| /** |
| * |
| * Licensed to the Apache Software Foundation (ASF) under one |
| * or more contributor license agreements. See the NOTICE file |
| * distributed with this work for additional information |
| * regarding copyright ownership. The ASF licenses this file |
| * to you under the Apache License, Version 2.0 (the |
| * "License"); you may not use this file except in compliance |
| * with the License. You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| |
| package org.apache.hadoop.hbase.master.balancer; |
| |
| import java.io.IOException; |
| import java.util.ArrayList; |
| import java.util.HashMap; |
| import java.util.HashSet; |
| import java.util.List; |
| import java.util.Map; |
| import java.util.Map.Entry; |
| import java.util.Random; |
| import java.util.Set; |
| |
| import org.apache.commons.logging.Log; |
| import org.apache.commons.logging.LogFactory; |
| import org.apache.hadoop.conf.Configuration; |
| import org.apache.hadoop.hbase.HConstants; |
| import org.apache.hadoop.hbase.HRegionInfo; |
| import org.apache.hadoop.hbase.MetaTableAccessor; |
| import org.apache.hadoop.hbase.ServerName; |
| import org.apache.hadoop.hbase.TableName; |
| import org.apache.hadoop.hbase.classification.InterfaceAudience; |
| import org.apache.hadoop.hbase.client.Connection; |
| import org.apache.hadoop.hbase.client.ConnectionFactory; |
| import org.apache.hadoop.hbase.client.Put; |
| import org.apache.hadoop.hbase.client.Table; |
| import org.apache.hadoop.hbase.master.RackManager; |
| import org.apache.hadoop.hbase.protobuf.ProtobufUtil; |
| import org.apache.hadoop.hbase.protobuf.generated.HBaseProtos; |
| import org.apache.hadoop.hbase.protobuf.generated.HBaseProtos.FavoredNodes; |
| import org.apache.hadoop.hbase.util.Bytes; |
| import org.apache.hadoop.hbase.util.EnvironmentEdgeManager; |
| |
| import com.google.protobuf.InvalidProtocolBufferException; |
| |
| /** |
| * Helper class for {@link FavoredNodeLoadBalancer} that has all the intelligence |
| * for racks, meta scans, etc. Instantiated by the {@link FavoredNodeLoadBalancer} |
| * when needed (from within calls like |
| * {@link FavoredNodeLoadBalancer#randomAssignment(HRegionInfo, List)}). |
| * |
| */ |
| @InterfaceAudience.Private |
| public class FavoredNodeAssignmentHelper { |
| private static final Log LOG = LogFactory.getLog(FavoredNodeAssignmentHelper.class); |
| private RackManager rackManager; |
| private Map<String, List<ServerName>> rackToRegionServerMap; |
| private List<String> uniqueRackList; |
| private Map<ServerName, String> regionServerToRackMap; |
| private Random random; |
| private List<ServerName> servers; |
| public static final byte [] FAVOREDNODES_QUALIFIER = Bytes.toBytes("fn"); |
| public final static short FAVORED_NODES_NUM = 3; |
| |
| public FavoredNodeAssignmentHelper(final List<ServerName> servers, Configuration conf) { |
| this(servers, new RackManager(conf)); |
| } |
| |
| public FavoredNodeAssignmentHelper(final List<ServerName> servers, |
| final RackManager rackManager) { |
| this.servers = servers; |
| this.rackManager = rackManager; |
| this.rackToRegionServerMap = new HashMap<String, List<ServerName>>(); |
| this.regionServerToRackMap = new HashMap<ServerName, String>(); |
| this.uniqueRackList = new ArrayList<String>(); |
| this.random = new Random(); |
| } |
| |
| /** |
| * Update meta table with favored nodes info |
| * @param regionToFavoredNodes map of HRegionInfo's to their favored nodes |
| * @param connection connection to be used |
| * @throws IOException |
| */ |
| public static void updateMetaWithFavoredNodesInfo( |
| Map<HRegionInfo, List<ServerName>> regionToFavoredNodes, |
| Connection connection) throws IOException { |
| List<Put> puts = new ArrayList<Put>(); |
| for (Map.Entry<HRegionInfo, List<ServerName>> entry : regionToFavoredNodes.entrySet()) { |
| Put put = makePutFromRegionInfo(entry.getKey(), entry.getValue()); |
