org.apache.hadoop.hbase.ipc.RpcServer.java Source code

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/**
 * 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.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.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.atomic.AtomicInteger;

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.classification.InterfaceAudience;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.hbase.CellScanner;
import org.apache.hadoop.hbase.DoNotRetryIOException;
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.monitoring.MonitoredRPCHandler;
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.regionserver.HRegionServer;
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.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.AccessControlException;
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.htrace.TraceInfo;
import org.codehaus.jackson.map.ObjectMapper;

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.Message.Builder;
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 {@link Responder} to pull from and return result to client.
 *
 * @see RpcClient
 */
@InterfaceAudience.Private
public class RpcServer implements RpcServerInterface {
    // The logging package is deliberately outside of standard o.a.h.h package so it is not on
    // by default.
    public static final Log LOG = LogFactory.getLog("org.apache.hadoop.ipc.RpcServer");

    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;

    static final int BUFFER_INITIAL_SIZE = 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 isa;
    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 #startThreads()}, 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 calle to {@link #openServer()}.
     */
    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 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;

    /**
     * Datastructure that holds all necessary to a method invocation and then afterward, carries
     * the result.
     */
    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;

        Call(int id, final BlockingService service, final MethodDescriptor md, RequestHeader header, Message param,
                CellScanner cellScanner, Connection connection, Responder responder, long size, TraceInfo tinfo) {
            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;
        }

        @Override
        public String toString() {
            return toShortString() + " param: "
                    + (this.param != null ? ProtobufUtil.getShortTextFormat(this.param) : "") + " connection: "
                    + connection.toString();
        }

        protected RequestHeader getHeader() {
            return this.header;
        }

        /*
         * Short string representation without param info because param itself could be huge depends on
         * the payload of a command
         */
        @SuppressWarnings("deprecation")
        String toShortString() {
            String serviceName = this.connection.service != null
                    ? this.connection.service.getDescriptorForType().getName()
                    : "null";
            StringBuilder sb = new StringBuilder();
            sb.append("callId: ");
            sb.append(this.id);
            sb.append(" service: ");
            sb.append(serviceName);
            sb.append(" methodName: ");
            sb.append((this.md != null) ? this.md.getName() : "");
            sb.append(" size: ");
            sb.append(StringUtils.humanReadableInt(this.size));
            sb.append(" connection: ");
            sb.append(connection.toString());
            return sb.toString();
        }

        String toTraceString() {
            String serviceName = this.connection.service != null
                    ? this.connection.service.getDescriptorForType().getName()
                    : "";
            String methodName = (this.md != null) ? this.md.getName() : "";
            String result = serviceName + "." + methodName;
            return result;
        }

        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());
                }
                ByteBuffer cellBlock = ipcUtil.buildCellBlock(this.connection.codec,
                        this.connection.compressionCodec, cells);
                if (cellBlock != null) {
                    CellBlockMeta.Builder cellBlockBuilder = CellBlockMeta.newBuilder();
                    // Presumes the cellBlock bytebuffer has been flipped so limit has total size in it.
                    cellBlockBuilder.setLength(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())
                        + (cellBlock == null ? 0 : cellBlock.limit());
                ByteBuffer bbTotalSize = ByteBuffer.wrap(Bytes.toBytes(totalSize));
                bc = new BufferChain(bbTotalSize, bbHeader, bbResult, 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 (bc == null)
                return bc;
            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.isDebugEnabled())
                LOG.debug("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 {
            if (!this.delayResponse) {
                this.responder.doRespond(this);
            }
        }
    }

    /** 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 = conf.getInt("ipc.server.listen.queue.size", 128);

        private ExecutorService readPool;

        public Listener(final String name) throws IOException {
            super(name);
            // Create a new server socket and set to non blocking mode
            acceptChannel = ServerSocketChannel.open();
            acceptChannel.configureBlocking(false);

            // Bind the server socket to the local host and port
            bind(acceptChannel.socket(), isa, 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,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).");

            // 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();
            }

            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) {
                    SelectionKey key = null;
                    try {
                        readSelector.select();
                        while (adding) {
                            this.wait(1000);
                        }

                        Iterator<SelectionKey> iter = readSelector.selectedKeys().iterator();
                        while (iter.hasNext()) {
                            key = iter.next();
                            iter.remove();
                            if (key.isValid()) {
                                if (key.isReadable()) {
                                    doRead(key);
                                }
                            }
                            key = null;
                        }
                    } catch (InterruptedException e) {
                        LOG.debug("Interrupted while sleeping");
                        return;
                    } catch (IOException ex) {
                        LOG.error(getName() + ": error 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) {
                        }
                        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) {
                }

