/**
    * 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.ipc;
  
  import io.netty.channel.Channel;
  import io.netty.channel.EventLoopGroup;
  import io.netty.channel.nio.NioEventLoopGroup;
  import io.netty.channel.socket.nio.NioSocketChannel;
  import io.netty.util.concurrent.DefaultThreadFactory;
  
  import java.io.IOException;
  import java.net.SocketAddress;
  
  import org.apache.hadoop.conf.Configuration;
  import org.apache.hadoop.hbase.HBaseInterfaceAudience;
  import org.apache.hadoop.hbase.HConstants;
  import org.apache.hadoop.hbase.classification.InterfaceAudience;
  import org.apache.hadoop.hbase.client.MetricsConnection;
  import org.apache.hadoop.hbase.util.Pair;
  
  /**
   * Netty client for the requests and responses.
   */
  @InterfaceAudience.LimitedPrivate(HBaseInterfaceAudience.CONFIG)
  public class NettyRpcClient extends AbstractRpcClient<NettyRpcConnection> {
  
    final EventLoopGroup group;
  
    final Class<? extends Channel> channelClass;
  
    private final boolean shutdownGroupWhenClose;
  
    public NettyRpcClient(Configuration configuration, String clusterId, SocketAddress localAddress,
        MetricsConnection metrics) {
      super(configuration, clusterId, localAddress, metrics);
      Pair<EventLoopGroup, Class<? extends Channel>> groupAndChannelClass = NettyRpcClientConfigHelper
          .getEventLoopConfig(conf);
      if (groupAndChannelClass == null) {
        // Use our own EventLoopGroup.
        this.group = new NioEventLoopGroup(0,
            new DefaultThreadFactory("IPC-NioEventLoopGroup", true, Thread.MAX_PRIORITY));
        this.channelClass = NioSocketChannel.class;
        this.shutdownGroupWhenClose = true;
      } else {
        this.group = groupAndChannelClass.getFirst();
        this.channelClass = groupAndChannelClass.getSecond();
        this.shutdownGroupWhenClose = false;
      }
    }
  
    /** Used in test only. */
    NettyRpcClient(Configuration configuration) {
      this(configuration, HConstants.CLUSTER_ID_DEFAULT, null, null);
    }
  
    @Override
    protected NettyRpcConnection createConnection(ConnectionId remoteId) throws IOException {
      return new NettyRpcConnection(this, remoteId);
    }
  
    @Override
    protected void closeInternal() {
      if (shutdownGroupWhenClose) {
        group.shutdownGracefully();
      }
    }
  }