| if (put != null) { |
| puts.add(put); |
| } |
| } |
| MetaTableAccessor.putsToMetaTable(connection, puts); |
| LOG.info("Added " + puts.size() + " regions in META"); |
| } |
| |
| /** |
| * Update meta table with favored nodes info |
| * @param regionToFavoredNodes |
| * @param conf |
| * @throws IOException |
| */ |
| public static void updateMetaWithFavoredNodesInfo( |
| Map<HRegionInfo, List<ServerName>> regionToFavoredNodes, |
| Configuration conf) throws IOException { |
| List<Put> puts = new ArrayList<Put>(); |
| for (Map.Entry<HRegionInfo, List<ServerName>> entry : regionToFavoredNodes.entrySet()) { |
| Put put = makePutFromRegionInfo(entry.getKey(), entry.getValue()); |
| if (put != null) { |
| puts.add(put); |
| } |
| } |
| // Write the region assignments to the meta table. |
| // TODO: See above overrides take a Connection rather than a Configuration only the |
| // Connection is a short circuit connection. That is not going to good in all cases, when |
| // master and meta are not colocated. Fix when this favored nodes feature is actually used |
| // someday. |
| try (Connection connection = ConnectionFactory.createConnection(conf)) { |
| try (Table metaTable = connection.getTable(TableName.META_TABLE_NAME)) { |
| metaTable.put(puts); |
| } |
| } |
| LOG.info("Added " + puts.size() + " regions in META"); |
| } |
| |
| /** |
| * Generates and returns a Put containing the region info for the catalog table |
| * and the servers |
| * @param regionInfo |
| * @param favoredNodeList |
| * @return Put object |
| */ |
| static Put makePutFromRegionInfo(HRegionInfo regionInfo, List<ServerName>favoredNodeList) |
| throws IOException { |
| Put put = null; |
| if (favoredNodeList != null) { |
| put = MetaTableAccessor.makePutFromRegionInfo(regionInfo); |
| byte[] favoredNodes = getFavoredNodes(favoredNodeList); |
| put.addImmutable(HConstants.CATALOG_FAMILY, FAVOREDNODES_QUALIFIER, |
| EnvironmentEdgeManager.currentTime(), favoredNodes); |
| LOG.info("Create the region " + regionInfo.getRegionNameAsString() + |
| " with favored nodes " + Bytes.toString(favoredNodes)); |
| } |
| return put; |
| } |
| |
| /** |
| * @param favoredNodes The PB'ed bytes of favored nodes |
| * @return the array of {@link ServerName} for the byte array of favored nodes. |
| * @throws InvalidProtocolBufferException |
| */ |
| public static ServerName[] getFavoredNodesList(byte[] favoredNodes) |
| throws InvalidProtocolBufferException { |
| FavoredNodes f = FavoredNodes.parseFrom(favoredNodes); |
| List<HBaseProtos.ServerName> protoNodes = f.getFavoredNodeList(); |
| ServerName[] servers = new ServerName[protoNodes.size()]; |
| int i = 0; |
| for (HBaseProtos.ServerName node : protoNodes) { |
| servers[i++] = ProtobufUtil.toServerName(node); |
| } |
| return servers; |
| } |
| |
| /** |
| * @param serverAddrList |
| * @return PB'ed bytes of {@link FavoredNodes} generated by the server list. |
| */ |
| public static byte[] getFavoredNodes(List<ServerName> serverAddrList) { |
| FavoredNodes.Builder f = FavoredNodes.newBuilder(); |
| for (ServerName s : serverAddrList) { |
| HBaseProtos.ServerName.Builder b = HBaseProtos.ServerName.newBuilder(); |
| b.setHostName(s.getHostname()); |
| b.setPort(s.getPort()); |
| b.setStartCode(s.getStartcode()); |
| f.addFavoredNode(b.build()); |
| } |
| return f.build().toByteArray(); |
| } |
| |
| // Place the regions round-robin across the racks picking one server from each |
| // rack at a time. Start with a random rack, and a random server from every rack. |
| // If a rack doesn't have enough servers it will go to the next rack and so on. |
| // for choosing a primary. |
| // For example, if 4 racks (r1 .. r4) with 8 servers (s1..s8) each, one possible |
| // placement could be r2:s5, r3:s5, r4:s5, r1:s5, r2:s6, r3:s6.. |
| // If there were fewer servers in one rack, say r3, which had 3 servers, one possible |
