org.apache98.hadoop.hbase.ipc.RpcClient.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.apache98.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.apache98.hadoop.hbase.ipc;

import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.FilterInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.ConnectException;
import java.net.InetSocketAddress;
import java.net.Socket;
import java.net.SocketAddress;
import java.net.SocketException;
import java.net.SocketTimeoutException;
import java.net.UnknownHostException;
import java.nio.ByteBuffer;
import java.security.PrivilegedExceptionAction;
import java.util.HashMap;
import java.util.Iterator;
import java.util.LinkedList;
import java.util.Map;
import java.util.Map.Entry;
import java.util.Random;
import java.util.concurrent.ConcurrentSkipListMap;
import java.util.concurrent.atomic.AtomicBoolean;
import java.util.concurrent.atomic.AtomicLong;

import javax.net.SocketFactory;
import javax.security.sasl.SaslException;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache98.hadoop.PackageNameFix;
import org.apache98.hadoop.conf.Configuration;
import org.apache98.hadoop.hbase.CellScanner;
import org.apache98.hadoop.hbase.DoNotRetryIOException;
import org.apache98.hadoop.hbase.HBaseIOException;
import org.apache98.hadoop.hbase.HConstants;
import org.apache98.hadoop.hbase.ServerName;
import org.apache98.hadoop.hbase.classification.InterfaceAudience;
import org.apache98.hadoop.hbase.classification.InterfaceStability;
import org.apache98.hadoop.hbase.codec.Codec;
import org.apache98.hadoop.hbase.codec.KeyValueCodec;
import org.apache98.hadoop.hbase.protobuf.ProtobufUtil;
import org.apache98.hadoop.hbase.protobuf.generated.AuthenticationProtos;
import org.apache98.hadoop.hbase.protobuf.generated.RPCProtos.CellBlockMeta;
import org.apache98.hadoop.hbase.protobuf.generated.RPCProtos.ConnectionHeader;
import org.apache98.hadoop.hbase.protobuf.generated.RPCProtos.ExceptionResponse;
import org.apache98.hadoop.hbase.protobuf.generated.RPCProtos.RequestHeader;
import org.apache98.hadoop.hbase.protobuf.generated.RPCProtos.ResponseHeader;
import org.apache98.hadoop.hbase.protobuf.generated.RPCProtos.UserInformation;
import org.apache98.hadoop.hbase.protobuf.generated.TracingProtos.RPCTInfo;
import org.apache98.hadoop.hbase.security.AuthMethod;
import org.apache98.hadoop.hbase.security.HBaseSaslRpcClient;
import org.apache98.hadoop.hbase.security.SaslUtil.QualityOfProtection;
import org.apache98.hadoop.hbase.security.SecurityInfo;
import org.apache98.hadoop.hbase.security.User;
import org.apache98.hadoop.hbase.security.UserProvider;
import org.apache98.hadoop.hbase.security.token.AuthenticationTokenSelector;
import org.apache98.hadoop.hbase.util.EnvironmentEdgeManager;
import org.apache98.hadoop.hbase.util.ExceptionUtil;
import org.apache98.hadoop.hbase.util.Pair;
import org.apache98.hadoop.hbase.util.PoolMap;
import org.apache98.hadoop.hbase.util.PoolMap.PoolType;
import org.apache98.hadoop.io.IOUtils;
import org.apache98.hadoop.io.Text;
import org.apache98.hadoop.io.compress.CompressionCodec;
import org.apache98.hadoop.ipc.RemoteException;
import org.apache98.hadoop.net.NetUtils;
import org.apache98.hadoop.security.SecurityUtil;
import org.apache98.hadoop.security.UserGroupInformation;
import org.apache98.hadoop.security.token.Token;
import org.apache98.hadoop.security.token.TokenIdentifier;
import org.apache98.hadoop.security.token.TokenSelector;
import org.cloudera.htrace.Span;
import org.cloudera.htrace.Trace;

import com.google.common.annotations.VisibleForTesting;
import com.google.protobuf98.BlockingRpcChannel;
import com.google.protobuf98.Descriptors.MethodDescriptor;
import com.google.protobuf98.Message;
import com.google.protobuf98.Message.Builder;
import com.google.protobuf98.RpcController;
import com.google.protobuf98.ServiceException;
import com.google.protobuf98.TextFormat;

/**
 * Does RPC against a cluster. Manages connections per regionserver in the cluster.
 * <p>
 * See HBaseServer
 */
@InterfaceAudience.Private
public class RpcClient {
    // The LOG key is intentionally not from this package to avoid ipc logging at DEBUG (all under
    // o.a.h.hbase is set to DEBUG as default).
    public static final Log LOG = LogFactory.getLog("org.apache98.hadoop.ipc.RpcClient");
    protected final PoolMap<ConnectionId, Connection> connections;

    protected int counter; // counter for call ids
    protected final AtomicBoolean running = new AtomicBoolean(true); // if client runs
    final protected Configuration conf;
    final protected int maxIdleTime; // connections will be culled if it was idle for
    // maxIdleTime microsecs
    final protected int maxRetries; // the max. no. of retries for socket connections
    final protected long failureSleep; // Time to sleep before retry on failure.
    protected final boolean tcpNoDelay; // if T then disable Nagle's Algorithm
    protected final boolean tcpKeepAlive; // if T then use keepalives
    protected int pingInterval; // how often sends ping to the server in msecs
    protected FailedServers failedServers;
    private final Codec codec;
    private final CompressionCodec compressor;
    private final IPCUtil ipcUtil;

    protected final SocketFactory socketFactory; // how to create sockets
    protected String clusterId;
    protected final SocketAddress localAddr;

    private final boolean fallbackAllowed;
    private UserProvider userProvider;

    final public static String PING_INTERVAL_NAME = "hbase.ipc.ping.interval";
    final public static String SOCKET_TIMEOUT = "hbase.ipc.socket.timeout";
    final static int DEFAULT_PING_INTERVAL = 60000; // 1 min
    final static int DEFAULT_SOCKET_TIMEOUT = 20000; // 20 seconds
    final static int PING_CALL_ID = -1;

    public final static String FAILED_SERVER_EXPIRY_KEY = "hbase.ipc.client.failed.servers.expiry";
    public final static int FAILED_SERVER_EXPIRY_DEFAULT = 2000;

    public static final String IPC_CLIENT_FALLBACK_TO_SIMPLE_AUTH_ALLOWED_KEY = "hbase.ipc.client.fallback-to-simple-auth-allowed";
    public static final boolean IPC_CLIENT_FALLBACK_TO_SIMPLE_AUTH_ALLOWED_DEFAULT = false;

    // thread-specific RPC timeout, which may override that of what was passed in.
    // This is used to change dynamically the timeout (for read only) when retrying: if
    // the time allowed for the operation is less than the usual socket timeout, then
    // we lower the timeout. This is subject to race conditions, and should be used with
    // extreme caution.
    private static ThreadLocal<Integer> rpcTimeout = new ThreadLocal<Integer>() {
        @Override
        protected Integer initialValue() {
            return HConstants.DEFAULT_HBASE_CLIENT_OPERATION_TIMEOUT;
        }
    };

    protected final static Map<AuthenticationProtos.TokenIdentifier.Kind, TokenSelector<? extends TokenIdentifier>> tokenHandlers = new HashMap<AuthenticationProtos.TokenIdentifier.Kind, TokenSelector<? extends TokenIdentifier>>();

    static {
        tokenHandlers.put(AuthenticationProtos.TokenIdentifier.Kind.HBASE_AUTH_TOKEN,
                new AuthenticationTokenSelector());
    }

