HBASE-3939 Some crossports of Hadoop IPC fixes

git-svn-id: https://svn.apache.org/repos/asf/hbase/trunk@1198573 13f79535-47bb-0310-9956-ffa450edef68

CHANGES.txt

@@ -727,6 +727,7 @@ Release 0.92.0 - Unreleased
                hbase.master.ServerManager#waitForRegionServers (nkeywal)
    HBASE-4703  Improvements in tests (nkeywal)
    HBASE-4611  Add support for Phabricator/Differential as an alternative code review tool
+   HBASE-3939  Some crossports of Hadoop IPC fixes
 
   TASKS
    HBASE-3559  Move report of split to master OFF the heartbeat channel

src/main/java/org/apache/hadoop/hbase/coprocessor/AggregateImplementation.java

@@ -28,6 +28,7 @@ import org.apache.commons.logging.LogFactory;
 import org.apache.hadoop.hbase.KeyValue;
 import org.apache.hadoop.hbase.client.Scan;
 import org.apache.hadoop.hbase.filter.FirstKeyOnlyFilter;
+import org.apache.hadoop.hbase.ipc.ProtocolSignature;
 import org.apache.hadoop.hbase.regionserver.InternalScanner;
 import org.apache.hadoop.hbase.util.Pair;
 
@@ -39,6 +40,16 @@ public class AggregateImplementation extends BaseEndpointCoprocessor implements
     AggregateProtocol {
   protected static Log log = LogFactory.getLog(AggregateImplementation.class);
 
+  @Override
+  public ProtocolSignature getProtocolSignature(
+      String protocol, long version, int clientMethodsHashCode)
+  throws IOException {
+    if (AggregateProtocol.class.getName().equals(protocol)) {
+      return new ProtocolSignature(AggregateProtocol.VERSION, null);
+    }
+    throw new IOException("Unknown protocol: " + protocol);
+  }
+
   @Override
   public <T, S> T getMax(ColumnInterpreter<T, S> ci, Scan scan)
       throws IOException {

src/main/java/org/apache/hadoop/hbase/coprocessor/AggregateProtocol.java

@@ -39,6 +39,7 @@ import org.apache.hadoop.hbase.util.Pair;
  * input parameters.
  */
 public interface AggregateProtocol extends CoprocessorProtocol {
+  public static final long VERSION = 1L;
 
   /**
    * Gives the maximum for a given combination of column qualifier and column

src/main/java/org/apache/hadoop/hbase/coprocessor/BaseEndpointCoprocessor.java

@@ -21,6 +21,7 @@ import java.io.IOException;
 import org.apache.hadoop.hbase.Coprocessor;
 import org.apache.hadoop.hbase.CoprocessorEnvironment;
 import org.apache.hadoop.hbase.ipc.CoprocessorProtocol;
+import org.apache.hadoop.hbase.ipc.ProtocolSignature;
 import org.apache.hadoop.hbase.ipc.VersionedProtocol;
 
 /**
@@ -61,6 +62,13 @@ public abstract class BaseEndpointCoprocessor implements Coprocessor,
   @Override
   public void stop(CoprocessorEnvironment env) { }
 
+  @Override
+  public ProtocolSignature getProtocolSignature(
+      String protocol, long version, int clientMethodsHashCode)
+  throws IOException {
+    return new ProtocolSignature(VERSION, null);
+  }
+
   @Override
   public long getProtocolVersion(String protocol, long clientVersion)
   throws IOException {

src/main/java/org/apache/hadoop/hbase/ipc/CoprocessorProtocol.java

@@ -19,8 +19,6 @@
  */
 package org.apache.hadoop.hbase.ipc;
 
-import org.apache.hadoop.hbase.ipc.VersionedProtocol;
-
 /**
  * All custom RPC protocols to be exported by Coprocessors must extend this interface.
  *
@@ -37,4 +35,5 @@ import org.apache.hadoop.hbase.ipc.VersionedProtocol;
  * </p>
  */
 public interface CoprocessorProtocol extends VersionedProtocol {
+  public static final long VERSION = 1L;
 }

src/main/java/org/apache/hadoop/hbase/ipc/HBaseClient.java

@@ -566,6 +566,7 @@ public class HBaseClient {
           // Currently length if present is unused.
           in.readInt();
         }
+        int state = in.readInt(); // Read the state.  Currently unused.
         if (isError) {
           //noinspection ThrowableInstanceNeverThrown
           call.setException(new RemoteException( WritableUtils.readString(in),