                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 = 0;
            Connection c = (Connection) key.attachment();
            if (c == null) {
                return;
            }
            c.setLastContact(System.currentTimeMillis());
            try {
                count = c.readAndProcess();
            } catch (InterruptedException ieo) {
                throw ieo;
            } catch (Exception e) {
                LOG.info(getName() + ": count of bytes read: " + count, e);
                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);
                // c = null;
            } else {
                c.setLastContact(System.currentTimeMillis());
            }
        }

        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 int pending; // connections waiting to register

        Responder() throws IOException {
            this.setName("RpcServer.responder");
            this.setDaemon(true);
            writeSelector = Selector.open(); // create a selector
            pending = 0;
        }

        @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);
                }
            }
        }

        private void doRunLoop() {
            long lastPurgeTime = 0; // last check for old calls.
            while (running) {
                try {
                    waitPending(); // If a channel is being registered, wait.
                    writeSelector.select(purgeTimeout);
                    Iterator<SelectionKey> iter = writeSelector.selectedKeys().iterator();
                    while (iter.hasNext()) {
                        SelectionKey key = iter.next();
                        iter.remove();
                        try {
                            if (key.isValid() && key.isWritable()) {
                                doAsyncWrite(key);
                            }
                        } catch (IOException e) {
                            LOG.info(getName() + ": asyncWrite", e);
                        }
                    }
                    long now = System.currentTimeMillis();
                    if (now < lastPurgeTime + purgeTimeout) {
                        continue;
                    }
                    lastPurgeTime = now;
                    //
                    // If there were some calls that have not been sent out for a
                    // long time, discard them.
                    //
                    if (LOG.isDebugEnabled())
                        LOG.debug(getName() + ": checking for old call responses.");
                    ArrayList<Call> calls;

                    // get the list of channels from list of keys.
                    synchronized (writeSelector.keys()) {
                        calls = new ArrayList<Call>(writeSelector.keys().size());
                        iter = writeSelector.keys().iterator();
                        while (iter.hasNext()) {
                            SelectionKey key = iter.next();
                            Call call = (Call) key.attachment();
                            if (call != null && key.channel() == call.connection.channel) {
                                calls.add(call);
                            }
                        }
                    }

                    for (Call call : calls) {
                        try {
                            doPurge(call, now);
                        } catch (IOException e) {
                            LOG.warn(getName() + ": error in purging old calls " + e);
                        }
                    }
                } 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));
                }
            }
            LOG.info(getName() + ": stopped");
        }

        private void doAsyncWrite(SelectionKey key) throws IOException {
            Call call = (Call) key.attachment();
            if (call == null) {
                return;
            }
            if (key.channel() != call.connection.channel) {
                throw new IOException("doAsyncWrite: bad channel");
            }

            synchronized (call.connection.responseQueue) {
                if (processResponse(call.connection.responseQueue, false)) {
                    try {
                        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);
                    }
                }
            }
        }

        //
        // Remove calls that have been pending in the responseQueue
        // for a long time.
        //
        private void doPurge(Call call, long now) throws IOException {
            synchronized (call.connection.responseQueue) {
                Iterator<Call> iter = call.connection.responseQueue.listIterator(0);
                while (iter.hasNext()) {
                    Call nextCall = iter.next();
                    if (now > nextCall.timestamp + purgeTimeout) {
                        closeConnection(nextCall.connection);
                        break;
                    }
                }
            }
        }

        // Processes one response. Returns true if there are no more pending
        // data for this channel.
        //
        private boolean processResponse(final LinkedList<Call> responseQueue, boolean inHandler)
                throws IOException {
            boolean error = true;
            boolean done = false; // there is more data for this channel.
            int numElements;
            Call call = null;
            try {
                //noinspection SynchronizationOnLocalVariableOrMethodParameter
                synchronized (responseQueue) {
                    //
                    // If there are no items for this channel, then we are done
                    //
                    numElements = responseQueue.size();
                    if (numElements == 0) {
                        error = false;
                        return true; // no more data for this channel.
                    }
                    //
                    // Extract the first call
                    //
                    call = responseQueue.removeFirst();
                    SocketChannel channel = call.connection.channel;
                    //
                    // Send as much data as we can in the non-blocking fashion
                    //
                    long numBytes = channelWrite(channel, call.response);
                    if (numBytes < 0) {
                        return true;
                    }
                    if (!call.response.hasRemaining()) {
                        call.connection.decRpcCount();
                        //noinspection RedundantIfStatement
                        if (numElements == 1) { // last call fully processes.
                            done = true; // no more data for this channel.
                        } else {
                            done = false; // more calls pending to be sent.
                        }
                        if (LOG.isDebugEnabled()) {
                            LOG.debug(getName() + ": callId: " + call.id + " wrote " + numBytes + " bytes.");
                        }
                    } else {
                        //
                        // If we were unable to write the entire response out, then
                        // insert in Selector queue.
                        //
                        call.connection.responseQueue.addFirst(call);

