)
throws IOException {
HRegionLocation location;
// If we are supposed to be using the cache, look in the cache to see if
// we already have the region.
if (useCache) {
location = getCachedLocation(tableName, row);
if (location != null) {
return location;
}
}
// build the key of the meta region we should be looking for.
// the extra 9's on the end are necessary to allow "exact" matches
// without knowing the precise region names.
byte [] metaKey = HRegionInfo.createRegionName(tableName, row,
HConstants.NINES, false);
for (int tries = 0; true; tries++) {
if (tries >= numRetries) {
throw new NoServerForRegionException("Unable to find region for "
+ Bytes.toStringBinary(row) + " after " + numRetries + " tries.");
}
HRegionLocation metaLocation = null;
try {
// locate the root or meta region
metaLocation = locateRegion(parentTable, metaKey);
// If null still, go around again.
if (metaLocation == null) continue;
HRegionInterface server =
getHRegionConnection(metaLocation.getServerAddress());
Result regionInfoRow = null;
// This block guards against two threads trying to load the meta
// region at the same time. The first will load the meta region and
// the second will use the value that the first one found.
synchronized (regionLockObject) {
// If the parent table is META, we may want to pre-fetch some
// region info into the global region cache for this table.
if (Bytes.equals(parentTable, HConstants.META_TABLE_NAME) &&
(getRegionCachePrefetch(tableName)) ) {
prefetchRegionCache(tableName, row);
}
// Check the cache again for a hit in case some other thread made the
// same query while we were waiting on the lock. If not supposed to
// be using the cache, delete any existing cached location so it won't
// interfere.
if (useCache) {
location = getCachedLocation(tableName, row);
if (location != null) {
return location;
}
} else {
deleteCachedLocation(tableName, row);
}
// Query the root or meta region for the location of the meta region
regionInfoRow = server.getClosestRowBefore(
metaLocation.getRegionInfo().getRegionName(), metaKey,
HConstants.CATALOG_FAMILY);
}
if (regionInfoRow == null) {
throw new TableNotFoundException(Bytes.toString(tableName));
}
byte[] value = regionInfoRow.getValue(HConstants.CATALOG_FAMILY,
HConstants.REGIONINFO_QUALIFIER);
if (value == null || value.length == 0) {
throw new IOException("HRegionInfo was null or empty in " +
Bytes.toString(parentTable) + ", row=" + regionInfoRow);
}
// convert the row result into the HRegionLocation we need!
HRegionInfo regionInfo = (HRegionInfo) Writables.getWritable(
value, new HRegionInfo());
// possible we got a region of a different table...
if (!Bytes.equals(regionInfo.getTableDesc().getName(), tableName)) {
throw new TableNotFoundException(
"Table '" + Bytes.toString(tableName) + "' was not found.");
}
if (regionInfo.isOffline()) {
throw new RegionOfflineException("region offline: " +
regionInfo.getRegionNameAsString());
}
value = regionInfoRow.getValue(HConstants.CATALOG_FAMILY,
HConstants.SERVER_QUALIFIER);
String serverAddress = "";
if(value != null) {
serverAddress = Bytes.toString(value);
}
if (serverAddress.equals("")) {
throw new NoServerForRegionException("No server address listed " +
"in " + Bytes.toString(parentTable) + " for region " +
regionInfo.getRegionNameAsString());
}
// instantiate the location
location = new HRegionLocation(regionInfo,
new HServerAddress(serverAddress));
cacheLocation(tableName, location);
return location;
} catch (TableNotFoundException e) {
// if we got this error, probably means the table just plain doesn't
// exist. rethrow the error immediately. this should always be coming
// from the HTable constructor.
throw e;
} catch (IOException e) {
if (e instanceof RemoteException) {
e = RemoteExceptionHandler.decodeRemoteException(
(RemoteException) e);
}
if (tries < numRetries - 1) {
if (LOG.isDebugEnabled()) {
LOG.debug("locateRegionInMeta parentTable=" +
Bytes.toString(parentTable) + ", metaLocation=" +
((metaLocation == null)? "null": metaLocation) + ", attempt=" +
tries + " of " +
this.numRetries + " failed; retrying after sleep of " +
getPauseTime(tries) + " because: " + e.getMessage());
}
} else {
throw e;
}
// Only relocate the parent region if necessary
if(!(e instanceof RegionOfflineException ||
e instanceof NoServerForRegionException)) {
relocateRegion(parentTable, metaKey);
}
}
try{
Thread.sleep(getPauseTime(tries));
} catch (InterruptedException e) {
Thread.currentThread().interrupt();
throw new IOException("Giving up trying to location region in " +
"meta: thread is interrupted.");
}
}
}
/*
* Search the cache for a location that fits our table and row key.
