/**
    * 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.regionserver;
  
  import java.io.IOException;
  import java.util.List;
  
  import org.apache.commons.logging.Log;
  import org.apache.commons.logging.LogFactory;
  import org.apache.hadoop.hbase.classification.InterfaceAudience;
  import org.apache.hadoop.conf.Configuration;
  import org.apache.hadoop.hbase.TableName;
  import org.apache.hadoop.hbase.HConstants;
  import org.apache.hadoop.hbase.HTableDescriptor;
  
  /**
   * Split size is the number of regions that are on this server that all are
   * of the same table, cubed, times 2x the region flush size OR the maximum
   * region split size, whichever is smaller.  For example, if the flush size
   * is 128M, then after two flushes (256MB) we will split which will make two regions
   * that will split when their size is 2^3 * 128M*2 = 2048M.  If one of these
   * regions splits, then there are three regions and now the split size is
   * 3^3 * 128M*2 =  6912M, and so on until we reach the configured
   * maximum filesize and then from there on out, we'll use that.
   */
  @InterfaceAudience.Private
  public class IncreasingToUpperBoundRegionSplitPolicy
  extends ConstantSizeRegionSplitPolicy {
    static final Log LOG =
      LogFactory.getLog(IncreasingToUpperBoundRegionSplitPolicy.class);
    private long initialSize;
  
    @Override
    protected void configureForRegion(HRegion region) {
      super.configureForRegion(region);
      Configuration conf = getConf();
      this.initialSize = conf.getLong("hbase.increasing.policy.initial.size", -1);
      if (this.initialSize > 0) {
        return;
      }
      HTableDescriptor desc = region.getTableDesc();
      if (desc != null) {
        this.initialSize = 2*desc.getMemStoreFlushSize();
      }
      if (this.initialSize <= 0) {
        this.initialSize = 2*conf.getLong(HConstants.HREGION_MEMSTORE_FLUSH_SIZE,
          HTableDescriptor.DEFAULT_MEMSTORE_FLUSH_SIZE);
      }
    }
  
    @Override
    protected boolean shouldSplit() {
      boolean force = region.shouldForceSplit();
      boolean foundABigStore = false;
      // Get count of regions that have the same common table as this.region
      int tableRegionsCount = getCountOfCommonTableRegions();
      // Get size to check
      long sizeToCheck = getSizeToCheck(tableRegionsCount);
  
      for (Store store : region.getStores()) {
        // If any of the stores is unable to split (eg they contain reference files)
        // then don't split
        if ((!store.canSplit())) {
          return false;
        }
  
        // Mark if any store is big enough
        long size = store.getSize();
        if (size > sizeToCheck) {
          LOG.debug("ShouldSplit because " + store.getColumnFamilyName() +
            " size=" + size + ", sizeToCheck=" + sizeToCheck +
            ", regionsWithCommonTable=" + tableRegionsCount);
          foundABigStore = true;
        }
      }
  
      return foundABigStore | force;
    }
  
    /**
     * @return Region max size or <code>count of regions squared * flushsize, which ever is
     * smaller; guard against there being zero regions on this server.
     */
    protected long getSizeToCheck(final int tableRegionsCount) {
     // safety check for 100 to avoid numerical overflow in extreme cases
     return tableRegionsCount == 0 || tableRegionsCount > 100 ? getDesiredMaxFileSize():
       Math.min(getDesiredMaxFileSize(),
         this.initialSize * tableRegionsCount * tableRegionsCount * tableRegionsCount);
   }
 
   /**
    * @return Count of regions on this server that share the table this.region
    * belongs to
    */
   private int getCountOfCommonTableRegions() {
     RegionServerServices rss = this.region.getRegionServerServices();
     // Can be null in tests
     if (rss == null) return 0;
     TableName tablename = this.region.getTableDesc().getTableName();
     int tableRegionsCount = 0;
     try {
       List<Region> hri = rss.getOnlineRegions(tablename);
       tableRegionsCount = hri == null || hri.isEmpty()? 0: hri.size();
     } catch (IOException e) {
       LOG.debug("Failed getOnlineRegions " + tablename, e);
     }
     return tableRegionsCount;
   }
 }