    @VisibleForTesting
    public static String getDefaultCodec(final Configuration c) {
        // If "hbase.client.default.rpc.codec" is empty string -- you can't set it to null because
        // Configuration will complain -- then no default codec (and we'll pb everything). Else
        // default is KeyValueCodec
        return c.get("hbase.client.default.rpc.codec", KeyValueCodec.class.getCanonicalName());
    }

    public static int getRpcTimeout() {
        return rpcTimeout.get();
    }

    /**
     * Returns the lower of the thread-local RPC time from {@link #setRpcTimeout(int)} and the given
     * default timeout.
     */
    public static int getRpcTimeout(int defaultTimeout) {
        return Math.min(defaultTimeout, rpcTimeout.get());
    }

    public static void resetRpcTimeout() {
        rpcTimeout.remove();
    }

    /**
     * set the ping interval value in configuration
     * 
     * @param conf
     *            Configuration
     * @param pingInterval
     *            the ping interval
     */
    // Any reason we couldn't just do tcp keepalive instead of this pingery?
    // St.Ack 20130121
    public static void setPingInterval(Configuration conf, int pingInterval) {
        conf.setInt(PING_INTERVAL_NAME, pingInterval);
    }

    public static void setRpcTimeout(int t) {
        rpcTimeout.set(t);
    }

    /**
     * Set the socket timeout
     * 
     * @param conf
     *            Configuration
     * @param socketTimeout
     *            the socket timeout
     */
    public static void setSocketTimeout(Configuration conf, int socketTimeout) {
        conf.setInt(SOCKET_TIMEOUT, socketTimeout);
    }

    /**
     * Return the pool size specified in the configuration, which is applicable only if
     * the pool type is {@link PoolType#RoundRobin}.
     * 
     * @param config
     * @return the maximum pool size
     */
    protected static int getPoolSize(Configuration config) {
        return config.getInt(HConstants.HBASE_CLIENT_IPC_POOL_SIZE, 1);
    }

    /**
     * Return the pool type specified in the configuration, which must be set to
     * either {@link PoolType#RoundRobin} or {@link PoolType#ThreadLocal},
     * otherwise default to the former.
     * 
     * For applications with many user threads, use a small round-robin pool. For
     * applications with few user threads, you may want to try using a
     * thread-local pool. In any case, the number of {@link RpcClient} instances
     * should not exceed the operating system's hard limit on the number of
     * connections.
     * 
     * @param config
     *            configuration
     * @return either a {@link PoolType#RoundRobin} or {@link PoolType#ThreadLocal}
     */
    protected static PoolType getPoolType(Configuration config) {
        return PoolType.valueOf(config.get(HConstants.HBASE_CLIENT_IPC_POOL_TYPE), PoolType.RoundRobin,
                PoolType.ThreadLocal);
    }

    /**
     * Get the ping interval from configuration;
     * If not set in the configuration, return the default value.
     * 
     * @param conf
     *            Configuration
     * @return the ping interval
     */
    static int getPingInterval(Configuration conf) {
        return conf.getInt(PING_INTERVAL_NAME, conf.getInt("ipc.ping.interval", DEFAULT_PING_INTERVAL));
    }

    /**
     * @return the socket timeout
     */
    static int getSocketTimeout(Configuration conf) {
        return conf.getInt(SOCKET_TIMEOUT, conf.getInt("ipc.socket.timeout", DEFAULT_SOCKET_TIMEOUT));
    }

    /**
     * Encapsulate the ugly casting and RuntimeException conversion in private method.
     * 
     * @param conf
     * @return The compressor to use on this client.
     */
    private static CompressionCodec getCompressor(final Configuration conf) {
        String className = conf.get("hbase.client.rpc.compressor", null);
        if (className == null || className.isEmpty()) {
            return null;
        }
        try {
            return (CompressionCodec) Class.forName(className).newInstance();
        } catch (Exception e) {
            throw new RuntimeException("Failed getting compressor " + className, e);
        }
    }

    @edu.umd.cs.findbugs.annotations.SuppressWarnings(value = "IS2_INCONSISTENT_SYNC", justification = "Presume sync not needed setting socket timeout")
    private static void setSocketTimeout(final Socket socket, final int rpcTimeout)
            throws java.net.SocketException {
        if (socket == null) {
            return;
        }
        socket.setSoTimeout(rpcTimeout);
    }

    /**
     * Construct an IPC client for the cluster <code>clusterId</code> with the default SocketFactory
     * 
     * @param conf
     *            configuration
     * @param clusterId
     */
    public RpcClient(Configuration conf, String clusterId) {
        this(conf, clusterId, NetUtils.getDefaultSocketFactory(conf), null);
    }

    /**
     * Construct an IPC client for the cluster <code>clusterId</code> with the default SocketFactory
     * 
     * @param conf
     *            configuration
     * @param clusterId
     * @param localAddr
     *            client socket bind address.
     */
    public RpcClient(Configuration conf, String clusterId, SocketAddress localAddr) {
        this(conf, clusterId, NetUtils.getDefaultSocketFactory(conf), localAddr);
    }

    /**
     * Construct an IPC cluster client whose values are of the {@link Message} class.
     * 
     * @param conf
     *            configuration
     * @param clusterId
     * @param factory
     *            socket factory
     */
    RpcClient(Configuration conf, String clusterId, SocketFactory factory) {
        this(conf, clusterId, factory, null);
    }

    /**
     * Construct an IPC cluster client whose values are of the {@link Message} class.
     * 
     * @param conf
     *            configuration
     * @param clusterId
     * @param factory
     *            socket factory
     * @param localAddr
     *            client socket bind address
     */
    RpcClient(Configuration conf, String clusterId, SocketFactory factory, SocketAddress localAddr) {
        this.maxIdleTime = conf.getInt("hbase.ipc.client.connection.maxidletime", 10000); // 10s
        this.maxRetries = conf.getInt("hbase.ipc.client.connect.max.retries", 0);
        this.failureSleep = conf.getLong(HConstants.HBASE_CLIENT_PAUSE, HConstants.DEFAULT_HBASE_CLIENT_PAUSE);
        this.tcpNoDelay = conf.getBoolean("hbase.ipc.client.tcpnodelay", true);
        this.tcpKeepAlive = conf.getBoolean("hbase.ipc.client.tcpkeepalive", true);
        this.pingInterval = getPingInterval(conf);
        this.ipcUtil = new IPCUtil(conf);
        this.conf = conf;
        this.codec = getCodec();
        this.compressor = getCompressor(conf);
        this.socketFactory = factory;
        this.clusterId = clusterId != null ? clusterId : HConstants.CLUSTER_ID_DEFAULT;
        this.connections = new PoolMap<ConnectionId, Connection>(getPoolType(conf), getPoolSize(conf));
        this.failedServers = new FailedServers(conf);
        this.fallbackAllowed = conf.getBoolean(IPC_CLIENT_FALLBACK_TO_SIMPLE_AUTH_ALLOWED_KEY,
                IPC_CLIENT_FALLBACK_TO_SIMPLE_AUTH_ALLOWED_DEFAULT);
        this.localAddr = localAddr;
        this.userProvider = UserProvider.instantiate(conf);
        // login the server principal (if using secure Hadoop)
        if (LOG.isDebugEnabled()) {
            LOG.debug("Codec=" + this.codec + ", compressor=" + this.compressor + ", tcpKeepAlive="
                    + this.tcpKeepAlive + ", tcpNoDelay=" + this.tcpNoDelay + ", maxIdleTime=" + this.maxIdleTime
                    + ", maxRetries=" + this.maxRetries + ", fallbackAllowed=" + this.fallbackAllowed
                    + ", ping interval=" + this.pingInterval + "ms" + ", bind address="
                    + (this.localAddr != null ? this.localAddr : "null"));
        }
    }