| // placement could be r2:s5, <skip-r3>, r4:s5, r1:s5, r2:s6, <skip-r3> ... |
| // The regions should be distributed proportionately to the racksizes |
| void placePrimaryRSAsRoundRobin(Map<ServerName, List<HRegionInfo>> assignmentMap, |
| Map<HRegionInfo, ServerName> primaryRSMap, List<HRegionInfo> regions) { |
| List<String> rackList = new ArrayList<String>(rackToRegionServerMap.size()); |
| rackList.addAll(rackToRegionServerMap.keySet()); |
| int rackIndex = random.nextInt(rackList.size()); |
| int maxRackSize = 0; |
| for (Map.Entry<String,List<ServerName>> r : rackToRegionServerMap.entrySet()) { |
| if (r.getValue().size() > maxRackSize) { |
| maxRackSize = r.getValue().size(); |
| } |
| } |
| int numIterations = 0; |
| int firstServerIndex = random.nextInt(maxRackSize); |
| // Initialize the current processing host index. |
| int serverIndex = firstServerIndex; |
| for (HRegionInfo regionInfo : regions) { |
| List<ServerName> currentServerList; |
| String rackName; |
| while (true) { |
| rackName = rackList.get(rackIndex); |
| numIterations++; |
| // Get the server list for the current rack |
| currentServerList = rackToRegionServerMap.get(rackName); |
| |
| if (serverIndex >= currentServerList.size()) { //not enough machines in this rack |
| if (numIterations % rackList.size() == 0) { |
| if (++serverIndex >= maxRackSize) serverIndex = 0; |
| } |
| if ((++rackIndex) >= rackList.size()) { |
| rackIndex = 0; // reset the rack index to 0 |
| } |
| } else break; |
| } |
| |
| // Get the current process region server |
| ServerName currentServer = currentServerList.get(serverIndex); |
| |
| // Place the current region with the current primary region server |
| primaryRSMap.put(regionInfo, currentServer); |
| List<HRegionInfo> regionsForServer = assignmentMap.get(currentServer); |
| if (regionsForServer == null) { |
| regionsForServer = new ArrayList<HRegionInfo>(); |
| assignmentMap.put(currentServer, regionsForServer); |
| } |
| regionsForServer.add(regionInfo); |
| |
| // Set the next processing index |
| if (numIterations % rackList.size() == 0) { |
| ++serverIndex; |
| } |
| if ((++rackIndex) >= rackList.size()) { |
| rackIndex = 0; // reset the rack index to 0 |
| } |
| } |
| } |
| |
| Map<HRegionInfo, ServerName[]> placeSecondaryAndTertiaryRS( |
| Map<HRegionInfo, ServerName> primaryRSMap) { |
| Map<HRegionInfo, ServerName[]> secondaryAndTertiaryMap = |
| new HashMap<HRegionInfo, ServerName[]>(); |
| for (Map.Entry<HRegionInfo, ServerName> entry : primaryRSMap.entrySet()) { |
| // Get the target region and its primary region server rack |
| HRegionInfo regionInfo = entry.getKey(); |
| ServerName primaryRS = entry.getValue(); |
| try { |
| // Create the secondary and tertiary region server pair object. |
| ServerName[] favoredNodes; |
| // Get the rack for the primary region server |
| String primaryRack = rackManager.getRack(primaryRS); |
| |
| if (getTotalNumberOfRacks() == 1) { |
| favoredNodes = singleRackCase(regionInfo, primaryRS, primaryRack); |
| } else { |
| favoredNodes = multiRackCase(regionInfo, primaryRS, primaryRack); |
| } |
| if (favoredNodes != null) { |
| secondaryAndTertiaryMap.put(regionInfo, favoredNodes); |
| LOG.debug("Place the secondary and tertiary region server for region " |
| + regionInfo.getRegionNameAsString()); |
| } |
| } catch (Exception e) { |
| LOG.warn("Cannot place the favored nodes for region " + |
| regionInfo.getRegionNameAsString() + " because " + e, e); |
| continue; |
| } |
| } |
| return secondaryAndTertiaryMap; |
| } |
| |
| private Map<ServerName, Set<HRegionInfo>> mapRSToPrimaries( |
| Map<HRegionInfo, ServerName> primaryRSMap) { |
| Map<ServerName, Set<HRegionInfo>> primaryServerMap = |
| new HashMap<ServerName, Set<HRegionInfo>>(); |
| for (Entry<HRegionInfo, ServerName> e : primaryRSMap.entrySet()) { |
| Set<HRegionInfo> currentSet = primaryServerMap.get(e.getValue()); |
| if (currentSet == null) { |
| currentSet = new HashSet<HRegionInfo>(); |
