/**
* 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;
import java.io.IOException;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.HashSet;
import java.util.List;
import java.util.Map;
import java.util.Set;
import java.util.TreeMap;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.classification.InterfaceAudience;
import org.apache.hadoop.hbase.HRegionInfo;
import org.apache.hadoop.hbase.RegionTransition;
import org.apache.hadoop.hbase.Server;
import org.apache.hadoop.hbase.ServerLoad;
import org.apache.hadoop.hbase.ServerName;
import org.apache.hadoop.hbase.catalog.MetaReader;
import org.apache.hadoop.hbase.master.RegionState.State;
import org.apache.hadoop.hbase.util.Bytes;
import org.apache.hadoop.hbase.util.Pair;
/**
* Region state accountant. It holds the states of all regions in the memory.
* In normal scenario, it should match the meta table and the true region states.
*
* This map is used by AssignmentManager to track region states.
*/
@InterfaceAudience.Private
public class RegionStates {
private static final Log LOG = LogFactory.getLog(RegionStates.class);
/**
* Regions currently in transition.
*/
final HashMap<String, RegionState> regionsInTransition;
/**
* Region encoded name to state map.
* All the regions should be in this map.
*/
private final Map<String, RegionState> regionStates;
/**
* Server to regions assignment map.
* Contains the set of regions currently assigned to a given server.
*/
private final Map<ServerName, Set<HRegionInfo>> serverHoldings;
/**
* Region to server assignment map.
* Contains the server a given region is currently assigned to.
*/
private final TreeMap<HRegionInfo, ServerName> regionAssignments;
private final ServerManager serverManager;
private final Server server;
RegionStates(final Server master, final ServerManager serverManager) {
regionStates = new HashMap<String, RegionState>();
regionsInTransition = new HashMap<String, RegionState>();
serverHoldings = new HashMap<ServerName, Set<HRegionInfo>>();
regionAssignments = new TreeMap<HRegionInfo, ServerName>();
this.serverManager = serverManager;
this.server = master;
}
/**
* @return an unmodifiable the region assignment map
*/
@SuppressWarnings("unchecked")
public synchronized Map<HRegionInfo, ServerName> getRegionAssignments() {
return (Map<HRegionInfo, ServerName>)regionAssignments.clone();
}
public synchronized ServerName getRegionServerOfRegion(HRegionInfo hri) {
return regionAssignments.get(hri);
}
/**
* Get regions in transition and their states
*/
@SuppressWarnings("unchecked")
public synchronized Map<String, RegionState> getRegionsInTransition() {
return (Map<String, RegionState>)regionsInTransition.clone();
}
/**
* @return True if specified region in transition.
*/
public synchronized boolean isRegionInTransition(final HRegionInfo hri) {
return regionsInTransition.containsKey(hri.getEncodedName());
}
/**
* @return True if specified region in transition.
*/
public synchronized boolean isRegionInTransition(final String regionName) {
return regionsInTransition.containsKey(regionName);
}
/**
* @return True if any region in transition.
*/
public synchronized boolean isRegionsInTransition() {
return !regionsInTransition.isEmpty();
}
/**
* @return True if specified region assigned.
*/
public synchronized boolean isRegionAssigned(final HRegionInfo hri) {
return regionAssignments.containsKey(hri);
}
/**
* @return the server the specified region assigned to; null if not assigned.
*/
public synchronized ServerName getAssignedServer(final HRegionInfo hri) {
return regionAssignments.get(hri);
}
/**
* Wait for the state map to be updated by assignment manager.
*/
public synchronized void waitForUpdate(
final long timeout) throws InterruptedException {
this.wait(timeout);
}
/**
* Get region transition state
*/
public synchronized RegionState
getRegionTransitionState(final HRegionInfo hri) {
return regionsInTransition.get(hri.getEncodedName());
}
/**
* Get region transition state
*/
public synchronized RegionState
getRegionTransitionState(final String regionName) {
return regionsInTransition.get(regionName);
}
/**
* Add a list of regions to RegionStates. The initial state is OFFLINE.
* If any region is already in RegionStates, that region will be skipped.
*/
public synchronized void createRegionStates(
final List<HRegionInfo> hris) {
for (HRegionInfo hri: hris) {
createRegionState(hri);
}
}
/**
* Add a region to RegionStates. The initial state is OFFLINE.
