/**
    * 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 static org.apache.hadoop.fs.CommonConfigurationKeysPublic.HADOOP_SECURITY_AUTHORIZATION;
  
  import java.io.ByteArrayInputStream;
  import java.io.ByteArrayOutputStream;
  import java.io.DataOutputStream;
  import java.io.IOException;
  import java.net.BindException;
  import java.net.InetAddress;
  import java.net.InetSocketAddress;
  import java.net.ServerSocket;
  import java.net.Socket;
  import java.net.SocketException;
  import java.net.UnknownHostException;
  import java.nio.ByteBuffer;
  import java.nio.channels.CancelledKeyException;
  import java.nio.channels.Channels;
  import java.nio.channels.ClosedChannelException;
  import java.nio.channels.GatheringByteChannel;
  import java.nio.channels.ReadableByteChannel;
  import java.nio.channels.SelectionKey;
  import java.nio.channels.Selector;
  import java.nio.channels.ServerSocketChannel;
  import java.nio.channels.SocketChannel;
  import java.nio.channels.WritableByteChannel;
  import java.security.PrivilegedExceptionAction;
  import java.util.ArrayList;
  import java.util.Arrays;
  import java.util.Collections;
  import java.util.HashMap;
  import java.util.Iterator;
  import java.util.LinkedList;
  import java.util.List;
  import java.util.Map;
  import java.util.Random;
  import java.util.Set;
  import java.util.concurrent.ConcurrentHashMap;
  import java.util.concurrent.ConcurrentLinkedDeque;
  import java.util.concurrent.ExecutorService;
  import java.util.concurrent.Executors;
  import java.util.concurrent.atomic.AtomicInteger;
  import java.util.concurrent.locks.Lock;
  import java.util.concurrent.locks.ReentrantLock;
  
  import javax.security.sasl.Sasl;
  import javax.security.sasl.SaslException;
  import javax.security.sasl.SaslServer;
  
  import org.apache.commons.logging.Log;
  import org.apache.commons.logging.LogFactory;
  import org.apache.hadoop.hbase.classification.InterfaceAudience;
  import org.apache.hadoop.hbase.classification.InterfaceStability;
  import org.apache.hadoop.conf.Configuration;
  import org.apache.hadoop.hbase.CellScanner;
  import org.apache.hadoop.hbase.DoNotRetryIOException;
  import org.apache.hadoop.hbase.HBaseIOException;
  import org.apache.hadoop.hbase.HBaseInterfaceAudience;
  import org.apache.hadoop.hbase.HConstants;
  import org.apache.hadoop.hbase.HRegionInfo;
  import org.apache.hadoop.hbase.Server;
  import org.apache.hadoop.hbase.TableName;
  import org.apache.hadoop.hbase.client.Operation;
  import org.apache.hadoop.hbase.codec.Codec;
  import org.apache.hadoop.hbase.exceptions.RegionMovedException;
  import org.apache.hadoop.hbase.io.ByteBufferOutputStream;
  import org.apache.hadoop.hbase.io.BoundedByteBufferPool;
  import org.apache.hadoop.hbase.monitoring.MonitoredRPCHandler;
  import org.apache.hadoop.hbase.monitoring.TaskMonitor;
  import org.apache.hadoop.hbase.protobuf.ProtobufUtil;
  import org.apache.hadoop.hbase.protobuf.generated.RPCProtos.CellBlockMeta;
  import org.apache.hadoop.hbase.protobuf.generated.RPCProtos.ConnectionHeader;
  import org.apache.hadoop.hbase.protobuf.generated.RPCProtos.ExceptionResponse;
  import org.apache.hadoop.hbase.protobuf.generated.RPCProtos.RequestHeader;
  import org.apache.hadoop.hbase.protobuf.generated.RPCProtos.ResponseHeader;
  import org.apache.hadoop.hbase.protobuf.generated.RPCProtos.UserInformation;
  import org.apache.hadoop.hbase.protobuf.generated.RPCProtos.VersionInfo;
  import org.apache.hadoop.hbase.regionserver.HRegionServer;
  import org.apache.hadoop.hbase.security.AccessDeniedException;
  import org.apache.hadoop.hbase.security.AuthMethod;
  import org.apache.hadoop.hbase.security.HBasePolicyProvider;
 import org.apache.hadoop.hbase.security.HBaseSaslRpcServer;
 import org.apache.hadoop.hbase.security.User;
 import org.apache.hadoop.hbase.security.HBaseSaslRpcServer.SaslDigestCallbackHandler;
 import org.apache.hadoop.hbase.security.HBaseSaslRpcServer.SaslGssCallbackHandler;
 import org.apache.hadoop.hbase.security.SaslStatus;
 import org.apache.hadoop.hbase.security.SaslUtil;
 import org.apache.hadoop.hbase.security.UserProvider;
 import org.apache.hadoop.hbase.security.token.AuthenticationTokenSecretManager;
 import org.apache.hadoop.hbase.util.Bytes;
 import org.apache.hadoop.hbase.util.Counter;
 import org.apache.hadoop.hbase.util.Pair;
 import org.apache.hadoop.io.BytesWritable;
 import org.apache.hadoop.io.IntWritable;
 import org.apache.hadoop.io.Writable;
 import org.apache.hadoop.io.WritableUtils;
 import org.apache.hadoop.io.compress.CompressionCodec;
 import org.apache.hadoop.security.UserGroupInformation;
 import org.apache.hadoop.security.UserGroupInformation.AuthenticationMethod;
 import org.apache.hadoop.security.authorize.AuthorizationException;
 import org.apache.hadoop.security.authorize.PolicyProvider;
 import org.apache.hadoop.security.authorize.ProxyUsers;
 import org.apache.hadoop.security.authorize.ServiceAuthorizationManager;
 import org.apache.hadoop.security.token.SecretManager;
 import org.apache.hadoop.security.token.SecretManager.InvalidToken;
 import org.apache.hadoop.security.token.TokenIdentifier;
 import org.apache.hadoop.util.StringUtils;
 import org.codehaus.jackson.map.ObjectMapper;
 import org.apache.htrace.TraceInfo;
 
 import com.google.common.util.concurrent.ThreadFactoryBuilder;
 import com.google.protobuf.BlockingService;
 import com.google.protobuf.CodedInputStream;
 import com.google.protobuf.Descriptors.MethodDescriptor;
 import com.google.protobuf.Message;
 import com.google.protobuf.ServiceException;
 import com.google.protobuf.TextFormat;
 
 /**
  * An RPC server that hosts protobuf described Services.
  *
  * An RpcServer instance has a Listener that hosts the socket.  Listener has fixed number
  * of Readers in an ExecutorPool, 10 by default.  The Listener does an accept and then
  * round robin a Reader is chosen to do the read.  The reader is registered on Selector.  Read does
  * total read off the channel and the parse from which it makes a Call.  The call is wrapped in a
  * CallRunner and passed to the scheduler to be run.  Reader goes back to see if more to be done
  * and loops till done.
  *
  * <p>Scheduler can be variously implemented but default simple scheduler has handlers to which it
  * has given the queues into which calls (i.e. CallRunner instances) are inserted.  Handlers run
  * taking from the queue.  They run the CallRunner#run method on each item gotten from queue
  * and keep taking while the server is up.
  *
  * CallRunner#run executes the call.  When done, asks the included Call to put itself on new
  * queue for Responder to pull from and return result to client.
  *
  * @see RpcClientImpl
  */
 @InterfaceAudience.LimitedPrivate({HBaseInterfaceAudience.COPROC, HBaseInterfaceAudience.PHOENIX})
 @InterfaceStability.Evolving
 public class RpcServer implements RpcServerInterface {
   public static final Log LOG = LogFactory.getLog(RpcServer.class);
   private static final CallQueueTooBigException CALL_QUEUE_TOO_BIG_EXCEPTION
       = new CallQueueTooBigException();
 
   private final boolean authorize;
   private boolean isSecurityEnabled;
 
   public static final byte CURRENT_VERSION = 0;
 
   /**
    * How many calls/handler are allowed in the queue.
    */
   static final int DEFAULT_MAX_CALLQUEUE_LENGTH_PER_HANDLER = 10;
 
   /**
    * The maximum size that we can hold in the RPC queue
    */
   private static final int DEFAULT_MAX_CALLQUEUE_SIZE = 1024 * 1024 * 1024;
 
   private static final String WARN_DELAYED_CALLS = "hbase.ipc.warn.delayedrpc.number";
 
   private static final int DEFAULT_WARN_DELAYED_CALLS = 1000;
 
   private final int warnDelayedCalls;
 
   private AtomicInteger delayedCalls;
   private final IPCUtil ipcUtil;
 
   private static final String AUTH_FAILED_FOR = "Auth failed for ";
   private static final String AUTH_SUCCESSFUL_FOR = "Auth successful for ";
   private static final Log AUDITLOG = LogFactory.getLog("SecurityLogger." +
     Server.class.getName());
   protected SecretManager<TokenIdentifier> secretManager;
   protected ServiceAuthorizationManager authManager;
 
   /** This is set to Call object before Handler invokes an RPC and ybdie
    * after the call returns.
    */
   protected static final ThreadLocal<Call> CurCall = new ThreadLocal<Call>();
 
   /** Keeps MonitoredRPCHandler per handler thread. */
   static final ThreadLocal<MonitoredRPCHandler> MONITORED_RPC
       = new ThreadLocal<MonitoredRPCHandler>();
 
   protected final InetSocketAddress bindAddress;
   protected int port;                             // port we listen on
   private int readThreads;                        // number of read threads
   protected int maxIdleTime;                      // the maximum idle time after
                                                   // which a client may be
                                                   // disconnected
   protected int thresholdIdleConnections;         // the number of idle
                                                   // connections after which we
                                                   // will start cleaning up idle
                                                   // connections
   int maxConnectionsToNuke;                       // the max number of
                                                   // connections to nuke
                                                   // during a cleanup
 
   protected MetricsHBaseServer metrics;
 
   protected final Configuration conf;
 
   private int maxQueueSize;
   protected int socketSendBufferSize;
   protected final boolean tcpNoDelay;   // if T then disable Nagle's Algorithm
   protected final boolean tcpKeepAlive; // if T then use keepalives
   protected final long purgeTimeout;    // in milliseconds
 
   /**
    * This flag is used to indicate to sub threads when they should go down.  When we call
    * {@link #start()}, all threads started will consult this flag on whether they should
    * keep going.  It is set to false when {@link #stop()} is called.
    */
   volatile boolean running = true;
 
   /**
    * This flag is set to true after all threads are up and 'running' and the server is then opened
    * for business by the call to {@link #start()}.
    */
   volatile boolean started = false;
 
   /**
    * This is a running count of the size of all outstanding calls by size.
    */
   protected final Counter callQueueSize = new Counter();
 
   protected final List<Connection> connectionList =
     Collections.synchronizedList(new LinkedList<Connection>());
   //maintain a list
   //of client connections
   private Listener listener = null;
   protected Responder responder = null;
   protected AuthenticationTokenSecretManager authTokenSecretMgr = null;
   protected int numConnections = 0;
 
   protected HBaseRPCErrorHandler errorHandler = null;
 
   private static final String WARN_RESPONSE_TIME = "hbase.ipc.warn.response.time";
   private static final String WARN_RESPONSE_SIZE = "hbase.ipc.warn.response.size";
 
