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/*
* 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.assignment;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.Comparator;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.SortedSet;
import java.util.TreeSet;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentSkipListMap;
import java.util.concurrent.atomic.AtomicInteger;
import java.util.function.Predicate;
import java.util.stream.Collectors;
import org.apache.hadoop.hbase.HRegionLocation;
import org.apache.hadoop.hbase.ServerName;
import org.apache.hadoop.hbase.TableName;
import org.apache.hadoop.hbase.client.RegionInfo;
import org.apache.hadoop.hbase.client.TableState;
import org.apache.hadoop.hbase.master.RegionState;
import org.apache.hadoop.hbase.master.RegionState.State;
import org.apache.hadoop.hbase.master.TableStateManager;
import org.apache.hadoop.hbase.util.Bytes;
import org.apache.yetus.audience.InterfaceAudience;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
/**
* RegionStates contains a set of Maps that describes the in-memory state of the AM, with the
* regions available in the system, the region in transition, the offline regions and the servers
* holding regions.
*/
@InterfaceAudience.Private
public class RegionStates {
private static final Logger LOG = LoggerFactory.getLogger(RegionStates.class);
// This comparator sorts the RegionStates by time stamp then Region name.
// Comparing by timestamp alone can lead us to discard different RegionStates that happen
// to share a timestamp.
private static class RegionStateStampComparator implements Comparator {
@Override
public int compare(final RegionState l, final RegionState r) {
int stampCmp = Long.compare(l.getStamp(), r.getStamp());
return stampCmp != 0 ? stampCmp : RegionInfo.COMPARATOR.compare(l.getRegion(), r.getRegion());
}
}
public final static RegionStateStampComparator REGION_STATE_STAMP_COMPARATOR =
new RegionStateStampComparator();
// TODO: Replace the ConcurrentSkipListMaps
/**
* RegionName -- i.e. RegionInfo.getRegionName() -- as bytes to {@link RegionStateNode}
*/
private final ConcurrentSkipListMap regionsMap =
new ConcurrentSkipListMap(Bytes.BYTES_COMPARATOR);
private final ConcurrentSkipListMap regionInTransition =
new ConcurrentSkipListMap(RegionInfo.COMPARATOR);
/**
* Regions marked as offline on a read of hbase:meta. Unused or at least, once offlined, regions
* have no means of coming on line again. TODO.
*/
private final ConcurrentSkipListMap regionOffline =
new ConcurrentSkipListMap();
private final ConcurrentSkipListMap regionFailedOpen =
new ConcurrentSkipListMap(Bytes.BYTES_COMPARATOR);
private final ConcurrentHashMap serverMap =
new ConcurrentHashMap();
public RegionStates() {
}
/**
* Called on stop of AssignmentManager.
*/
public void clear() {
regionsMap.clear();
regionInTransition.clear();
regionOffline.clear();
serverMap.clear();
}
public boolean isRegionInRegionStates(final RegionInfo hri) {
return (regionsMap.containsKey(hri.getRegionName()) || regionInTransition.containsKey(hri)
|| regionOffline.containsKey(hri));
}
// ==========================================================================
// RegionStateNode helpers
// ==========================================================================
RegionStateNode createRegionStateNode(RegionInfo regionInfo) {
RegionStateNode newNode = new RegionStateNode(regionInfo, regionInTransition);
RegionStateNode oldNode = regionsMap.putIfAbsent(regionInfo.getRegionName(), newNode);
return oldNode != null ? oldNode : newNode;
}
public RegionStateNode getOrCreateRegionStateNode(RegionInfo regionInfo) {
RegionStateNode node = getRegionStateNodeFromName(regionInfo.getRegionName());
return node != null ? node : createRegionStateNode(regionInfo);
}
RegionStateNode getRegionStateNodeFromName(byte[] regionName) {
return regionsMap.get(regionName);
}
public RegionStateNode getRegionStateNode(RegionInfo regionInfo) {
return getRegionStateNodeFromName(regionInfo.getRegionName());
}
public void deleteRegion(final RegionInfo regionInfo) {
regionsMap.remove(regionInfo.getRegionName());
// See HBASE-20860
// After master restarts, merged regions' RIT state may not be cleaned,
// making sure they are cleaned here
if (regionInTransition.containsKey(regionInfo)) {
regionInTransition.remove(regionInfo);
}
// Remove from the offline regions map too if there.