src/main/java/org/apache/hadoop/hbase/ipc/HBaseServer.java

@@ -21,6 +21,7 @@
 package org.apache.hadoop.hbase.ipc;
 
 import java.io.ByteArrayInputStream;
+import java.io.ByteArrayOutputStream;
 import java.io.DataInputStream;
 import java.io.DataOutputStream;
 import java.io.IOException;
@@ -65,6 +66,7 @@ import org.apache.hadoop.hbase.util.ByteBufferOutputStream;
 import org.apache.hadoop.hbase.util.Bytes;
 import org.apache.hadoop.io.Writable;
 import org.apache.hadoop.io.WritableUtils;
+import org.apache.hadoop.ipc.RPC.VersionMismatch;
 import org.apache.hadoop.hbase.ipc.VersionedProtocol;
 import org.apache.hadoop.security.UserGroupInformation;
 import org.apache.hadoop.util.ReflectionUtils;
@@ -88,7 +90,7 @@ public abstract class HBaseServer implements RpcServer {
    * The first four bytes of Hadoop RPC connections
    */
   public static final ByteBuffer HEADER = ByteBuffer.wrap("hrpc".getBytes());
-  public static final byte CURRENT_VERSION = 3;
+  public static final byte CURRENT_VERSION = 4;
 
   /**
    * How many calls/handler are allowed in the queue.
@@ -273,8 +275,8 @@ public abstract class HBaseServer implements RpcServer {
       return param.toString() + " from " + connection.toString();
     }
 
-    private synchronized void setResponse(Object value, String errorClass,
-        String error) {
+    private synchronized void setResponse(Object value, Status status,
+        String errorClass, String error) {
       // Avoid overwriting an error value in the response.  This can happen if
       // endDelayThrowing is called by another thread before the actual call
       // returning.
@@ -323,6 +325,7 @@ public abstract class HBaseServer implements RpcServer {
         // Place holder for length set later below after we
         // fill the buffer with data.
         out.writeInt(0xdeadbeef);
+        out.writeInt(status.state);
       } catch (IOException e) {
         errorClass = e.getClass().getName();
         error = StringUtils.stringifyException(e);
@@ -358,7 +361,7 @@ public abstract class HBaseServer implements RpcServer {
       this.delayResponse = false;
       delayedCalls.decrementAndGet();
       if (this.delayReturnValue)
-        this.setResponse(result, null, null);
+        this.setResponse(result, Status.SUCCESS, null, null);
       this.responder.doRespond(this);
     }
 
@@ -381,7 +384,7 @@ public abstract class HBaseServer implements RpcServer {
 
     @Override
     public synchronized void endDelayThrowing(Throwable t) throws IOException {
-      this.setResponse(null, t.getClass().toString(),
+      this.setResponse(null, Status.ERROR, t.getClass().toString(),
           StringUtils.stringifyException(t));
       this.delayResponse = false;
       this.sendResponseIfReady();
@@ -443,8 +446,7 @@ public abstract class HBaseServer implements RpcServer {
         new ThreadFactoryBuilder().setNameFormat(
           "IPC Reader %d on port " + port).setDaemon(true).build());
       for (int i = 0; i < readThreads; ++i) {
-        Selector readSelector = Selector.open();
-        Reader reader = new Reader(readSelector);
+        Reader reader = new Reader();
         readers[i] = reader;
         readPool.execute(reader);
       }
@@ -458,13 +460,25 @@ public abstract class HBaseServer implements RpcServer {
 
     private class Reader implements Runnable {
       private volatile boolean adding = false;
-      private Selector readSelector = null;
+      private final Selector readSelector;
 
-      Reader(Selector readSelector) {
-        this.readSelector = readSelector;
+      Reader() throws IOException {
+        this.readSelector = Selector.open();
       }
       public void run() {
-        synchronized(this) {
+        LOG.info("Starting " + getName());
+        try {
+          doRunLoop();
+        } finally {
+          try {
+            readSelector.close();
+          } catch (IOException ioe) {
+            LOG.error("Error closing read selector in " + getName(), ioe);
+          }
+        }
+      }
+
+      private synchronized void doRunLoop() {
         while (running) {
           SelectionKey key = null;
           try {
@@ -486,7 +500,7 @@ public abstract class HBaseServer implements RpcServer {
             }
           } catch (InterruptedException e) {
             if (running) {                      // unexpected -- log it
-                LOG.info(getName() + "caught: " +
+              LOG.info(getName() + " unexpectedly interrupted: " +
                   StringUtils.stringifyException(e));
             }
           } catch (IOException ex) {
@@ -494,7 +508,6 @@ public abstract class HBaseServer implements RpcServer {
           }
         }
       }
-      }
 
