HDFS-15790. Make ProtobufRpcEngineProtos and ProtobufRpcEngineProtos2 Co-Exist (#2767)

(cherry picked from commit 2bbeae3240)

 Conflicts:
	hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/ipc/ProtobufRpcEngine.java

hadoop-common-project/hadoop-common/pom.xml

@@ -418,7 +418,12 @@
           </execution>
           <execution>
             <id>src-test-compile-protoc</id>
-            <configuration><skip>false</skip></configuration>
+            <configuration>
+              <skip>false</skip>
+              <excludes>
+                <exclude>*legacy.proto</exclude>
+              </excludes>
+            </configuration>
           </execution>
         </executions>
       </plugin>
@@ -439,6 +444,10 @@
             <id>replace-generated-test-sources</id>
             <configuration>
               <skip>false</skip>
+              <excludes>
+                <exclude>**/TestProtosLegacy.java</exclude>
+                <exclude>**/TestRpcServiceProtosLegacy.java</exclude>
+              </excludes>
             </configuration>
           </execution>
           <execution>
@@ -451,6 +460,7 @@
                 <exclude>**/RpcWritable.java</exclude>
                 <exclude>**/ProtobufRpcEngineCallback.java</exclude>
                 <exclude>**/ProtobufRpcEngine.java</exclude>
+                <exclude>**/ProtobufRpcEngine2.java</exclude>
                 <exclude>**/ProtobufRpcEngineProtos.java</exclude>
               </excludes>
             </configuration>
@@ -459,6 +469,9 @@
             <id>replace-test-sources</id>
             <configuration>
               <skip>false</skip>
+              <excludes>
+                <exclude>**/TestProtoBufRpc.java</exclude>
+              </excludes>
             </configuration>
           </execution>
         </executions>
@@ -1050,6 +1063,18 @@
                   </sources>
                 </configuration>
               </execution>
+              <execution>
+                <id>add-test-source-legacy-protobuf</id>
+                <phase>generate-test-sources</phase>
+                <goals>
+                  <goal>add-test-source</goal>
+                </goals>
+                <configuration>
+                  <sources>
+                    <source>${basedir}/src/test/arm-java</source>
+                  </sources>
+                </configuration>
+              </execution>
             </executions>
           </plugin>
         </plugins>
@@ -1091,6 +1116,28 @@
                   </includes>
                 </configuration>
               </execution>
+              <execution>
+                <id>src-test-compile-protoc-legacy</id>
+                <phase>generate-test-sources</phase>
+                <goals>
+                  <goal>compile</goal>
+                </goals>
+                <configuration>
+                  <skip>false</skip>
+                  <!--Generating with old protobuf version for backward compatibility-->
+                  <protocArtifact>
+                    com.google.protobuf:protoc:${protobuf.version}:exe:${os.detected.classifier}
+                  </protocArtifact>
+                  <includeDependenciesInDescriptorSet>false</includeDependenciesInDescriptorSet>
+                  <protoSourceRoot>${basedir}/src/test/proto</protoSourceRoot>
+                  <outputDirectory>${project.build.directory}/generated-test-sources/java</outputDirectory>
+                  <clearOutputDirectory>false</clearOutputDirectory>
+                  <includes>
+                    <include>test_legacy.proto</include>
+                    <include>test_rpc_service_legacy.proto</include>
+                  </includes>
+                </configuration>
+              </execution>
              </executions>
           </plugin>
         </plugins>

hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/ipc/ProtobufRpcEngine.java