    /**
     * Interrupt the connections to the given ip:port server. This should be called if the server
     * is known as actually dead. This will not prevent current operation to be retried, and,
     * depending on their own behavior, they may retry on the same server. This can be a feature,
     * for example at startup. In any case, they're likely to get connection refused (if the
     * process died) or no route to host: i.e. there next retries should be faster and with a
     * safe exception.
     */
    public void cancelConnections(String hostname, int port, IOException ioe) {
        synchronized (connections) {
            for (Connection connection : connections.values()) {
                if (connection.isAlive() && connection.getRemoteAddress().getPort() == port
                        && connection.getRemoteAddress().getHostName().equals(hostname)) {
                    LOG.info("The server on " + hostname + ":" + port + " is dead - stopping the connection "
                            + connection.remoteId);
                    connection.closeConnection();
                    // We could do a connection.interrupt(), but it's safer not to do it, as the
                    // interrupted exception behavior is not defined nor enforced enough.
                }
            }
        }
    }

    /**
     * Creates a "channel" that can be used by a blocking protobuf service. Useful setting up
     * protobuf blocking stubs.
     * 
     * @param sn
     * @param ticket
     * @param rpcTimeout
     * @return A blocking rpc channel that goes via this rpc client instance.
     */
    public BlockingRpcChannel createBlockingRpcChannel(final ServerName sn, final User ticket,
            final int rpcTimeout) {
        return new BlockingRpcChannelImplementation(this, sn, ticket, rpcTimeout);
    }

    /**
     * Stop all threads related to this client. No further calls may be made
     * using this client.
     */
    public void stop() {
        if (LOG.isDebugEnabled()) {
            LOG.debug("Stopping rpc client");
        }
        if (!running.compareAndSet(true, false)) {
            return;
        }

        // wake up all connections
        synchronized (connections) {
            for (Connection conn : connections.values()) {
                conn.interrupt();
            }
        }

        // wait until all connections are closed
        while (!connections.isEmpty()) {
            try {
                Thread.sleep(100);
            } catch (InterruptedException ignored) {
            }
        }
    }

    /**
     * Creates a connection. Can be overridden by a subclass for testing.
     * 
     * @param remoteId
     *            - the ConnectionId to use for the connection creation.
     */
    protected Connection createConnection(ConnectionId remoteId, final Codec codec,
            final CompressionCodec compressor) throws IOException {
        return new Connection(remoteId, codec, compressor);
    }

    /*
     * Get a connection from the pool, or create a new one and add it to the
     * pool. Connections to a given host/port are reused.
     */
    protected Connection getConnection(User ticket, Call call, InetSocketAddress addr, int rpcTimeout,
            final Codec codec, final CompressionCodec compressor) throws IOException, InterruptedException {
        if (!running.get()) {
            throw new StoppedRpcClientException();
        }
        Connection connection;
        ConnectionId remoteId = new ConnectionId(ticket, call.md.getService().getName(), addr, rpcTimeout);
        synchronized (connections) {
            connection = connections.get(remoteId);
            if (connection == null) {
                connection = createConnection(remoteId, this.codec, this.compressor);
                connections.put(remoteId, connection);
            }
        }
        connection.addCall(call);

        // we don't invoke the method below inside "synchronized (connections)"
        // block above. The reason for that is if the server happens to be slow,
        // it will take longer to establish a connection and that will slow the
        // entire system down.
        // Moreover, if the connection is currently created, there will be many threads
        // waiting here; as setupIOstreams is synchronized. If the connection fails with a
        // timeout, they will all fail simultaneously. This is checked in setupIOstreams.
        connection.setupIOstreams();
        return connection;
    }

    /**
     * Take an IOException and the address we were trying to connect to
     * and return an IOException with the input exception as the cause.
     * The new exception provides the stack trace of the place where
     * the exception is thrown and some extra diagnostics information.
     * If the exception is ConnectException or SocketTimeoutException,
     * return a new one of the same type; Otherwise return an IOException.
     * 
     * @param addr
     *            target address
     * @param exception
     *            the relevant exception
     * @return an exception to throw
     */
    protected IOException wrapException(InetSocketAddress addr, IOException exception) {
        if (exception instanceof ConnectException) {
            // connection refused; include the host:port in the error
            return (ConnectException) new ConnectException(
                    "Call to " + addr + " failed on connection exception: " + exception).initCause(exception);
        } else if (exception instanceof SocketTimeoutException) {
            return (SocketTimeoutException) new SocketTimeoutException(
                    "Call to " + addr + " failed because " + exception).initCause(exception);
        } else {
            return (IOException) new IOException("Call to " + addr + " failed on local exception: " + exception)
                    .initCause(exception);
        }
    }

    Pair<Message, CellScanner> call(MethodDescriptor md, Message param, CellScanner cells, Message returnType,
            User ticket, InetSocketAddress addr, int rpcTimeout) throws InterruptedException, IOException {
        return call(md, param, cells, returnType, ticket, addr, rpcTimeout, HConstants.NORMAL_QOS);
    }

    /**
     * Make a call, passing <code>param</code>, to the IPC server running at <code>address</code> which is servicing the
     * <code>protocol</code> protocol,
     * with the <code>ticket</code> credentials, returning the value.
     * Throws exceptions if there are network problems or if the remote code
     * threw an exception.
     * 
     * @param md
     * @param param
     * @param cells
     * @param addr
     * @param returnType
     * @param ticket
     *            Be careful which ticket you pass. A new user will mean a new Connection.
     *            {@link UserProvider#getCurrent()} makes a new instance of User each time so will be a
     *            new Connection each time.
     * @param rpcTimeout
     * @return A pair with the Message response and the Cell data (if any).
     * @throws InterruptedException
     * @throws IOException
     */
    Pair<Message, CellScanner> call(MethodDescriptor md, Message param, CellScanner cells, Message returnType,
            User ticket, InetSocketAddress addr, int rpcTimeout, int priority)
            throws InterruptedException, IOException {
        Call call = new Call(md, param, cells, returnType);
        Connection connection = getConnection(ticket, call, addr, rpcTimeout, this.codec, this.compressor);
        connection.writeRequest(call, priority); // send the parameter

        // noinspection SynchronizationOnLocalVariableOrMethodParameter
        synchronized (call) {
            while (!call.done) {
                if (connection.shouldCloseConnection.get()) {
                    throw new IOException("Unexpected closed connection");
                }
                call.wait(1000); // wait for the result
            }

            if (call.error != null) {
                if (call.error instanceof RemoteException) {
                    call.error.fillInStackTrace();
                    throw call.error;
                }
                // local exception
                throw wrapException(addr, call.error);
            }
            return new Pair<Message, CellScanner>(call.response, call.cells);
        }
    }

    /**
     * Make a blocking call. Throws exceptions if there are network problems or if the remote code
     * threw an exception.
     * 
     * @param md
     * @param controller
     * @param param
     * @param returnType
     * @param isa
     * @param ticket
     *            Be careful which ticket you pass. A new user will mean a new Connection.
     *            {@link UserProvider#getCurrent()} makes a new instance of User each time so will be a
     *            new Connection each time.
     * @param rpcTimeout
     * @return A pair with the Message response and the Cell data (if any).
     * @throws InterruptedException
     * @throws IOException
     */
    Message callBlockingMethod(MethodDescriptor md, RpcController controller, Message param, Message returnType,
            final User ticket, final InetSocketAddress isa, final int rpcTimeout) throws ServiceException {
        long startTime = 0;
        if (LOG.isTraceEnabled()) {
            startTime = System.currentTimeMillis();
        }
        PayloadCarryingRpcController pcrc = (PayloadCarryingRpcController) controller;
        CellScanner cells = null;
        if (pcrc != null) {
            cells = pcrc.cellScanner();
            // Clear it here so we don't by mistake try and these cells processing results.
            pcrc.setCellScanner(null);
        }
        Pair<Message, CellScanner> val = null;
        try {
            val = call(md, param, cells, returnType, ticket, isa, rpcTimeout,
                    pcrc != null ? pcrc.getPriority() : HConstants.NORMAL_QOS);
            if (pcrc != null) {
                // Shove the results into controller so can be carried across the proxy/pb service void.
                if (val.getSecond() != null) {
                    pcrc.setCellScanner(val.getSecond());
                }
            } else if (val.getSecond() != null) {
                throw new ServiceException("Client dropping data on the floor!");
            }

            if (LOG.isTraceEnabled()) {
                long callTime = System.currentTimeMillis() - startTime;
                if (LOG.isTraceEnabled()) {
                    LOG.trace("Call: " + md.getName() + ", callTime: " + callTime + "ms");
                }
            }
            return val.getFirst();
        } catch (Throwable e) {
            throw new ServiceException(e);
        }
    }