       /**
        * This gets reader into the state that waits for the new channel
@@ -730,7 +743,7 @@ public abstract class HBaseServer implements RpcServer {
 
   // Sends responses of RPC back to clients.
   private class Responder extends Thread {
-    private Selector writeSelector;
+    private final Selector writeSelector;
     private int pending;         // connections waiting to register
 
     final static int PURGE_INTERVAL = 900000; // 15mins
@@ -746,6 +759,19 @@ public abstract class HBaseServer implements RpcServer {
     public void run() {
       LOG.info(getName() + ": starting");
       SERVER.set(HBaseServer.this);
+      try {
+        doRunLoop();
+      } finally {
+        LOG.info("Stopping " + this.getName());
+        try {
+          writeSelector.close();
+        } catch (IOException ioe) {
+          LOG.error("Couldn't close write selector in " + this.getName(), ioe);
+        }
+      }
+    }
+
+    private void doRunLoop() {
       long lastPurgeTime = 0;   // last check for old calls.
 
       while (running) {
@@ -1106,6 +1132,7 @@ public abstract class HBaseServer implements RpcServer {
                      hostAddress + ":" + remotePort +
                      " got version " + version +
                      " expected version " + CURRENT_VERSION);
+            setupBadVersionResponse(version);
             return -1;
           }
           dataLengthBuffer.clear();
@@ -1144,6 +1171,30 @@ public abstract class HBaseServer implements RpcServer {
       }
     }
 
+    /**
+     * Try to set up the response to indicate that the client version
+     * is incompatible with the server. This can contain special-case
+     * code to speak enough of past IPC protocols to pass back
+     * an exception to the caller.
+     * @param clientVersion the version the caller is using
+     * @throws IOException
+     */
+    private void setupBadVersionResponse(int clientVersion) throws IOException {
+      String errMsg = "Server IPC version " + CURRENT_VERSION +
+      " cannot communicate with client version " + clientVersion;
+      ByteArrayOutputStream buffer = new ByteArrayOutputStream();
+
+      if (clientVersion >= 3) {
+        Call fakeCall =  new Call(-1, null, this, responder);
+        // Versions 3 and greater can interpret this exception
+        // response in the same manner
+        setupResponse(buffer, fakeCall, Status.FATAL,
+            null, VersionMismatch.class.getName(), errMsg);
+
+        responder.doRespond(fakeCall);
+      }
+    }
+
     /// Reads the connection header following version
     private void processHeader() throws IOException {
       DataInputStream in =
@@ -1170,9 +1221,22 @@ public abstract class HBaseServer implements RpcServer {
       if (LOG.isDebugEnabled())
         LOG.debug(" got call #" + id + ", " + array.length + " bytes");
 
-      Writable param = ReflectionUtils.newInstance(paramClass, conf);           // read param
+      Writable param;
+      try {
+        param = ReflectionUtils.newInstance(paramClass, conf);//read param
         param.readFields(dis);
+      } catch (Throwable t) {
+        LOG.warn("Unable to read call parameters for client " +
+                 getHostAddress(), t);
+        final Call readParamsFailedCall = new Call(id, null, this, responder);
+        ByteArrayOutputStream responseBuffer = new ByteArrayOutputStream();
 
+        setupResponse(responseBuffer, readParamsFailedCall, Status.FATAL, null,
+            t.getClass().getName(),
+            "IPC server unable to read call parameters: " + t.getMessage());
+        responder.doRespond(readParamsFailedCall);
+        return;
+      }
       Call call = new Call(id, param, this, responder);
 
       if (priorityCallQueue != null && getQosLevel(param) > highPriorityLevel) {
@@ -1251,7 +1315,9 @@ public abstract class HBaseServer implements RpcServer {
           // Set the response for undelayed calls and delayed calls with
           // undelayed responses.
           if (!call.isDelayed() || !call.isReturnValueDelayed()) {
-            call.setResponse(value, errorClass, error);
+            call.setResponse(value,
+              errorClass == null? Status.SUCCESS: Status.ERROR,
+                errorClass, error);
           }
           call.sendResponseIfReady();
         } catch (InterruptedException e) {
@@ -1356,6 +1422,41 @@ public abstract class HBaseServer implements RpcServer {
     responder = new Responder();
   }
 