                        if (inHandler) {
                            // set the serve time when the response has to be sent later
                            call.timestamp = System.currentTimeMillis();
                            if (enqueueInSelector(call))
                                done = true;
                        }
                        if (LOG.isDebugEnabled()) {
                            LOG.debug(getName() + call.toShortString() + " partially sent, wrote " + numBytes
                                    + " bytes.");
                        }
                    }
                    error = false; // everything went off well
                }
            } finally {
                if (error && call != null) {
                    LOG.warn(getName() + call.toShortString() + ": output error -- closing");
                    done = true; // error. no more data for this channel.
                    closeConnection(call.connection);
                }
            }
            return done;
        }

        //
        // Enqueue for background thread to send responses out later.
        //
        private boolean enqueueInSelector(Call call) throws IOException {
            boolean done = false;
            incPending();
            try {
                // Wake up the thread blocked on select, only then can the call
                // to channel.register() complete.
                SocketChannel channel = call.connection.channel;
                writeSelector.wakeup();
                channel.register(writeSelector, SelectionKey.OP_WRITE, call);
            } catch (ClosedChannelException e) {
                //It's OK.  Channel might be closed else where.
                done = true;
            } finally {
                decPending();
            }
            return done;
        }

        //
        // Enqueue a response from the application.
        //
        void doRespond(Call call) throws IOException {
            // set the serve time when the response has to be sent later
            call.timestamp = System.currentTimeMillis();

            boolean doRegister = false;
            synchronized (call.connection.responseQueue) {
                call.connection.responseQueue.addLast(call);
                if (call.connection.responseQueue.size() == 1) {
                    doRegister = !processResponse(call.connection.responseQueue, false);
                }
            }
            if (doRegister) {
                enqueueInSelector(call);
            }
        }

        private synchronized void incPending() { // call waiting to be enqueued.
            pending++;
        }

        private synchronized void decPending() { // call done enqueueing.
            pending--;
            notify();
        }

        private synchronized void waitPending() throws InterruptedException {
            while (pending > 0) {
                wait();
            }
        }
    }

    @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 LinkedList<Call> responseQueue;
        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 AUTHROIZATION_FAILED_CALLID = -1;
        private final Call authFailedCall = new Call(AUTHROIZATION_FAILED_CALLID, null, null, null, null, null,
                this, null, 0, 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);

        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();
            this.responseQueue = new LinkedList<Call>();
            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 long getLastContact() {
            return lastContact;
        }

        /* 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 AccessControlException("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.isDebugEnabled())
                    LOG.debug("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 = null;
                try {
                    if (saslServer == null) {
                        switch (authMethod) {
                        case DIGEST:
                            if (secretManager == null) {
                                throw new AccessControlException(
                                        "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 AccessControlException(
                                        "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 AccessControlException("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) {
                }
            }
        }

        /**
         * Read off the wire.
         * @return Returns -1 if failure (and caller will close connection) else return how many
         * bytes were read and processed
         * @throws IOException
         * @throws InterruptedException
         */
        public int readAndProcess() throws IOException, InterruptedException {
            while (true) {
                // 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;
                if (this.dataLengthBuffer.remaining() > 0) {
                    count = channelRead(channel, this.dataLengthBuffer);
                    if (count < 0 || this.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) {
                    // Check for 'HBas' magic.
                    this.dataLengthBuffer.flip();
                    if (!HConstants.RPC_HEADER.equals(dataLengthBuffer)) {
                        return doBadPreambleHandling("Expected HEADER="
                                + Bytes.toStringBinary(HConstants.RPC_HEADER.array()) + " 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) {
                        AccessControlException ae = new AccessControlException("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;
                    }
                    connectionPreambleRead = true;
                    // Preamble checks out. Go around again to read actual connection header.
                    dataLengthBuffer.clear();
                    continue;
                }
                // 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) {
                        throw new IllegalArgumentException(
                                "Unexpected data length " + dataLength + "!! from " + getHostAddress());
                    }
                    data = ByteBuffer.allocate(dataLength);
                    incRpcCount(); // Increment the rpc count
                }
                count = channelRead(channel, data);
                if (count < 0) {
                    return count;
                } else if (data.remaining() == 0) {
                    dataLengthBuffer.clear();
                    data.flip();
                    if (skipInitialSaslHandshake) {
                        data = null;
                        skipInitialSaslHandshake = false;
                        continue;
                    }
                    boolean headerRead = connectionHeaderRead;
                    if (useSasl) {
                        saslReadAndProcess(data.array());
                    } else {
                        processOneRpc(data.array());
                    }
                    this.data = null;
                    if (!headerRead) {
                        continue;
                    }
                } else {
                    // More to read still; go around again.
                    if (LOG.isTraceEnabled())
                        LOG.trace("Continue to read rest of data " + data.remaining());
                    continue;
                }
                return count;
            }
        }

