/**
    *
    * 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 io.netty.bootstrap.Bootstrap;
  import io.netty.bootstrap.ChannelFactory;
  import io.netty.buffer.Unpooled;
  import io.netty.channel.Channel;
  import io.netty.channel.ChannelException;
  import io.netty.channel.ChannelHandlerContext;
  import io.netty.channel.ChannelOption;
  import io.netty.channel.EventLoopGroup;
  import io.netty.channel.nio.NioEventLoopGroup;
  import io.netty.channel.socket.DatagramChannel;
  import io.netty.channel.socket.DatagramPacket;
  import io.netty.channel.socket.InternetProtocolFamily;
  import io.netty.channel.socket.nio.NioDatagramChannel;
  import io.netty.handler.codec.MessageToMessageEncoder;
  import io.netty.util.internal.StringUtil;
  
  import java.io.Closeable;
  import java.io.IOException;
  import java.net.Inet6Address;
  import java.net.InetAddress;
  import java.net.InetSocketAddress;
  import java.net.NetworkInterface;
  import java.net.UnknownHostException;
  import java.util.ArrayList;
  import java.util.Collections;
  import java.util.Comparator;
  import java.util.List;
  import java.util.Map;
  import java.util.concurrent.ConcurrentHashMap;
  import java.util.concurrent.ConcurrentMap;
  
  import org.apache.hadoop.conf.Configuration;
  import org.apache.hadoop.hbase.ClusterStatus;
  import org.apache.hadoop.hbase.HBaseInterfaceAudience;
  import org.apache.hadoop.hbase.HConstants;
  import org.apache.hadoop.hbase.ScheduledChore;
  import org.apache.hadoop.hbase.ServerName;
  import org.apache.hadoop.hbase.classification.InterfaceAudience;
  import org.apache.hadoop.hbase.protobuf.generated.ClusterStatusProtos;
  import org.apache.hadoop.hbase.util.Addressing;
  import org.apache.hadoop.hbase.util.EnvironmentEdgeManager;
  import org.apache.hadoop.hbase.util.ExceptionUtil;
  import org.apache.hadoop.hbase.util.Pair;
  import org.apache.hadoop.hbase.util.ReflectionUtils;
  import org.apache.hadoop.hbase.util.Threads;
  import org.apache.hadoop.hbase.util.VersionInfo;
  
  
  /**
   * Class to publish the cluster status to the client. This allows them to know immediately
   *  the dead region servers, hence to cut the connection they have with them, eventually stop
   *  waiting on the socket. This improves the mean time to recover, and as well allows to increase
   *  on the client the different timeouts, as the dead servers will be detected separately.
   */
  @InterfaceAudience.Private
  public class ClusterStatusPublisher extends ScheduledChore {
    /**
     * The implementation class used to publish the status. Default is null (no publish).
     * Use org.apache.hadoop.hbase.master.ClusterStatusPublisher.MulticastPublisher to multicast the
     * status.
     */
    public static final String STATUS_PUBLISHER_CLASS = "hbase.status.publisher.class";
    public static final Class<? extends ClusterStatusPublisher.Publisher>
        DEFAULT_STATUS_PUBLISHER_CLASS =
        org.apache.hadoop.hbase.master.ClusterStatusPublisher.MulticastPublisher.class;
  
    /**
     * The minimum time between two status messages, in milliseconds.
     */
    public static final String STATUS_PUBLISH_PERIOD = "hbase.status.publish.period";
    public static final int DEFAULT_STATUS_PUBLISH_PERIOD = 10000;
  
    private long lastMessageTime = 0;
    private final HMaster master;
    private final int messagePeriod; // time between two message
    private final ConcurrentMap<ServerName, Integer> lastSent =
       new ConcurrentHashMap<ServerName, Integer>();
   private Publisher publisher;
   private boolean connected = false;
 
   /**
    * We want to limit the size of the protobuf message sent, do fit into a single packet.
    * a reasonable size for ip / ethernet is less than 1Kb.
    */
   public final static int MAX_SERVER_PER_MESSAGE = 10;
 