+  /**
+   * Setup response for the IPC Call.
+   *
+   * @param response buffer to serialize the response into
+   * @param call {@link Call} to which we are setting up the response
+   * @param status {@link Status} of the IPC call
+   * @param rv return value for the IPC Call, if the call was successful
+   * @param errorClass error class, if the the call failed
+   * @param error error message, if the call failed
+   * @throws IOException
+   */
+  private void setupResponse(ByteArrayOutputStream response,
+                             Call call, Status status,
+                             Writable rv, String errorClass, String error)
+  throws IOException {
+    response.reset();
+    DataOutputStream out = new DataOutputStream(response);
+
+    if (status == Status.SUCCESS) {
+      try {
+        rv.write(out);
+        call.setResponse(rv, status, null, null);
+      } catch (Throwable t) {
+        LOG.warn("Error serializing call response for call " + call, t);
+        // Call back to same function - this is OK since the
+        // buffer is reset at the top, and since status is changed
+        // to ERROR it won't infinite loop.
+        call.setResponse(null, status.ERROR, t.getClass().getName(),
+            StringUtils.stringifyException(t));
+      }
+    } else {
+      call.setResponse(rv, status, errorClass, error);
+    }
+  }
+
   protected void closeConnection(Connection connection) {
     synchronized (connectionList) {
       if (connectionList.remove(connection))

src/main/java/org/apache/hadoop/hbase/ipc/Invocation.java

@@ -22,20 +22,25 @@ package org.apache.hadoop.hbase.ipc;
 import org.apache.hadoop.conf.Configurable;
 import org.apache.hadoop.conf.Configuration;
 import org.apache.hadoop.hbase.io.HbaseObjectWritable;
-import org.apache.hadoop.io.Writable;
+import org.apache.hadoop.io.VersionedWritable;
 
 import java.io.DataInput;
 import java.io.DataOutput;
 import java.io.IOException;
+import java.lang.reflect.Field;
 import java.lang.reflect.Method;
 
 /** A method invocation, including the method name and its parameters.*/
-public class Invocation implements Writable, Configurable {
+public class Invocation extends VersionedWritable implements Configurable {
   protected String methodName;
-  @SuppressWarnings("unchecked")
+  @SuppressWarnings("rawtypes")
   protected Class[] parameterClasses;
   protected Object[] parameters;
   protected Configuration conf;
+  private long clientVersion;
+  private int clientMethodsHash;
+
+  private static byte RPC_VERSION = 1;
 
   public Invocation() {}
 
@@ -43,20 +48,56 @@ public class Invocation implements Writable, Configurable {
     this.methodName = method.getName();
     this.parameterClasses = method.getParameterTypes();
     this.parameters = parameters;
+    if (method.getDeclaringClass().equals(VersionedProtocol.class)) {
+      //VersionedProtocol is exempted from version check.
+      clientVersion = 0;
+      clientMethodsHash = 0;
+    } else {
+      try {
+        Field versionField = method.getDeclaringClass().getField("VERSION");
+        versionField.setAccessible(true);
+        this.clientVersion = versionField.getLong(method.getDeclaringClass());
+      } catch (NoSuchFieldException ex) {
+        throw new RuntimeException("The " + method.getDeclaringClass(), ex);
+      } catch (IllegalAccessException ex) {
+        throw new RuntimeException(ex);
+      }
+      this.clientMethodsHash = ProtocolSignature.getFingerprint(method
+          .getDeclaringClass().getMethods());
+    }
   }
 
   /** @return The name of the method invoked. */
   public String getMethodName() { return methodName; }
 
   /** @return The parameter classes. */
-  @SuppressWarnings("unchecked")
+  @SuppressWarnings({ "rawtypes" })
   public Class[] getParameterClasses() { return parameterClasses; }
 
   /** @return The parameter instances. */
   public Object[] getParameters() { return parameters; }
 
+  long getProtocolVersion() {
+    return clientVersion;
+  }
+
+  protected int getClientMethodsHash() {
+    return clientMethodsHash;
+  }
+
+  /**
+   * Returns the rpc version used by the client.
+   * @return rpcVersion
+   */
+  public long getRpcVersion() {
+    return RPC_VERSION;
+  }
+
   public void readFields(DataInput in) throws IOException {
+    super.readFields(in);
     methodName = in.readUTF();
+    clientVersion = in.readLong();
+    clientMethodsHash = in.readInt();
     parameters = new Object[in.readInt()];
     parameterClasses = new Class[parameters.length];
     HbaseObjectWritable objectWritable = new HbaseObjectWritable();
@@ -68,7 +109,10 @@ public class Invocation implements Writable, Configurable {
   }
 