        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);
            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 AccessControlException("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);
                    }
                }
            }
        }

        /**
         * Set up cell block codecs
         * @param header
         * @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 = -1;
                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 AccessControlException("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();
            RequestHeader header = RequestHeader.newBuilder().mergeFrom(buf, offset, headerSize).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);
                ByteArrayOutputStream responseBuffer = new ByteArrayOutputStream();
                setupResponse(responseBuffer, callTooBig, new CallQueueTooBigException(),
                        "Call queue is full, is 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 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) {
                        param = builder.mergeFrom(buf, offset, paramSize).build();
                    }
                    offset += paramSize;
                }
                if (header.hasCellBlockMeta()) {
                    cellScanner = ipcUtil.createCellScanner(this.codec, this.compressionCodec, buf, offset,
                            buf.length);
                }
            } catch (Throwable t) {
                String msg = "Unable to read call parameter from client " + getHostAddress();
                LOG.warn(msg, 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);
                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);
            scheduler.dispatch(new CallRunner(RpcServer.this, call, userProvider));
        }

        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());
                if (LOG.isDebugEnabled()) {
                    LOG.debug("Authorized " + TextFormat.shortDebugString(connectionHeader));
                }
                metrics.authorizationSuccess();
            } catch (AuthorizationException ae) {
                LOG.debug("Connection authorization failed: " + ae.getMessage(), ae);
                metrics.authorizationFailure();
                setupResponse(authFailedResponse, authFailedCall, ae, ae.getMessage());
                responder.doRespond(authFailedCall);
                return false;
            }
            return true;
        }

        protected synchronized void close() {
            disposeSasl();
            data = null;
            this.dataLengthBuffer = 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 isa Where to listen
     * @param conf
     * @throws IOException
     */
    public RpcServer(final Server server, final String name, final List<BlockingServiceAndInterface> services,
            final InetSocketAddress isa, Configuration conf, RpcScheduler scheduler) throws IOException {
        this.server = server;
        this.services = services;
        this.isa = isa;
        this.conf = conf;
        this.socketSendBufferSize = 0;
        this.maxQueueSize = this.conf.getInt("ipc.server.max.callqueue.size", DEFAULT_MAX_CALLQUEUE_SIZE);
        this.readThreads = conf.getInt("ipc.server.read.threadpool.size", 10);
        this.maxIdleTime = 2 * conf.getInt("ipc.client.connection.maxidletime", 1000);
        this.maxConnectionsToNuke = conf.getInt("ipc.client.kill.max", 10);
        this.thresholdIdleConnections = conf.getInt("ipc.client.idlethreshold", 4000);
        this.purgeTimeout = conf.getLong("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("ipc.server.tcpnodelay", true);
        this.tcpKeepAlive = conf.getBoolean("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
     * @param t
     * @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;
        AuthenticationTokenSecretManager mgr = createSecretManager();
        if (mgr != null) {
            setSecretManager(mgr);
            mgr.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.
     */
    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);
            int processingTime = (int) (System.currentTimeMillis() - startTime);
            int qTime = (int) (startTime - receiveTime);
            if (LOG.isTraceEnabled()) {
                LOG.trace(CurCall.get().toString() + ", response " + TextFormat.shortDebugString(result)
                        + " queueTime: " + qTime + " processingTime: " + processingTime);
            }
            metrics.dequeuedCall(qTime);
            metrics.processedCall(processingTime);
            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.
                StringBuilder buffer = new StringBuilder(256);
                buffer.append(md.getName());
                buffer.append("(");
                buffer.append(param.getClass().getName());
                buffer.append(")");
                logResponse(new Object[] { param }, md.getName(), buffer.toString(),
                        (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)
                e = e.getCause();
            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;
        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.
     * @return the socket (ip+port) on which the RPC server is listening to.
     */
    @Override
    public synchronized InetSocketAddress getListenerAddress() {
        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
     */
    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 RpcCallConext backed by the currently ongoing call (gotten from a thread local)
     */
    public static RpcCallContext getCurrentCall() {
        return CurCall.get();
    }

    /**
     * @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();
    }

    /** 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;
    }

    /** Returns remote address as a string when invoked inside an RPC.
     *  Returns null in case of an error.
     *  @return String
     */
    public static String getRemoteAddress() {
        Call call = CurCall.get();
        if (call != null) {
            return call.connection.getHostAddress();
        }
        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;
        }
    }

    public RpcScheduler getScheduler() {
        return scheduler;
    }
}