/**
    * 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 org.apache.hadoop.hbase.classification.InterfaceAudience;
  import org.apache.hadoop.hbase.io.MetricsIOSource;
  import org.apache.hadoop.hbase.io.MetricsIOSourceImpl;
  import org.apache.hadoop.hbase.io.MetricsIOWrapper;
  
  /**
   * Factory to create MetricsRegionServerSource when given a  MetricsRegionServerWrapper
   */
  @InterfaceAudience.Private
  public class MetricsRegionServerSourceFactoryImpl implements MetricsRegionServerSourceFactory {
    public static enum FactoryStorage {
      INSTANCE;
      private Object aggLock = new Object();
      private MetricsRegionAggregateSourceImpl aggImpl;
      private MetricsTableAggregateSourceImpl tblAggImpl;
    }
  
    private synchronized MetricsRegionAggregateSourceImpl getAggregate() {
      synchronized (FactoryStorage.INSTANCE.aggLock) {
        if (FactoryStorage.INSTANCE.aggImpl == null) {
          FactoryStorage.INSTANCE.aggImpl = new MetricsRegionAggregateSourceImpl();
        }
        return FactoryStorage.INSTANCE.aggImpl;
      }
    }
  
    @Override
    public synchronized MetricsTableAggregateSourceImpl getTableAggregate() {
      synchronized (FactoryStorage.INSTANCE.aggLock) {
        if (FactoryStorage.INSTANCE.tblAggImpl == null) {
          FactoryStorage.INSTANCE.tblAggImpl = new MetricsTableAggregateSourceImpl();
        }
        return FactoryStorage.INSTANCE.tblAggImpl;
      }
    }
  
    @Override
    public synchronized MetricsRegionServerSource createServer(MetricsRegionServerWrapper regionServerWrapper) {
      return new MetricsRegionServerSourceImpl(regionServerWrapper);
    }
  
    @Override
    public MetricsRegionSource createRegion(MetricsRegionWrapper wrapper) {
      return new MetricsRegionSourceImpl(wrapper, getAggregate());
    }
  
    @Override
    public MetricsTableSource createTable(String table, MetricsTableWrapperAggregate wrapper) {
      return new MetricsTableSourceImpl(table, getTableAggregate(), wrapper);
    }
  
    public MetricsIOSource createIO(MetricsIOWrapper wrapper) {
      return new MetricsIOSourceImpl(wrapper);
    }
  }