/**
    * 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 org.apache.commons.logging.Log;
  import org.apache.commons.logging.LogFactory;
  import org.apache.hadoop.hbase.HConstants;
  import org.apache.hadoop.hbase.ScheduledChore;
  import org.apache.hadoop.hbase.classification.InterfaceAudience;
  import org.apache.hadoop.hbase.master.HMaster;
  
  /**
   * Chore that will call HMaster.balance{@link org.apache.hadoop.hbase.master.HMaster#balance()} when
   * needed.
   */
  @InterfaceAudience.Private
  public class BalancerChore extends ScheduledChore {
    private static final Log LOG = LogFactory.getLog(BalancerChore.class);
  
    private final HMaster master;
  
    public BalancerChore(HMaster master) {
      super(master.getServerName() + "-BalancerChore", master, master.getConfiguration().getInt(
        HConstants.HBASE_BALANCER_PERIOD, HConstants.DEFAULT_HBASE_BALANCER_PERIOD));
      this.master = master;
    }
  
    @Override
    protected void chore() {
      try {
        master.balance();
      } catch (IOException e) {
        LOG.error("Failed to balance.", e);
      }
    }
  }