* If it is already in RegionStates, this call has no effect,
* and the original state is returned.
*/
public synchronized RegionState createRegionState(final HRegionInfo hri) {
String regionName = hri.getEncodedName();
RegionState regionState = regionStates.get(regionName);
if (regionState != null) {
LOG.warn("Tried to create a state of a region already in RegionStates "
+ hri + ", used existing state: " + regionState
+ ", ignored new state: state=OFFLINE, server=null");
} else {
regionState = new RegionState(hri, State.OFFLINE);
regionStates.put(regionName, regionState);
}
return regionState;
}
/**
* Update a region state. If it is not splitting,
* it will be put in transition if not already there.
*/
public synchronized RegionState updateRegionState(
final HRegionInfo hri, final State state) {
RegionState regionState = regionStates.get(hri.getEncodedName());
ServerName serverName = (regionState == null || state == State.CLOSED
|| state == State.OFFLINE) ? null : regionState.getServerName();
return updateRegionState(hri, state, serverName);
}
/**
* Update a region state. If it is not splitting,
* it will be put in transition if not already there.
*
* If we can't find the region info based on the region name in
* the transition, log a warning and return null.
*/
public synchronized RegionState updateRegionState(
final RegionTransition transition, final State state) {
byte[] regionName = transition.getRegionName();
HRegionInfo regionInfo = getRegionInfo(regionName);
if (regionInfo == null) {
String prettyRegionName = HRegionInfo.prettyPrint(
HRegionInfo.encodeRegionName(regionName));
LOG.warn("Failed to find region " + prettyRegionName
+ " in updating its state to " + state
+ " based on region transition " + transition);
return null;
}
return updateRegionState(regionInfo, state,
transition.getServerName());
}
/**
* Update a region state. If it is not splitting,
* it will be put in transition if not already there.
*/
public synchronized RegionState updateRegionState(
final HRegionInfo hri, final State state, final ServerName serverName) {
ServerName newServerName = serverName;
if (serverName != null &&
(state == State.CLOSED || state == State.OFFLINE)) {
LOG.warn("Closed region " + hri + " still on "
+ serverName + "? Ignored, reset it to null");
newServerName = null;
}
String regionName = hri.getEncodedName();
RegionState regionState = new RegionState(
hri, state, System.currentTimeMillis(), newServerName);
RegionState oldState = regionStates.put(regionName, regionState);
LOG.info("Region " + hri + " transitioned from " + oldState + " to " + regionState);
if (state != State.SPLITTING && (newServerName != null
|| (state != State.PENDING_CLOSE && state != State.CLOSING))) {
regionsInTransition.put(regionName, regionState);
}
// notify the change
this.notifyAll();
return regionState;
}
/**
* A region is online, won't be in transition any more.
* We can't confirm it is really online on specified region server
* because it hasn't been put in region server's online region list yet.
*/
public synchronized void regionOnline(
final HRegionInfo hri, final ServerName serverName) {
String regionName = hri.getEncodedName();
RegionState oldState = regionStates.get(regionName);
if (oldState == null) {
LOG.warn("Online a region not in RegionStates: " + hri);
} else {
State state = oldState.getState();
ServerName sn = oldState.getServerName();
if (state != State.OPEN || sn == null || !sn.equals(serverName)) {
LOG.debug("Online a region with current state=" + state + ", expected state=OPEN"
+ ", assigned to server: " + sn + " expected " + serverName);
}
}
updateRegionState(hri, State.OPEN, serverName);
regionsInTransition.remove(regionName);
ServerName oldServerName = regionAssignments.put(hri, serverName);
if (!serverName.equals(oldServerName)) {
LOG.info("Onlined region " + hri + " on " + serverName);
Set<HRegionInfo> regions = serverHoldings.get(serverName);
if (regions == null) {
regions = new HashSet<HRegionInfo>();
serverHoldings.put(serverName, regions);
}
regions.add(hri);
if (oldServerName != null) {
LOG.info("Offlined region " + hri + " from " + oldServerName);
serverHoldings.get(oldServerName).remove(hri);
}
}
}
/**
* A region is offline, won't be in transition any more.