   /** Default value for above params */
   private static final int DEFAULT_WARN_RESPONSE_TIME = 10000; // milliseconds
   private static final int DEFAULT_WARN_RESPONSE_SIZE = 100 * 1024 * 1024;
 
   private static final ObjectMapper MAPPER = new ObjectMapper();
 
   private final int warnResponseTime;
   private final int warnResponseSize;
   private final Server server;
   private final List<BlockingServiceAndInterface> services;
 
   private final RpcScheduler scheduler;
 
   private UserProvider userProvider;
 
   private final BoundedByteBufferPool reservoir;
 
 
   /**
    * Datastructure that holds all necessary to a method invocation and then afterward, carries
    * the result.
    */
   @InterfaceAudience.LimitedPrivate({HBaseInterfaceAudience.COPROC, HBaseInterfaceAudience.PHOENIX})
   @InterfaceStability.Evolving
   public class Call implements RpcCallContext {
     protected int id;                             // the client's call id
     protected BlockingService service;
     protected MethodDescriptor md;
     protected RequestHeader header;
     protected Message param;                      // the parameter passed
     // Optional cell data passed outside of protobufs.
     protected CellScanner cellScanner;
     protected Connection connection;              // connection to client
     protected long timestamp;      // the time received when response is null
                                    // the time served when response is not null
     /**
      * Chain of buffers to send as response.
      */
     protected BufferChain response;
     protected boolean delayResponse;
     protected Responder responder;
     protected boolean delayReturnValue;           // if the return value should be
                                                   // set at call completion
     protected long size;                          // size of current call
     protected boolean isError;
     protected TraceInfo tinfo;
     private ByteBuffer cellBlock = null;
 
     private User user;
     private InetAddress remoteAddress;
 
     Call(int id, final BlockingService service, final MethodDescriptor md, RequestHeader header,
          Message param, CellScanner cellScanner, Connection connection, Responder responder,
          long size, TraceInfo tinfo, final InetAddress remoteAddress) {
       this.id = id;
       this.service = service;
       this.md = md;
       this.header = header;
       this.param = param;
       this.cellScanner = cellScanner;
       this.connection = connection;
       this.timestamp = System.currentTimeMillis();
       this.response = null;
       this.delayResponse = false;
       this.responder = responder;
       this.isError = false;
       this.size = size;
       this.tinfo = tinfo;
       this.user = connection.user == null? null: userProvider.create(connection.user);
       this.remoteAddress = remoteAddress;
     }
 
     /**
      * Call is done. Execution happened and we returned results to client. It is now safe to
      * cleanup.
      */
     void done() {
       if (this.cellBlock != null) {
         // Return buffer to reservoir now we are done with it.
         reservoir.putBuffer(this.cellBlock);
         this.cellBlock = null;
       }
       this.connection.decRpcCount();  // Say that we're done with this call.
     }
 
     @Override
     public String toString() {
       return toShortString() + " param: " +
         (this.param != null? ProtobufUtil.getShortTextFormat(this.param): "") +
         " connection: " + connection.toString();
     }
 
     protected RequestHeader getHeader() {
       return this.header;
     }
 
     public boolean hasPriority() {
       return this.header.hasPriority();
     }
 
     public int getPriority() {
       return this.header.getPriority();
     }
 
     /*
      * Short string representation without param info because param itself could be huge depends on
      * the payload of a command
      */
     String toShortString() {
       String serviceName = this.connection.service != null ?
           this.connection.service.getDescriptorForType().getName() : "null";
       return "callId: " + this.id + " service: " + serviceName +
           " methodName: " + ((this.md != null) ? this.md.getName() : "n/a") +
           " size: " + StringUtils.TraditionalBinaryPrefix.long2String(this.size, "", 1) +
           " connection: " + connection.toString();
     }
 
     String toTraceString() {
       String serviceName = this.connection.service != null ?
                            this.connection.service.getDescriptorForType().getName() : "";
       String methodName = (this.md != null) ? this.md.getName() : "";
       return serviceName + "." + methodName;
     }
 
     protected synchronized void setSaslTokenResponse(ByteBuffer response) {
       this.response = new BufferChain(response);
     }
 
     protected synchronized void setResponse(Object m, final CellScanner cells,
         Throwable t, String errorMsg) {
       if (this.isError) return;
       if (t != null) this.isError = true;
       BufferChain bc = null;
       try {
         ResponseHeader.Builder headerBuilder = ResponseHeader.newBuilder();
         // Presume it a pb Message.  Could be null.
         Message result = (Message)m;
         // Call id.
         headerBuilder.setCallId(this.id);
         if (t != null) {
           ExceptionResponse.Builder exceptionBuilder = ExceptionResponse.newBuilder();
           exceptionBuilder.setExceptionClassName(t.getClass().getName());
           exceptionBuilder.setStackTrace(errorMsg);
           exceptionBuilder.setDoNotRetry(t instanceof DoNotRetryIOException);
           if (t instanceof RegionMovedException) {
             // Special casing for this exception.  This is only one carrying a payload.
             // Do this instead of build a generic system for allowing exceptions carry
             // any kind of payload.
             RegionMovedException rme = (RegionMovedException)t;
             exceptionBuilder.setHostname(rme.getHostname());
             exceptionBuilder.setPort(rme.getPort());
           }
           // Set the exception as the result of the method invocation.
           headerBuilder.setException(exceptionBuilder.build());
         }
         // Pass reservoir to buildCellBlock. Keep reference to returne so can add it back to the
         // reservoir when finished. This is hacky and the hack is not contained but benefits are
         // high when we can avoid a big buffer allocation on each rpc.
         this.cellBlock = ipcUtil.buildCellBlock(this.connection.codec,
           this.connection.compressionCodec, cells, reservoir);
         if (this.cellBlock != null) {
           CellBlockMeta.Builder cellBlockBuilder = CellBlockMeta.newBuilder();
           // Presumes the cellBlock bytebuffer has been flipped so limit has total size in it.
           cellBlockBuilder.setLength(this.cellBlock.limit());
           headerBuilder.setCellBlockMeta(cellBlockBuilder.build());
         }
         Message header = headerBuilder.build();
 
         // Organize the response as a set of bytebuffers rather than collect it all together inside
         // one big byte array; save on allocations.
         ByteBuffer bbHeader = IPCUtil.getDelimitedMessageAsByteBuffer(header);
         ByteBuffer bbResult = IPCUtil.getDelimitedMessageAsByteBuffer(result);
         int totalSize = bbHeader.capacity() + (bbResult == null? 0: bbResult.limit()) +
           (this.cellBlock == null? 0: this.cellBlock.limit());
         ByteBuffer bbTotalSize = ByteBuffer.wrap(Bytes.toBytes(totalSize));
         bc = new BufferChain(bbTotalSize, bbHeader, bbResult, this.cellBlock);
         if (connection.useWrap) {
           bc = wrapWithSasl(bc);
         }
       } catch (IOException e) {
         LOG.warn("Exception while creating response " + e);
       }
       this.response = bc;
     }
 
     private BufferChain wrapWithSasl(BufferChain bc)
         throws IOException {
       if (!this.connection.useSasl) return bc;
       // Looks like no way around this; saslserver wants a byte array.  I have to make it one.
       // THIS IS A BIG UGLY COPY.
       byte [] responseBytes = bc.getBytes();
       byte [] token;
       // synchronization may be needed since there can be multiple Handler
       // threads using saslServer to wrap responses.
       synchronized (connection.saslServer) {
         token = connection.saslServer.wrap(responseBytes, 0, responseBytes.length);
       }
       if (LOG.isTraceEnabled()) {
         LOG.trace("Adding saslServer wrapped token of size " + token.length
             + " as call response.");
       }
 
       ByteBuffer bbTokenLength = ByteBuffer.wrap(Bytes.toBytes(token.length));
       ByteBuffer bbTokenBytes = ByteBuffer.wrap(token);
       return new BufferChain(bbTokenLength, bbTokenBytes);
     }
 
     @Override
     public synchronized void endDelay(Object result) throws IOException {
       assert this.delayResponse;
       assert this.delayReturnValue || result == null;
       this.delayResponse = false;
       delayedCalls.decrementAndGet();
       if (this.delayReturnValue) {
         this.setResponse(result, null, null, null);
       }
       this.responder.doRespond(this);
     }
 
     @Override
     public synchronized void endDelay() throws IOException {
       this.endDelay(null);
     }
 
     @Override
     public synchronized void startDelay(boolean delayReturnValue) {
       assert !this.delayResponse;
       this.delayResponse = true;
       this.delayReturnValue = delayReturnValue;
       int numDelayed = delayedCalls.incrementAndGet();
       if (numDelayed > warnDelayedCalls) {
         LOG.warn("Too many delayed calls: limit " + warnDelayedCalls + " current " + numDelayed);
       }
     }
 
     @Override
     public synchronized void endDelayThrowing(Throwable t) throws IOException {
       this.setResponse(null, null, t, StringUtils.stringifyException(t));
       this.delayResponse = false;
       this.sendResponseIfReady();
     }
 
     @Override
     public synchronized boolean isDelayed() {
       return this.delayResponse;
     }
 
     @Override
     public synchronized boolean isReturnValueDelayed() {
       return this.delayReturnValue;
     }
 
     @Override
     public boolean isClientCellBlockSupport() {
       return this.connection != null && this.connection.codec != null;
     }
 
     @Override
     public long disconnectSince() {
       if (!connection.channel.isOpen()) {
         return System.currentTimeMillis() - timestamp;
       } else {
         return -1L;
       }
     }
 
     public long getSize() {
       return this.size;
     }
 
     /**
      * If we have a response, and delay is not set, then respond
      * immediately.  Otherwise, do not respond to client.  This is
      * called by the RPC code in the context of the Handler thread.
      */
     public synchronized void sendResponseIfReady() throws IOException {
       // set param null to reduce memory pressure
       this.param = null;
       if (!this.delayResponse) {
         this.responder.doRespond(this);
       }
     }
 
     public UserGroupInformation getRemoteUser() {
       return connection.user;
     }
 
     @Override
     public User getRequestUser() {
       return user;
     }
 
     @Override
     public String getRequestUserName() {
       User user = getRequestUser();
       return user == null? null: user.getShortName();
     }
 
     @Override
     public InetAddress getRemoteAddress() {
       return remoteAddress;
     }
 
     @Override
     public VersionInfo getClientVersionInfo() {
       return connection.getVersionInfo();
     }
   }
 
   /** Listens on the socket. Creates jobs for the handler threads*/
   private class Listener extends Thread {
 
     private ServerSocketChannel acceptChannel = null; //the accept channel
     private Selector selector = null; //the selector that we use for the server
     private Reader[] readers = null;
     private int currentReader = 0;
     private Random rand = new Random();
     private long lastCleanupRunTime = 0; //the last time when a cleanup connec-
                                          //-tion (for idle connections) ran
     private long cleanupInterval = 10000; //the minimum interval between
                                           //two cleanup runs
     private int backlogLength;
 
     private ExecutorService readPool;
 
     public Listener(final String name) throws IOException {
       super(name);
       backlogLength = conf.getInt("hbase.ipc.server.listen.queue.size", 128);
       // Create a new server socket and set to non blocking mode
       acceptChannel = ServerSocketChannel.open();
       acceptChannel.configureBlocking(false);
 