| } |
| currentSet.add(e.getKey()); |
| primaryServerMap.put(e.getValue(), currentSet); |
| } |
| return primaryServerMap; |
| } |
| |
| /** |
| * For regions that share the primary, avoid placing the secondary and tertiary |
| * on a same RS. Used for generating new assignments for the |
| * primary/secondary/tertiary RegionServers |
| * @param primaryRSMap |
| * @return the map of regions to the servers the region-files should be hosted on |
| */ |
| public Map<HRegionInfo, ServerName[]> placeSecondaryAndTertiaryWithRestrictions( |
| Map<HRegionInfo, ServerName> primaryRSMap) { |
| Map<ServerName, Set<HRegionInfo>> serverToPrimaries = |
| mapRSToPrimaries(primaryRSMap); |
| Map<HRegionInfo, ServerName[]> secondaryAndTertiaryMap = |
| new HashMap<HRegionInfo, ServerName[]>(); |
| |
| for (Entry<HRegionInfo, ServerName> entry : primaryRSMap.entrySet()) { |
| // Get the target region and its primary region server rack |
| HRegionInfo regionInfo = entry.getKey(); |
| ServerName primaryRS = entry.getValue(); |
| try { |
| // Get the rack for the primary region server |
| String primaryRack = rackManager.getRack(primaryRS); |
| ServerName[] favoredNodes = null; |
| if (getTotalNumberOfRacks() == 1) { |
| // Single rack case: have to pick the secondary and tertiary |
| // from the same rack |
| favoredNodes = singleRackCase(regionInfo, primaryRS, primaryRack); |
| } else { |
| favoredNodes = multiRackCaseWithRestrictions(serverToPrimaries, |
| secondaryAndTertiaryMap, primaryRack, primaryRS, regionInfo); |
| } |
| if (favoredNodes != null) { |
| secondaryAndTertiaryMap.put(regionInfo, favoredNodes); |
| LOG.debug("Place the secondary and tertiary region server for region " |
| + regionInfo.getRegionNameAsString()); |
| } |
| } catch (Exception e) { |
| LOG.warn("Cannot place the favored nodes for region " |
| + regionInfo.getRegionNameAsString() + " because " + e, e); |
| continue; |
| } |
| } |
| return secondaryAndTertiaryMap; |
| } |
| |
| private ServerName[] multiRackCaseWithRestrictions( |
| Map<ServerName, Set<HRegionInfo>> serverToPrimaries, |
| Map<HRegionInfo, ServerName[]> secondaryAndTertiaryMap, |
| String primaryRack, ServerName primaryRS, HRegionInfo regionInfo) throws IOException { |
| // Random to choose the secondary and tertiary region server |
| // from another rack to place the secondary and tertiary |
| // Random to choose one rack except for the current rack |
| Set<String> rackSkipSet = new HashSet<String>(); |
| rackSkipSet.add(primaryRack); |
| String secondaryRack = getOneRandomRack(rackSkipSet); |
| List<ServerName> serverList = getServersFromRack(secondaryRack); |
| Set<ServerName> serverSet = new HashSet<ServerName>(); |
| serverSet.addAll(serverList); |
| ServerName[] favoredNodes; |
| if (serverList.size() >= 2) { |
| // Randomly pick up two servers from this secondary rack |
| // Skip the secondary for the tertiary placement |
| // skip the servers which share the primary already |
| Set<HRegionInfo> primaries = serverToPrimaries.get(primaryRS); |
| Set<ServerName> skipServerSet = new HashSet<ServerName>(); |
| while (true) { |
| ServerName[] secondaryAndTertiary = null; |
| if (primaries.size() > 1) { |
| // check where his tertiary and secondary are |
| for (HRegionInfo primary : primaries) { |
| secondaryAndTertiary = secondaryAndTertiaryMap.get(primary); |
| if (secondaryAndTertiary != null) { |
| if (regionServerToRackMap.get(secondaryAndTertiary[0]).equals(secondaryRack)) { |
| skipServerSet.add(secondaryAndTertiary[0]); |
| } |
| if (regionServerToRackMap.get(secondaryAndTertiary[1]).equals(secondaryRack)) { |
| skipServerSet.add(secondaryAndTertiary[1]); |
| } |
| } |
| } |
| } |
| if (skipServerSet.size() + 2 <= serverSet.size()) |
| break; |
| skipServerSet.clear(); |
| rackSkipSet.add(secondaryRack); |
| // we used all racks |
| if (rackSkipSet.size() == getTotalNumberOfRacks()) { |