   /**
    * If a server dies, we're sending the information multiple times in case a receiver misses the
    * message.
    */
   public final static int NB_SEND = 5;
 
   public ClusterStatusPublisher(HMaster master, Configuration conf,
                                 Class<? extends Publisher> publisherClass)
       throws IOException {
     super("HBase clusterStatusPublisher for " + master.getName(), master, conf.getInt(
       STATUS_PUBLISH_PERIOD, DEFAULT_STATUS_PUBLISH_PERIOD));
     this.master = master;
     this.messagePeriod = conf.getInt(STATUS_PUBLISH_PERIOD, DEFAULT_STATUS_PUBLISH_PERIOD);
     try {
       this.publisher = publisherClass.newInstance();
     } catch (InstantiationException e) {
       throw new IOException("Can't create publisher " + publisherClass.getName(), e);
     } catch (IllegalAccessException e) {
       throw new IOException("Can't create publisher " + publisherClass.getName(), e);
     }
     this.publisher.connect(conf);
     connected = true;
   }
 
   // For tests only
   protected ClusterStatusPublisher() {
     master = null;
     messagePeriod = 0;
   }
 
   @Override
   protected void chore() {
     if (!connected) {
       return;
     }
 
     List<ServerName> sns = generateDeadServersListToSend();
     if (sns.isEmpty()) {
       // Nothing to send. Done.
       return;
     }
 
     final long curTime = EnvironmentEdgeManager.currentTime();
     if (lastMessageTime > curTime - messagePeriod) {
       // We already sent something less than 10 second ago. Done.
       return;
     }
 
     // Ok, we're going to send something then.
     lastMessageTime = curTime;
 
     // We're reusing an existing protobuf message, but we don't send everything.
     // This could be extended in the future, for example if we want to send stuff like the
     //  hbase:meta server name.
     ClusterStatus cs = new ClusterStatus(VersionInfo.getVersion(),
         master.getMasterFileSystem().getClusterId().toString(),
         null,
         sns,
         master.getServerName(),
         null,
         null,
         null,
         null);
 
 
     publisher.publish(cs);
   }
 
   protected void cleanup() {
     connected = false;
     publisher.close();
   }
 
   /**
    * Create the dead server to send. A dead server is sent NB_SEND times. We send at max
    * MAX_SERVER_PER_MESSAGE at a time. if there are too many dead servers, we send the newly
    * dead first.
    */
   protected List<ServerName> generateDeadServersListToSend() {
     // We're getting the message sent since last time, and add them to the list
     long since = EnvironmentEdgeManager.currentTime() - messagePeriod * 2;
     for (Pair<ServerName, Long> dead : getDeadServers(since)) {
       lastSent.putIfAbsent(dead.getFirst(), 0);
     }
 
     // We're sending the new deads first.
     List<Map.Entry<ServerName, Integer>> entries = new ArrayList<Map.Entry<ServerName, Integer>>();
     entries.addAll(lastSent.entrySet());
     Collections.sort(entries, new Comparator<Map.Entry<ServerName, Integer>>() {
       @Override
       public int compare(Map.Entry<ServerName, Integer> o1, Map.Entry<ServerName, Integer> o2) {
         return o1.getValue().compareTo(o2.getValue());
       }
     });
 
     // With a limit of MAX_SERVER_PER_MESSAGE
     int max = entries.size() > MAX_SERVER_PER_MESSAGE ? MAX_SERVER_PER_MESSAGE : entries.size();
     List<ServerName> res = new ArrayList<ServerName>(max);
 
     for (int i = 0; i < max; i++) {
       Map.Entry<ServerName, Integer> toSend = entries.get(i);
       if (toSend.getValue() >= (NB_SEND - 1)) {
         lastSent.remove(toSend.getKey());
       } else {
         lastSent.replace(toSend.getKey(), toSend.getValue(), toSend.getValue() + 1);
       }
 
       res.add(toSend.getKey());
     }
 
     return res;
   }
 
   /**
    * Get the servers which died since a given timestamp.
    * protected because it can be subclassed by the tests.
    */
   protected List<Pair<ServerName, Long>> getDeadServers(long since) {
     if (master.getServerManager() == null) {
       return Collections.emptyList();
     }
 
     return master.getServerManager().getDeadServers().copyDeadServersSince(since);
   }
 
 
   public interface Publisher extends Closeable {
 
     void connect(Configuration conf) throws IOException;
 
     void publish(ClusterStatus cs);
 