       // Bind the server socket to the binding addrees (can be different from the default interface)
       bind(acceptChannel.socket(), bindAddress, backlogLength);
       port = acceptChannel.socket().getLocalPort(); //Could be an ephemeral port
       // create a selector;
       selector= Selector.open();
 
       readers = new Reader[readThreads];
       readPool = Executors.newFixedThreadPool(readThreads,
         new ThreadFactoryBuilder().setNameFormat(
           "RpcServer.reader=%d,bindAddress=" + bindAddress.getHostName() +
           ",port=" + port).setDaemon(true).build());
       for (int i = 0; i < readThreads; ++i) {
         Reader reader = new Reader();
         readers[i] = reader;
         readPool.execute(reader);
       }
       LOG.info(getName() + ": started " + readThreads + " reader(s) listening on port=" + port);
 
       // Register accepts on the server socket with the selector.
       acceptChannel.register(selector, SelectionKey.OP_ACCEPT);
       this.setName("RpcServer.listener,port=" + port);
       this.setDaemon(true);
     }
 
 
     private class Reader implements Runnable {
       private volatile boolean adding = false;
       private final Selector readSelector;
 
       Reader() throws IOException {
         this.readSelector = Selector.open();
       }
       @Override
       public void run() {
         try {
           doRunLoop();
         } finally {
           try {
             readSelector.close();
           } catch (IOException ioe) {
             LOG.error(getName() + ": error closing read selector in " + getName(), ioe);
           }
         }
       }
 
       private synchronized void doRunLoop() {
         while (running) {
           try {
             readSelector.select();
             while (adding) {
               this.wait(1000);
             }
 
             Iterator<SelectionKey> iter = readSelector.selectedKeys().iterator();
             while (iter.hasNext()) {
               SelectionKey key = iter.next();
               iter.remove();
               if (key.isValid()) {
                 if (key.isReadable()) {
                   doRead(key);
                 }
               }
             }
           } catch (InterruptedException e) {
             LOG.debug("Interrupted while sleeping");
             return;
           } catch (IOException ex) {
             LOG.info(getName() + ": IOException in Reader", ex);
           }
         }
       }
 
       /**
        * This gets reader into the state that waits for the new channel
        * to be registered with readSelector. If it was waiting in select()
        * the thread will be woken up, otherwise whenever select() is called
        * it will return even if there is nothing to read and wait
        * in while(adding) for finishAdd call
        */
       public void startAdd() {
         adding = true;
         readSelector.wakeup();
       }
 
       public synchronized SelectionKey registerChannel(SocketChannel channel)
         throws IOException {
         return channel.register(readSelector, SelectionKey.OP_READ);
       }
 
       public synchronized void finishAdd() {
         adding = false;
         this.notify();
       }
     }
 
     /** cleanup connections from connectionList. Choose a random range
      * to scan and also have a limit on the number of the connections
      * that will be cleanedup per run. The criteria for cleanup is the time
      * for which the connection was idle. If 'force' is true then all
      * connections will be looked at for the cleanup.
      * @param force all connections will be looked at for cleanup
      */
     private void cleanupConnections(boolean force) {
       if (force || numConnections > thresholdIdleConnections) {
         long currentTime = System.currentTimeMillis();
         if (!force && (currentTime - lastCleanupRunTime) < cleanupInterval) {
           return;
         }
         int start = 0;
         int end = numConnections - 1;
         if (!force) {
           start = rand.nextInt() % numConnections;
           end = rand.nextInt() % numConnections;
           int temp;
           if (end < start) {
             temp = start;
             start = end;
             end = temp;
           }
         }
         int i = start;
         int numNuked = 0;
         while (i <= end) {
           Connection c;
           synchronized (connectionList) {
             try {
               c = connectionList.get(i);
             } catch (Exception e) {return;}
           }
           if (c.timedOut(currentTime)) {
             if (LOG.isDebugEnabled())
               LOG.debug(getName() + ": disconnecting client " + c.getHostAddress());
             closeConnection(c);
             numNuked++;
             end--;
             //noinspection UnusedAssignment
             c = null;
             if (!force && numNuked == maxConnectionsToNuke) break;
           }
           else i++;
         }
         lastCleanupRunTime = System.currentTimeMillis();
       }
     }
 
     @Override
     public void run() {
       LOG.info(getName() + ": starting");
       while (running) {
         SelectionKey key = null;
         try {
           selector.select(); // FindBugs IS2_INCONSISTENT_SYNC
           Iterator<SelectionKey> iter = selector.selectedKeys().iterator();
           while (iter.hasNext()) {
             key = iter.next();
             iter.remove();
             try {
               if (key.isValid()) {
                 if (key.isAcceptable())
                   doAccept(key);
               }
             } catch (IOException ignored) {
               if (LOG.isTraceEnabled()) LOG.trace("ignored", ignored);
             }
             key = null;
           }
         } catch (OutOfMemoryError e) {
           if (errorHandler != null) {
             if (errorHandler.checkOOME(e)) {
               LOG.info(getName() + ": exiting on OutOfMemoryError");
               closeCurrentConnection(key, e);
               cleanupConnections(true);
               return;
             }
           } else {
             // we can run out of memory if we have too many threads
             // log the event and sleep for a minute and give
             // some thread(s) a chance to finish
             LOG.warn(getName() + ": OutOfMemoryError in server select", e);
             closeCurrentConnection(key, e);
             cleanupConnections(true);
             try {
               Thread.sleep(60000);
             } catch (InterruptedException ex) {
               LOG.debug("Interrupted while sleeping");
               return;
             }
           }
         } catch (Exception e) {
           closeCurrentConnection(key, e);
         }
         cleanupConnections(false);
       }
 
       LOG.info(getName() + ": stopping");
 
       synchronized (this) {
         try {
           acceptChannel.close();
           selector.close();
         } catch (IOException ignored) {
           if (LOG.isTraceEnabled()) LOG.trace("ignored", ignored);
         }
 
         selector= null;
         acceptChannel= null;
 
         // clean up all connections
         while (!connectionList.isEmpty()) {
           closeConnection(connectionList.remove(0));
         }
       }
     }
 
     private void closeCurrentConnection(SelectionKey key, Throwable e) {
       if (key != null) {
         Connection c = (Connection)key.attachment();
         if (c != null) {
           if (LOG.isDebugEnabled()) {
             LOG.debug(getName() + ": disconnecting client " + c.getHostAddress() +
                 (e != null ? " on error " + e.getMessage() : ""));
           }
           closeConnection(c);
           key.attach(null);
         }
       }
     }
 
     InetSocketAddress getAddress() {
       return (InetSocketAddress)acceptChannel.socket().getLocalSocketAddress();
     }
 
     void doAccept(SelectionKey key) throws IOException, OutOfMemoryError {
       Connection c;
       ServerSocketChannel server = (ServerSocketChannel) key.channel();
 
       SocketChannel channel;
       while ((channel = server.accept()) != null) {
         try {
           channel.configureBlocking(false);
           channel.socket().setTcpNoDelay(tcpNoDelay);
           channel.socket().setKeepAlive(tcpKeepAlive);
         } catch (IOException ioe) {
           channel.close();
           throw ioe;
         }
 
         Reader reader = getReader();
         try {
           reader.startAdd();
           SelectionKey readKey = reader.registerChannel(channel);
           c = getConnection(channel, System.currentTimeMillis());
           readKey.attach(c);
           synchronized (connectionList) {
             connectionList.add(numConnections, c);
             numConnections++;
           }
           if (LOG.isDebugEnabled())
             LOG.debug(getName() + ": connection from " + c.toString() +
                 "; # active connections: " + numConnections);
         } finally {
           reader.finishAdd();
         }
       }
     }
 
     void doRead(SelectionKey key) throws InterruptedException {
       int count;
       Connection c = (Connection) key.attachment();
       if (c == null) {
         return;
       }
       c.setLastContact(System.currentTimeMillis());
       try {
         count = c.readAndProcess();
 
         if (count > 0) {
           c.setLastContact(System.currentTimeMillis());
         }
 
       } catch (InterruptedException ieo) {
         throw ieo;
       } catch (Exception e) {
         if (LOG.isDebugEnabled()) {
           LOG.debug(getName() + ": Caught exception while reading:" + e.getMessage());
         }
         count = -1; //so that the (count < 0) block is executed
       }
       if (count < 0) {
         if (LOG.isDebugEnabled()) {
           LOG.debug(getName() + ": DISCONNECTING client " + c.toString() +
               " because read count=" + count +
               ". Number of active connections: " + numConnections);
         }
         closeConnection(c);
       }
     }
 
     synchronized void doStop() {
       if (selector != null) {
         selector.wakeup();
         Thread.yield();
       }
       if (acceptChannel != null) {
         try {
           acceptChannel.socket().close();
         } catch (IOException e) {
           LOG.info(getName() + ": exception in closing listener socket. " + e);
         }
       }
       readPool.shutdownNow();
     }
 
     // The method that will return the next reader to work with
     // Simplistic implementation of round robin for now
     Reader getReader() {
       currentReader = (currentReader + 1) % readers.length;
       return readers[currentReader];
     }
   }
 
   // Sends responses of RPC back to clients.
   protected class Responder extends Thread {
     private final Selector writeSelector;
     private final Set<Connection> writingCons =
         Collections.newSetFromMap(new ConcurrentHashMap<Connection, Boolean>());
 
     Responder() throws IOException {
       this.setName("RpcServer.responder");
       this.setDaemon(true);
       writeSelector = Selector.open(); // create a selector
     }
 
     @Override
     public void run() {
       LOG.info(getName() + ": starting");
       try {
         doRunLoop();
       } finally {
         LOG.info(getName() + ": stopping");
         try {
           writeSelector.close();
         } catch (IOException ioe) {
           LOG.error(getName() + ": couldn't close write selector", ioe);
         }
       }
     }
 
     /**
      * Take the list of the connections that want to write, and register them
      * in the selector.
      */
     private void registerWrites() {
       Iterator<Connection> it = writingCons.iterator();
       while (it.hasNext()) {
         Connection c = it.next();
         it.remove();
         SelectionKey sk = c.channel.keyFor(writeSelector);
         try {
           if (sk == null) {
             try {
               c.channel.register(writeSelector, SelectionKey.OP_WRITE, c);
             } catch (ClosedChannelException e) {
               // ignore: the client went away.
               if (LOG.isTraceEnabled()) LOG.trace("ignored", e);
             }
           } else {
             sk.interestOps(SelectionKey.OP_WRITE);
           }
         } catch (CancelledKeyException e) {
           // ignore: the client went away.
           if (LOG.isTraceEnabled()) LOG.trace("ignored", e);
         }
       }
     }
 