@@ -31,8 +31,6 @@
 import org.apache.hadoop.io.Writable;
 import org.apache.hadoop.io.retry.RetryPolicy;
 import org.apache.hadoop.ipc.Client.ConnectionId;
-import org.apache.hadoop.ipc.RPC.RpcInvoker;
-import org.apache.hadoop.ipc.RPC.RpcKind;
 import org.apache.hadoop.ipc.protobuf.ProtobufRpcEngineProtos.RequestHeaderProto;
 import org.apache.hadoop.security.UserGroupInformation;
 import org.apache.hadoop.security.token.SecretManager;
@@ -68,9 +66,8 @@ public class ProtobufRpcEngine implements RpcEngine {
       ASYNC_RETURN_MESSAGE = new ThreadLocal<>();
 
   static { // Register the rpcRequest deserializer for ProtobufRpcEngine
-    org.apache.hadoop.ipc.Server.registerProtocolEngine(
+    //These will be used in server side, which is always ProtobufRpcEngine2
-        RPC.RpcKind.RPC_PROTOCOL_BUFFER, RpcProtobufRequest.class,
+    ProtobufRpcEngine2.registerProtocolEngine();
-        new Server.ProtoBufRpcInvoker());
   }
 
   private static final ClientCache CLIENTS = new ClientCache();
@@ -353,8 +350,6 @@ static Client getClient(Configuration conf) {
         RpcWritable.Buffer.class);
   }
 
- 
-
   @Override
   public RPC.Server getServer(Class<?> protocol, Object protocolImpl,
       String bindAddress, int port, int numHandlers, int numReaders,
@@ -367,24 +362,16 @@ public RPC.Server getServer(Class<?> protocol, Object protocolImpl,
         portRangeConfig, alignmentContext);
   }
 
-  public static class Server extends RPC.Server {
+  /**
+   * Server implementation is always ProtobufRpcEngine2 based implementation,
+   * supports backward compatibility for protobuf 2.5 based implementations,
+   * which uses non-shaded protobuf classes.
+   */
+  public static class Server extends ProtobufRpcEngine2.Server {
 
     static final ThreadLocal<ProtobufRpcEngineCallback> currentCallback =
         new ThreadLocal<>();
 
-    static final ThreadLocal<CallInfo> currentCallInfo = new ThreadLocal<>();
-    private static final RpcInvoker RPC_INVOKER = new ProtoBufRpcInvoker();
-
-    static class CallInfo {
-      private final RPC.Server server;
-      private final String methodName;
-
-      public CallInfo(RPC.Server server, String methodName) {
-        this.server = server;
-        this.methodName = methodName;
-      }
-    }
-
     static class ProtobufRpcEngineCallbackImpl
         implements ProtobufRpcEngineCallback {
 
@@ -394,9 +381,9 @@ static class ProtobufRpcEngineCallbackImpl
       private final long setupTime;
 
       public ProtobufRpcEngineCallbackImpl() {
-        this.server = currentCallInfo.get().server;
+        this.server = CURRENT_CALL_INFO.get().getServer();
         this.call = Server.getCurCall().get();
-        this.methodName = currentCallInfo.get().methodName;
+        this.methodName = CURRENT_CALL_INFO.get().getMethodName();
         this.setupTime = Time.now();
       }
 
@@ -443,144 +430,58 @@ public Server(Class<?> protocolClass, Object protocolImpl,
         SecretManager<? extends TokenIdentifier> secretManager, 
         String portRangeConfig, AlignmentContext alignmentContext)
         throws IOException {
-      super(bindAddress, port, null, numHandlers,
+      super(protocolClass, protocolImpl, conf, bindAddress, port, numHandlers,
-          numReaders, queueSizePerHandler, conf,
+          numReaders, queueSizePerHandler, verbose, secretManager,
-          serverNameFromClass(protocolImpl.getClass()), secretManager,
+          portRangeConfig, alignmentContext);
-          portRangeConfig);
-      setAlignmentContext(alignmentContext);
-      this.verbose = verbose;  
-      registerProtocolAndImpl(RPC.RpcKind.RPC_PROTOCOL_BUFFER, protocolClass,
-          protocolImpl);
-    }
-
-    @Override
-    protected RpcInvoker getServerRpcInvoker(RpcKind rpcKind) {
-      if (rpcKind == RpcKind.RPC_PROTOCOL_BUFFER) {
-        return RPC_INVOKER;
-      }
-      return super.getServerRpcInvoker(rpcKind);
     }
 