   public void write(DataOutput out) throws IOException {
+    super.write(out);
     out.writeUTF(this.methodName);
+    out.writeLong(clientVersion);
+    out.writeInt(clientMethodsHash);
     out.writeInt(parameterClasses.length);
     for (int i = 0; i < parameterClasses.length; i++) {
       HbaseObjectWritable.writeObject(out, parameters[i], parameterClasses[i],
@@ -87,6 +131,9 @@ public class Invocation implements Writable, Configurable {
       buffer.append(parameters[i]);
     }
     buffer.append(")");
+    buffer.append(", rpc version="+RPC_VERSION);
+    buffer.append(", client version="+clientVersion);
+    buffer.append(", methodsFingerPrint="+clientMethodsHash);
     return buffer.toString();
   }
 
@@ -98,4 +145,8 @@ public class Invocation implements Writable, Configurable {
     return this.conf;
   }
 
+  @Override
+  public byte getVersion() {
+    return RPC_VERSION;
+  }
 }

src/main/java/org/apache/hadoop/hbase/ipc/ProtocolSignature.java

@@ -0,0 +1,241 @@
+/**
+ * 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 java.io.DataInput;
+import java.io.DataOutput;
+import java.io.IOException;
+import java.lang.reflect.Method;
+import java.util.Arrays;
+import java.util.HashMap;
+
+import org.apache.hadoop.io.Writable;
+import org.apache.hadoop.io.WritableFactories;
+import org.apache.hadoop.io.WritableFactory;
+
+public class ProtocolSignature implements Writable {
+  static {               // register a ctor
+    WritableFactories.setFactory
+      (ProtocolSignature.class,
+       new WritableFactory() {
+         public Writable newInstance() { return new ProtocolSignature(); }
+       });
+  }
+
+  private long version;
+  private int[] methods = null; // an array of method hash codes
+
+  /**
+   * default constructor
+   */
+  public ProtocolSignature() {
+  }
+
+  /**
+   * Constructor
+   *
+   * @param version server version
+   * @param methodHashcodes hash codes of the methods supported by server
+   */
+  public ProtocolSignature(long version, int[] methodHashcodes) {
+    this.version = version;
+    this.methods = methodHashcodes;
+  }
+
+  public long getVersion() {
+    return version;
+  }
+
+  public int[] getMethods() {
+    return methods;
+  }
+
+  @Override
+  public void readFields(DataInput in) throws IOException {
+    version = in.readLong();
+    boolean hasMethods = in.readBoolean();
+    if (hasMethods) {
+      int numMethods = in.readInt();
+      methods = new int[numMethods];
+      for (int i=0; i<numMethods; i++) {
+        methods[i] = in.readInt();
+      }
+    }
+  }
+
+  @Override
+  public void write(DataOutput out) throws IOException {
+    out.writeLong(version);
+    if (methods == null) {
+      out.writeBoolean(false);
+    } else {
+      out.writeBoolean(true);
+      out.writeInt(methods.length);
+      for (int method : methods) {
+        out.writeInt(method);
+      }
+    }
+  }
+
+  /**
+   * Calculate a method's hash code considering its method
+   * name, returning type, and its parameter types
+   *
+   * @param method a method
+   * @return its hash code
+   */
+  static int getFingerprint(Method method) {
+    int hashcode = method.getName().hashCode();
+    hashcode =  hashcode + 31*method.getReturnType().getName().hashCode();
+    for (Class<?> type : method.getParameterTypes()) {
+      hashcode = 31*hashcode ^ type.getName().hashCode();
+    }
+    return hashcode;
+  }
+
+  /**
+   * Convert an array of Method into an array of hash codes
+   *
+   * @param methods
+   * @return array of hash codes
+   */
+  private static int[] getFingerprints(Method[] methods) {
+    if (methods == null) {
+      return null;
+    }
+    int[] hashCodes = new int[methods.length];
+    for (int i = 0; i<methods.length; i++) {
+      hashCodes[i] = getFingerprint(methods[i]);
+    }
+    return hashCodes;
+  }
+
+  /**
+   * Get the hash code of an array of methods