     /**
      * Add a connection to the list that want to write,
      */
     public void registerForWrite(Connection c) {
       if (writingCons.add(c)) {
         writeSelector.wakeup();
       }
     }
 
     private void doRunLoop() {
       long lastPurgeTime = 0;   // last check for old calls.
       while (running) {
         try {
           registerWrites();
           int keyCt = writeSelector.select(purgeTimeout);
           if (keyCt == 0) {
             continue;
           }
 
           Set<SelectionKey> keys = writeSelector.selectedKeys();
           Iterator<SelectionKey> iter = keys.iterator();
           while (iter.hasNext()) {
             SelectionKey key = iter.next();
             iter.remove();
             try {
               if (key.isValid() && key.isWritable()) {
                 doAsyncWrite(key);
               }
             } catch (IOException e) {
               LOG.debug(getName() + ": asyncWrite", e);
             }
           }
 
           lastPurgeTime = purge(lastPurgeTime);
 
         } catch (OutOfMemoryError e) {
           if (errorHandler != null) {
             if (errorHandler.checkOOME(e)) {
               LOG.info(getName() + ": exiting on OutOfMemoryError");
               return;
             }
           } else {
             //
             // we can run out of memory if we have too many threads
             // log the event and sleep for a minute and give
             // some thread(s) a chance to finish
             //
             LOG.warn(getName() + ": OutOfMemoryError in server select", e);
             try {
               Thread.sleep(60000);
             } catch (InterruptedException ex) {
               LOG.debug("Interrupted while sleeping");
               return;
             }
           }
         } catch (Exception e) {
           LOG.warn(getName() + ": exception in Responder " +
               StringUtils.stringifyException(e), e);
         }
       }
       LOG.info(getName() + ": stopped");
     }
 
     /**
      * If there were some calls that have not been sent out for a
      * long time, we close the connection.
      * @return the time of the purge.
      */
     private long purge(long lastPurgeTime) {
       long now = System.currentTimeMillis();
       if (now < lastPurgeTime + purgeTimeout) {
         return lastPurgeTime;
       }
 
       ArrayList<Connection> conWithOldCalls = new ArrayList<Connection>();
       // get the list of channels from list of keys.
       synchronized (writeSelector.keys()) {
         for (SelectionKey key : writeSelector.keys()) {
           Connection connection = (Connection) key.attachment();
           if (connection == null) {
             throw new IllegalStateException("Coding error: SelectionKey key without attachment.");
           }
           Call call = connection.responseQueue.peekFirst();
           if (call != null && now > call.timestamp + purgeTimeout) {
             conWithOldCalls.add(call.connection);
           }
         }
       }
 
       // Seems safer to close the connection outside of the synchronized loop...
       for (Connection connection : conWithOldCalls) {
         closeConnection(connection);
       }
 
       return now;
     }
 
     private void doAsyncWrite(SelectionKey key) throws IOException {
       Connection connection = (Connection) key.attachment();
       if (connection == null) {
         throw new IOException("doAsyncWrite: no connection");
       }
       if (key.channel() != connection.channel) {
         throw new IOException("doAsyncWrite: bad channel");
       }
 
       if (processAllResponses(connection)) {
         try {
           // We wrote everything, so we don't need to be told when the socket is ready for
           //  write anymore.
          key.interestOps(0);
         } catch (CancelledKeyException e) {
           /* The Listener/reader might have closed the socket.
            * We don't explicitly cancel the key, so not sure if this will
            * ever fire.
            * This warning could be removed.
            */
           LOG.warn("Exception while changing ops : " + e);
         }
       }
     }
 
     /**
      * Process the response for this call. You need to have the lock on
      * {@link org.apache.hadoop.hbase.ipc.RpcServer.Connection#responseWriteLock}
      *
      * @param call the call
      * @return true if we proceed the call fully, false otherwise.
      * @throws IOException
      */
     private boolean processResponse(final Call call) throws IOException {
       boolean error = true;
       try {
         // Send as much data as we can in the non-blocking fashion
         long numBytes = channelWrite(call.connection.channel, call.response);
         if (numBytes < 0) {
           throw new HBaseIOException("Error writing on the socket " +
             "for the call:" + call.toShortString());
         }
         error = false;
       } finally {
         if (error) {
           LOG.debug(getName() + call.toShortString() + ": output error -- closing");
           closeConnection(call.connection);
         }
       }
 
       if (!call.response.hasRemaining()) {
         call.done();
         return true;
       } else {
         return false; // Socket can't take more, we will have to come back.
       }
     }
 
     /**
      * Process all the responses for this connection
      *
      * @return true if all the calls were processed or that someone else is doing it.
      * false if there * is still some work to do. In this case, we expect the caller to
      * delay us.
      * @throws IOException
      */
     private boolean processAllResponses(final Connection connection) throws IOException {
       // We want only one writer on the channel for a connection at a time.
       connection.responseWriteLock.lock();
       try {
         for (int i = 0; i < 20; i++) {
           // protection if some handlers manage to need all the responder
           Call call = connection.responseQueue.pollFirst();
           if (call == null) {
             return true;
           }
           if (!processResponse(call)) {
             connection.responseQueue.addFirst(call);
             return false;
           }
         }
       } finally {
         connection.responseWriteLock.unlock();
       }
 
       return connection.responseQueue.isEmpty();
     }
 
     //
     // Enqueue a response from the application.
     //
     void doRespond(Call call) throws IOException {
       boolean added = false;
 
       // If there is already a write in progress, we don't wait. This allows to free the handlers
       //  immediately for other tasks.
       if (call.connection.responseQueue.isEmpty() && call.connection.responseWriteLock.tryLock()) {
         try {
           if (call.connection.responseQueue.isEmpty()) {
             // If we're alone, we can try to do a direct call to the socket. It's
             //  an optimisation to save on context switches and data transfer between cores..
             if (processResponse(call)) {
               return; // we're done.
             }
             // Too big to fit, putting ahead.
             call.connection.responseQueue.addFirst(call);
             added = true; // We will register to the selector later, outside of the lock.
           }
         } finally {
           call.connection.responseWriteLock.unlock();
         }
       }
 
       if (!added) {
         call.connection.responseQueue.addLast(call);
       }
       call.responder.registerForWrite(call.connection);
 
       // set the serve time when the response has to be sent later
       call.timestamp = System.currentTimeMillis();
     }
   }
 
   @SuppressWarnings("serial")
   public static class CallQueueTooBigException extends IOException {
     CallQueueTooBigException() {
       super();
     }
   }
 
   /** Reads calls from a connection and queues them for handling. */
   @edu.umd.cs.findbugs.annotations.SuppressWarnings(
       value="VO_VOLATILE_INCREMENT",
       justification="False positive according to http://sourceforge.net/p/findbugs/bugs/1032/")
   public class Connection {
     // If initial preamble with version and magic has been read or not.
     private boolean connectionPreambleRead = false;
     // If the connection header has been read or not.
     private boolean connectionHeaderRead = false;
     protected SocketChannel channel;
     private ByteBuffer data;
     private ByteBuffer dataLengthBuffer;
     protected final ConcurrentLinkedDeque<Call> responseQueue = new ConcurrentLinkedDeque<Call>();
     private final Lock responseWriteLock = new ReentrantLock();
     private Counter rpcCount = new Counter(); // number of outstanding rpcs
     private long lastContact;
     private InetAddress addr;
     protected Socket socket;
     // Cache the remote host & port info so that even if the socket is
     // disconnected, we can say where it used to connect to.
     protected String hostAddress;
     protected int remotePort;
     ConnectionHeader connectionHeader;
     /**
      * Codec the client asked use.
      */
     private Codec codec;
     /**
      * Compression codec the client asked us use.
      */
     private CompressionCodec compressionCodec;
     BlockingService service;
     protected UserGroupInformation user = null;
     private AuthMethod authMethod;
     private boolean saslContextEstablished;
     private boolean skipInitialSaslHandshake;
     private ByteBuffer unwrappedData;
     // When is this set?  FindBugs wants to know!  Says NP
     private ByteBuffer unwrappedDataLengthBuffer = ByteBuffer.allocate(4);
     boolean useSasl;
     SaslServer saslServer;
     private boolean useWrap = false;
     // Fake 'call' for failed authorization response
     private static final int AUTHORIZATION_FAILED_CALLID = -1;
     private final Call authFailedCall =
       new Call(AUTHORIZATION_FAILED_CALLID, null, null, null, null, null, this, null, 0, null,
         null);
     private ByteArrayOutputStream authFailedResponse =
         new ByteArrayOutputStream();
     // Fake 'call' for SASL context setup
     private static final int SASL_CALLID = -33;
     private final Call saslCall =
       new Call(SASL_CALLID, this.service, null, null, null, null, this, null, 0, null, null);
 
     public UserGroupInformation attemptingUser = null; // user name before auth
 
     public Connection(SocketChannel channel, long lastContact) {
       this.channel = channel;
       this.lastContact = lastContact;
       this.data = null;
       this.dataLengthBuffer = ByteBuffer.allocate(4);
       this.socket = channel.socket();
       this.addr = socket.getInetAddress();
       if (addr == null) {
         this.hostAddress = "*Unknown*";
       } else {
         this.hostAddress = addr.getHostAddress();
       }
       this.remotePort = socket.getPort();
       if (socketSendBufferSize != 0) {
         try {
           socket.setSendBufferSize(socketSendBufferSize);
         } catch (IOException e) {
           LOG.warn("Connection: unable to set socket send buffer size to " +
                    socketSendBufferSize);
         }
       }
     }
 
       @Override
     public String toString() {
       return getHostAddress() + ":" + remotePort;
     }
 
     public String getHostAddress() {
       return hostAddress;
     }
 
     public InetAddress getHostInetAddress() {
       return addr;
     }
 
     public int getRemotePort() {
       return remotePort;
     }
 
     public void setLastContact(long lastContact) {
       this.lastContact = lastContact;
     }
 
     public VersionInfo getVersionInfo() {
       if (connectionHeader.hasVersionInfo()) {
         return connectionHeader.getVersionInfo();
       }
       return null;
     }
 
     /* Return true if the connection has no outstanding rpc */
     private boolean isIdle() {
       return rpcCount.get() == 0;
     }
 
     /* Decrement the outstanding RPC count */
     protected void decRpcCount() {
       rpcCount.decrement();
     }
 