* Return null if no suitable region is located. TODO: synchronization note
*
* <p>TODO: This method during writing consumes 15% of CPU doing lookup
* into the Soft Reference SortedMap. Improve.
*
* @param tableName
* @param row
* @return Null or region location found in cache.
*/
HRegionLocation getCachedLocation(final byte [] tableName,
final byte [] row) {
SoftValueSortedMap<byte [], HRegionLocation> tableLocations =
getTableLocations(tableName);
// start to examine the cache. we can only do cache actions
// if there's something in the cache for this table.
if (tableLocations.isEmpty()) {
return null;
}
HRegionLocation rl = tableLocations.get(row);
if (rl != null) {
return rl;
}
// Cut the cache so that we only get the part that could contain
// regions that match our key
SoftValueSortedMap<byte[], HRegionLocation> matchingRegions =
tableLocations.headMap(row);
// if that portion of the map is empty, then we're done. otherwise,
// we need to examine the cached location to verify that it is
// a match by end key as well.
if (!matchingRegions.isEmpty()) {
HRegionLocation possibleRegion =
matchingRegions.get(matchingRegions.lastKey());
// there is a possibility that the reference was garbage collected
// in the instant since we checked isEmpty().
if (possibleRegion != null) {
byte[] endKey = possibleRegion.getRegionInfo().getEndKey();
// make sure that the end key is greater than the row we're looking
// for, otherwise the row actually belongs in the next region, not
// this one. the exception case is when the endkey is
// HConstants.EMPTY_START_ROW, signifying that the region we're
// checking is actually the last region in the table.
if (Bytes.equals(endKey, HConstants.EMPTY_END_ROW) ||
KeyValue.getRowComparator(tableName).compareRows(endKey, 0, endKey.length,
row, 0, row.length) > 0) {
return possibleRegion;
}
}
}
// Passed all the way through, so we got nothin - complete cache miss
return null;
}
/**
* Delete a cached location
* @param tableName tableName
* @param row
*/
void deleteCachedLocation(final byte [] tableName, final byte [] row) {
synchronized (this.cachedRegionLocations) {
SoftValueSortedMap<byte [], HRegionLocation> tableLocations =
getTableLocations(tableName);
// start to examine the cache. we can only do cache actions
// if there's something in the cache for this table.
if (!tableLocations.isEmpty()) {
HRegionLocation rl = getCachedLocation(tableName, row);
if (rl != null) {
tableLocations.remove(rl.getRegionInfo().getStartKey());
if (LOG.isDebugEnabled()) {
LOG.debug("Removed " +
rl.getRegionInfo().getRegionNameAsString() +
" for tableName=" + Bytes.toString(tableName) +
" from cache " + "because of " + Bytes.toStringBinary(row));
}
}
}
}
}
/*
* @param tableName
* @return Map of cached locations for passed <code>tableName</code>
*/
private SoftValueSortedMap<byte [], HRegionLocation> getTableLocations(
final byte [] tableName) {
// find the map of cached locations for this table
Integer key = Bytes.mapKey(tableName);
SoftValueSortedMap<byte [], HRegionLocation> result;
synchronized (this.cachedRegionLocations) {
result = this.cachedRegionLocations.get(key);
// if tableLocations for this table isn't built yet, make one
if (result == null) {
result = new SoftValueSortedMap<byte [], HRegionLocation>(
Bytes.BYTES_COMPARATOR);
this.cachedRegionLocations.put(key, result);
}
}
return result;
}
@Override
public void clearRegionCache() {
synchronized(this.cachedRegionLocations) {
this.cachedRegionLocations.clear();
}
}
@Override
public void clearRegionCache(final byte [] tableName) {
synchronized (this.cachedRegionLocations) {
this.cachedRegionLocations.remove(Bytes.mapKey(tableName));
}
}
/*
* Put a newly discovered HRegionLocation into the cache.