     /**
-     * Protobuf invoker for {@link RpcInvoker}
+     * This implementation is same as
+     * ProtobufRpcEngine2.Server.ProtobufInvoker#call(..)
+     * except this implementation uses non-shaded protobuf classes from legacy
+     * protobuf version (default 2.5.0).
      */
-    static class ProtoBufRpcInvoker implements RpcInvoker {
+    static RpcWritable processCall(RPC.Server server,
-      private static ProtoClassProtoImpl getProtocolImpl(RPC.Server server,
+        String connectionProtocolName, RpcWritable.Buffer request,
-          String protoName, long clientVersion) throws RpcServerException {
+        String methodName, ProtoClassProtoImpl protocolImpl) throws Exception {
-        ProtoNameVer pv = new ProtoNameVer(protoName, clientVersion);
+      BlockingService service = (BlockingService) protocolImpl.protocolImpl;
-        ProtoClassProtoImpl impl = 
+      MethodDescriptor methodDescriptor = service.getDescriptorForType()
-            server.getProtocolImplMap(RPC.RpcKind.RPC_PROTOCOL_BUFFER).get(pv);
+          .findMethodByName(methodName);
-        if (impl == null) { // no match for Protocol AND Version
+      if (methodDescriptor == null) {
-          VerProtocolImpl highest = 
+        String msg = "Unknown method " + methodName + " called on "
-              server.getHighestSupportedProtocol(RPC.RpcKind.RPC_PROTOCOL_BUFFER, 
+                              + connectionProtocolName + " protocol.";
-                  protoName);
+        LOG.warn(msg);
-          if (highest == null) {
+        throw new RpcNoSuchMethodException(msg);
-            throw new RpcNoSuchProtocolException(
-                "Unknown protocol: " + protoName);
-          }
-          // protocol supported but not the version that client wants
-          throw new RPC.VersionMismatch(protoName, clientVersion,
-              highest.version);
-        }
-        return impl;
       }
+      Message prototype = service.getRequestPrototype(methodDescriptor);
+      Message param = request.getValue(prototype);
 