     /* Increment the outstanding RPC count */
     protected void incRpcCount() {
       rpcCount.increment();
     }
 
     protected boolean timedOut(long currentTime) {
       return isIdle() && currentTime - lastContact > maxIdleTime;
     }
 
     private UserGroupInformation getAuthorizedUgi(String authorizedId)
         throws IOException {
       if (authMethod == AuthMethod.DIGEST) {
         TokenIdentifier tokenId = HBaseSaslRpcServer.getIdentifier(authorizedId,
             secretManager);
         UserGroupInformation ugi = tokenId.getUser();
         if (ugi == null) {
           throw new AccessDeniedException(
               "Can't retrieve username from tokenIdentifier.");
         }
         ugi.addTokenIdentifier(tokenId);
         return ugi;
       } else {
         return UserGroupInformation.createRemoteUser(authorizedId);
       }
     }
 
     private void saslReadAndProcess(byte[] saslToken) throws IOException,
         InterruptedException {
       if (saslContextEstablished) {
         if (LOG.isTraceEnabled())
           LOG.trace("Have read input token of size " + saslToken.length
               + " for processing by saslServer.unwrap()");
 
         if (!useWrap) {
           processOneRpc(saslToken);
         } else {
           byte [] plaintextData = saslServer.unwrap(saslToken, 0, saslToken.length);
           processUnwrappedData(plaintextData);
         }
       } else {
         byte[] replyToken;
         try {
           if (saslServer == null) {
             switch (authMethod) {
             case DIGEST:
               if (secretManager == null) {
                 throw new AccessDeniedException(
                     "Server is not configured to do DIGEST authentication.");
               }
               saslServer = Sasl.createSaslServer(AuthMethod.DIGEST
                   .getMechanismName(), null, SaslUtil.SASL_DEFAULT_REALM,
                   SaslUtil.SASL_PROPS, new SaslDigestCallbackHandler(
                       secretManager, this));
               break;
             default:
               UserGroupInformation current = UserGroupInformation.getCurrentUser();
               String fullName = current.getUserName();
               if (LOG.isDebugEnabled()) {
                 LOG.debug("Kerberos principal name is " + fullName);
               }
               final String names[] = SaslUtil.splitKerberosName(fullName);
               if (names.length != 3) {
                 throw new AccessDeniedException(
                     "Kerberos principal name does NOT have the expected "
                         + "hostname part: " + fullName);
               }
               current.doAs(new PrivilegedExceptionAction<Object>() {
                 @Override
                 public Object run() throws SaslException {
                   saslServer = Sasl.createSaslServer(AuthMethod.KERBEROS
                       .getMechanismName(), names[0], names[1],
                       SaslUtil.SASL_PROPS, new SaslGssCallbackHandler());
                   return null;
                 }
               });
             }
             if (saslServer == null)
               throw new AccessDeniedException(
                   "Unable to find SASL server implementation for "
                       + authMethod.getMechanismName());
             if (LOG.isDebugEnabled()) {
               LOG.debug("Created SASL server with mechanism = " + authMethod.getMechanismName());
             }
           }
           if (LOG.isDebugEnabled()) {
             LOG.debug("Have read input token of size " + saslToken.length
                 + " for processing by saslServer.evaluateResponse()");
           }
           replyToken = saslServer.evaluateResponse(saslToken);
         } catch (IOException e) {
           IOException sendToClient = e;
           Throwable cause = e;
           while (cause != null) {
             if (cause instanceof InvalidToken) {
               sendToClient = (InvalidToken) cause;
               break;
             }
             cause = cause.getCause();
           }
           doRawSaslReply(SaslStatus.ERROR, null, sendToClient.getClass().getName(),
             sendToClient.getLocalizedMessage());
           metrics.authenticationFailure();
           String clientIP = this.toString();
           // attempting user could be null
           AUDITLOG.warn(AUTH_FAILED_FOR + clientIP + ":" + attemptingUser);
           throw e;
         }
         if (replyToken != null) {
           if (LOG.isDebugEnabled()) {
             LOG.debug("Will send token of size " + replyToken.length
                 + " from saslServer.");
           }
           doRawSaslReply(SaslStatus.SUCCESS, new BytesWritable(replyToken), null,
               null);
         }
         if (saslServer.isComplete()) {
           String qop = (String) saslServer.getNegotiatedProperty(Sasl.QOP);
           useWrap = qop != null && !"auth".equalsIgnoreCase(qop);
           user = getAuthorizedUgi(saslServer.getAuthorizationID());
           if (LOG.isDebugEnabled()) {
             LOG.debug("SASL server context established. Authenticated client: "
               + user + ". Negotiated QoP is "
               + saslServer.getNegotiatedProperty(Sasl.QOP));
           }
           metrics.authenticationSuccess();
           AUDITLOG.info(AUTH_SUCCESSFUL_FOR + user);
           saslContextEstablished = true;
         }
       }
     }
 
     /**
      * No protobuf encoding of raw sasl messages
      */
     private void doRawSaslReply(SaslStatus status, Writable rv,
         String errorClass, String error) throws IOException {
       ByteBufferOutputStream saslResponse = null;
       DataOutputStream out = null;
       try {
         // In my testing, have noticed that sasl messages are usually
         // in the ballpark of 100-200. That's why the initial capacity is 256.
         saslResponse = new ByteBufferOutputStream(256);
         out = new DataOutputStream(saslResponse);
         out.writeInt(status.state); // write status
         if (status == SaslStatus.SUCCESS) {
           rv.write(out);
         } else {
           WritableUtils.writeString(out, errorClass);
           WritableUtils.writeString(out, error);
         }
         saslCall.setSaslTokenResponse(saslResponse.getByteBuffer());
         saslCall.responder = responder;
         saslCall.sendResponseIfReady();
       } finally {
         if (saslResponse != null) {
           saslResponse.close();
         }
         if (out != null) {
           out.close();
         }
       }
     }
 
     private void disposeSasl() {
       if (saslServer != null) {
         try {
           saslServer.dispose();
           saslServer = null;
         } catch (SaslException ignored) {
           // Ignored. This is being disposed of anyway.
         }
       }
     }
 
     private int readPreamble() throws IOException {
       int count;
       // Check for 'HBas' magic.
       this.dataLengthBuffer.flip();
       if (!Arrays.equals(HConstants.RPC_HEADER, dataLengthBuffer.array())) {
         return doBadPreambleHandling("Expected HEADER=" +
             Bytes.toStringBinary(HConstants.RPC_HEADER) +
             " but received HEADER=" + Bytes.toStringBinary(dataLengthBuffer.array()) +
             " from " + toString());
       }
       // Now read the next two bytes, the version and the auth to use.
       ByteBuffer versionAndAuthBytes = ByteBuffer.allocate(2);
       count = channelRead(channel, versionAndAuthBytes);
       if (count < 0 || versionAndAuthBytes.remaining() > 0) {
         return count;
       }
       int version = versionAndAuthBytes.get(0);
       byte authbyte = versionAndAuthBytes.get(1);
       this.authMethod = AuthMethod.valueOf(authbyte);
       if (version != CURRENT_VERSION) {
         String msg = getFatalConnectionString(version, authbyte);
         return doBadPreambleHandling(msg, new WrongVersionException(msg));
       }
       if (authMethod == null) {
         String msg = getFatalConnectionString(version, authbyte);
         return doBadPreambleHandling(msg, new BadAuthException(msg));
       }
       if (isSecurityEnabled && authMethod == AuthMethod.SIMPLE) {
         AccessDeniedException ae = new AccessDeniedException("Authentication is required");
         setupResponse(authFailedResponse, authFailedCall, ae, ae.getMessage());
         responder.doRespond(authFailedCall);
         throw ae;
       }
       if (!isSecurityEnabled && authMethod != AuthMethod.SIMPLE) {
         doRawSaslReply(SaslStatus.SUCCESS, new IntWritable(
             SaslUtil.SWITCH_TO_SIMPLE_AUTH), null, null);
         authMethod = AuthMethod.SIMPLE;
         // client has already sent the initial Sasl message and we
         // should ignore it. Both client and server should fall back
         // to simple auth from now on.
         skipInitialSaslHandshake = true;
       }
       if (authMethod != AuthMethod.SIMPLE) {
         useSasl = true;
       }
 
       dataLengthBuffer.clear();
       connectionPreambleRead = true;
       return count;
     }
 
     private int read4Bytes() throws IOException {
       if (this.dataLengthBuffer.remaining() > 0) {
         return channelRead(channel, this.dataLengthBuffer);
       } else {
         return 0;
       }
     }
 
 
     /**
      * Read off the wire. If there is not enough data to read, update the connection state with
      *  what we have and returns.
      * @return Returns -1 if failure (and caller will close connection), else zero or more.
      * @throws IOException
      * @throws InterruptedException
      */
     public int readAndProcess() throws IOException, InterruptedException {
       // Try and read in an int.  If new connection, the int will hold the 'HBas' HEADER.  If it
       // does, read in the rest of the connection preamble, the version and the auth method.
       // Else it will be length of the data to read (or -1 if a ping).  We catch the integer
       // length into the 4-byte this.dataLengthBuffer.
       int count = read4Bytes();
       if (count < 0 || dataLengthBuffer.remaining() > 0) {
         return count;
       }
 
       // If we have not read the connection setup preamble, look to see if that is on the wire.
       if (!connectionPreambleRead) {
         count = readPreamble();
         if (!connectionPreambleRead) {
           return count;
         }
 
         count = read4Bytes();
         if (count < 0 || dataLengthBuffer.remaining() > 0) {
           return count;
         }
       }
 
       // We have read a length and we have read the preamble.  It is either the connection header
       // or it is a request.
       if (data == null) {
         dataLengthBuffer.flip();
         int dataLength = dataLengthBuffer.getInt();
         if (dataLength == RpcClient.PING_CALL_ID) {
           if (!useWrap) { //covers the !useSasl too
             dataLengthBuffer.clear();
             return 0;  //ping message
           }
         }
         if (dataLength < 0) { // A data length of zero is legal.
           throw new IllegalArgumentException("Unexpected data length "
               + dataLength + "!! from " + getHostAddress());
         }
         data = ByteBuffer.allocate(dataLength);
 
         // Increment the rpc count. This counter will be decreased when we write
         //  the response.  If we want the connection to be detected as idle properly, we
         //  need to keep the inc / dec correct.
         incRpcCount();
       }
 
       count = channelRead(channel, data);
 
       if (count >= 0 && data.remaining() == 0) { // count==0 if dataLength == 0
         process();
       }
 
       return count;
     }
 
     /**
      * Process the data buffer and clean the connection state for the next call.
      */
     private void process() throws IOException, InterruptedException {
       data.flip();
       try {
         if (skipInitialSaslHandshake) {
           skipInitialSaslHandshake = false;
           return;
         }
 
         if (useSasl) {
           saslReadAndProcess(data.array());
         } else {
           processOneRpc(data.array());
         }
 
       } finally {
         dataLengthBuffer.clear(); // Clean for the next call
         data = null; // For the GC
       }
     }
 
     private String getFatalConnectionString(final int version, final byte authByte) {
       return "serverVersion=" + CURRENT_VERSION +
       ", clientVersion=" + version + ", authMethod=" + authByte +
       ", authSupported=" + (authMethod != null) + " from " + toString();
     }
 
     private int doBadPreambleHandling(final String msg) throws IOException {
       return doBadPreambleHandling(msg, new FatalConnectionException(msg));
     }
 
     private int doBadPreambleHandling(final String msg, final Exception e) throws IOException {
       LOG.warn(msg);
       Call fakeCall = new Call(-1, null, null, null, null, null, this, responder, -1, null, null);
       setupResponse(null, fakeCall, e, msg);
       responder.doRespond(fakeCall);
       // Returning -1 closes out the connection.
       return -1;
     }
 