if (this.regionOffline.containsKey(regionInfo)) {
if (LOG.isTraceEnabled()) LOG.trace("Removing from regionOffline Map: " + regionInfo);
this.regionOffline.remove(regionInfo);
}
}
public void deleteRegions(final List regionInfos) {
regionInfos.forEach(this::deleteRegion);
}
List getTableRegionStateNodes(final TableName tableName) {
final ArrayList regions = new ArrayList();
for (RegionStateNode node : regionsMap.tailMap(tableName.getName()).values()) {
if (!node.getTable().equals(tableName)) break;
regions.add(node);
}
return regions;
}
ArrayList getTableRegionStates(final TableName tableName) {
final ArrayList regions = new ArrayList();
for (RegionStateNode node : regionsMap.tailMap(tableName.getName()).values()) {
if (!node.getTable().equals(tableName)) break;
regions.add(node.toRegionState());
}
return regions;
}
ArrayList getTableRegionsInfo(final TableName tableName) {
final ArrayList regions = new ArrayList();
for (RegionStateNode node : regionsMap.tailMap(tableName.getName()).values()) {
if (!node.getTable().equals(tableName)) break;
regions.add(node.getRegionInfo());
}
return regions;
}
/** Returns A view of region state nodes for all the regions. */
public Collection getRegionStateNodes() {
return Collections.unmodifiableCollection(regionsMap.values());
}
/** Returns A snapshot of region state nodes for all the regions. */
public ArrayList getRegionStates() {
final ArrayList regions = new ArrayList<>(regionsMap.size());
for (RegionStateNode node : regionsMap.values()) {
regions.add(node.toRegionState());
}
return regions;
}
// ==========================================================================
// RegionState helpers
// ==========================================================================
public RegionState getRegionState(final RegionInfo regionInfo) {
RegionStateNode regionStateNode = getRegionStateNode(regionInfo);
return regionStateNode == null ? null : regionStateNode.toRegionState();
}
public RegionState getRegionState(final String encodedRegionName) {
// TODO: Need a map but it is just dispatch merge...
for (RegionStateNode node : regionsMap.values()) {
if (node.getRegionInfo().getEncodedName().equals(encodedRegionName)) {
return node.toRegionState();
}
}
return null;
}
// ============================================================================================
// TODO: helpers
// ============================================================================================
public boolean hasTableRegionStates(final TableName tableName) {
// TODO
return !getTableRegionStates(tableName).isEmpty();
}
/** Returns Return online regions of table; does not include OFFLINE or SPLITTING regions. */
public List getRegionsOfTable(TableName table) {
return getRegionsOfTable(table, regionNode -> !regionNode.isInState(State.OFFLINE, State.SPLIT)
&& !regionNode.getRegionInfo().isSplitParent());
}
private HRegionLocation createRegionForReopen(RegionStateNode node) {
node.lock();
try {
if (!include(node, false)) {
return null;
}
if (node.isInState(State.OPEN)) {
return new HRegionLocation(node.getRegionInfo(), node.getRegionLocation(),
node.getOpenSeqNum());
} else if (node.isInState(State.OPENING)) {
return new HRegionLocation(node.getRegionInfo(), node.getRegionLocation(), -1);
} else {
return null;
}
} finally {
node.unlock();
}
}
/**
* Get the regions to be reopened when modifying a table.
*
* Notice that the {@code openSeqNum} in the returned HRegionLocation is also used to indicate the
* state of this region, positive means the region is in {@link State#OPEN}, -1 means
* {@link State#OPENING}. And for regions in other states we do not need reopen them.
*/
public List getRegionsOfTableForReopen(TableName tableName) {
return getTableRegionStateNodes(tableName).stream().map(this::createRegionForReopen)
.filter(r -> r != null).collect(Collectors.toList());
}
/**
* Check whether the region has been reopened. The meaning of the {@link HRegionLocation} is the
* same with {@link #getRegionsOfTableForReopen(TableName)}.