*/
private void cacheLocation(final byte [] tableName,
final HRegionLocation location) {
byte [] startKey = location.getRegionInfo().getStartKey();
SoftValueSortedMap<byte [], HRegionLocation> tableLocations =
getTableLocations(tableName);
if (tableLocations.put(startKey, location) == null) {
LOG.debug("Cached location for " +
location.getRegionInfo().getRegionNameAsString() +
" is " + location.getServerAddress());
}
}
public HRegionInterface getHRegionConnection(
HServerAddress regionServer, boolean getMaster)
throws IOException {
if (getMaster) {
getMaster();
}
HRegionInterface server;
String rsName = regionServer.toString();
// See if we already have a connection (common case)
server = this.servers.get(rsName);
if (server == null) {
// create a unique lock for this RS (if necessary)
this.connectionLock.putIfAbsent(rsName, rsName);
// get the RS lock
synchronized (this.connectionLock.get(rsName)) {
// do one more lookup in case we were stalled above
server = this.servers.get(rsName);
if (server == null) {
try {
// definitely a cache miss. establish an RPC for this RS
server = (HRegionInterface) HBaseRPC.waitForProxy(
serverInterfaceClass, HBaseRPCProtocolVersion.versionID,
regionServer.getInetSocketAddress(), this.conf,
this.maxRPCAttempts, this.rpcTimeout, this.rpcTimeout);
this.servers.put(rsName, server);
} catch (RemoteException e) {
LOG.warn("RemoteException connecting to RS", e);
// Throw what the RemoteException was carrying.
throw RemoteExceptionHandler.decodeRemoteException(e);
}
}
}
}
return server;
}
public HRegionInterface getHRegionConnection(
HServerAddress regionServer)
throws IOException {
return getHRegionConnection(regionServer, false);
}
/**
* Get the ZooKeeper instance for this TableServers instance.
*
* If ZK has not been initialized yet, this will connect to ZK.
* @returns zookeeper reference
* @throws ZooKeeperConnectionException if there's a problem connecting to zk
*/
public synchronized ZooKeeperWatcher getZooKeeperWatcher()
throws ZooKeeperConnectionException {
if(zooKeeper == null) {
try {
this.zooKeeper = new ZooKeeperWatcher(conf, "hconnection", this);
} catch(ZooKeeperConnectionException zce) {
throw zce;
} catch (IOException e) {
throw new ZooKeeperConnectionException("An error is preventing" +
" HBase from connecting to ZooKeeper", e);
}
}
return zooKeeper;
}
public <T> T getRegionServerWithRetries(ServerCallable<T> callable)
throws IOException, RuntimeException {
List<Throwable> exceptions = new ArrayList<Throwable>();
for(int tries = 0; tries < numRetries; tries++) {
try {
callable.instantiateServer(tries != 0);
callable.beforeCall();
return callable.call();
} catch (Throwable t) {
callable.shouldRetry(t);
t = translateException(t);
exceptions.add(t);
if (tries == numRetries - 1) {
throw new RetriesExhaustedException(callable.getServerName(),
callable.getRegionName(), callable.getRow(), tries, exceptions);
}
} finally {
callable.afterCall();
}
try {
Thread.sleep(getPauseTime(tries));
} catch (InterruptedException e) {
Thread.currentThread().interrupt();
throw new IOException("Giving up trying to get region server: thread is interrupted.");
}
}
return null;
}
public <T> T getRegionServerWithoutRetries(ServerCallable<T> callable)
throws IOException, RuntimeException {
try {
callable.instantiateServer(false);
return callable.call();
} catch (Throwable t) {
Throwable t2 = translateException(t);
if (t2 instanceof IOException) {
throw (IOException)t2;
} else {
throw new RuntimeException(t2);
}
}
}
private <R> Callable<MultiResponse> createCallable(final HServerAddress address,
final MultiAction multi, final byte [] tableName) {
final HConnection connection = this;
return new Callable<MultiResponse>() {
public MultiResponse call() throws IOException {
return getRegionServerWithoutRetries(
new ServerCallable<MultiResponse>(connection, tableName, null) {
public MultiResponse call() throws IOException {
return server.multi(multi);
}
@Override
public void instantiateServer(boolean reload) throws IOException {
server = connection.getHRegionConnection(address);
}
}
);
}
};
}
public void processBatch(List<Row> list,
final byte[] tableName,
ExecutorService pool,
Object[] results) throws IOException, InterruptedException {
// results must be the same size as list
if (results.length != list.size()) {
throw new IllegalArgumentException("argument results must be the same size as argument list");
}
if (list.size() == 0) {
return;
}
// Keep track of the most recent servers for any given item for better
// exceptional reporting.