     // Reads the connection header following version
     private void processConnectionHeader(byte[] buf) throws IOException {
       this.connectionHeader = ConnectionHeader.parseFrom(buf);
       String serviceName = connectionHeader.getServiceName();
       if (serviceName == null) throw new EmptyServiceNameException();
       this.service = getService(services, serviceName);
       if (this.service == null) throw new UnknownServiceException(serviceName);
       setupCellBlockCodecs(this.connectionHeader);
       UserGroupInformation protocolUser = createUser(connectionHeader);
       if (!useSasl) {
         user = protocolUser;
         if (user != null) {
           user.setAuthenticationMethod(AuthMethod.SIMPLE.authenticationMethod);
         }
       } else {
         // user is authenticated
         user.setAuthenticationMethod(authMethod.authenticationMethod);
         //Now we check if this is a proxy user case. If the protocol user is
         //different from the 'user', it is a proxy user scenario. However,
         //this is not allowed if user authenticated with DIGEST.
         if ((protocolUser != null)
             && (!protocolUser.getUserName().equals(user.getUserName()))) {
           if (authMethod == AuthMethod.DIGEST) {
             // Not allowed to doAs if token authentication is used
             throw new AccessDeniedException("Authenticated user (" + user
                 + ") doesn't match what the client claims to be ("
                 + protocolUser + ")");
           } else {
             // Effective user can be different from authenticated user
             // for simple auth or kerberos auth
             // The user is the real user. Now we create a proxy user
             UserGroupInformation realUser = user;
             user = UserGroupInformation.createProxyUser(protocolUser
                 .getUserName(), realUser);
             // Now the user is a proxy user, set Authentication method Proxy.
             user.setAuthenticationMethod(AuthenticationMethod.PROXY);
           }
         }
       }
       if (connectionHeader.hasVersionInfo()) {
         AUDITLOG.info("Connection from " + this.hostAddress + " port: " + this.remotePort
             + " with version info: "
             + TextFormat.shortDebugString(connectionHeader.getVersionInfo()));
       } else {
         AUDITLOG.info("Connection from " + this.hostAddress + " port: " + this.remotePort
             + " with unknown version info");
       }
     }
 
     /**
      * Set up cell block codecs
      * @throws FatalConnectionException
      */
     private void setupCellBlockCodecs(final ConnectionHeader header)
     throws FatalConnectionException {
       // TODO: Plug in other supported decoders.
       if (!header.hasCellBlockCodecClass()) return;
       String className = header.getCellBlockCodecClass();
       if (className == null || className.length() == 0) return;
       try {
         this.codec = (Codec)Class.forName(className).newInstance();
       } catch (Exception e) {
         throw new UnsupportedCellCodecException(className, e);
       }
       if (!header.hasCellBlockCompressorClass()) return;
       className = header.getCellBlockCompressorClass();
       try {
         this.compressionCodec = (CompressionCodec)Class.forName(className).newInstance();
       } catch (Exception e) {
         throw new UnsupportedCompressionCodecException(className, e);
       }
     }
 
     private void processUnwrappedData(byte[] inBuf) throws IOException,
     InterruptedException {
       ReadableByteChannel ch = Channels.newChannel(new ByteArrayInputStream(inBuf));
       // Read all RPCs contained in the inBuf, even partial ones
       while (true) {
         int count;
         if (unwrappedDataLengthBuffer.remaining() > 0) {
           count = channelRead(ch, unwrappedDataLengthBuffer);
           if (count <= 0 || unwrappedDataLengthBuffer.remaining() > 0)
             return;
         }
 
         if (unwrappedData == null) {
           unwrappedDataLengthBuffer.flip();
           int unwrappedDataLength = unwrappedDataLengthBuffer.getInt();
 
           if (unwrappedDataLength == RpcClient.PING_CALL_ID) {
             if (LOG.isDebugEnabled())
               LOG.debug("Received ping message");
             unwrappedDataLengthBuffer.clear();
             continue; // ping message
           }
           unwrappedData = ByteBuffer.allocate(unwrappedDataLength);
         }
 
         count = channelRead(ch, unwrappedData);
         if (count <= 0 || unwrappedData.remaining() > 0)
           return;
 
         if (unwrappedData.remaining() == 0) {
           unwrappedDataLengthBuffer.clear();
           unwrappedData.flip();
           processOneRpc(unwrappedData.array());
           unwrappedData = null;
         }
       }
     }
 
     private void processOneRpc(byte[] buf) throws IOException, InterruptedException {
       if (connectionHeaderRead) {
         processRequest(buf);
       } else {
         processConnectionHeader(buf);
         this.connectionHeaderRead = true;
         if (!authorizeConnection()) {
           // Throw FatalConnectionException wrapping ACE so client does right thing and closes
           // down the connection instead of trying to read non-existent retun.
           throw new AccessDeniedException("Connection from " + this + " for service " +
             connectionHeader.getServiceName() + " is unauthorized for user: " + user);
         }
       }
     }
 
     /**
      * @param buf Has the request header and the request param and optionally encoded data buffer
      * all in this one array.
      * @throws IOException
      * @throws InterruptedException
      */
     protected void processRequest(byte[] buf) throws IOException, InterruptedException {
       long totalRequestSize = buf.length;
       int offset = 0;
       // Here we read in the header.  We avoid having pb
       // do its default 4k allocation for CodedInputStream.  We force it to use backing array.
       CodedInputStream cis = CodedInputStream.newInstance(buf, offset, buf.length);
       int headerSize = cis.readRawVarint32();
       offset = cis.getTotalBytesRead();
       Message.Builder builder = RequestHeader.newBuilder();
       ProtobufUtil.mergeFrom(builder, buf, offset, headerSize);
       RequestHeader header = (RequestHeader) builder.build();
       offset += headerSize;
       int id = header.getCallId();
       if (LOG.isTraceEnabled()) {
         LOG.trace("RequestHeader " + TextFormat.shortDebugString(header) +
           " totalRequestSize: " + totalRequestSize + " bytes");
       }
       // Enforcing the call queue size, this triggers a retry in the client
       // This is a bit late to be doing this check - we have already read in the total request.
       if ((totalRequestSize + callQueueSize.get()) > maxQueueSize) {
         final Call callTooBig =
           new Call(id, this.service, null, null, null, null, this,
             responder, totalRequestSize, null, null);
         ByteArrayOutputStream responseBuffer = new ByteArrayOutputStream();
         metrics.exception(CALL_QUEUE_TOO_BIG_EXCEPTION);
         InetSocketAddress address = getListenerAddress();
         setupResponse(responseBuffer, callTooBig, CALL_QUEUE_TOO_BIG_EXCEPTION,
             "Call queue is full on " + (address != null ? address : "(channel closed)") +
                 ", is hbase.ipc.server.max.callqueue.size too small?");
         responder.doRespond(callTooBig);
         return;
       }
       MethodDescriptor md = null;
       Message param = null;
       CellScanner cellScanner = null;
       try {
         if (header.hasRequestParam() && header.getRequestParam()) {
           md = this.service.getDescriptorForType().findMethodByName(header.getMethodName());
           if (md == null) throw new UnsupportedOperationException(header.getMethodName());
           builder = this.service.getRequestPrototype(md).newBuilderForType();
           // To read the varint, I need an inputstream; might as well be a CIS.
           cis = CodedInputStream.newInstance(buf, offset, buf.length);
           int paramSize = cis.readRawVarint32();
           offset += cis.getTotalBytesRead();
           if (builder != null) {
             ProtobufUtil.mergeFrom(builder, buf, offset, paramSize);
             param = builder.build();
           }
           offset += paramSize;
         }
         if (header.hasCellBlockMeta()) {
           cellScanner = ipcUtil.createCellScanner(this.codec, this.compressionCodec,
             buf, offset, buf.length);
         }
       } catch (Throwable t) {
         InetSocketAddress address = getListenerAddress();
         String msg = (address != null ? address : "(channel closed)") +
             " is unable to read call parameter from client " + getHostAddress();
         LOG.warn(msg, t);
 
         metrics.exception(t);
 
         // probably the hbase hadoop version does not match the running hadoop version
         if (t instanceof LinkageError) {
           t = new DoNotRetryIOException(t);
         }
         // If the method is not present on the server, do not retry.
         if (t instanceof UnsupportedOperationException) {
           t = new DoNotRetryIOException(t);
         }
 
         final Call readParamsFailedCall =
           new Call(id, this.service, null, null, null, null, this,
             responder, totalRequestSize, null, null);
         ByteArrayOutputStream responseBuffer = new ByteArrayOutputStream();
         setupResponse(responseBuffer, readParamsFailedCall, t,
           msg + "; " + t.getMessage());
         responder.doRespond(readParamsFailedCall);
         return;
       }
 
       TraceInfo traceInfo = header.hasTraceInfo()
           ? new TraceInfo(header.getTraceInfo().getTraceId(), header.getTraceInfo().getParentId())
           : null;
       Call call = new Call(id, this.service, md, header, param, cellScanner, this, responder,
               totalRequestSize, traceInfo, RpcServer.getRemoteIp());
       scheduler.dispatch(new CallRunner(RpcServer.this, call));
     }
 
     private boolean authorizeConnection() throws IOException {
       try {
         // If auth method is DIGEST, the token was obtained by the
         // real user for the effective user, therefore not required to
         // authorize real user. doAs is allowed only for simple or kerberos
         // authentication
         if (user != null && user.getRealUser() != null
             && (authMethod != AuthMethod.DIGEST)) {
           ProxyUsers.authorize(user, this.getHostAddress(), conf);
         }
         authorize(user, connectionHeader, getHostInetAddress());
         metrics.authorizationSuccess();
       } catch (AuthorizationException ae) {
         if (LOG.isDebugEnabled()) {
           LOG.debug("Connection authorization failed: " + ae.getMessage(), ae);
         }
         metrics.authorizationFailure();
         setupResponse(authFailedResponse, authFailedCall,
           new AccessDeniedException(ae), ae.getMessage());
         responder.doRespond(authFailedCall);
         return false;
       }
       return true;
     }
 
     protected synchronized void close() {
       disposeSasl();
       data = null;
       if (!channel.isOpen())
         return;
       try {socket.shutdownOutput();} catch(Exception ignored) {} // FindBugs DE_MIGHT_IGNORE
       if (channel.isOpen()) {
         try {channel.close();} catch(Exception ignored) {}
       }
       try {socket.close();} catch(Exception ignored) {}
     }
 
     private UserGroupInformation createUser(ConnectionHeader head) {
       UserGroupInformation ugi = null;
 
       if (!head.hasUserInfo()) {
         return null;
       }
       UserInformation userInfoProto = head.getUserInfo();
       String effectiveUser = null;
       if (userInfoProto.hasEffectiveUser()) {
         effectiveUser = userInfoProto.getEffectiveUser();
       }
       String realUser = null;
       if (userInfoProto.hasRealUser()) {
         realUser = userInfoProto.getRealUser();
       }
       if (effectiveUser != null) {
         if (realUser != null) {
           UserGroupInformation realUserUgi =
               UserGroupInformation.createRemoteUser(realUser);
           ugi = UserGroupInformation.createProxyUser(effectiveUser, realUserUgi);
         } else {
           ugi = UserGroupInformation.createRemoteUser(effectiveUser);
         }
       }
       return ugi;
     }
   }
 