*
* For a region which is in {@link State#OPEN} before, if the region state is changed or the open
* seq num is changed, we can confirm that it has been reopened.
*
* For a region which is in {@link State#OPENING} before, usually it will be in {@link State#OPEN}
* now and we will schedule a MRP to reopen it. But there are several exceptions:
*
* - The region is in state other than {@link State#OPEN} or {@link State#OPENING}.
* - The location of the region has been changed
*
* Of course the region could still be in {@link State#OPENING} state and still on the same
* server, then here we will still return a {@link HRegionLocation} for it, just like
* {@link #getRegionsOfTableForReopen(TableName)}.
* @param oldLoc the previous state/location of this region
* @return null if the region has been reopened, otherwise a new {@link HRegionLocation} which
* means we still need to reopen the region.
* @see #getRegionsOfTableForReopen(TableName)
*/
public HRegionLocation checkReopened(HRegionLocation oldLoc) {
RegionStateNode node = getRegionStateNode(oldLoc.getRegion());
// HBASE-20921
// if the oldLoc's state node does not exist, that means the region is
// merged or split, no need to check it
if (node == null) {
return null;
}
node.lock();
try {
if (oldLoc.getSeqNum() >= 0) {
// in OPEN state before
if (node.isInState(State.OPEN)) {
if (node.getOpenSeqNum() > oldLoc.getSeqNum()) {
// normal case, the region has been reopened
return null;
} else {
// the open seq num does not change, need to reopen again
return new HRegionLocation(node.getRegionInfo(), node.getRegionLocation(),
node.getOpenSeqNum());
}
} else {
// the state has been changed so we can make sure that the region has been reopened(not
// finished maybe, but not a problem).
return null;
}
} else {
// in OPENING state before
if (!node.isInState(State.OPEN, State.OPENING)) {
// not in OPEN or OPENING state, then we can make sure that the region has been
// reopened(not finished maybe, but not a problem)
return null;
} else {
if (!node.getRegionLocation().equals(oldLoc.getServerName())) {
// the region has been moved, so we can make sure that the region has been reopened.
return null;
}
// normal case, we are still in OPENING state, or the reopen has been opened and the state
// is changed to OPEN.
long openSeqNum = node.isInState(State.OPEN) ? node.getOpenSeqNum() : -1;
return new HRegionLocation(node.getRegionInfo(), node.getRegionLocation(), openSeqNum);
}
}
} finally {
node.unlock();
}
}
/**
* Get the regions for enabling a table.
*
* Here we want the EnableTableProcedure to be more robust and can be used to fix some nasty
* states, so the checks in this method will be a bit strange. In general, a region can only be
* offline when it is split, for merging we will just delete the parent regions, but with HBCK we
* may force update the state of a region to fix some nasty bugs, so in this method we will try to
* bring the offline regions back if it is not split. That's why we only check for split state
* here.
*/
public List getRegionsOfTableForEnabling(TableName table) {
return getRegionsOfTable(table,
regionNode -> !regionNode.isInState(State.SPLIT) && !regionNode.getRegionInfo().isSplit());
}
/**
* Get the regions for deleting a table.
*
* Here we need to return all the regions irrespective of the states in order to archive them all.
* This is because if we don't archive OFFLINE/SPLIT regions and if a snapshot or a cloned table
* references to the regions, we will lose the data of the regions.
*/
public List getRegionsOfTableForDeleting(TableName table) {
return getTableRegionStateNodes(table).stream().map(RegionStateNode::getRegionInfo)
.collect(Collectors.toList());
}
/** Returns Return the regions of the table and filter them. */
private List getRegionsOfTable(TableName table, Predicate filter) {
return getTableRegionStateNodes(table).stream().filter(filter).map(n -> n.getRegionInfo())
.collect(Collectors.toList());
}
/**
* Utility. Whether to include region in list of regions. Default is to weed out split and offline
* regions.
* @return True if we should include the node (do not include if split or offline
* unless offline is set to true.