*/
public synchronized void regionOffline(final HRegionInfo hri) {
String regionName = hri.getEncodedName();
RegionState oldState = regionStates.get(regionName);
if (oldState == null) {
LOG.warn("Offline a region not in RegionStates: " + hri);
} else {
State state = oldState.getState();
ServerName sn = oldState.getServerName();
if (state != State.OFFLINE || sn != null) {
LOG.debug("Online a region with current state=" + state + ", expected state=OFFLINE"
+ ", assigned to server: " + sn + ", expected null");
}
}
updateRegionState(hri, State.OFFLINE);
regionsInTransition.remove(regionName);
ServerName oldServerName = regionAssignments.remove(hri);
if (oldServerName != null) {
LOG.info("Offlined region " + hri + " from " + oldServerName);
serverHoldings.get(oldServerName).remove(hri);
}
}
/**
* A server is offline, all regions on it are dead.
*/
public synchronized List<RegionState> serverOffline(final ServerName sn) {
// Clean up this server from map of servers to regions, and remove all regions
// of this server from online map of regions.
List<RegionState> rits = new ArrayList<RegionState>();
Set<HRegionInfo> assignedRegions = serverHoldings.get(sn);
if (assignedRegions == null) {
assignedRegions = new HashSet<HRegionInfo>();
}
for (HRegionInfo region : assignedRegions) {
regionAssignments.remove(region);
}
// See if any of the regions that were online on this server were in RIT
// If they are, normal timeouts will deal with them appropriately so
// let's skip a manual re-assignment.
for (RegionState state : regionsInTransition.values()) {
if (assignedRegions.contains(state.getRegion())) {
rits.add(state);
} else if (sn.equals(state.getServerName())) {
// Region is in transition on this region server, and this
// region is not open on this server. So the region must be
// moving to this server from another one (i.e. opening or
// pending open on this server, was open on another one
if (state.isPendingOpen() || state.isOpening()) {
state.setTimestamp(0); // timeout it, let timeout monitor reassign
} else {
LOG.warn("THIS SHOULD NOT HAPPEN: unexpected state "
+ state + " of region in transition on server " + sn);
}
}
}
assignedRegions.clear();
this.notifyAll();
return rits;
}
/**
* Gets the online regions of the specified table.
* This method looks at the in-memory state. It does not go to <code>.META.</code>.
* Only returns <em>online</em> regions. If a region on this table has been
* closed during a disable, etc., it will be included in the returned list.
* So, the returned list may not necessarily be ALL regions in this table, its
* all the ONLINE regions in the table.
* @param tableName
* @return Online regions from <code>tableName</code>
*/
public synchronized List<HRegionInfo> getRegionsOfTable(byte[] tableName) {
List<HRegionInfo> tableRegions = new ArrayList<HRegionInfo>();
// boundary needs to have table's name but regionID 0 so that it is sorted
// before all table's regions.
HRegionInfo boundary = new HRegionInfo(tableName, null, null, false, 0L);
for (HRegionInfo hri: regionAssignments.tailMap(boundary).keySet()) {
if(!Bytes.equals(hri.getTableName(), tableName)) break;
tableRegions.add(hri);
}
return tableRegions;
}
/**
* Wait on region to clear regions-in-transition.
* <p>
* If the region isn't in transition, returns immediately. Otherwise, method
* blocks until the region is out of transition.
*/
public synchronized void waitOnRegionToClearRegionsInTransition(
final HRegionInfo hri) throws InterruptedException {
if (!isRegionInTransition(hri)) return;
while(!server.isStopped() && isRegionInTransition(hri)) {
RegionState rs = getRegionState(hri);
LOG.info("Waiting on " + rs + " to clear regions-in-transition");
waitForUpdate(100);
}
if (server.isStopped()) {
LOG.info("Giving up wait on region in " +
"transition because stoppable.isStopped is set");
}
}
/**
* Waits until the specified region has completed assignment.
* <p>
* If the region is already assigned, returns immediately. Otherwise, method
* blocks until the region is assigned.