-      @Override 
+      Message result;
-      /**
+      Call currentCall = Server.getCurCall().get();
-       * This is a server side method, which is invoked over RPC. On success
+      try {
-       * the return response has protobuf response payload. On failure, the
+        server.rpcDetailedMetrics.init(protocolImpl.protocolClass);
-       * exception name and the stack trace are returned in the response.
+        CURRENT_CALL_INFO.set(new CallInfo(server, methodName));
-       * See {@link HadoopRpcResponseProto}
+        currentCall.setDetailedMetricsName(methodName);
-       * 
+        result = service.callBlockingMethod(methodDescriptor, null, param);
-       * In this method there three types of exceptions possible and they are
+        // Check if this needs to be a deferred response,
-       * returned in response as follows.
+        // by checking the ThreadLocal callback being set
-       * <ol>
+        if (currentCallback.get() != null) {
-       * <li> Exceptions encountered in this method that are returned 
+          currentCall.deferResponse();
-       * as {@link RpcServerException} </li>
+          currentCallback.set(null);
-       * <li> Exceptions thrown by the service is wrapped in ServiceException. 
+          return null;
-       * In that this method returns in response the exception thrown by the 
-       * service.</li>
-       * <li> Other exceptions thrown by the service. They are returned as
-       * it is.</li>
-       * </ol>
-       */
-      public Writable call(RPC.Server server, String connectionProtocolName,
-          Writable writableRequest, long receiveTime) throws Exception {
-        RpcProtobufRequest request = (RpcProtobufRequest) writableRequest;
-        RequestHeaderProto rpcRequest = request.getRequestHeader();
-        String methodName = rpcRequest.getMethodName();
-
-        /** 
-         * RPCs for a particular interface (ie protocol) are done using a
-         * IPC connection that is setup using rpcProxy.
-         * The rpcProxy's has a declared protocol name that is 
-         * sent form client to server at connection time. 
-         * 
-         * Each Rpc call also sends a protocol name 
-         * (called declaringClassprotocolName). This name is usually the same
-         * as the connection protocol name except in some cases. 
-         * For example metaProtocols such ProtocolInfoProto which get info
-         * about the protocol reuse the connection but need to indicate that
-         * the actual protocol is different (i.e. the protocol is
-         * ProtocolInfoProto) since they reuse the connection; in this case
-         * the declaringClassProtocolName field is set to the ProtocolInfoProto.
-         */
-
-        String declaringClassProtoName = 
-            rpcRequest.getDeclaringClassProtocolName();
-        long clientVersion = rpcRequest.getClientProtocolVersion();
-        return call(server, connectionProtocolName, request, receiveTime,
-            methodName, declaringClassProtoName, clientVersion);
-      }
-
-      protected Writable call(RPC.Server server, String connectionProtocolName,
-          RpcWritable.Buffer request, long receiveTime, String methodName,
-          String declaringClassProtoName, long clientVersion) throws Exception {
-        if (server.verbose)
-          LOG.info("Call: connectionProtocolName=" + connectionProtocolName + 
-              ", method=" + methodName);
-        
-        ProtoClassProtoImpl protocolImpl = getProtocolImpl(server, 
-                              declaringClassProtoName, clientVersion);
-        BlockingService service = (BlockingService) protocolImpl.protocolImpl;
-        MethodDescriptor methodDescriptor = service.getDescriptorForType()
-            .findMethodByName(methodName);
-        if (methodDescriptor == null) {
-          String msg = "Unknown method " + methodName + " called on " 
-                                + connectionProtocolName + " protocol.";
-          LOG.warn(msg);
-          throw new RpcNoSuchMethodException(msg);
         }
-        Message prototype = service.getRequestPrototype(methodDescriptor);
+      } catch (ServiceException e) {
-        Message param = request.getValue(prototype);
+        Exception exception = (Exception) e.getCause();
-
+        currentCall
-        Message result;
+            .setDetailedMetricsName(exception.getClass().getSimpleName());
-        Call currentCall = Server.getCurCall().get();
+        throw (Exception) e.getCause();
-        try {
+      } catch (Exception e) {
-          server.rpcDetailedMetrics.init(protocolImpl.protocolClass);
+        currentCall.setDetailedMetricsName(e.getClass().getSimpleName());
-          currentCallInfo.set(new CallInfo(server, methodName));
+        throw e;
-          currentCall.setDetailedMetricsName(methodName);
+      } finally {
-          result = service.callBlockingMethod(methodDescriptor, null, param);
+        CURRENT_CALL_INFO.set(null);
-          // Check if this needs to be a deferred response,
-          // by checking the ThreadLocal callback being set
-          if (currentCallback.get() != null) {
-            currentCall.deferResponse();
-            currentCallback.set(null);
-            return null;
-          }
-        } catch (ServiceException e) {
-          Exception exception = (Exception) e.getCause();
-          currentCall.setDetailedMetricsName(
-              exception.getClass().getSimpleName());
-          throw (Exception) e.getCause();
-        } catch (Exception e) {
-          currentCall.setDetailedMetricsName(e.getClass().getSimpleName());
-          throw e;
-        } finally {
-          currentCallInfo.set(null);
-        }
-        return RpcWritable.wrap(result);
       }
+      return RpcWritable.wrap(result);
     }
   }
 

hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/ipc/ProtobufRpcEngine2.java

@@ -18,9 +18,6 @@
 
 package org.apache.hadoop.ipc;
 