    /**
     * Encapsulate the ugly casting and RuntimeException conversion in private method.
     * 
     * @return Codec to use on this client.
     */
    Codec getCodec() {
        // For NO CODEC, "hbase.client.rpc.codec" must be configured with empty string AND
        // "hbase.client.default.rpc.codec" also -- because default is to do cell block encoding.
        String className = conf.get(HConstants.RPC_CODEC_CONF_KEY, getDefaultCodec(this.conf));
        if (className == null || className.length() == 0) {
            return null;
        }
        try {
            return (Codec) Class.forName(className).newInstance();
        } catch (Exception e) {
            throw new RuntimeException("Failed getting codec " + className, e);
        }
    }

    /**
     * Return the socket factory of this client
     * 
     * @return this client's socket factory
     */
    SocketFactory getSocketFactory() {
        return socketFactory;
    }

    /**
     * Blocking rpc channel that goes via hbase rpc.
     */
    // Public so can be subclassed for tests.
    public static class BlockingRpcChannelImplementation implements BlockingRpcChannel {
        private final InetSocketAddress isa;
        private volatile RpcClient rpcClient;
        private final int rpcTimeout;
        private final User ticket;

        protected BlockingRpcChannelImplementation(final RpcClient rpcClient, final ServerName sn,
                final User ticket, final int rpcTimeout) {
            this.isa = new InetSocketAddress(sn.getHostname(), sn.getPort());
            this.rpcClient = rpcClient;
            // Set the rpc timeout to be the minimum of configured timeout and whatever the current
            // thread local setting is.
            this.rpcTimeout = getRpcTimeout(rpcTimeout);
            this.ticket = ticket;
        }

        @Override
        public Message callBlockingMethod(MethodDescriptor md, RpcController controller, Message param,
                Message returnType) throws ServiceException {
            return this.rpcClient.callBlockingMethod(md, controller, param, returnType, this.ticket, this.isa,
                    this.rpcTimeout);
        }
    }

    /**
     * Client-side call timeout
     */
    @SuppressWarnings("serial")
    @InterfaceAudience.Public
    @InterfaceStability.Evolving
    public static class CallTimeoutException extends IOException {
        public CallTimeoutException(final String msg) {
            super(msg);
        }
    }

    @SuppressWarnings("serial")
    @InterfaceAudience.Public
    @InterfaceStability.Evolving
    // Shouldn't this be a DoNotRetryException? St.Ack 10/2/2013
    public static class FailedServerException extends HBaseIOException {
        public FailedServerException(String s) {
            super(s);
        }
    }

    /** A call waiting for a value. */
    protected class Call {
        final int id; // call id
        final Message param; // rpc request method param object
        /**
         * Optionally has cells when making call. Optionally has cells set on response. Used
         * passing cells to the rpc and receiving the response.
         */
        CellScanner cells;
        Message response; // value, null if error
        // The return type. Used to create shell into which we deserialize the response if any.
        Message responseDefaultType;
        IOException error; // exception, null if value
        boolean done; // true when call is done
        long startTime;
        final MethodDescriptor md;

        protected Call(final MethodDescriptor md, Message param, final CellScanner cells,
                final Message responseDefaultType) {
            this.param = param;
            this.md = md;
            this.cells = cells;
            this.startTime = System.currentTimeMillis();
            this.responseDefaultType = responseDefaultType;
            synchronized (RpcClient.this) {
                this.id = counter++;
            }
        }

        public long getStartTime() {
            return this.startTime;
        }

        /**
         * Set the exception when there is an error.
         * Notify the caller the call is done.
         * 
         * @param error
         *            exception thrown by the call; either local or remote
         */
        public void setException(IOException error) {
            this.error = error;
            callComplete();
        }

        /**
         * Set the return value when there is no error.
         * Notify the caller the call is done.
         * 
         * @param response
         *            return value of the call.
         * @param cells
         *            Can be null
         */
        public void setResponse(Message response, final CellScanner cells) {
            this.response = response;
            this.cells = cells;
            callComplete();
        }

        @Override
        public String toString() {
            return "callId: " + this.id + " methodName: " + this.md.getName() + " param {"
                    + (this.param != null ? ProtobufUtil.getShortTextFormat(this.param) : "") + "}";
        }

        /**
         * Indicate when the call is complete and the
         * value or error are available. Notifies by default.
         */
        protected synchronized void callComplete() {
            this.done = true;
            notify(); // notify caller
        }
    }

    /**
     * Thread that reads responses and notifies callers. Each connection owns a
     * socket connected to a remote address. Calls are multiplexed through this
     * socket: responses may be delivered out of order.
     */
    protected class Connection extends Thread {
        private ConnectionHeader header; // connection header
        protected ConnectionId remoteId;
        protected Socket socket = null; // connected socket
        protected DataInputStream in;
        protected DataOutputStream out;
        private InetSocketAddress server; // server ip:port
        private String serverPrincipal; // server's krb5 principal name
        private AuthMethod authMethod; // authentication method
        private boolean useSasl;
        private Token<? extends TokenIdentifier> token;
        private HBaseSaslRpcClient saslRpcClient;
        private int reloginMaxBackoff; // max pause before relogin on sasl failure
        private final Codec codec;
        private final CompressionCodec compressor;

        // currently active calls
        protected final ConcurrentSkipListMap<Integer, Call> calls = new ConcurrentSkipListMap<Integer, Call>();
        protected final AtomicLong lastActivity = new AtomicLong(); // last I/O activity time
        protected final AtomicBoolean shouldCloseConnection = new AtomicBoolean(); // indicate if the connection is closed
        protected IOException closeException; // close reason

        Connection(ConnectionId remoteId, final Codec codec, final CompressionCodec compressor) throws IOException {
            if (remoteId.getAddress().isUnresolved()) {
                throw new UnknownHostException("unknown host: " + remoteId.getAddress().getHostName());
            }
            this.server = remoteId.getAddress();
            this.codec = codec;
            this.compressor = compressor;

            UserGroupInformation ticket = remoteId.getTicket().getUGI();
            SecurityInfo securityInfo = SecurityInfo.getInfo(remoteId.getServiceName());
            this.useSasl = userProvider.isHBaseSecurityEnabled();
            if (useSasl && securityInfo != null) {
                AuthenticationProtos.TokenIdentifier.Kind tokenKind = securityInfo.getTokenKind();
                if (tokenKind != null) {
                    TokenSelector<? extends TokenIdentifier> tokenSelector = tokenHandlers.get(tokenKind);
                    if (tokenSelector != null) {
                        token = tokenSelector.selectToken(new Text(clusterId), ticket.getTokens());
                    } else if (LOG.isDebugEnabled()) {
                        LOG.debug("No token selector found for type " + tokenKind);
                    }
                }
                String serverKey = securityInfo.getServerPrincipal();
                if (serverKey == null) {
                    throw new IOException("Can't obtain server Kerberos config key from SecurityInfo");
                }
                serverPrincipal = SecurityUtil.getServerPrincipal(conf.get(serverKey),
                        server.getAddress().getCanonicalHostName().toLowerCase());
                if (LOG.isDebugEnabled()) {
                    LOG.debug("RPC Server Kerberos principal name for service=" + remoteId.getServiceName() + " is "
                            + serverPrincipal);
                }
            }

            if (!useSasl) {
                authMethod = AuthMethod.SIMPLE;
            } else if (token != null) {
                authMethod = AuthMethod.DIGEST;
            } else {
                authMethod = AuthMethod.KERBEROS;
            }

            if (LOG.isDebugEnabled()) {
                LOG.debug("Use " + authMethod + " authentication for service " + remoteId.serviceName + ", sasl="
                        + useSasl);
            }
            reloginMaxBackoff = conf.getInt("hbase.security.relogin.maxbackoff", 5000);
            this.remoteId = remoteId;