+   * Methods are sorted before hashcode is calculated.
+   * So the returned value is irrelevant of the method order in the array.
+   *
+   * @param methods an array of methods
+   * @return the hash code
+   */
+  static int getFingerprint(Method[] methods) {
+    return getFingerprint(getFingerprints(methods));
+  }
+
+  /**
+   * Get the hash code of an array of hashcodes
+   * Hashcodes are sorted before hashcode is calculated.
+   * So the returned value is irrelevant of the hashcode order in the array.
+   *
+   * @param methods an array of methods
+   * @return the hash code
+   */
+  static int getFingerprint(int[] hashcodes) {
+    Arrays.sort(hashcodes);
+    return Arrays.hashCode(hashcodes);
+
+  }
+  private static class ProtocolSigFingerprint {
+    private ProtocolSignature signature;
+    private int fingerprint;
+
+    ProtocolSigFingerprint(ProtocolSignature sig, int fingerprint) {
+      this.signature = sig;
+      this.fingerprint = fingerprint;
+    }
+  }
+
+  /**
+   * A cache that maps a protocol's name to its signature & finger print
+   */
+  final private static HashMap<String, ProtocolSigFingerprint> 
+     PROTOCOL_FINGERPRINT_CACHE =
+       new HashMap<String, ProtocolSigFingerprint>();
+
+  /**
+   * Return a protocol's signature and finger print from cache
+   *
+   * @param protocol a protocol class
+   * @param serverVersion protocol version
+   * @return its signature and finger print
+   */
+  private static ProtocolSigFingerprint getSigFingerprint(
+      Class <? extends VersionedProtocol> protocol, long serverVersion) {
+    String protocolName = protocol.getName();
+    synchronized (PROTOCOL_FINGERPRINT_CACHE) {
+      ProtocolSigFingerprint sig = PROTOCOL_FINGERPRINT_CACHE.get(protocolName);
+      if (sig == null) {
+        int[] serverMethodHashcodes = getFingerprints(protocol.getMethods());
+        sig = new ProtocolSigFingerprint(
+            new ProtocolSignature(serverVersion, serverMethodHashcodes),
+            getFingerprint(serverMethodHashcodes));
+        PROTOCOL_FINGERPRINT_CACHE.put(protocolName, sig);
+      }
+      return sig;
+    }
+  }
+
+  /**
+   * Get a server protocol's signature
+   *
+   * @param clientMethodsHashCode client protocol methods hashcode
+   * @param serverVersion server protocol version
+   * @param protocol protocol
+   * @return the server's protocol signature
+   */
+  static ProtocolSignature getProtocolSignature(
+      int clientMethodsHashCode,
+      long serverVersion,
+      Class<? extends VersionedProtocol> protocol) {
+    // try to get the finger print & signature from the cache
+    ProtocolSigFingerprint sig = getSigFingerprint(protocol, serverVersion);
+
+    // check if the client side protocol matches the one on the server side
+    if (clientMethodsHashCode == sig.fingerprint) {
+      return new ProtocolSignature(serverVersion, null);  // null indicates a match
+    }
+
+    return sig.signature;
+  }
+
+  /**
+   * Get a server protocol's signature
+   *
+   * @param server server implementation
+   * @param protocol server protocol
+   * @param clientVersion client's version
+   * @param clientMethodsHash client's protocol's hash code
+   * @return the server protocol's signature
+   * @throws IOException if any error occurs
+   */
+  @SuppressWarnings("unchecked")
+  public static ProtocolSignature getProtocolSignature(VersionedProtocol server,
+      String protocol,
+      long clientVersion, int clientMethodsHash) throws IOException {
+    Class<? extends VersionedProtocol> inter;
+    try {
+      inter = (Class<? extends VersionedProtocol>)Class.forName(protocol);
+    } catch (Exception e) {
+      throw new IOException(e);
+    }
+    long serverVersion = server.getProtocolVersion(protocol, clientVersion);
+    return ProtocolSignature.getProtocolSignature(
+        clientMethodsHash, serverVersion, inter);
+  }
+}