*/
private boolean include(final RegionStateNode node, final boolean offline) {
if (LOG.isTraceEnabled()) {
LOG.trace("WORKING ON " + node + " " + node.getRegionInfo());
}
final RegionInfo hri = node.getRegionInfo();
if (node.isInState(State.SPLIT) || hri.isSplit()) {
return false;
}
if ((node.isInState(State.OFFLINE) || hri.isOffline()) && !offline) {
return false;
}
return (!hri.isOffline() && !hri.isSplit()) || ((hri.isOffline() || hri.isSplit()) && offline);
}
// ============================================================================================
// Split helpers
// These methods will only be called in ServerCrashProcedure, and at the end of SCP we will remove
// the ServerStateNode by calling removeServer.
// ============================================================================================
private void setServerState(ServerName serverName, ServerState state) {
ServerStateNode serverNode = getOrCreateServer(serverName);
synchronized (serverNode) {
serverNode.setState(state);
}
}
/**
* Call this when we start meta log splitting a crashed Server.
* @see #metaLogSplit(ServerName)
*/
public void metaLogSplitting(ServerName serverName) {
setServerState(serverName, ServerState.SPLITTING_META);
}
/**
* Called after we've split the meta logs on a crashed Server.
* @see #metaLogSplitting(ServerName)
*/
public void metaLogSplit(ServerName serverName) {
setServerState(serverName, ServerState.SPLITTING_META_DONE);
}
/**
* Call this when we start log splitting for a crashed Server.
* @see #logSplit(ServerName)
*/
public void logSplitting(final ServerName serverName) {
setServerState(serverName, ServerState.SPLITTING);
}
/**
* Called after we've split all logs on a crashed Server.
* @see #logSplitting(ServerName)
*/
public void logSplit(final ServerName serverName) {
setServerState(serverName, ServerState.OFFLINE);
}
public void updateRegionState(RegionInfo regionInfo, State state) {
RegionStateNode regionNode = getOrCreateRegionStateNode(regionInfo);
regionNode.lock();
try {
regionNode.setState(state);
} finally {
regionNode.unlock();
}
}
// ============================================================================================
// TODO:
// ============================================================================================
public List getAssignedRegions() {
final List result = new ArrayList();
for (RegionStateNode node : regionsMap.values()) {
if (!node.isInTransition()) {
result.add(node.getRegionInfo());
}
}
return result;
}
public boolean isRegionInState(RegionInfo regionInfo, State... state) {
RegionStateNode regionNode = getRegionStateNode(regionInfo);
if (regionNode != null) {
regionNode.lock();
try {
return regionNode.isInState(state);
} finally {
regionNode.unlock();
}
}
return false;
}
public boolean isRegionOnline(final RegionInfo regionInfo) {
return isRegionInState(regionInfo, State.OPEN);
}
/** Returns True if region is offline (In OFFLINE or CLOSED state). */
public boolean isRegionOffline(final RegionInfo regionInfo) {
return isRegionInState(regionInfo, State.OFFLINE, State.CLOSED);
}
public Map>
getSnapShotOfAssignment(final Collection regions) {
final Map> result = new HashMap>();
if (regions != null) {
for (RegionInfo hri : regions) {
final RegionStateNode node = getRegionStateNode(hri);
if (node == null) {
continue;
}
createSnapshot(node, result);
}
} else {
for (RegionStateNode node : regionsMap.values()) {
if (node == null) {
continue;
}
createSnapshot(node, result);
}
}
return result;
}
private void createSnapshot(RegionStateNode node, Map> result) {
final ServerName serverName = node.getRegionLocation();
if (serverName == null) {
return;
}
List serverRegions = result.get(serverName);
if (serverRegions == null) {
serverRegions = new ArrayList();
result.put(serverName, serverRegions);
}
serverRegions.add(node.getRegionInfo());
}
public Map getRegionAssignments() {
final HashMap assignments = new HashMap();
for (RegionStateNode node : regionsMap.values()) {
assignments.put(node.getRegionInfo(), node.getRegionLocation());
}
return assignments;
}
public Map> getRegionByStateOfTable(TableName tableName) {
final State[] states = State.values();
final Map> tableRegions =
new HashMap>(states.length);
for (int i = 0; i < states.length; ++i) {
tableRegions.put(states[i], new ArrayList());
}
for (RegionStateNode node : regionsMap.values()) {
if (node.getTable().equals(tableName)) {
tableRegions.get(node.getState()).add(node.getRegionInfo());
}
}
return tableRegions;
}
public ServerName getRegionServerOfRegion(RegionInfo regionInfo) {
RegionStateNode regionNode = getRegionStateNode(regionInfo);
if (regionNode != null) {
regionNode.lock();
try {
ServerName server = regionNode.getRegionLocation();
return server != null ? server : regionNode.getLastHost();
} finally {
regionNode.unlock();
}
}
return null;
}
/**
* 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 open or opening assignments.