-import org.apache.hadoop.thirdparty.com.google.common.annotations.VisibleForTesting;
-import org.apache.hadoop.thirdparty.protobuf.*;
-import org.apache.hadoop.thirdparty.protobuf.Descriptors.MethodDescriptor;
 import org.apache.hadoop.classification.InterfaceAudience;
 import org.apache.hadoop.classification.InterfaceStability;
 import org.apache.hadoop.classification.InterfaceStability.Unstable;
@@ -33,6 +30,12 @@
 import org.apache.hadoop.security.UserGroupInformation;
 import org.apache.hadoop.security.token.SecretManager;
 import org.apache.hadoop.security.token.TokenIdentifier;
+import org.apache.hadoop.thirdparty.com.google.common.annotations.VisibleForTesting;
+import org.apache.hadoop.thirdparty.protobuf.BlockingService;
+import org.apache.hadoop.thirdparty.protobuf.Descriptors.MethodDescriptor;
+import org.apache.hadoop.thirdparty.protobuf.Message;
+import org.apache.hadoop.thirdparty.protobuf.ServiceException;
+import org.apache.hadoop.thirdparty.protobuf.TextFormat;
 import org.apache.hadoop.util.Time;
 import org.apache.hadoop.util.concurrent.AsyncGet;
 import org.apache.htrace.core.TraceScope;
@@ -61,9 +64,16 @@ public class ProtobufRpcEngine2 implements RpcEngine {
       ASYNC_RETURN_MESSAGE = new ThreadLocal<>();
 
   static { // Register the rpcRequest deserializer for ProtobufRpcEngine
-    org.apache.hadoop.ipc.Server.registerProtocolEngine(
+    registerProtocolEngine();
-        RPC.RpcKind.RPC_PROTOCOL_BUFFER, RpcProtobufRequest.class,
+  }
-        new Server.ProtoBufRpcInvoker());
+
+  static void registerProtocolEngine() {
+    if (Server.getRpcInvoker(RPC.RpcKind.RPC_PROTOCOL_BUFFER) == null) {
+      org.apache.hadoop.ipc.Server
+          .registerProtocolEngine(RPC.RpcKind.RPC_PROTOCOL_BUFFER,
+              ProtobufRpcEngine2.RpcProtobufRequest.class,
+              new Server.ProtoBufRpcInvoker());
+    }
   }
 
   private static final ClientCache CLIENTS = new ClientCache();
@@ -383,6 +393,14 @@ static class CallInfo {
         this.server = server;
         this.methodName = methodName;
       }
+
+      public RPC.Server getServer() {
+        return server;
+      }
+
+      public String getMethodName() {
+        return methodName;
+      }
     }
 
     static class ProtobufRpcEngineCallbackImpl
@@ -394,9 +412,9 @@ static class ProtobufRpcEngineCallbackImpl
       private final long setupTime;
 
       ProtobufRpcEngineCallbackImpl() {
-        this.server = CURRENT_CALL_INFO.get().server;
+        this.server = CURRENT_CALL_INFO.get().getServer();
         this.call = Server.getCurCall().get();
-        this.methodName = CURRENT_CALL_INFO.get().methodName;
+        this.methodName = CURRENT_CALL_INFO.get().getMethodName();
         this.setupTime = Time.now();
       }
 
@@ -417,7 +435,7 @@ public void error(Throwable t) {
     }
 
     @InterfaceStability.Unstable
-    public static ProtobufRpcEngineCallback2 registerForDeferredResponse() {
+    public static ProtobufRpcEngineCallback2 registerForDeferredResponse2() {
       ProtobufRpcEngineCallback2 callback = new ProtobufRpcEngineCallbackImpl();
       CURRENT_CALLBACK.set(callback);
       return callback;
@@ -453,6 +471,17 @@ public Server(Class<?> protocolClass, Object protocolImpl,
           protocolImpl);
     }
 
+    //Use the latest protobuf rpc invoker itself as that is backward compatible.
+    private static final RpcInvoker RPC_INVOKER = new ProtoBufRpcInvoker();
+
+    @Override
+    protected RpcInvoker getServerRpcInvoker(RPC.RpcKind rpcKind) {
+      if (rpcKind == RPC.RpcKind.RPC_PROTOCOL_BUFFER) {
+        return RPC_INVOKER;
+      }
+      return super.getServerRpcInvoker(rpcKind);
+    }
+
     /**
      * Protobuf invoker for {@link RpcInvoker}.
      */
@@ -524,6 +553,7 @@ public Writable call(RPC.Server server, String connectionProtocolName,
             methodName, declaringClassProtoName, clientVersion);
       }
 