   /**
    * Datastructure for passing a {@link BlockingService} and its associated class of
    * protobuf service interface.  For example, a server that fielded what is defined
    * in the client protobuf service would pass in an implementation of the client blocking service
    * and then its ClientService.BlockingInterface.class.  Used checking connection setup.
    */
   public static class BlockingServiceAndInterface {
     private final BlockingService service;
     private final Class<?> serviceInterface;
     public BlockingServiceAndInterface(final BlockingService service,
         final Class<?> serviceInterface) {
       this.service = service;
       this.serviceInterface = serviceInterface;
     }
     public Class<?> getServiceInterface() {
       return this.serviceInterface;
     }
     public BlockingService getBlockingService() {
       return this.service;
     }
   }
 
   /**
    * Constructs a server listening on the named port and address.
    * @param server hosting instance of {@link Server}. We will do authentications if an
    * instance else pass null for no authentication check.
    * @param name Used keying this rpc servers' metrics and for naming the Listener thread.
    * @param services A list of services.
    * @param bindAddress Where to listen
    * @param conf
    * @param scheduler
    */
   public RpcServer(final Server server, final String name,
       final List<BlockingServiceAndInterface> services,
       final InetSocketAddress bindAddress, Configuration conf,
       RpcScheduler scheduler)
       throws IOException {
     this.reservoir = new BoundedByteBufferPool(
       conf.getInt("hbase.ipc.server.reservoir.max.buffer.size",  1024 * 1024),
       conf.getInt("hbase.ipc.server.reservoir.initial.buffer.size", 16 * 1024),
       // Make the max twice the number of handlers to be safe.
       conf.getInt("hbase.ipc.server.reservoir.initial.max",
         conf.getInt(HConstants.REGION_SERVER_HANDLER_COUNT,
           HConstants.DEFAULT_REGION_SERVER_HANDLER_COUNT) * 2));
     this.server = server;
     this.services = services;
     this.bindAddress = bindAddress;
     this.conf = conf;
     this.socketSendBufferSize = 0;
     this.maxQueueSize =
       this.conf.getInt("hbase.ipc.server.max.callqueue.size", DEFAULT_MAX_CALLQUEUE_SIZE);
     this.readThreads = conf.getInt("hbase.ipc.server.read.threadpool.size", 10);
     this.maxIdleTime = 2 * conf.getInt("hbase.ipc.client.connection.maxidletime", 1000);
     this.maxConnectionsToNuke = conf.getInt("hbase.ipc.client.kill.max", 10);
     this.thresholdIdleConnections = conf.getInt("hbase.ipc.client.idlethreshold", 4000);
     this.purgeTimeout = conf.getLong("hbase.ipc.client.call.purge.timeout",
       2 * HConstants.DEFAULT_HBASE_RPC_TIMEOUT);
     this.warnResponseTime = conf.getInt(WARN_RESPONSE_TIME, DEFAULT_WARN_RESPONSE_TIME);
     this.warnResponseSize = conf.getInt(WARN_RESPONSE_SIZE, DEFAULT_WARN_RESPONSE_SIZE);
 
     // Start the listener here and let it bind to the port
     listener = new Listener(name);
     this.port = listener.getAddress().getPort();
 
     this.metrics = new MetricsHBaseServer(name, new MetricsHBaseServerWrapperImpl(this));
     this.tcpNoDelay = conf.getBoolean("hbase.ipc.server.tcpnodelay", true);
     this.tcpKeepAlive = conf.getBoolean("hbase.ipc.server.tcpkeepalive", true);
 
     this.warnDelayedCalls = conf.getInt(WARN_DELAYED_CALLS, DEFAULT_WARN_DELAYED_CALLS);
     this.delayedCalls = new AtomicInteger(0);
     this.ipcUtil = new IPCUtil(conf);
 
 
     // Create the responder here
     responder = new Responder();
     this.authorize = conf.getBoolean(HADOOP_SECURITY_AUTHORIZATION, false);
     this.userProvider = UserProvider.instantiate(conf);
     this.isSecurityEnabled = userProvider.isHBaseSecurityEnabled();
     if (isSecurityEnabled) {
       HBaseSaslRpcServer.init(conf);
     }
     this.scheduler = scheduler;
     this.scheduler.init(new RpcSchedulerContext(this));
   }
 
   /**
    * Subclasses of HBaseServer can override this to provide their own
    * Connection implementations.
    */
   protected Connection getConnection(SocketChannel channel, long time) {
     return new Connection(channel, time);
   }
 
   /**
    * Setup response for the RPC Call.
    *
    * @param response buffer to serialize the response into
    * @param call {@link Call} to which we are setting up the response
    * @param error error message, if the call failed
    * @throws IOException
    */
   private void setupResponse(ByteArrayOutputStream response, Call call, Throwable t, String error)
   throws IOException {
     if (response != null) response.reset();
     call.setResponse(null, null, t, error);
   }
 
   protected void closeConnection(Connection connection) {
     synchronized (connectionList) {
       if (connectionList.remove(connection)) {
         numConnections--;
       }
     }
     connection.close();
   }
 
   Configuration getConf() {
     return conf;
   }
 
   /** Sets the socket buffer size used for responding to RPCs.
    * @param size send size
    */
   @Override
   public void setSocketSendBufSize(int size) { this.socketSendBufferSize = size; }
 
   @Override
   public boolean isStarted() {
     return this.started;
   }
 
   /** Starts the service.  Must be called before any calls will be handled. */
   @Override
   public synchronized void start() {
     if (started) return;
     authTokenSecretMgr = createSecretManager();
     if (authTokenSecretMgr != null) {
       setSecretManager(authTokenSecretMgr);
       authTokenSecretMgr.start();
     }
     this.authManager = new ServiceAuthorizationManager();
     HBasePolicyProvider.init(conf, authManager);
     responder.start();
     listener.start();
     scheduler.start();
     started = true;
   }
 
   @Override
   public void refreshAuthManager(PolicyProvider pp) {
     // Ignore warnings that this should be accessed in a static way instead of via an instance;
     // it'll break if you go via static route.
     this.authManager.refresh(this.conf, pp);
   }
 
   private AuthenticationTokenSecretManager createSecretManager() {
     if (!isSecurityEnabled) return null;
     if (server == null) return null;
     Configuration conf = server.getConfiguration();
     long keyUpdateInterval =
         conf.getLong("hbase.auth.key.update.interval", 24*60*60*1000);
     long maxAge =
         conf.getLong("hbase.auth.token.max.lifetime", 7*24*60*60*1000);
     return new AuthenticationTokenSecretManager(conf, server.getZooKeeper(),
         server.getServerName().toString(), keyUpdateInterval, maxAge);
   }
 
   public SecretManager<? extends TokenIdentifier> getSecretManager() {
     return this.secretManager;
   }
 
   @SuppressWarnings("unchecked")
   public void setSecretManager(SecretManager<? extends TokenIdentifier> secretManager) {
     this.secretManager = (SecretManager<TokenIdentifier>) secretManager;
   }
 
   /**
    * This is a server side method, which is invoked over RPC. On success
    * the return response has protobuf response payload. On failure, the
    * exception name and the stack trace are returned in the protobuf response.
    */
   @Override
   public Pair<Message, CellScanner> call(BlockingService service, MethodDescriptor md,
       Message param, CellScanner cellScanner, long receiveTime, MonitoredRPCHandler status)
   throws IOException {
     try {
       status.setRPC(md.getName(), new Object[]{param}, receiveTime);
       // TODO: Review after we add in encoded data blocks.
       status.setRPCPacket(param);
       status.resume("Servicing call");
       //get an instance of the method arg type
       long startTime = System.currentTimeMillis();
       PayloadCarryingRpcController controller = new PayloadCarryingRpcController(cellScanner);
       Message result = service.callBlockingMethod(md, controller, param);
       long endTime = System.currentTimeMillis();
       int processingTime = (int) (endTime - startTime);
       int qTime = (int) (startTime - receiveTime);
       int totalTime = (int) (endTime - receiveTime);
       if (LOG.isTraceEnabled()) {
         LOG.trace(CurCall.get().toString() +
             ", response " + TextFormat.shortDebugString(result) +
             " queueTime: " + qTime +
             " processingTime: " + processingTime +
             " totalTime: " + totalTime);
       }
       metrics.dequeuedCall(qTime);
       metrics.processedCall(processingTime);
       metrics.totalCall(totalTime);
       long responseSize = result.getSerializedSize();
       // log any RPC responses that are slower than the configured warn
       // response time or larger than configured warning size
       boolean tooSlow = (processingTime > warnResponseTime && warnResponseTime > -1);
       boolean tooLarge = (responseSize > warnResponseSize && warnResponseSize > -1);
       if (tooSlow || tooLarge) {
         // when tagging, we let TooLarge trump TooSmall to keep output simple
         // note that large responses will often also be slow.
         logResponse(new Object[]{param},
             md.getName(), md.getName() + "(" + param.getClass().getName() + ")",
             (tooLarge ? "TooLarge" : "TooSlow"),
             status.getClient(), startTime, processingTime, qTime,
             responseSize);
       }
       return new Pair<Message, CellScanner>(result, controller.cellScanner());
     } catch (Throwable e) {
       // The above callBlockingMethod will always return a SE.  Strip the SE wrapper before
       // putting it on the wire.  Its needed to adhere to the pb Service Interface but we don't
       // need to pass it over the wire.
       if (e instanceof ServiceException) {
         if (e.getCause() == null) {
           LOG.debug("Caught a ServiceException with null cause", e);
         } else {
           e = e.getCause();
         }
       }
 
       // increment the number of requests that were exceptions.
       metrics.exception(e);
 
       if (e instanceof LinkageError) throw new DoNotRetryIOException(e);
       if (e instanceof IOException) throw (IOException)e;
       LOG.error("Unexpected throwable object ", e);
       throw new IOException(e.getMessage(), e);
     }
   }
 
   /**
    * Logs an RPC response to the LOG file, producing valid JSON objects for
    * client Operations.
    * @param params The parameters received in the call.
    * @param methodName The name of the method invoked
    * @param call The string representation of the call
    * @param tag  The tag that will be used to indicate this event in the log.
    * @param clientAddress   The address of the client who made this call.
    * @param startTime       The time that the call was initiated, in ms.
    * @param processingTime  The duration that the call took to run, in ms.
    * @param qTime           The duration that the call spent on the queue
    *                        prior to being initiated, in ms.
    * @param responseSize    The size in bytes of the response buffer.
    */
   void logResponse(Object[] params, String methodName, String call, String tag,
       String clientAddress, long startTime, int processingTime, int qTime,
       long responseSize)
           throws IOException {
     // base information that is reported regardless of type of call
     Map<String, Object> responseInfo = new HashMap<String, Object>();
     responseInfo.put("starttimems", startTime);
     responseInfo.put("processingtimems", processingTime);
     responseInfo.put("queuetimems", qTime);
     responseInfo.put("responsesize", responseSize);
     responseInfo.put("client", clientAddress);
     responseInfo.put("class", server == null? "": server.getClass().getSimpleName());
     responseInfo.put("method", methodName);
     if (params.length == 2 && server instanceof HRegionServer &&
         params[0] instanceof byte[] &&
         params[1] instanceof Operation) {
       // if the slow process is a query, we want to log its table as well
       // as its own fingerprint
       TableName tableName = TableName.valueOf(
           HRegionInfo.parseRegionName((byte[]) params[0])[0]);
       responseInfo.put("table", tableName.getNameAsString());
       // annotate the response map with operation details
       responseInfo.putAll(((Operation) params[1]).toMap());
       // report to the log file
       LOG.warn("(operation" + tag + "): " +
                MAPPER.writeValueAsString(responseInfo));
     } else if (params.length == 1 && server instanceof HRegionServer &&
         params[0] instanceof Operation) {
       // annotate the response map with operation details
       responseInfo.putAll(((Operation) params[0]).toMap());
       // report to the log file
       LOG.warn("(operation" + tag + "): " +
                MAPPER.writeValueAsString(responseInfo));
     } else {
       // can't get JSON details, so just report call.toString() along with
       // a more generic tag.
       responseInfo.put("call", call);
       LOG.warn("(response" + tag + "): " + MAPPER.writeValueAsString(responseInfo));
     }
   }
 