*/
public Map>>
getAssignmentsForBalancer(TableStateManager tableStateManager, List onlineServers) {
final Map>> result = new HashMap<>();
for (RegionStateNode node : regionsMap.values()) {
// DisableTableProcedure first sets the table state to DISABLED and then force unassigns
// the regions in a loop. The balancer should ignore all regions for tables in DISABLED
// state because even if still currently open we expect them to be offlined very soon.
if (isTableDisabled(tableStateManager, node.getTable())) {
if (LOG.isTraceEnabled()) {
LOG.trace("Ignoring {} because table is disabled", node);
}
continue;
}
// When balancing, we are only interested in OPEN or OPENING regions. These can be
// expected to remain online until the next balancer iteration or unless the balancer
// decides to move it. Regions in other states are not eligible for balancing, because
// they are closing, splitting, merging, or otherwise already in transition.
if (!node.isInState(State.OPEN, State.OPENING)) {
if (LOG.isTraceEnabled()) {
LOG.trace("Ignoring {} because region is not OPEN or OPENING", node);
}
continue;
}
Map> tableResult =
result.computeIfAbsent(node.getTable(), t -> new HashMap<>());
final ServerName serverName = node.getRegionLocation();
// A region in ONLINE or OPENING state should have a location.
if (serverName == null) {
LOG.warn("Skipping, no server for {}", node);
continue;
}
List serverResult =
tableResult.computeIfAbsent(serverName, s -> new ArrayList<>());
serverResult.add(node.getRegionInfo());
}
// Add online servers with no assignment for the table.
for (Map> table : result.values()) {
for (ServerName serverName : onlineServers) {
table.computeIfAbsent(serverName, key -> new ArrayList<>());
}
}
return result;
}
private boolean isTableDisabled(final TableStateManager tableStateManager,
final TableName tableName) {
return tableStateManager.isTableState(tableName, TableState.State.DISABLED,
TableState.State.DISABLING);
}
// ==========================================================================
// Region in transition helpers
// ==========================================================================
public boolean hasRegionsInTransition() {
return !regionInTransition.isEmpty();
}
public boolean isRegionInTransition(final RegionInfo regionInfo) {
final RegionStateNode node = regionInTransition.get(regionInfo);
return node != null ? node.isInTransition() : false;
}
public RegionState getRegionTransitionState(RegionInfo hri) {
RegionStateNode node = regionInTransition.get(hri);
if (node == null) {
return null;
}
node.lock();
try {
return node.isInTransition() ? node.toRegionState() : null;
} finally {
node.unlock();
}
}
public List getRegionsInTransition() {
return new ArrayList(regionInTransition.values());
}
/**
* Get the number of regions in transition.
*/
public int getRegionsInTransitionCount() {
return regionInTransition.size();
}
public List getRegionsStateInTransition() {
final List rit = new ArrayList(regionInTransition.size());
for (RegionStateNode node : regionInTransition.values()) {
rit.add(node.toRegionState());
}
return rit;
}
public SortedSet getRegionsInTransitionOrderedByTimestamp() {
final SortedSet rit = new TreeSet(REGION_STATE_STAMP_COMPARATOR);
for (RegionStateNode node : regionInTransition.values()) {
rit.add(node.toRegionState());
}
return rit;
}
// ==========================================================================
// Region offline helpers
// ==========================================================================
// TODO: Populated when we read meta but regions never make it out of here.
public void addToOfflineRegions(final RegionStateNode regionNode) {
LOG.info("Added to offline, CURRENTLY NEVER CLEARED!!! " + regionNode);
regionOffline.put(regionNode.getRegionInfo(), regionNode);
}
// TODO: Unused.