+      @SuppressWarnings("deprecation")
       protected Writable call(RPC.Server server, String connectionProtocolName,
           RpcWritable.Buffer request, long receiveTime, String methodName,
           String declaringClassProtoName, long clientVersion) throws Exception {
@@ -534,6 +564,21 @@ protected Writable call(RPC.Server server, String connectionProtocolName,
 
         ProtoClassProtoImpl protocolImpl = getProtocolImpl(server,
                               declaringClassProtoName, clientVersion);
+        if (protocolImpl.isShadedPBImpl()) {
+          return call(server, connectionProtocolName, request, methodName,
+              protocolImpl);
+        }
+        //Legacy protobuf implementation. Handle using legacy (Non-shaded)
+        // protobuf classes.
+        return ProtobufRpcEngine.Server
+            .processCall(server, connectionProtocolName, request, methodName,
+                protocolImpl);
+      }
+
+      private RpcWritable call(RPC.Server server,
+          String connectionProtocolName, RpcWritable.Buffer request,
+          String methodName, ProtoClassProtoImpl protocolImpl)
+          throws Exception {
         BlockingService service = (BlockingService) protocolImpl.protocolImpl;
         MethodDescriptor methodDescriptor = service.getDescriptorForType()
             .findMethodByName(methodName);

hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/ipc/RPC.java

@@ -937,11 +937,18 @@ public int hashCode() {
     */
    static class ProtoClassProtoImpl {
      final Class<?> protocolClass;
-     final Object protocolImpl; 
+      final Object protocolImpl;
+      private final boolean shadedPBImpl;
+
      ProtoClassProtoImpl(Class<?> protocolClass, Object protocolImpl) {
        this.protocolClass = protocolClass;
        this.protocolImpl = protocolImpl;
+       this.shadedPBImpl = protocolImpl instanceof BlockingService;
      }
+
+      public boolean isShadedPBImpl() {
+        return shadedPBImpl;
+      }
    }
 
    ArrayList<Map<ProtoNameVer, ProtoClassProtoImpl>> protocolImplMapArray = 

hadoop-common-project/hadoop-common/src/test/java/org/apache/hadoop/ipc/TestProtoBufRpc.java

@@ -17,12 +17,10 @@
  */
 package org.apache.hadoop.ipc;
 
-import org.apache.hadoop.thirdparty.protobuf.BlockingService;
-import org.apache.hadoop.thirdparty.protobuf.RpcController;
-import org.apache.hadoop.thirdparty.protobuf.ServiceException;
 import org.apache.commons.lang3.StringUtils;
 import org.apache.hadoop.conf.Configuration;
 import org.apache.hadoop.fs.CommonConfigurationKeys;
+import org.apache.hadoop.ipc.RPC.RpcKind;
 import org.apache.hadoop.ipc.metrics.RpcMetrics;
 import org.apache.hadoop.ipc.protobuf.RpcHeaderProtos.RpcResponseHeaderProto.RpcErrorCodeProto;
 import org.apache.hadoop.ipc.protobuf.TestProtos;
@@ -30,38 +28,71 @@
 import org.apache.hadoop.ipc.protobuf.TestProtos.EchoResponseProto;
 import org.apache.hadoop.ipc.protobuf.TestProtos.EmptyRequestProto;
 import org.apache.hadoop.ipc.protobuf.TestProtos.EmptyResponseProto;
+import org.apache.hadoop.ipc.protobuf.TestProtosLegacy;
 import org.apache.hadoop.ipc.protobuf.TestRpcServiceProtos.TestProtobufRpc2Proto;
 import org.apache.hadoop.ipc.protobuf.TestRpcServiceProtos.TestProtobufRpcProto;
+import org.apache.hadoop.ipc.protobuf.TestRpcServiceProtosLegacy;
 import org.apache.hadoop.metrics2.MetricsRecordBuilder;
 import org.apache.hadoop.net.NetUtils;
 import org.apache.hadoop.test.GenericTestUtils;
+import org.apache.hadoop.thirdparty.protobuf.BlockingService;
+import org.apache.hadoop.thirdparty.protobuf.RpcController;
+import org.apache.hadoop.thirdparty.protobuf.ServiceException;
 import org.junit.After;
 import org.junit.Before;
 import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.junit.runners.Parameterized;
+import org.junit.runners.Parameterized.Parameters;
 