HServerAddress [] lastServers = new HServerAddress[results.length];
List<Row> workingList = new ArrayList<Row>(list);
boolean retry = true;
Throwable singleRowCause = null;
for (int tries = 0; tries < numRetries && retry; ++tries) {
// sleep first, if this is a retry
if (tries >= 1) {
long sleepTime = getPauseTime(tries);
LOG.debug("Retry " +tries+ ", sleep for " +sleepTime+ "ms!");
Thread.sleep(sleepTime);
}
// step 1: break up into regionserver-sized chunks and build the data structs
Map<HServerAddress, MultiAction> actionsByServer = new HashMap<HServerAddress, MultiAction>();
for (int i = 0; i < workingList.size(); i++) {
Row row = workingList.get(i);
if (row != null) {
HRegionLocation loc = locateRegion(tableName, row.getRow(), true);
HServerAddress address = loc.getServerAddress();
byte[] regionName = loc.getRegionInfo().getRegionName();
MultiAction actions = actionsByServer.get(address);
if (actions == null) {
actions = new MultiAction();
actionsByServer.put(address, actions);
}
Action action = new Action(regionName, row, i);
lastServers[i] = address;
actions.add(regionName, action);
}
}
// step 2: make the requests
Map<HServerAddress,Future<MultiResponse>> futures =
new HashMap<HServerAddress, Future<MultiResponse>>(actionsByServer.size());
for (Entry<HServerAddress, MultiAction> e : actionsByServer.entrySet()) {
futures.put(e.getKey(), pool.submit(createCallable(e.getKey(), e.getValue(), tableName)));
}
// step 3: collect the failures and successes and prepare for retry
for (Entry<HServerAddress, Future<MultiResponse>> responsePerServer : futures.entrySet()) {
HServerAddress address = responsePerServer.getKey();
try {
Future<MultiResponse> future = responsePerServer.getValue();
MultiResponse resp = future.get();
if (resp == null) {
// Entire server failed
LOG.debug("Failed all for server: " + address + ", removing from cache");
continue;
}
for (Entry<byte[], List<Pair<Integer,Object>>> e : resp.getResults().entrySet()) {
byte[] regionName = e.getKey();
List<Pair<Integer, Object>> regionResults = e.getValue();
for (Pair<Integer, Object> regionResult : regionResults) {
if (regionResult == null) {
// if the first/only record is 'null' the entire region failed.
LOG.debug("Failures for region: " +
Bytes.toStringBinary(regionName) +
", removing from cache");
} else {
// Result might be an Exception, including DNRIOE
results[regionResult.getFirst()] = regionResult.getSecond();
}
}
}
} catch (ExecutionException e) {
LOG.debug("Failed all from " + address, e);
}
}
// step 4: identify failures and prep for a retry (if applicable).
// Find failures (i.e. null Result), and add them to the workingList (in
// order), so they can be retried.
retry = false;
workingList.clear();
for (int i = 0; i < results.length; i++) {
// if null (fail) or instanceof Throwable && not instanceof DNRIOE
// then retry that row. else dont.
if (results[i] == null ||
(results[i] instanceof Throwable &&
!(results[i] instanceof DoNotRetryIOException))) {
retry = true;
Row row = list.get(i);
workingList.add(row);
deleteCachedLocation(tableName, row.getRow());
} else {
// add null to workingList, so the order remains consistent with the original list argument.
workingList.add(null);
}
}
}
if (retry) {
// Simple little check for 1 item failures.
if (singleRowCause != null) {
throw new IOException(singleRowCause);
}
}
List<Throwable> exceptions = new ArrayList<Throwable>();
List<Row> actions = new ArrayList<Row>();
List<HServerAddress> addresses = new ArrayList<HServerAddress>();
for (int i = 0 ; i < results.length; i++) {
if (results[i] == null || results[i] instanceof Throwable) {
exceptions.add((Throwable)results[i]);
actions.add(list.get(i));
addresses.add(lastServers[i]);
}
}
if (!exceptions.isEmpty()) {
throw new RetriesExhaustedWithDetailsException(exceptions,
actions,
addresses);
}
}
/**
* @deprecated Use HConnectionManager::processBatch instead.
*/
public void processBatchOfPuts(List<Put> list,
final byte[] tableName,
ExecutorService pool) throws IOException {
Object[] results = new Object[list.size()];
try {
processBatch((List) list, tableName, pool, results);
} catch (InterruptedException e) {
throw new IOException(e);
} finally {
// mutate list so that it is empty for complete success, or contains only failed records
// results are returned in the same order as the requests in list
// walk the list backwards, so we can remove from list without impacting the indexes of earlier members
for (int i = results.length - 1; i>=0; i--) {
if (results[i] instanceof Result) {
// successful Puts are removed from the list here.
list.remove(i);
}
}
}
}
private Throwable translateException(Throwable t) throws IOException {
if (t instanceof UndeclaredThrowableException) {
t = t.getCause();
}
if (t instanceof RemoteException) {
t = RemoteExceptionHandler.decodeRemoteException((RemoteException)t);
}
if (t instanceof DoNotRetryIOException) {
throw (DoNotRetryIOException)t;
}
return t;
}
/*
* Return the number of cached region for a table. It will only be called
* from a unit test.