| // remove the last two added and break |
| skipServerSet.remove(secondaryAndTertiary[0]); |
| skipServerSet.remove(secondaryAndTertiary[1]); |
| break; |
| } |
| secondaryRack = getOneRandomRack(rackSkipSet); |
| serverList = getServersFromRack(secondaryRack); |
| serverSet = new HashSet<ServerName>(); |
| serverSet.addAll(serverList); |
| } |
| |
| // Place the secondary RS |
| ServerName secondaryRS = getOneRandomServer(secondaryRack, skipServerSet); |
| skipServerSet.add(secondaryRS); |
| // Place the tertiary RS |
| ServerName tertiaryRS = getOneRandomServer(secondaryRack, skipServerSet); |
| |
| if (secondaryRS == null || tertiaryRS == null) { |
| LOG.error("Cannot place the secondary and tertiary" |
| + " region server for region " |
| + regionInfo.getRegionNameAsString()); |
| } |
| // Create the secondary and tertiary pair |
| favoredNodes = new ServerName[2]; |
| favoredNodes[0] = secondaryRS; |
| favoredNodes[1] = tertiaryRS; |
| } else { |
| // Pick the secondary rs from this secondary rack |
| // and pick the tertiary from another random rack |
| favoredNodes = new ServerName[2]; |
| ServerName secondary = getOneRandomServer(secondaryRack); |
| favoredNodes[0] = secondary; |
| |
| // Pick the tertiary |
| if (getTotalNumberOfRacks() == 2) { |
| // Pick the tertiary from the same rack of the primary RS |
| Set<ServerName> serverSkipSet = new HashSet<ServerName>(); |
| serverSkipSet.add(primaryRS); |
| favoredNodes[1] = getOneRandomServer(primaryRack, serverSkipSet); |
| } else { |
| // Pick the tertiary from another rack |
| rackSkipSet.add(secondaryRack); |
| String tertiaryRandomRack = getOneRandomRack(rackSkipSet); |
| favoredNodes[1] = getOneRandomServer(tertiaryRandomRack); |
| } |
| } |
| return favoredNodes; |
| } |
| |
| private ServerName[] singleRackCase(HRegionInfo regionInfo, |
| ServerName primaryRS, |
| String primaryRack) throws IOException { |
| // Single rack case: have to pick the secondary and tertiary |
| // from the same rack |
| List<ServerName> serverList = getServersFromRack(primaryRack); |
| if (serverList.size() <= 2) { |
| // Single region server case: cannot not place the favored nodes |
| // on any server; |
| return null; |
| } else { |
| // Randomly select two region servers from the server list and make sure |
| // they are not overlap with the primary region server; |
| Set<ServerName> serverSkipSet = new HashSet<ServerName>(); |
| serverSkipSet.add(primaryRS); |
| |
| // Place the secondary RS |
| ServerName secondaryRS = getOneRandomServer(primaryRack, serverSkipSet); |
| // Skip the secondary for the tertiary placement |
| serverSkipSet.add(secondaryRS); |
| |
| // Place the tertiary RS |
| ServerName tertiaryRS = |
| getOneRandomServer(primaryRack, serverSkipSet); |
| |
| if (secondaryRS == null || tertiaryRS == null) { |
| LOG.error("Cannot place the secondary and terinary" + |
| "region server for region " + |
| regionInfo.getRegionNameAsString()); |
| } |
| // Create the secondary and tertiary pair |
| ServerName[] favoredNodes = new ServerName[2]; |
| favoredNodes[0] = secondaryRS; |
| favoredNodes[1] = tertiaryRS; |
| return favoredNodes; |
| } |
| } |
| |
| private ServerName[] multiRackCase(HRegionInfo regionInfo, |
| ServerName primaryRS, |
| String primaryRack) throws IOException { |
| |
| // Random to choose the secondary and tertiary region server |
| // from another rack to place the secondary and tertiary |
| |
| // Random to choose one rack except for the current rack |
| Set<String> rackSkipSet = new HashSet<String>(); |
| rackSkipSet.add(primaryRack); |
| ServerName[] favoredNodes = new ServerName[2]; |
| String secondaryRack = getOneRandomRack(rackSkipSet); |
| List<ServerName> serverList = getServersFromRack(secondaryRack); |
| if (serverList.size() >= 2) { |
| // Randomly pick up two servers from this secondary rack |
| |
| // Place the secondary RS |
| ServerName secondaryRS = getOneRandomServer(secondaryRack); |