*/
public synchronized void waitForAssignment(
final HRegionInfo hri) throws InterruptedException {
if (!isRegionAssigned(hri)) return;
while(!server.isStopped() && !isRegionAssigned(hri)) {
RegionState rs = getRegionState(hri);
LOG.info("Waiting on " + rs + " to be assigned");
waitForUpdate(100);
}
if (server.isStopped()) {
LOG.info("Giving up wait on region " +
"assignment because stoppable.isStopped is set");
}
}
/**
* Compute the average load across all region servers.
* Currently, this uses a very naive computation - just uses the number of
* regions being served, ignoring stats about number of requests.
* @return the average load
*/
protected synchronized double getAverageLoad() {
int numServers = 0, totalLoad = 0;
for (Map.Entry<ServerName, Set<HRegionInfo>> e: serverHoldings.entrySet()) {
Set<HRegionInfo> regions = e.getValue();
ServerName serverName = e.getKey();
int regionCount = regions.size();
if (regionCount > 0 || serverManager.isServerOnline(serverName)) {
totalLoad += regionCount;
numServers++;
}
}
return numServers == 0 ? 0.0 :
(double)totalLoad / (double)numServers;
}
/**
* This is an EXPENSIVE clone. Cloning though is the safest thing to do.
* Can't let out original since it can change and at least the load balancer
* wants to iterate this exported list. We need to synchronize on regions
* since all access to this.servers is under a lock on this.regions.
*
* @return A clone of current assignments by table.
*/
protected Map<String, Map<ServerName, List<HRegionInfo>>> getAssignmentsByTable() {
Map<String, Map<ServerName, List<HRegionInfo>>> result =
new HashMap<String, Map<ServerName,List<HRegionInfo>>>();
synchronized (this) {
if (!server.getConfiguration().getBoolean("hbase.master.loadbalance.bytable", false)) {
Map<ServerName, List<HRegionInfo>> svrToRegions =
new HashMap<ServerName, List<HRegionInfo>>(serverHoldings.size());
for (Map.Entry<ServerName, Set<HRegionInfo>> e: serverHoldings.entrySet()) {
svrToRegions.put(e.getKey(), new ArrayList<HRegionInfo>(e.getValue()));
}
result.put("ensemble", svrToRegions);
} else {
for (Map.Entry<ServerName, Set<HRegionInfo>> e: serverHoldings.entrySet()) {
for (HRegionInfo hri: e.getValue()) {
if (hri.isMetaRegion() || hri.isRootRegion()) continue;
String tablename = hri.getTableNameAsString();
Map<ServerName, List<HRegionInfo>> svrToRegions = result.get(tablename);
if (svrToRegions == null) {
svrToRegions = new HashMap<ServerName, List<HRegionInfo>>(serverHoldings.size());
result.put(tablename, svrToRegions);
}
List<HRegionInfo> regions = svrToRegions.get(e.getKey());
if (regions == null) {
regions = new ArrayList<HRegionInfo>();
svrToRegions.put(e.getKey(), regions);
}
regions.add(hri);
}
}
}
}
Map<ServerName, ServerLoad>
onlineSvrs = serverManager.getOnlineServers();
// Take care of servers w/o assignments.
for (Map<ServerName, List<HRegionInfo>> map: result.values()) {
for (ServerName svr: onlineSvrs.keySet()) {
if (!map.containsKey(svr)) {
map.put(svr, new ArrayList<HRegionInfo>());
}
}
}
return result;
}
protected synchronized RegionState getRegionState(final HRegionInfo hri) {
return regionStates.get(hri.getEncodedName());
}
protected synchronized RegionState getRegionState(final String regionName) {
return regionStates.get(regionName);
}
/**
* Get the HRegionInfo from cache, if not there, from the META table
* @param regionName
* @return HRegionInfo for the region
*/
protected HRegionInfo getRegionInfo(final byte [] regionName) {
String encodedName = HRegionInfo.encodeRegionName(regionName);
RegionState regionState = regionStates.get(encodedName);
if (regionState != null) {
return regionState.getRegion();
}
try {
Pair<HRegionInfo, ServerName> p =
MetaReader.getRegion(server.getCatalogTracker(), regionName);
HRegionInfo hri = p == null ? null : p.getFirst();
if (hri != null) {
createRegionState(hri);
}
return hri;
} catch (IOException e) {
server.abort("Aborting because error occoured while reading " +
Bytes.toStringBinary(regionName) + " from .META.", e);
return null;
}
}
}