            ConnectionHeader.Builder builder = ConnectionHeader.newBuilder();
            builder.setServiceName(remoteId.getServiceName());
            UserInformation userInfoPB;
            if ((userInfoPB = getUserInfo(ticket)) != null) {
                builder.setUserInfo(userInfoPB);
            }
            if (this.codec != null) {
                String className = PackageNameFix.remove98(this.codec.getClass().getCanonicalName());
                builder.setCellBlockCodecClass(className);
            }
            if (this.compressor != null) {
                String className = PackageNameFix.remove98(this.compressor.getClass().getCanonicalName());
                builder.setCellBlockCompressorClass(className);
            }
            this.header = builder.build();

            this.setName("IPC Client (" + socketFactory.hashCode() + ") connection to "
                    + remoteId.getAddress().toString()
                    + ((ticket == null) ? " from an unknown user" : (" from " + ticket.getUserName())));
            this.setDaemon(true);
        }

        public InetSocketAddress getRemoteAddress() {
            return remoteId.getAddress();
        }

        @Override
        public void run() {
            if (LOG.isDebugEnabled()) {
                LOG.debug(getName() + ": starting, connections " + connections.size());
            }

            try {
                while (waitForWork()) { // Wait here for work - read or close connection
                    readResponse();
                }
            } catch (Throwable t) {
                LOG.warn(getName() + ": unexpected exception receiving call responses", t);
                markClosed(new IOException("Unexpected exception receiving call responses", t));
            }

            close();

            if (LOG.isDebugEnabled()) {
                LOG.debug(getName() + ": stopped, connections " + connections.size());
            }
        }

        /**
         * Add a call to this connection's call queue and notify
         * a listener; synchronized. If the connection is dead, the call is not added, and the
         * caller is notified.
         * This function can return a connection that is already marked as 'shouldCloseConnection'
         * It is up to the user code to check this status.
         * 
         * @param call
         *            to add
         */
        @edu.umd.cs.findbugs.annotations.SuppressWarnings(value = "NN_NAKED_NOTIFY", justification = "Notify because new call available for processing")
        protected synchronized void addCall(Call call) {
            // If the connection is about to close, we manage this as if the call was already added
            // to the connection calls list. If not, the connection creations are serialized, as
            // mentioned in HBASE-6364
            if (this.shouldCloseConnection.get()) {
                if (this.closeException == null) {
                    call.setException(new IOException(
                            "Call " + call.id + " not added as the connection " + remoteId + " is closing"));
                } else {
                    call.setException(this.closeException);
                }
                synchronized (call) {
                    call.notifyAll();
                }
            } else {
                calls.put(call.id, call);
                synchronized (call) {
                    notify();
                }
            }
        }

        /* Cleanup all calls and mark them as done */
        protected void cleanupCalls() {
            cleanupCalls(0);
        }

        @edu.umd.cs.findbugs.annotations.SuppressWarnings(value = "NN_NAKED_NOTIFY", justification = "Notify because timedout")
        protected void cleanupCalls(long rpcTimeout) {
            Iterator<Entry<Integer, Call>> itor = calls.entrySet().iterator();
            while (itor.hasNext()) {
                Call c = itor.next().getValue();
                long waitTime = System.currentTimeMillis() - c.getStartTime();
                if (waitTime >= rpcTimeout) {
                    if (this.closeException == null) {
                        // There may be no exception in the case that there are many calls
                        // being multiplexed over this connection and these are succeeding
                        // fine while this Call object is taking a long time to finish
                        // over on the server; e.g. I just asked the regionserver to bulk
                        // open 3k regions or its a big fat multiput into a heavily-loaded
                        // server (Perhaps this only happens at the extremes?)
                        this.closeException = new CallTimeoutException(
                                "Call id=" + c.id + ", waitTime=" + waitTime + ", rpcTimetout=" + rpcTimeout);
                    }
                    c.setException(this.closeException);
                    synchronized (c) {
                        c.notifyAll();
                    }
                    itor.remove();
                } else {
                    break;
                }
            }
            try {
                if (!calls.isEmpty()) {
                    Call firstCall = calls.get(calls.firstKey());
                    long maxWaitTime = System.currentTimeMillis() - firstCall.getStartTime();
                    if (maxWaitTime < rpcTimeout) {
                        rpcTimeout -= maxWaitTime;
                    }
                }
                if (!shouldCloseConnection.get()) {
                    closeException = null;
                    setSocketTimeout(socket, (int) rpcTimeout);
                }
            } catch (SocketException e) {
                LOG.debug("Couldn't lower timeout, which may result in longer than expected calls");
            }
        }

        /** Close the connection. */
        protected synchronized void close() {
            if (!shouldCloseConnection.get()) {
                LOG.error(getName() + ": the connection is not in the closed state");
                return;
            }

            // release the resources
            // first thing to do;take the connection out of the connection list
            synchronized (connections) {
                connections.removeValue(remoteId, this);
            }

            // close the streams and therefore the socket
            if (this.out != null) {
                synchronized (this.out) {
                    IOUtils.closeStream(out);
                    this.out = null;
                }
            }
            IOUtils.closeStream(in);
            this.in = null;
            disposeSasl();

            // clean up all calls
            if (closeException == null) {
                if (!calls.isEmpty()) {
                    LOG.warn(getName() + ": connection is closed for no cause and calls are not empty. "
                            + "#Calls: " + calls.size());

                    // clean up calls anyway
                    closeException = new IOException("Unexpected closed connection");
                    cleanupCalls();
                }
            } else {
                // log the info
                if (LOG.isDebugEnabled()) {
                    LOG.debug(getName() + ": closing ipc connection to " + server + ": "
                            + closeException.getMessage(), closeException);
                }

                // cleanup calls
                cleanupCalls();
            }
            if (LOG.isDebugEnabled()) {
                LOG.debug(getName() + ": closed");
            }
        }

        protected void closeConnection() {
            if (socket == null) {
                return;
            }

            // close the current connection
            try {
                if (socket.getOutputStream() != null) {
                    socket.getOutputStream().close();
                }
            } catch (IOException ignored) { // Can happen if the socket is already closed
            }
            try {
                if (socket.getInputStream() != null) {
                    socket.getInputStream().close();
                }
            } catch (IOException ignored) { // Can happen if the socket is already closed
            }
            try {
                if (socket.getChannel() != null) {
                    socket.getChannel().close();
                }
            } catch (IOException ignored) { // Can happen if the socket is already closed
            }
            try {
                socket.close();
            } catch (IOException e) {
                LOG.warn("Not able to close a socket", e);
            }

            // set socket to null so that the next call to setupIOstreams
            // can start the process of connect all over again.
            socket = null;
        }

        protected synchronized void markClosed(IOException e) {
            if (shouldCloseConnection.compareAndSet(false, true)) {
                closeException = e;
                notifyAll();
            }
        }

        /*
         * Receive a response.
         * Because only one receiver, so no synchronization on in.
         */
        protected void readResponse() {
            if (shouldCloseConnection.get()) {
                return;
            }
            touch();
            int totalSize = -1;
            try {
                // See HBaseServer.Call.setResponse for where we write out the response.
                // Total size of the response. Unused. But have to read it in anyways.
                totalSize = in.readInt();