     @Override
     void close();
   }
 
   @InterfaceAudience.LimitedPrivate(HBaseInterfaceAudience.CONFIG)
   public static class MulticastPublisher implements Publisher {
     private DatagramChannel channel;
     private final EventLoopGroup group = new NioEventLoopGroup(
         1, Threads.newDaemonThreadFactory("hbase-master-clusterStatusPublisher"));
 
     public MulticastPublisher() {
     }
 
     @Override
     public void connect(Configuration conf) throws IOException {
       String mcAddress = conf.get(HConstants.STATUS_MULTICAST_ADDRESS,
           HConstants.DEFAULT_STATUS_MULTICAST_ADDRESS);
       int port = conf.getInt(HConstants.STATUS_MULTICAST_PORT,
           HConstants.DEFAULT_STATUS_MULTICAST_PORT);
 
       final InetAddress ina;
       try {
         ina = InetAddress.getByName(mcAddress);
       } catch (UnknownHostException e) {
         close();
         throw new IOException("Can't connect to " + mcAddress, e);
       }
 
       final InetSocketAddress isa = new InetSocketAddress(mcAddress, port);
 
       InternetProtocolFamily family;
       InetAddress localAddress;
       if (ina instanceof Inet6Address) {
         localAddress = Addressing.getIp6Address();
         family = InternetProtocolFamily.IPv6;
       }else{
         localAddress = Addressing.getIp4Address();
         family = InternetProtocolFamily.IPv4;
       }
       NetworkInterface ni = NetworkInterface.getByInetAddress(localAddress);
 
       Bootstrap b = new Bootstrap();
       b.group(group)
       .channelFactory(new HBaseDatagramChannelFactory<Channel>(NioDatagramChannel.class, family))
       .option(ChannelOption.SO_REUSEADDR, true)
       .handler(new ClusterStatusEncoder(isa));
 
       try {
         channel = (DatagramChannel) b.bind(new InetSocketAddress(0)).sync().channel();
         channel.joinGroup(ina, ni, null, channel.newPromise()).sync();
         channel.connect(isa).sync();
       } catch (InterruptedException e) {
         close();
         throw ExceptionUtil.asInterrupt(e);
       }
     }
 
     private static final class HBaseDatagramChannelFactory<T extends Channel> implements ChannelFactory<T> {
       private final Class<? extends T> clazz;
       private InternetProtocolFamily family;
 
       HBaseDatagramChannelFactory(Class<? extends T> clazz, InternetProtocolFamily family) {
           this.clazz = clazz;
           this.family = family;
       }
 
       @Override
       public T newChannel() {
           try {
             return ReflectionUtils.instantiateWithCustomCtor(clazz.getName(),
               new Class[] { InternetProtocolFamily.class }, new Object[] { family });
 
           } catch (Throwable t) {
               throw new ChannelException("Unable to create Channel from class " + clazz, t);
           }
       }
 
       @Override
       public String toString() {
           return StringUtil.simpleClassName(clazz) + ".class";
       }
   }
 
     private static class ClusterStatusEncoder extends MessageToMessageEncoder<ClusterStatus> {
       final private InetSocketAddress isa;
 
       private ClusterStatusEncoder(InetSocketAddress isa) {
         this.isa = isa;
       }
 
       @Override
       protected void encode(ChannelHandlerContext channelHandlerContext,
                             ClusterStatus clusterStatus, List<Object> objects) {
         ClusterStatusProtos.ClusterStatus csp = clusterStatus.convert();
         objects.add(new DatagramPacket(Unpooled.wrappedBuffer(csp.toByteArray()), isa));
       }
     }
 
     @Override
     public void publish(ClusterStatus cs) {
       channel.writeAndFlush(cs).syncUninterruptibly();
     }
 
     @Override
     public void close() {
       if (channel != null) {
         channel.close();
       }
       group.shutdownGracefully();
     }
   }
 }