public void removeFromOfflineRegions(final RegionInfo regionInfo) {
regionOffline.remove(regionInfo);
}
// ==========================================================================
// Region FAIL_OPEN helpers
// ==========================================================================
public static final class RegionFailedOpen {
private final RegionStateNode regionNode;
private volatile Exception exception = null;
private AtomicInteger retries = new AtomicInteger();
public RegionFailedOpen(final RegionStateNode regionNode) {
this.regionNode = regionNode;
}
public RegionStateNode getRegionStateNode() {
return regionNode;
}
public RegionInfo getRegionInfo() {
return regionNode.getRegionInfo();
}
public int incrementAndGetRetries() {
return this.retries.incrementAndGet();
}
public int getRetries() {
return retries.get();
}
public void setException(final Exception exception) {
this.exception = exception;
}
public Exception getException() {
return this.exception;
}
}
public RegionFailedOpen addToFailedOpen(final RegionStateNode regionNode) {
final byte[] key = regionNode.getRegionInfo().getRegionName();
RegionFailedOpen node = regionFailedOpen.get(key);
if (node == null) {
RegionFailedOpen newNode = new RegionFailedOpen(regionNode);
RegionFailedOpen oldNode = regionFailedOpen.putIfAbsent(key, newNode);
node = oldNode != null ? oldNode : newNode;
}
return node;
}
public RegionFailedOpen getFailedOpen(final RegionInfo regionInfo) {
return regionFailedOpen.get(regionInfo.getRegionName());
}
public void removeFromFailedOpen(final RegionInfo regionInfo) {
regionFailedOpen.remove(regionInfo.getRegionName());
}
public List getRegionFailedOpen() {
if (regionFailedOpen.isEmpty()) return Collections.emptyList();
ArrayList regions = new ArrayList(regionFailedOpen.size());
for (RegionFailedOpen r : regionFailedOpen.values()) {
regions.add(r.getRegionStateNode().toRegionState());
}
return regions;
}
// ==========================================================================
// Servers
// ==========================================================================
/**
* Be judicious calling this method. Do it on server register ONLY otherwise you could mess up
* online server accounting. TOOD: Review usage and convert to {@link #getServerNode(ServerName)}
* where we can.
*/
public ServerStateNode getOrCreateServer(final ServerName serverName) {
ServerStateNode node = serverMap.get(serverName);
if (node == null) {
node = new ServerStateNode(serverName);
ServerStateNode oldNode = serverMap.putIfAbsent(serverName, node);
node = oldNode != null ? oldNode : node;
}
return node;
}
/**
* Called by SCP at end of successful processing.
*/
public void removeServer(final ServerName serverName) {
serverMap.remove(serverName);
}
/** Returns Pertinent ServerStateNode or NULL if none found (Do not make modifications). */
public ServerStateNode getServerNode(final ServerName serverName) {
return serverMap.get(serverName);
}
public double getAverageLoad() {
int numServers = 0;
int totalLoad = 0;
for (ServerStateNode node : serverMap.values()) {
totalLoad += node.getRegionCount();
numServers++;
}
return numServers == 0 ? 0.0 : (double) totalLoad / (double) numServers;
}
public ServerStateNode addRegionToServer(final RegionStateNode regionNode) {
ServerStateNode serverNode = getOrCreateServer(regionNode.getRegionLocation());
serverNode.addRegion(regionNode);
return serverNode;
}
public ServerStateNode removeRegionFromServer(final ServerName serverName,
final RegionStateNode regionNode) {
ServerStateNode serverNode = getOrCreateServer(serverName);
serverNode.removeRegion(regionNode);
return serverNode;
}
// ==========================================================================
// ToString helpers
// ==========================================================================
public static String regionNamesToString(final Collection regions) {
final StringBuilder sb = new StringBuilder();
final Iterator it = regions.iterator();
sb.append("[");
if (it.hasNext()) {
sb.append(Bytes.toStringBinary(it.next()));
while (it.hasNext()) {
sb.append(", ");
sb.append(Bytes.toStringBinary(it.next()));
}
}
sb.append("]");
return sb.toString();
}
}