                // Read the header
                ResponseHeader responseHeader = ResponseHeader.parseDelimitedFrom(in);
                int id = responseHeader.getCallId();
                if (LOG.isDebugEnabled()) {
                    LOG.debug(getName() + ": got response header " + TextFormat.shortDebugString(responseHeader)
                            + ", totalSize: " + totalSize + " bytes");
                }
                Call call = calls.get(id);
                if (call == null) {
                    // So we got a response for which we have no corresponding 'call' here on the client-side.
                    // We probably timed out waiting, cleaned up all references, and now the server decides
                    // to return a response. There is nothing we can do w/ the response at this stage. Clean
                    // out the wire of the response so its out of the way and we can get other responses on
                    // this connection.
                    int readSoFar = IPCUtil.getTotalSizeWhenWrittenDelimited(responseHeader);
                    int whatIsLeftToRead = totalSize - readSoFar;
                    LOG.debug("Unknown callId: " + id + ", skipping over this response of " + whatIsLeftToRead
                            + " bytes");
                    IOUtils.skipFully(in, whatIsLeftToRead);
                }
                if (responseHeader.hasException()) {
                    ExceptionResponse exceptionResponse = responseHeader.getException();
                    RemoteException re = createRemoteException(exceptionResponse);
                    if (isFatalConnectionException(exceptionResponse)) {
                        markClosed(re);
                    } else {
                        if (call != null) {
                            call.setException(re);
                        }
                    }
                } else {
                    Message value = null;
                    // Call may be null because it may have timedout and been cleaned up on this side already
                    if (call != null && call.responseDefaultType != null) {
                        Builder builder = call.responseDefaultType.newBuilderForType();
                        builder.mergeDelimitedFrom(in);
                        value = builder.build();
                    }
                    CellScanner cellBlockScanner = null;
                    if (responseHeader.hasCellBlockMeta()) {
                        int size = responseHeader.getCellBlockMeta().getLength();
                        byte[] cellBlock = new byte[size];
                        IOUtils.readFully(this.in, cellBlock, 0, cellBlock.length);
                        cellBlockScanner = ipcUtil.createCellScanner(this.codec, this.compressor, cellBlock);
                    }
                    // it's possible that this call may have been cleaned up due to a RPC
                    // timeout, so check if it still exists before setting the value.
                    if (call != null) {
                        call.setResponse(value, cellBlockScanner);
                    }
                }
                if (call != null) {
                    calls.remove(id);
                }
            } catch (IOException e) {
                if (e instanceof SocketTimeoutException && remoteId.rpcTimeout > 0) {
                    // Clean up open calls but don't treat this as a fatal condition,
                    // since we expect certain responses to not make it by the specified
                    // {@link ConnectionId#rpcTimeout}.
                    closeException = e;
                } else {
                    // Treat this as a fatal condition and close this connection
                    markClosed(e);
                }
            } finally {
                if (remoteId.rpcTimeout > 0) {
                    cleanupCalls(remoteId.rpcTimeout);
                }
            }
        }

        /*
         * Send a ping to the server if the time elapsed
         * since last I/O activity is equal to or greater than the ping interval
         */
        protected synchronized void sendPing() throws IOException {
            // Can we do tcp keepalive instead of this pinging?
            long curTime = System.currentTimeMillis();
            if (curTime - lastActivity.get() >= pingInterval) {
                lastActivity.set(curTime);
                // noinspection SynchronizeOnNonFinalField
                synchronized (this.out) {
                    out.writeInt(PING_CALL_ID);
                    out.flush();
                }
            }
        }

        protected synchronized void setupConnection() throws IOException {
            short ioFailures = 0;
            short timeoutFailures = 0;
            while (true) {
                try {
                    this.socket = socketFactory.createSocket();
                    this.socket.setTcpNoDelay(tcpNoDelay);
                    this.socket.setKeepAlive(tcpKeepAlive);
                    if (localAddr != null) {
                        this.socket.bind(localAddr);
                    }
                    // connection time out is 20s
                    NetUtils.connect(this.socket, remoteId.getAddress(), getSocketTimeout(conf));
                    if (remoteId.rpcTimeout > 0) {
                        pingInterval = remoteId.rpcTimeout; // overwrite pingInterval
                    }
                    this.socket.setSoTimeout(pingInterval);
                    return;
                } catch (SocketTimeoutException toe) {
                    /*
                     * The max number of retries is 45,
                     * which amounts to 20s*45 = 15 minutes retries.
                     */
                    handleConnectionFailure(timeoutFailures++, maxRetries, toe);
                } catch (IOException ie) {
                    handleConnectionFailure(ioFailures++, maxRetries, ie);
                }
            }
        }

        protected synchronized void setupIOstreams() throws IOException, InterruptedException {
            if (socket != null || shouldCloseConnection.get()) {
                return;
            }

            if (failedServers.isFailedServer(remoteId.getAddress())) {
                if (LOG.isDebugEnabled()) {
                    LOG.debug("Not trying to connect to " + server + " this server is in the failed servers list");
                }
                IOException e = new FailedServerException("This server is in the failed servers list: " + server);
                markClosed(e);
                close();
                throw e;
            }

            try {
                if (LOG.isDebugEnabled()) {
                    LOG.debug("Connecting to " + server);
                }
                short numRetries = 0;
                final short MAX_RETRIES = 5;
                Random rand = null;
                while (true) {
                    setupConnection();
                    InputStream inStream = NetUtils.getInputStream(socket);
                    // This creates a socket with a write timeout. This timeout cannot be changed,
                    // RpcClient allows to change the timeout dynamically, but we can only
                    // change the read timeout today.
                    OutputStream outStream = NetUtils.getOutputStream(socket, pingInterval);
                    // Write out the preamble -- MAGIC, version, and auth to use.
                    writeConnectionHeaderPreamble(outStream);
                    if (useSasl) {
                        final InputStream in2 = inStream;
                        final OutputStream out2 = outStream;
                        UserGroupInformation ticket = remoteId.getTicket().getUGI();
                        if (authMethod == AuthMethod.KERBEROS) {
                            if (ticket != null && ticket.getRealUser() != null) {
                                ticket = ticket.getRealUser();
                            }
                        }
                        boolean continueSasl = false;
                        if (ticket == null) {
                            throw new FatalConnectionException("ticket/user is null");
                        }
                        try {
                            continueSasl = ticket.doAs(new PrivilegedExceptionAction<Boolean>() {
                                @Override
                                public Boolean run() throws IOException {
                                    return setupSaslConnection(in2, out2);
                                }
                            });
                        } catch (Exception ex) {
                            if (rand == null) {
                                rand = new Random();
                            }
                            handleSaslConnectionFailure(numRetries++, MAX_RETRIES, ex, rand, ticket);
                            continue;
                        }
                        if (continueSasl) {
                            // Sasl connect is successful. Let's set up Sasl i/o streams.
                            inStream = saslRpcClient.getInputStream(inStream);
                            outStream = saslRpcClient.getOutputStream(outStream);
                        } else {
                            // fall back to simple auth because server told us so.
                            authMethod = AuthMethod.SIMPLE;
                            useSasl = false;
                        }
                    }
                    this.in = new DataInputStream(new BufferedInputStream(new PingInputStream(inStream)));
                    this.out = new DataOutputStream(new BufferedOutputStream(outStream));
                    // Now write out the connection header
                    writeConnectionHeader();

                    // update last activity time
                    touch();

                    // start the receiver thread after the socket connection has been set up
                    start();
                    return;
                }
            } catch (Throwable t) {
                failedServers.addToFailedServers(remoteId.address);
                IOException e = null;
                if (t instanceof LinkageError) {
                    // probably the hbase hadoop version does not match the running hadoop version
                    e = new DoNotRetryIOException(t);
                    markClosed(e);
                } else if (t instanceof IOException) {
                    e = (IOException) t;
                    markClosed(e);
                } else {
                    e = new IOException("Could not set up IO Streams", t);
                    markClosed(e);
                }
                close();
                throw e;
            }
        }

        /** Update lastActivity with the current time. */
        protected void touch() {
            lastActivity.set(System.currentTimeMillis());
        }