 import java.io.IOException;
 import java.net.URISyntaxException;
+import java.util.ArrayList;
+import java.util.Collection;
 import java.util.concurrent.TimeoutException;
 
-import static org.assertj.core.api.Assertions.assertThat;
 import static org.apache.hadoop.test.MetricsAsserts.assertCounterGt;
 import static org.apache.hadoop.test.MetricsAsserts.getMetrics;
+import static org.assertj.core.api.Assertions.assertThat;
 import static org.junit.Assert.fail;
+import static org.junit.Assume.assumeFalse;
 
 /**
  * Test for testing protocol buffer based RPC mechanism.
  * This test depends on test.proto definition of types in src/test/proto
  * and protobuf service definition from src/test/test_rpc_service.proto
  */
+@RunWith(Parameterized.class)
 public class TestProtoBufRpc extends TestRpcBase {
   private static RPC.Server server;
   private final static int SLEEP_DURATION = 1000;
 
+  /**
+   * Test with legacy protobuf implementation in same server.
+   */
+  private boolean testWithLegacy;
+  /**
+   * Test with legacy protobuf implementation loaded first while creating the
+   * RPC server.
+   */
+  private boolean testWithLegacyFirst;
+
+  public TestProtoBufRpc(Boolean testWithLegacy, Boolean testWithLegacyFirst) {
+    this.testWithLegacy = testWithLegacy;
+    this.testWithLegacyFirst = testWithLegacyFirst;
+  }
+
   @ProtocolInfo(protocolName = "testProto2", protocolVersion = 1)
   public interface TestRpcService2 extends
       TestProtobufRpc2Proto.BlockingInterface {
   }
 
+  @ProtocolInfo(protocolName="testProtoLegacy", protocolVersion = 1)
+  public interface TestRpcService2Legacy
+      extends TestRpcServiceProtosLegacy.
+      TestProtobufRpc2Proto.BlockingInterface {
+  }
+
   public static class PBServer2Impl implements TestRpcService2 {
 
     @Override
@@ -88,12 +119,58 @@ public TestProtos.SleepResponseProto sleep(RpcController controller,
     }
   }
 
