/*
    * 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 org.apache.hadoop.conf.Configuration;
  import org.apache.hadoop.hbase.ChoreService;
  import org.apache.hadoop.hbase.HConstants;
  import org.apache.hadoop.hbase.classification.InterfaceAudience;
  import org.apache.hadoop.hbase.conf.ConfigurationObserver;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  /**
   * Config manager for RegionsRecovery Chore - Dynamically reload config and update chore
   * accordingly
   */
  @InterfaceAudience.Private
  public class RegionsRecoveryConfigManager implements ConfigurationObserver {
  
    private static final Logger LOG = LoggerFactory.getLogger(RegionsRecoveryConfigManager.class);
  
    private final HMaster hMaster;
    private int prevMaxStoreFileRefCount;
    private int prevRegionsRecoveryInterval;
  
    RegionsRecoveryConfigManager(final HMaster hMaster) {
      this.hMaster = hMaster;
      Configuration conf = hMaster.getConfiguration();
      this.prevMaxStoreFileRefCount = getMaxStoreFileRefCount(conf);
      this.prevRegionsRecoveryInterval = getRegionsRecoveryChoreInterval(conf);
    }
  
    @Override
    public void onConfigurationChange(Configuration conf) {
      final int newMaxStoreFileRefCount = getMaxStoreFileRefCount(conf);
      final int newRegionsRecoveryInterval = getRegionsRecoveryChoreInterval(conf);
  
      if (prevMaxStoreFileRefCount == newMaxStoreFileRefCount
          && prevRegionsRecoveryInterval == newRegionsRecoveryInterval) {
        // no need to re-schedule the chore with updated config
        // as there is no change in desired configs
        return;
      }
  
      LOG.info("Config Reload for RegionsRecovery Chore. prevMaxStoreFileRefCount: {}," +
          " newMaxStoreFileRefCount: {}, prevRegionsRecoveryInterval: {}, " +
          "newRegionsRecoveryInterval: {}", prevMaxStoreFileRefCount, newMaxStoreFileRefCount,
        prevRegionsRecoveryInterval, newRegionsRecoveryInterval);
  
      RegionsRecoveryChore regionsRecoveryChore = new RegionsRecoveryChore(this.hMaster,
        conf, this.hMaster);
      ChoreService choreService = this.hMaster.getChoreService();
  
      // Regions Reopen based on very high storeFileRefCount is considered enabled
      // only if hbase.regions.recovery.store.file.ref.count has value > 0
  
      synchronized (this) {
        if (newMaxStoreFileRefCount > 0) {
          // reschedule the chore
          // provide mayInterruptIfRunning - false to take care of completion
          // of in progress task if any
          choreService.cancelChore(regionsRecoveryChore, false);
          choreService.scheduleChore(regionsRecoveryChore);
        } else {
          choreService.cancelChore(regionsRecoveryChore, false);
        }
        this.prevMaxStoreFileRefCount = newMaxStoreFileRefCount;
        this.prevRegionsRecoveryInterval = newRegionsRecoveryInterval;
      }
    }
  
    private int getMaxStoreFileRefCount(Configuration configuration) {
      return configuration.getInt(
        HConstants.STORE_FILE_REF_COUNT_THRESHOLD,
        HConstants.DEFAULT_STORE_FILE_REF_COUNT_THRESHOLD);
    }
  
    private int getRegionsRecoveryChoreInterval(Configuration configuration) {
      return configuration.getInt(
        HConstants.REGIONS_RECOVERY_INTERVAL,
        HConstants.DEFAULT_REGIONS_RECOVERY_INTERVAL);
    }
  
 }