        /*
         * wait till someone signals us to start reading RPC response or
         * it is idle too long, it is marked as to be closed,
         * or the client is marked as not running.
         * 
         * Return true if it is time to read a response; false otherwise.
         */
        protected synchronized boolean waitForWork() {
            if (calls.isEmpty() && !shouldCloseConnection.get() && running.get()) {
                long timeout = maxIdleTime - (System.currentTimeMillis() - lastActivity.get());
                if (timeout > 0) {
                    try {
                        wait(timeout);
                    } catch (InterruptedException ie) {
                        Thread.currentThread().interrupt();
                    }
                }
            }

            if (!calls.isEmpty() && !shouldCloseConnection.get() && running.get()) {
                return true;
            } else if (shouldCloseConnection.get()) {
                return false;
            } else if (calls.isEmpty()) { // idle connection closed or stopped
                markClosed(null);
                return false;
            } else { // get stopped but there are still pending requests
                markClosed((IOException) new IOException().initCause(new InterruptedException()));
                return false;
            }
        }

        /**
         * Initiates a call by sending the parameter to the remote server.
         * Note: this is not called from the Connection thread, but by other
         * threads.
         * 
         * @param call
         * @param priority
         * @see #readResponse()
         */
        protected void writeRequest(Call call, final int priority) {
            if (shouldCloseConnection.get()) {
                return;
            }
            try {
                RequestHeader.Builder builder = RequestHeader.newBuilder();
                builder.setCallId(call.id);
                if (Trace.isTracing()) {
                    Span s = Trace.currentSpan();
                    builder.setTraceInfo(
                            RPCTInfo.newBuilder().setParentId(s.getSpanId()).setTraceId(s.getTraceId()));
                }
                builder.setMethodName(call.md.getName());
                builder.setRequestParam(call.param != null);
                ByteBuffer cellBlock = ipcUtil.buildCellBlock(this.codec, this.compressor, call.cells);
                if (cellBlock != null) {
                    CellBlockMeta.Builder cellBlockBuilder = CellBlockMeta.newBuilder();
                    cellBlockBuilder.setLength(cellBlock.limit());
                    builder.setCellBlockMeta(cellBlockBuilder.build());
                }
                // Only pass priority if there one. Let zero be same as no priority.
                if (priority != 0) {
                    builder.setPriority(priority);
                }
                // noinspection SynchronizeOnNonFinalField
                RequestHeader header = builder.build();
                synchronized (this.out) { // FindBugs IS2_INCONSISTENT_SYNC
                    IPCUtil.write(this.out, header, call.param, cellBlock);
                }
                if (LOG.isDebugEnabled()) {
                    LOG.debug(getName() + ": wrote request header " + TextFormat.shortDebugString(header));
                }
            } catch (IOException e) {
                synchronized (this) {
                    if (!shouldCloseConnection.get()) {
                        markClosed(e);
                        interrupt();
                    }
                }
            }
        }

        /**
         * @param e
         * @return RemoteException made from passed <code>e</code>
         */
        private RemoteException createRemoteException(final ExceptionResponse e) {
            String innerExceptionClassName = e.getExceptionClassName();
            boolean doNotRetry = e.getDoNotRetry();
            return e.hasHostname() ?
            // If a hostname then add it to the RemoteWithExtrasException
                    new RemoteWithExtrasException(innerExceptionClassName, e.getStackTrace(), e.getHostname(),
                            e.getPort(), doNotRetry)
                    : new RemoteWithExtrasException(innerExceptionClassName, e.getStackTrace(), doNotRetry);
        }

        private synchronized void disposeSasl() {
            if (saslRpcClient != null) {
                try {
                    saslRpcClient.dispose();
                    saslRpcClient = null;
                } catch (IOException ioe) {
                    LOG.error("Error disposing of SASL client", ioe);
                }
            }
        }

        private UserInformation getUserInfo(UserGroupInformation ugi) {
            if (ugi == null || authMethod == AuthMethod.DIGEST) {
                // Don't send user for token auth
                return null;
            }
            UserInformation.Builder userInfoPB = UserInformation.newBuilder();
            if (authMethod == AuthMethod.KERBEROS) {
                // Send effective user for Kerberos auth
                userInfoPB.setEffectiveUser(ugi.getUserName());
            } else if (authMethod == AuthMethod.SIMPLE) {
                // Send both effective user and real user for simple auth
                userInfoPB.setEffectiveUser(ugi.getUserName());
                if (ugi.getRealUser() != null) {
                    userInfoPB.setRealUser(ugi.getRealUser().getUserName());
                }
            }
            return userInfoPB.build();
        }

        /**
         * Handle connection failures
         * 
         * If the current number of retries is equal to the max number of retries,
         * stop retrying and throw the exception; Otherwise backoff N seconds and
         * try connecting again.
         * 
         * This Method is only called from inside setupIOstreams(), which is
         * synchronized. Hence the sleep is synchronized; the locks will be retained.
         * 
         * @param curRetries
         *            current number of retries
         * @param maxRetries
         *            max number of retries allowed
         * @param ioe
         *            failure reason
         * @throws IOException
         *             if max number of retries is reached
         */
        private void handleConnectionFailure(int curRetries, int maxRetries, IOException ioe) throws IOException {
            closeConnection();

            // throw the exception if the maximum number of retries is reached
            if (curRetries >= maxRetries || ExceptionUtil.isInterrupt(ioe)) {
                throw ioe;
            }

            // otherwise back off and retry
            try {
                Thread.sleep(failureSleep);
            } catch (InterruptedException ie) {
                ExceptionUtil.rethrowIfInterrupt(ie);
            }

            LOG.info("Retrying connect to server: " + remoteId.getAddress() + " after sleeping " + failureSleep
                    + "ms. Already tried " + curRetries + " time(s).");
        }

        /**
         * If multiple clients with the same principal try to connect
         * to the same server at the same time, the server assumes a
         * replay attack is in progress. This is a feature of kerberos.
         * In order to work around this, what is done is that the client
         * backs off randomly and tries to initiate the connection
         * again.
         * The other problem is to do with ticket expiry. To handle that,
         * a relogin is attempted.
         * <p>
         * The retry logic is governed by the {@link #shouldAuthenticateOverKrb} method. In case when the user doesn't
         * have valid credentials, we don't need to retry (from cache or ticket). In such cases, it is prudent to throw
         * a runtime exception when we receive a SaslException from the underlying authentication implementation, so
         * there is no retry from other high level (for eg, HCM or HBaseAdmin).
         * </p>
         */
        private synchronized void handleSaslConnectionFailure(final int currRetries, final int maxRetries,
                final Exception ex, final Random rand, final UserGroupInformation user)
                throws IOException, InterruptedException {
            user.doAs(new PrivilegedExceptionAction<Object>() {
                @Override
                public Object run() throws IOException, InterruptedException {
                    closeConnection();
                    if (shouldAuthenticateOverKrb()) {
                        if (currRetries < maxRetries) {
                            LOG.debug("Exception encountered while connecting to " + "the server : " + ex);
                            // try re-login
                            if (UserGroupInformation.isLoginKeytabBased()) {
                                UserGroupInformation.getLoginUser().reloginFromKeytab();
                            } else {
                                UserGroupInformation.getLoginUser().reloginFromTicketCache();
                            }
                            disposeSasl();
                            // have granularity of milliseconds
                            // we are sleeping with the Connection lock held but since this
                            // connection instance is being used for connecting to the server
                            // in question, it is okay
                            Thread.sleep((rand.nextInt(reloginMaxBackoff) + 1));
                            return null;
                        } else {
                            String msg = "Couldn't setup connection for "
                                    + UserGroupInformation.getLoginUser().getUserName() + " to " + serverPrincipal;
                            LOG.warn(msg);
                            throw (IOException) new IOException(msg).initCause(ex);
                        }
                    } else {
                        LOG.warn("Exception encountered while connecting to " + "the server : " + ex);
                    }
                    if (ex instanceof RemoteException) {
                        throw (RemoteException) ex;
                    }
                    if (ex instanceof SaslException) {
                        String msg = "SASL authentication failed."
                                + " The most likely cause is missing or invalid credentials."
                                + " Consider 'kinit'.";
                        LOG.fatal(msg, ex);
                        throw new RuntimeException(msg, ex);
                    }
                    throw new IOException(ex);
                }
            });
        }