src/main/java/org/apache/hadoop/hbase/ipc/Status.java

@@ -0,0 +1,32 @@
+/**
+ * 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;
+
+/**
+ * Status of a Hadoop IPC call.
+ */
+enum Status {
+  SUCCESS (0),
+  ERROR (1),
+  FATAL (-1);
+
+  int state;
+  private Status(int state) {
+    this.state = state;
+  }
+}

src/main/java/org/apache/hadoop/hbase/ipc/VersionedProtocol.java

@@ -24,9 +24,6 @@ import java.io.IOException;
  * Superclass of all protocols that use Hadoop RPC.
  * Subclasses of this interface are also supposed to have
  * a static final long versionID field.
- *
- * This has been copied from the Hadoop IPC project so that
- * we can run on multiple different versions of Hadoop.
  */
 public interface VersionedProtocol {
 
@@ -40,4 +37,18 @@ public interface VersionedProtocol {
   @Deprecated
   public long getProtocolVersion(String protocol,
                                  long clientVersion) throws IOException;
+
+  /**
+   * Return protocol version corresponding to protocol interface.
+   * @param protocol The classname of the protocol interface
+   * @param clientVersion The version of the protocol that the client speaks
+   * @param clientMethodsHash the hashcode of client protocol methods
+   * @return the server protocol signature containing its version and
+   *         a list of its supported methods
+   * @see ProtocolSignature#getProtocolSignature(VersionedProtocol, String,
+   *                long, int) for a default implementation
+   */
+  public ProtocolSignature getProtocolSignature(String protocol,
+                                 long clientVersion,
+                                 int clientMethodsHash) throws IOException;
 }

src/main/java/org/apache/hadoop/hbase/ipc/WritableRpcEngine.java

@@ -43,6 +43,7 @@ import org.apache.hadoop.hbase.regionserver.HRegionServer;
 import org.apache.hadoop.hbase.util.Bytes;
 import org.apache.hadoop.hbase.util.Objects;
 import org.apache.hadoop.io.*;
+import org.apache.hadoop.ipc.RPC;
 import org.apache.hadoop.hbase.ipc.VersionedProtocol;
 import org.apache.hadoop.security.UserGroupInformation;
 import org.apache.hadoop.security.authorize.ServiceAuthorizationManager;
@@ -335,6 +336,21 @@ class WritableRpcEngine implements RpcEngine {
                                    call.getParameterClasses());
         method.setAccessible(true);
 
+        //Verify protocol version.
+        //Bypass the version check for VersionedProtocol
+        if (!method.getDeclaringClass().equals(VersionedProtocol.class)) {
+          long clientVersion = call.getProtocolVersion();
+          ProtocolSignature serverInfo = ((VersionedProtocol) instance)
+              .getProtocolSignature(protocol.getCanonicalName(), call
+                  .getProtocolVersion(), call.getClientMethodsHash());
+          long serverVersion = serverInfo.getVersion();
+          if (serverVersion != clientVersion) {
+            LOG.warn("Version mismatch: client version=" + clientVersion
+                + ", server version=" + serverVersion);
+            throw new RPC.VersionMismatch(protocol.getName(), clientVersion,
+                serverVersion);
+          }
+        }
         Object impl = null;
         if (protocol.isAssignableFrom(this.implementation)) {
           impl = this.instance;

src/main/java/org/apache/hadoop/hbase/master/HMaster.java

@@ -61,6 +61,7 @@ import org.apache.hadoop.hbase.ipc.HBaseRPC;
 import org.apache.hadoop.hbase.ipc.HBaseServer;
 import org.apache.hadoop.hbase.ipc.HMasterInterface;
 import org.apache.hadoop.hbase.ipc.HMasterRegionInterface;
+import org.apache.hadoop.hbase.ipc.ProtocolSignature;
 import org.apache.hadoop.hbase.ipc.RpcServer;
 import org.apache.hadoop.hbase.master.handler.CreateTableHandler;
 import org.apache.hadoop.hbase.master.handler.DeleteTableHandler;
@@ -561,6 +562,18 @@ implements HMasterInterface, HMasterRegionInterface, MasterServices, Server {
     return assigned;
   }
 
+  @Override
+  public ProtocolSignature getProtocolSignature(
+      String protocol, long version, int clientMethodsHashCode)
+  throws IOException {
+    if (HMasterInterface.class.getName().equals(protocol)) {
+      return new ProtocolSignature(HMasterInterface.VERSION, null);
+    } else if (HMasterRegionInterface.class.getName().equals(protocol)) {
+      return new ProtocolSignature(HMasterRegionInterface.VERSION, null);
+    }
+    throw new IOException("Unknown protocol: " + protocol);
+  }
+
   public long getProtocolVersion(String protocol, long clientVersion) {
     if (HMasterInterface.class.getName().equals(protocol)) {
       return HMasterInterface.VERSION;

src/main/java/org/apache/hadoop/hbase/regionserver/HRegionServer.java

@@ -112,6 +112,7 @@ import org.apache.hadoop.hbase.ipc.HBaseRpcMetrics;
 import org.apache.hadoop.hbase.ipc.HMasterRegionInterface;
 import org.apache.hadoop.hbase.ipc.HRegionInterface;
 import org.apache.hadoop.hbase.ipc.Invocation;
+import org.apache.hadoop.hbase.ipc.ProtocolSignature;
 import org.apache.hadoop.hbase.ipc.RpcServer;
 import org.apache.hadoop.hbase.ipc.ServerNotRunningYetException;
 import org.apache.hadoop.hbase.regionserver.Leases.LeaseStillHeldException;
@@ -2869,6 +2870,17 @@ public class HRegionServer implements HRegionInterface, HBaseRPCErrorHandler,
     }
   }
 