| |
| // Skip the secondary for the tertiary placement |
| Set<ServerName> skipServerSet = new HashSet<ServerName>(); |
| skipServerSet.add(secondaryRS); |
| // Place the tertiary RS |
| ServerName tertiaryRS = getOneRandomServer(secondaryRack, skipServerSet); |
| |
| if (secondaryRS == null || tertiaryRS == null) { |
| LOG.error("Cannot place the secondary and terinary" + |
| "region server for region " + |
| regionInfo.getRegionNameAsString()); |
| } |
| // Create the secondary and tertiary pair |
| favoredNodes[0] = secondaryRS; |
| favoredNodes[1] = tertiaryRS; |
| } else { |
| // Pick the secondary rs from this secondary rack |
| // and pick the tertiary from another random rack |
| favoredNodes[0] = getOneRandomServer(secondaryRack); |
| |
| // Pick the tertiary |
| if (getTotalNumberOfRacks() == 2) { |
| // Pick the tertiary from the same rack of the primary RS |
| Set<ServerName> serverSkipSet = new HashSet<ServerName>(); |
| serverSkipSet.add(primaryRS); |
| favoredNodes[1] = getOneRandomServer(primaryRack, serverSkipSet); |
| } else { |
| // Pick the tertiary from another rack |
| rackSkipSet.add(secondaryRack); |
| String tertiaryRandomRack = getOneRandomRack(rackSkipSet); |
| favoredNodes[1] = getOneRandomServer(tertiaryRandomRack); |
| } |
| } |
| return favoredNodes; |
| } |
| |
| boolean canPlaceFavoredNodes() { |
| int serverSize = this.regionServerToRackMap.size(); |
| return (serverSize >= FAVORED_NODES_NUM); |
| } |
| |
| public void initialize() { |
| for (ServerName sn : this.servers) { |
| String rackName = this.rackManager.getRack(sn); |
| List<ServerName> serverList = this.rackToRegionServerMap.get(rackName); |
| if (serverList == null) { |
| serverList = new ArrayList<ServerName>(); |
| // Add the current rack to the unique rack list |
| this.uniqueRackList.add(rackName); |
| } |
| if (!serverList.contains(sn)) { |
| serverList.add(sn); |
| this.rackToRegionServerMap.put(rackName, serverList); |
| this.regionServerToRackMap.put(sn, rackName); |
| } |
| } |
| } |
| |
| private int getTotalNumberOfRacks() { |
| return this.uniqueRackList.size(); |
| } |
| |
| private List<ServerName> getServersFromRack(String rack) { |
| return this.rackToRegionServerMap.get(rack); |
| } |
| |
| private ServerName getOneRandomServer(String rack, |
| Set<ServerName> skipServerSet) throws IOException { |
| if(rack == null) return null; |
| List<ServerName> serverList = this.rackToRegionServerMap.get(rack); |
| if (serverList == null) return null; |
| |
| // Get a random server except for any servers from the skip set |
| if (skipServerSet != null && serverList.size() <= skipServerSet.size()) { |
| throw new IOException("Cannot randomly pick another random server"); |
| } |
| |
| ServerName randomServer; |
| do { |
| int randomIndex = random.nextInt(serverList.size()); |
| randomServer = serverList.get(randomIndex); |
| } while (skipServerSet != null && skipServerSet.contains(randomServer)); |
| |
| return randomServer; |
| } |
| |
| private ServerName getOneRandomServer(String rack) throws IOException { |
| return this.getOneRandomServer(rack, null); |
| } |
| |
| private String getOneRandomRack(Set<String> skipRackSet) throws IOException { |
| if (skipRackSet == null || uniqueRackList.size() <= skipRackSet.size()) { |
| throw new IOException("Cannot randomly pick another random server"); |
| } |
| |
| String randomRack; |
| do { |
| int randomIndex = random.nextInt(this.uniqueRackList.size()); |
| randomRack = this.uniqueRackList.get(randomIndex); |
| } while (skipRackSet.contains(randomRack)); |
| |
| return randomRack; |
| } |
| |
| public static String getFavoredNodesAsString(List<ServerName> nodes) { |
| StringBuffer strBuf = new StringBuffer(); |
| int i = 0; |
| for (ServerName node : nodes) { |
| strBuf.append(node.getHostAndPort()); |
| if (++i != nodes.size()) strBuf.append(";"); |
| } |
| return strBuf.toString(); |
| } |
| } |