   /** Stops the service.  No new calls will be handled after this is called. */
   @Override
   public synchronized void stop() {
     LOG.info("Stopping server on " + port);
     running = false;
     if (authTokenSecretMgr != null) {
       authTokenSecretMgr.stop();
       authTokenSecretMgr = null;
     }
     listener.interrupt();
     listener.doStop();
     responder.interrupt();
     scheduler.stop();
     notifyAll();
   }
 
   /** Wait for the server to be stopped.
    * Does not wait for all subthreads to finish.
    *  See {@link #stop()}.
    * @throws InterruptedException e
    */
   @Override
   public synchronized void join() throws InterruptedException {
     while (running) {
       wait();
     }
   }
 
   /**
    * Return the socket (ip+port) on which the RPC server is listening to. May return null if
    * the listener channel is closed.
    * @return the socket (ip+port) on which the RPC server is listening to, or null if this
    * information cannot be determined
    */
   @Override
   public synchronized InetSocketAddress getListenerAddress() {
     if (listener == null) {
       return null;
     }
     return listener.getAddress();
   }
 
   /**
    * Set the handler for calling out of RPC for error conditions.
    * @param handler the handler implementation
    */
   @Override
   public void setErrorHandler(HBaseRPCErrorHandler handler) {
     this.errorHandler = handler;
   }
 
   @Override
   public HBaseRPCErrorHandler getErrorHandler() {
     return this.errorHandler;
   }
 
   /**
    * Returns the metrics instance for reporting RPC call statistics
    */
   @Override
   public MetricsHBaseServer getMetrics() {
     return metrics;
   }
 
   @Override
   public void addCallSize(final long diff) {
     this.callQueueSize.add(diff);
   }
 
   /**
    * Authorize the incoming client connection.
    *
    * @param user client user
    * @param connection incoming connection
    * @param addr InetAddress of incoming connection
    * @throws org.apache.hadoop.security.authorize.AuthorizationException
    *         when the client isn't authorized to talk the protocol
    */
   public void authorize(UserGroupInformation user, ConnectionHeader connection, InetAddress addr)
   throws AuthorizationException {
     if (authorize) {
       Class<?> c = getServiceInterface(services, connection.getServiceName());
       this.authManager.authorize(user != null ? user : null, c, getConf(), addr);
     }
   }
 
   /**
    * When the read or write buffer size is larger than this limit, i/o will be
    * done in chunks of this size. Most RPC requests and responses would be
    * be smaller.
    */
   private static int NIO_BUFFER_LIMIT = 64 * 1024; //should not be more than 64KB.
 
   /**
    * This is a wrapper around {@link java.nio.channels.WritableByteChannel#write(java.nio.ByteBuffer)}.
    * If the amount of data is large, it writes to channel in smaller chunks.
    * This is to avoid jdk from creating many direct buffers as the size of
    * buffer increases. This also minimizes extra copies in NIO layer
    * as a result of multiple write operations required to write a large
    * buffer.
    *
    * @param channel writable byte channel to write to
    * @param bufferChain Chain of buffers to write
    * @return number of bytes written
    * @throws java.io.IOException e
    * @see java.nio.channels.WritableByteChannel#write(java.nio.ByteBuffer)
    */
   protected long channelWrite(GatheringByteChannel channel, BufferChain bufferChain)
   throws IOException {
     long count =  bufferChain.write(channel, NIO_BUFFER_LIMIT);
     if (count > 0) this.metrics.sentBytes(count);
     return count;
   }
 
   /**
    * This is a wrapper around {@link java.nio.channels.ReadableByteChannel#read(java.nio.ByteBuffer)}.
    * If the amount of data is large, it writes to channel in smaller chunks.
    * This is to avoid jdk from creating many direct buffers as the size of
    * ByteBuffer increases. There should not be any performance degredation.
    *
    * @param channel writable byte channel to write on
    * @param buffer buffer to write
    * @return number of bytes written
    * @throws java.io.IOException e
    * @see java.nio.channels.ReadableByteChannel#read(java.nio.ByteBuffer)
    */
   protected int channelRead(ReadableByteChannel channel,
                                    ByteBuffer buffer) throws IOException {
 
     int count = (buffer.remaining() <= NIO_BUFFER_LIMIT) ?
            channel.read(buffer) : channelIO(channel, null, buffer);
     if (count > 0) {
       metrics.receivedBytes(count);
     }
     return count;
   }
 
   /**
    * Helper for {@link #channelRead(java.nio.channels.ReadableByteChannel, java.nio.ByteBuffer)}
    * and {@link #channelWrite(GatheringByteChannel, BufferChain)}. Only
    * one of readCh or writeCh should be non-null.
    *
    * @param readCh read channel
    * @param writeCh write channel
    * @param buf buffer to read or write into/out of
    * @return bytes written
    * @throws java.io.IOException e
    * @see #channelRead(java.nio.channels.ReadableByteChannel, java.nio.ByteBuffer)
    * @see #channelWrite(GatheringByteChannel, BufferChain)
    */
   private static int channelIO(ReadableByteChannel readCh,
                                WritableByteChannel writeCh,
                                ByteBuffer buf) throws IOException {
 
     int originalLimit = buf.limit();
     int initialRemaining = buf.remaining();
     int ret = 0;
 
     while (buf.remaining() > 0) {
       try {
         int ioSize = Math.min(buf.remaining(), NIO_BUFFER_LIMIT);
         buf.limit(buf.position() + ioSize);
 
         ret = (readCh == null) ? writeCh.write(buf) : readCh.read(buf);
 
         if (ret < ioSize) {
           break;
         }
 
       } finally {
         buf.limit(originalLimit);
       }
     }
 
     int nBytes = initialRemaining - buf.remaining();
     return (nBytes > 0) ? nBytes : ret;
   }
 
   /**
    * Needed for features such as delayed calls.  We need to be able to store the current call
    * so that we can complete it later or ask questions of what is supported by the current ongoing
    * call.
    * @return An RpcCallContext backed by the currently ongoing call (gotten from a thread local)
    */
   public static RpcCallContext getCurrentCall() {
     return CurCall.get();
   }
 
   public static boolean isInRpcCallContext() {
     return CurCall.get() != null;
   }
 
   /**
    * Returns the user credentials associated with the current RPC request or
    * <code>null</code> if no credentials were provided.
    * @return A User
    */
   public static User getRequestUser() {
     RpcCallContext ctx = getCurrentCall();
     return ctx == null? null: ctx.getRequestUser();
   }
 
   /**
    * Returns the username for any user associated with the current RPC
    * request or <code>null</code> if no user is set.
    */
   public static String getRequestUserName() {
     User user = getRequestUser();
     return user == null? null: user.getShortName();
   }
 
   /**
    * @return Address of remote client if a request is ongoing, else null
    */
   public static InetAddress getRemoteAddress() {
     RpcCallContext ctx = getCurrentCall();
     return ctx == null? null: ctx.getRemoteAddress();
   }
 
   /**
    * @param serviceName Some arbitrary string that represents a 'service'.
    * @param services Available service instances
    * @return Matching BlockingServiceAndInterface pair
    */
   static BlockingServiceAndInterface getServiceAndInterface(
       final List<BlockingServiceAndInterface> services, final String serviceName) {
     for (BlockingServiceAndInterface bs : services) {
       if (bs.getBlockingService().getDescriptorForType().getName().equals(serviceName)) {
         return bs;
       }
     }
     return null;
   }
 
   /**
    * @param serviceName Some arbitrary string that represents a 'service'.
    * @param services Available services and their service interfaces.
    * @return Service interface class for <code>serviceName</code>
    */
   static Class<?> getServiceInterface(
       final List<BlockingServiceAndInterface> services,
       final String serviceName) {
     BlockingServiceAndInterface bsasi =
         getServiceAndInterface(services, serviceName);
     return bsasi == null? null: bsasi.getServiceInterface();
   }
 
   /**
    * @param serviceName Some arbitrary string that represents a 'service'.
    * @param services Available services and their service interfaces.
    * @return BlockingService that goes with the passed <code>serviceName</code>
    */
   static BlockingService getService(
       final List<BlockingServiceAndInterface> services,
       final String serviceName) {
     BlockingServiceAndInterface bsasi =
         getServiceAndInterface(services, serviceName);
     return bsasi == null? null: bsasi.getBlockingService();
   }
 
   static MonitoredRPCHandler getStatus() {
     // It is ugly the way we park status up in RpcServer.  Let it be for now.  TODO.
     MonitoredRPCHandler status = RpcServer.MONITORED_RPC.get();
     if (status != null) {
       return status;
     }
     status = TaskMonitor.get().createRPCStatus(Thread.currentThread().getName());
     status.pause("Waiting for a call");
     RpcServer.MONITORED_RPC.set(status);
     return status;
   }
 
   /** Returns the remote side ip address when invoked inside an RPC
    *  Returns null incase of an error.
    *  @return InetAddress
    */
   public static InetAddress getRemoteIp() {
     Call call = CurCall.get();
     if (call != null && call.connection.socket != null) {
       return call.connection.socket.getInetAddress();
     }
     return null;
   }
 
 
   /**
    * A convenience method to bind to a given address and report
    * better exceptions if the address is not a valid host.
    * @param socket the socket to bind
    * @param address the address to bind to
    * @param backlog the number of connections allowed in the queue
    * @throws BindException if the address can't be bound
    * @throws UnknownHostException if the address isn't a valid host name
    * @throws IOException other random errors from bind
    */
   public static void bind(ServerSocket socket, InetSocketAddress address,
                           int backlog) throws IOException {
     try {
       socket.bind(address, backlog);
     } catch (BindException e) {
       BindException bindException =
         new BindException("Problem binding to " + address + " : " +
             e.getMessage());
       bindException.initCause(e);
       throw bindException;
     } catch (SocketException e) {
       // If they try to bind to a different host's address, give a better
       // error message.
       if ("Unresolved address".equals(e.getMessage())) {
         throw new UnknownHostException("Invalid hostname for server: " +
                                        address.getHostName());
       }
       throw e;
     }
   }
 
   @Override
   public RpcScheduler getScheduler() {
     return scheduler;
   }
 }