/*
    * 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.chaos.actions;
  
  import java.util.List;
  
  import org.apache.commons.lang.math.RandomUtils;
  import org.apache.hadoop.hbase.HBaseTestingUtility;
  import org.apache.hadoop.hbase.HRegionInfo;
  import org.apache.hadoop.hbase.TableName;
  import org.apache.hadoop.hbase.client.Admin;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  /**
   * Action to merge regions of a table.
   */
  public class MergeRandomAdjacentRegionsOfTableAction extends Action {
    private static final Logger LOG =
        LoggerFactory.getLogger(MergeRandomAdjacentRegionsOfTableAction.class);
    private final TableName tableName;
    private final long sleepTime;
  
    public MergeRandomAdjacentRegionsOfTableAction(TableName tableName) {
      this(-1, tableName);
    }
  
    public MergeRandomAdjacentRegionsOfTableAction(int sleepTime, TableName tableName) {
      this.tableName = tableName;
      this.sleepTime = sleepTime;
    }
  
    @Override protected Logger getLogger() {
      return LOG;
    }
  
    @Override
    public void perform() throws Exception {
      HBaseTestingUtility util = context.getHBaseIntegrationTestingUtility();
      Admin admin = util.getHBaseAdmin();
  
      getLogger().info("Performing action: Merge random adjacent regions of table " + tableName);
      List<HRegionInfo> regions = admin.getTableRegions(tableName);
      if (regions == null || regions.size() < 2) {
        getLogger().info("Table " + tableName + " doesn't have enough regions to merge");
        return;
      }
  
      int i = RandomUtils.nextInt(regions.size() - 1);
      HRegionInfo a = regions.get(i++);
      HRegionInfo b = regions.get(i);
      getLogger().debug("Merging " + a.getRegionNameAsString() + " and " + b.getRegionNameAsString());
  
      // Don't try the merge if we're stopping
      if (context.isStopping()) {
        return;
      }
  
      try {
        admin.mergeRegions(a.getEncodedNameAsBytes(), b.getEncodedNameAsBytes(), false);
      } catch (Exception ex) {
        getLogger().warn("Merge failed, might be caused by other chaos: " + ex.getMessage());
      }
      if (sleepTime > 0) {
        Thread.sleep(sleepTime);
      }
    }
  }