*/
int getNumberOfCachedRegionLocations(final byte[] tableName) {
Integer key = Bytes.mapKey(tableName);
synchronized (this.cachedRegionLocations) {
SoftValueSortedMap<byte[], HRegionLocation> tableLocs =
this.cachedRegionLocations.get(key);
if (tableLocs == null) {
return 0;
}
return tableLocs.values().size();
}
}
/**
* Check the region cache to see whether a region is cached yet or not.
* Called by unit tests.
* @param tableName tableName
* @param row row
* @return Region cached or not.
*/
boolean isRegionCached(final byte[] tableName, final byte[] row) {
HRegionLocation location = getCachedLocation(tableName, row);
return location != null;
}
public void setRegionCachePrefetch(final byte[] tableName,
final boolean enable) {
if (!enable) {
regionCachePrefetchDisabledTables.add(Bytes.mapKey(tableName));
}
else {
regionCachePrefetchDisabledTables.remove(Bytes.mapKey(tableName));
}
}
public boolean getRegionCachePrefetch(final byte[] tableName) {
return !regionCachePrefetchDisabledTables.contains(Bytes.mapKey(tableName));
}
public void prewarmRegionCache(final byte[] tableName,
final Map<HRegionInfo, HServerAddress> regions) {
for (Map.Entry<HRegionInfo, HServerAddress> e : regions.entrySet()) {
cacheLocation(tableName,
new HRegionLocation(e.getKey(), e.getValue()));
}
}
@Override
public void abort(final String msg, Throwable t) {
if (t instanceof KeeperException.SessionExpiredException) {
try {
LOG.info("This client just lost it's session with ZooKeeper, trying" +
" to reconnect.");
resetZooKeeperTrackers();
LOG.info("Reconnected successfully. This disconnect could have been" +
" caused by a network partition or a long-running GC pause," +
" either way it's recommended that you verify your environment.");
return;
} catch (ZooKeeperConnectionException e) {
LOG.error("Could not reconnect to ZooKeeper after session" +
" expiration, aborting");
t = e;
}
}
if (t != null) LOG.fatal(msg, t);
else LOG.fatal(msg);
this.closed = true;
}
public void stopProxyOnClose(boolean stopProxy) {
this.stopProxy = stopProxy;
}
/**
* Increment this client's reference count.
*/
void incCount() {
++refCount;
}
/**
* Decrement this client's reference count.
*/
void decCount() {
if (refCount > 0) {
--refCount;
}
}
/**
* Return if this client has no reference
*
* @return true if this client has no reference; false otherwise
*/
boolean isZeroReference() {
return refCount == 0;
}
void close(boolean stopProxy) {
if (this.closed) {
return;
}
if (master != null) {
if (stopProxy) {
HBaseRPC.stopProxy(master);
}
master = null;
masterChecked = false;
}
if (stopProxy) {
for (HRegionInterface i : servers.values()) {
HBaseRPC.stopProxy(i);
}
}
this.servers.clear();
if (this.zooKeeper != null) {
LOG.info("Closed zookeeper sessionid=0x"
+ Long.toHexString(this.zooKeeper.getZooKeeper().getSessionId()));
this.zooKeeper.close();
this.zooKeeper = null;
}
this.closed = true;
}
public void close() {
HConnectionManager.deleteConnection(this, stopProxy);
LOG.debug("The connection to " + this.zooKeeper + " has been closed.");
}
/**
* Close the connection for good, regardless of what the current value of
* {@link #refCount} is. Ideally, {@link refCount} should be zero at this
* point, which would be the case if all of its consumers close the
* connection. However, on the off chance that someone is unable to close
* the connection, perhaps because it bailed out prematurely, the method
* below will ensure that this {@link Connection} instance is cleaned up.
* Caveat: The JVM may take an unknown amount of time to call finalize on an
* unreachable object, so our hope is that every consumer cleans up after
* itself, like any good citizen.
*/
@Override
protected void finalize() throws Throwable {
// Pretend as if we are about to release the last remaining reference
refCount = 1;
close();
LOG.debug("The connection to " + this.zooKeeper
+ " was closed by the finalize method.");
}
}
}
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