        /**
         * @param e
         * @return True if the exception is a fatal connection exception.
         */
        private boolean isFatalConnectionException(final ExceptionResponse e) {
            return e.getExceptionClassName().equals(FatalConnectionException.class.getName());
        }

        private synchronized boolean setupSaslConnection(final InputStream in2, final OutputStream out2)
                throws IOException {
            saslRpcClient = new HBaseSaslRpcClient(authMethod, token, serverPrincipal, fallbackAllowed,
                    conf.get("hbase.rpc.protection", QualityOfProtection.AUTHENTICATION.name().toLowerCase()));
            return saslRpcClient.saslConnect(in2, out2);
        }

        private synchronized boolean shouldAuthenticateOverKrb() throws IOException {
            UserGroupInformation loginUser = UserGroupInformation.getLoginUser();
            UserGroupInformation currentUser = UserGroupInformation.getCurrentUser();
            UserGroupInformation realUser = currentUser.getRealUser();
            return authMethod == AuthMethod.KERBEROS && loginUser != null &&
            // Make sure user logged in using Kerberos either keytab or TGT
                    loginUser.hasKerberosCredentials() &&
                    // relogin only in case it is the login user (e.g. JT)
                    // or superuser (like oozie).
                    (loginUser.equals(currentUser) || loginUser.equals(realUser));
        }

        /**
         * Write the connection header.
         * Out is not synchronized because only the first thread does this.
         */
        private void writeConnectionHeader() throws IOException {
            synchronized (this.out) {
                this.out.writeInt(this.header.getSerializedSize());
                this.header.writeTo(this.out);
                this.out.flush();
            }
        }

        /**
         * Write the RPC header: <MAGIC WORD -- 'HBas'> <ONEBYTE_VERSION> <ONEBYTE_AUTH_TYPE>
         */
        private void writeConnectionHeaderPreamble(OutputStream outStream) throws IOException {
            // Assemble the preamble up in a buffer first and then send it. Writing individual elements,
            // they are getting sent across piecemeal according to wireshark and then server is messing
            // up the reading on occasion (the passed in stream is not buffered yet).

            // Preamble is six bytes -- 'HBas' + VERSION + AUTH_CODE
            int rpcHeaderLen = HConstants.RPC_HEADER.array().length;
            byte[] preamble = new byte[rpcHeaderLen + 2];
            System.arraycopy(HConstants.RPC_HEADER.array(), 0, preamble, 0, rpcHeaderLen);
            preamble[rpcHeaderLen] = HConstants.RPC_CURRENT_VERSION;
            preamble[rpcHeaderLen + 1] = authMethod.code;
            outStream.write(preamble);
            outStream.flush();
        }

        /**
         * This class sends a ping to the remote side when timeout on
         * reading. If no failure is detected, it retries until at least
         * a byte is read.
         */
        protected class PingInputStream extends FilterInputStream {
            /* constructor */
            protected PingInputStream(InputStream in) {
                super(in);
            }

            /**
             * Read a byte from the stream.
             * Send a ping if timeout on read. Retries if no failure is detected
             * until a byte is read.
             * 
             * @throws IOException
             *             for any IO problem other than socket timeout
             */
            @Override
            public int read() throws IOException {
                do {
                    try {
                        return super.read();
                    } catch (SocketTimeoutException e) {
                        handleTimeout(e);
                    }
                } while (true);
            }

            /**
             * Read bytes into a buffer starting from offset <code>off</code> Send a ping if timeout on read. Retries if
             * no failure is detected
             * until a byte is read.
             * 
             * @return the total number of bytes read; -1 if the connection is closed.
             */
            @Override
            public int read(byte[] buf, int off, int len) throws IOException {
                do {
                    try {
                        return super.read(buf, off, len);
                    } catch (SocketTimeoutException e) {
                        handleTimeout(e);
                    }
                } while (true);
            }

            /*
             * Process timeout exception
             * if the connection is not going to be closed, send a ping.
             * otherwise, throw the timeout exception.
             */
            private void handleTimeout(SocketTimeoutException e) throws IOException {
                if (shouldCloseConnection.get() || !running.get() || remoteId.rpcTimeout > 0) {
                    throw e;
                }
                sendPing();
            }
        }
    }

    /**
     * This class holds the address and the user ticket, etc. The client connections
     * to servers are uniquely identified by <remoteAddress, ticket, serviceName, rpcTimeout>
     */
    protected static class ConnectionId {
        final InetSocketAddress address;
        final User ticket;
        final int rpcTimeout;
        private static final int PRIME = 16777619;
        final String serviceName;

        ConnectionId(User ticket, String serviceName, InetSocketAddress address, int rpcTimeout) {
            this.address = address;
            this.ticket = ticket;
            this.rpcTimeout = rpcTimeout;
            this.serviceName = serviceName;
        }

        @Override
        public boolean equals(Object obj) {
            if (obj instanceof ConnectionId) {
                ConnectionId id = (ConnectionId) obj;
                return address.equals(id.address)
                        && ((ticket != null && ticket.equals(id.ticket)) || (ticket == id.ticket))
                        && rpcTimeout == id.rpcTimeout && this.serviceName == id.serviceName;
            }
            return false;
        }

        @Override
        // simply use the default Object#hashcode() ?
        public int hashCode() {
            int hashcode = (address.hashCode()
                    + PRIME * (PRIME * this.serviceName.hashCode() ^ (ticket == null ? 0 : ticket.hashCode())))
                    ^ rpcTimeout;
            return hashcode;
        }

        @Override
        public String toString() {
            return this.address.toString() + "/" + this.serviceName + "/" + this.ticket + "/" + this.rpcTimeout;
        }

        InetSocketAddress getAddress() {
            return address;
        }

        String getServiceName() {
            return this.serviceName;
        }

        User getTicket() {
            return ticket;
        }
    }

    /**
     * A class to manage a list of servers that failed recently.
     */
    static class FailedServers {
        private final LinkedList<Pair<Long, String>> failedServers = new LinkedList<Pair<Long, java.lang.String>>();
        private final int recheckServersTimeout;

        FailedServers(Configuration conf) {
            this.recheckServersTimeout = conf.getInt(FAILED_SERVER_EXPIRY_KEY, FAILED_SERVER_EXPIRY_DEFAULT);
        }

        /**
         * Add an address to the list of the failed servers list.
         */
        public synchronized void addToFailedServers(InetSocketAddress address) {
            final long expiry = EnvironmentEdgeManager.currentTimeMillis() + recheckServersTimeout;
            failedServers.addFirst(new Pair<Long, String>(expiry, address.toString()));
        }

        /**
         * Check if the server should be considered as bad. Clean the old entries of the list.
         * 
         * @return true if the server is in the failed servers list
         */
        public synchronized boolean isFailedServer(final InetSocketAddress address) {
            if (failedServers.isEmpty()) {
                return false;
            }

            final String lookup = address.toString();
            final long now = EnvironmentEdgeManager.currentTimeMillis();

            // iterate, looking for the search entry and cleaning expired entries
            Iterator<Pair<Long, String>> it = failedServers.iterator();
            while (it.hasNext()) {
                Pair<Long, String> cur = it.next();
                if (cur.getFirst() < now) {
                    it.remove();
                } else {
                    if (lookup.equals(cur.getSecond())) {
                        return true;
                    }
                }
            }

            return false;
        }
    }
}