+  @Override
+  @QosPriority(priority=HIGH_QOS)
+  public ProtocolSignature getProtocolSignature(
+      String protocol, long version, int clientMethodsHashCode)
+  throws IOException {
+    if (protocol.equals(HRegionInterface.class.getName())) {
+      return new ProtocolSignature(HRegionInterface.VERSION, null);
+    }
+    throw new IOException("Unknown protocol: " + protocol);
+  }
+
   @Override
   @QosPriority(priority=HIGH_QOS)
   public long getProtocolVersion(final String protocol, final long clientVersion)

src/test/java/org/apache/hadoop/hbase/ipc/TestDelayedRpc.java

@@ -25,6 +25,7 @@ import static org.junit.Assert.assertTrue;
 import static org.junit.Assert.fail;
 
 import java.io.IOException;
+import java.lang.reflect.Method;
 import java.net.InetSocketAddress;
 import java.util.ArrayList;
 import java.util.List;
@@ -85,8 +86,8 @@ public class TestDelayedRpc {
     th2.join();
     th3.join();
 
-    assertEquals(results.get(0).intValue(), UNDELAYED);
-    assertEquals(results.get(1).intValue(), UNDELAYED);
+    assertEquals(UNDELAYED, results.get(0).intValue());
+    assertEquals(UNDELAYED, results.get(1).intValue());
     assertEquals(results.get(2).intValue(), delayReturnValue ? DELAYED :
         0xDEADBEEF);
   }
@@ -157,6 +158,7 @@ public class TestDelayedRpc {
   }
 
   public interface TestRpc extends VersionedProtocol {
+    public static final long VERSION = 1L;
     int test(boolean delay);
   }
 
@@ -202,6 +204,17 @@ public class TestDelayedRpc {
     public long getProtocolVersion(String arg0, long arg1) throws IOException {
       return 0;
     }
+
+    @Override
+    public ProtocolSignature getProtocolSignature(String protocol,
+        long clientVersion, int clientMethodsHash) throws IOException {
+      Method [] methods = this.getClass().getMethods();
+      int [] hashes = new int [methods.length];
+      for (int i = 0; i < methods.length; i++) {
+        hashes[i] = methods[i].hashCode();
+      }
+      return new ProtocolSignature(clientVersion, hashes);
+    }
   }
 
   private static class TestThread extends Thread {
@@ -283,5 +296,11 @@ public class TestDelayedRpc {
     public long getProtocolVersion(String arg0, long arg1) throws IOException {
       return 0;
     }
+
+    @Override
+    public ProtocolSignature getProtocolSignature(String protocol,
+        long clientVersion, int clientMethodsHash) throws IOException {
+      return new ProtocolSignature(clientVersion, new int [] {});
+    }
   }
 }

src/test/java/org/apache/hadoop/hbase/regionserver/TestServerCustomProtocol.java

@@ -39,6 +39,9 @@ import org.apache.hadoop.hbase.client.Row;
 import org.apache.hadoop.hbase.client.coprocessor.Batch;
 import org.apache.hadoop.hbase.coprocessor.CoprocessorHost;
 import org.apache.hadoop.hbase.ipc.CoprocessorProtocol;
+import org.apache.hadoop.hbase.ipc.HMasterInterface;
+import org.apache.hadoop.hbase.ipc.HMasterRegionInterface;
+import org.apache.hadoop.hbase.ipc.ProtocolSignature;
 import org.apache.hadoop.hbase.util.Bytes;
 import org.apache.hadoop.hbase.util.JVMClusterUtil;
 import org.apache.hadoop.hbase.ipc.VersionedProtocol;
@@ -59,8 +62,7 @@ public class TestServerCustomProtocol {
 
   /* Test protocol implementation */
   public static class PingHandler implements Coprocessor, PingProtocol, VersionedProtocol {
-    static int VERSION = 1;
-
+    static long VERSION = 1;
     private int counter = 0;
     @Override
     public String ping() {
@@ -89,6 +91,13 @@ public class TestServerCustomProtocol {
       return "Hello, "+name;
     }
 
+    @Override
+    public ProtocolSignature getProtocolSignature(
+        String protocol, long version, int clientMethodsHashCode)
+    throws IOException {
+      return new ProtocolSignature(VERSION, null);
+    }
+
     @Override
     public long getProtocolVersion(String s, long l) throws IOException {
       return VERSION;