| /** |
| * |
| * 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 edu.umd.cs.findbugs.annotations.NonNull; |
| import java.io.IOException; |
| import java.util.List; |
| import java.util.Map; |
| import org.apache.hadoop.conf.Configurable; |
| import org.apache.hadoop.conf.Configuration; |
| import org.apache.hadoop.hbase.ClusterMetrics; |
| import org.apache.hadoop.hbase.ServerName; |
| import org.apache.hadoop.hbase.Stoppable; |
| import org.apache.hadoop.hbase.TableName; |
| import org.apache.hadoop.hbase.client.RegionInfo; |
| import org.apache.hadoop.hbase.conf.ConfigurationObserver; |
| import org.apache.hadoop.hbase.master.balancer.ClusterInfoProvider; |
| import org.apache.yetus.audience.InterfaceAudience; |
| |
| /** |
| * Makes decisions about the placement and movement of Regions across RegionServers. |
| * <p/> |
| * Cluster-wide load balancing will occur only when there are no regions in transition and according |
| * to a fixed period of a time using {@link #balanceCluster(Map)}. |
| * <p/> |
| * On cluster startup, bulk assignment can be used to determine locations for all Regions in a |
| * cluster. |
| * <p/> |
| * This class produces plans for the {@code AssignmentManager} to execute. |
| */ |
| @InterfaceAudience.Private |
| public interface LoadBalancer extends Configurable, Stoppable, ConfigurationObserver { |
| |
| // Used to signal to the caller that the region(s) cannot be assigned |
| // We deliberately use 'localhost' so the operation will fail fast |
| ServerName BOGUS_SERVER_NAME = ServerName.valueOf("localhost,1,1"); |
| |
| /** |
| * Config for pluggable load balancers. |
| * @deprecated since 3.0.0, will be removed in 4.0.0. In the new implementation, as the base load |
| * balancer will always be the rs group based one, you should just use |
| * {@link org.apache.hadoop.hbase.HConstants#HBASE_MASTER_LOADBALANCER_CLASS} to |
| * config the per group load balancer. |
| */ |
| @Deprecated |
| String HBASE_RSGROUP_LOADBALANCER_CLASS = "hbase.rsgroup.grouploadbalancer.class"; |
| /** |
| * Set the current cluster status. This allows a LoadBalancer to map host name to a server |
| */ |
| void setClusterMetrics(ClusterMetrics st); |
| |
| |
| /** |
| * Set the cluster info provider. Usually it is just a wrapper of master. |
| */ |
| void setClusterInfoProvider(ClusterInfoProvider provider); |
| |
| /** |
| * Perform the major balance operation for cluster. |
| * @param loadOfAllTable region load of servers for all table |
| * @return a list of regions to be moved, including source and destination, or null if cluster is |
| * already balanced |
| */ |
| List<RegionPlan> balanceCluster(Map<TableName, Map<ServerName, List<RegionInfo>>> loadOfAllTable) |
| throws IOException; |
| |
| /** |
| * Perform a Round Robin assignment of regions. |
| * @return Map of servername to regioninfos |
| */ |
| @NonNull |
| Map<ServerName, List<RegionInfo>> roundRobinAssignment(List<RegionInfo> regions, |
| List<ServerName> servers) throws IOException; |
| |
| /** |
| * Assign regions to the previously hosting region server |
| * @return List of plans |
| */ |
| @NonNull |
| Map<ServerName, List<RegionInfo>> retainAssignment(Map<RegionInfo, ServerName> regions, |
| List<ServerName> servers) throws IOException; |
| |
| /** |
| * Get a random region server from the list |
| * @param regionInfo Region for which this selection is being done. |
| */ |
| ServerName randomAssignment(RegionInfo regionInfo, List<ServerName> servers) throws IOException; |
| |
| /** |
| * Initialize the load balancer. Must be called after setters. |
| */ |
| void initialize() throws IOException; |
| |
| /** |
| * Marks the region as online at balancer. |
| */ |
| void regionOnline(RegionInfo regionInfo, ServerName sn); |
| |
| /** |
| * Marks the region as offline at balancer. |
| */ |
| void regionOffline(RegionInfo regionInfo); |
| |
| /** |
| * Notification that config has changed |
| */ |
| @Override |
| void onConfigurationChange(Configuration conf); |
| |
| /** |
| * If balancer needs to do initialization after Master has started up, lets do that here. |
| */ |
| void postMasterStartupInitialize(); |
| |
| /*Updates balancer status tag reported to JMX*/ |
| void updateBalancerStatus(boolean status); |
| } |