+  public static class PBServer2ImplLegacy implements TestRpcService2Legacy {
+
+    @Override
+    public TestProtosLegacy.EmptyResponseProto ping2(
+        com.google.protobuf.RpcController unused,
+        TestProtosLegacy.EmptyRequestProto request)
+        throws com.google.protobuf.ServiceException {
+      return TestProtosLegacy.EmptyResponseProto.newBuilder().build();
+    }
+
+    @Override
+    public TestProtosLegacy.EchoResponseProto echo2(
+        com.google.protobuf.RpcController unused,
+        TestProtosLegacy.EchoRequestProto request)
+        throws com.google.protobuf.ServiceException {
+      return TestProtosLegacy.EchoResponseProto.newBuilder()
+          .setMessage(request.getMessage()).build();
+    }
+
+    @Override
+    public TestProtosLegacy.SleepResponseProto sleep(
+        com.google.protobuf.RpcController controller,
+        TestProtosLegacy.SleepRequestProto request)
+        throws com.google.protobuf.ServiceException {
+      try {
+        Thread.sleep(request.getMilliSeconds());
+      } catch (InterruptedException ex) {
+      }
+      return TestProtosLegacy.SleepResponseProto.newBuilder().build();
+    }
+  }
+
+  @Parameters
+  public static Collection<Object[]> params() {
+    Collection<Object[]> params = new ArrayList<Object[]>();
+    params.add(new Object[] {Boolean.TRUE, Boolean.TRUE });
+    params.add(new Object[] {Boolean.TRUE, Boolean.FALSE });
+    params.add(new Object[] {Boolean.FALSE, Boolean.FALSE });
+    return params;
+  }
+
   @Before
+  @SuppressWarnings("deprecation")
   public void setUp() throws IOException { // Setup server for both protocols
     conf = new Configuration();
     conf.setInt(CommonConfigurationKeys.IPC_MAXIMUM_DATA_LENGTH, 1024);
     conf.setBoolean(CommonConfigurationKeys.IPC_SERVER_LOG_SLOW_RPC, true);
     // Set RPC engine to protobuf RPC engine
+    if (testWithLegacy) {
+      RPC.setProtocolEngine(conf, TestRpcService2Legacy.class,
+          ProtobufRpcEngine.class);
+    }
     RPC.setProtocolEngine(conf, TestRpcService.class, ProtobufRpcEngine2.class);
     RPC.setProtocolEngine(conf, TestRpcService2.class,
         ProtobufRpcEngine2.class);
@@ -103,9 +180,21 @@ public void setUp() throws IOException { // Setup server for both protocols
     BlockingService service = TestProtobufRpcProto
         .newReflectiveBlockingService(serverImpl);
 
-    // Get RPC server for server side implementation
+    if (testWithLegacy && testWithLegacyFirst) {
-    server = new RPC.Builder(conf).setProtocol(TestRpcService.class)
+      PBServer2ImplLegacy server2ImplLegacy = new PBServer2ImplLegacy();
-        .setInstance(service).setBindAddress(ADDRESS).setPort(PORT).build();
+      com.google.protobuf.BlockingService legacyService =
+          TestRpcServiceProtosLegacy.TestProtobufRpc2Proto
+              .newReflectiveBlockingService(server2ImplLegacy);
+      server = new RPC.Builder(conf).setProtocol(TestRpcService2Legacy.class)
+          .setInstance(legacyService).setBindAddress(ADDRESS).setPort(PORT)
+          .build();
+      server.addProtocol(RpcKind.RPC_PROTOCOL_BUFFER, TestRpcService.class,
+          service);
+    } else {
+      // Get RPC server for server side implementation
+      server = new RPC.Builder(conf).setProtocol(TestRpcService.class)
+          .setInstance(service).setBindAddress(ADDRESS).setPort(PORT).build();
+    }
     addr = NetUtils.getConnectAddress(server);
 
     // now the second protocol
@@ -115,6 +204,16 @@ public void setUp() throws IOException { // Setup server for both protocols
 
     server.addProtocol(RPC.RpcKind.RPC_PROTOCOL_BUFFER, TestRpcService2.class,
         service2);
+
+    if (testWithLegacy && !testWithLegacyFirst) {
+      PBServer2ImplLegacy server2ImplLegacy = new PBServer2ImplLegacy();
+      com.google.protobuf.BlockingService legacyService =
+          TestRpcServiceProtosLegacy.TestProtobufRpc2Proto
+              .newReflectiveBlockingService(server2ImplLegacy);
+      server
+          .addProtocol(RpcKind.RPC_PROTOCOL_BUFFER, TestRpcService2Legacy.class,
+              legacyService);
+    }
     server.start();
   }
   
@@ -128,6 +227,10 @@ private TestRpcService2 getClient2() throws IOException {
     return RPC.getProxy(TestRpcService2.class, 0, addr, conf);
   }
 
+  private TestRpcService2Legacy getClientLegacy() throws IOException {
+    return RPC.getProxy(TestRpcService2Legacy.class, 0, addr, conf);
+  }
+
   @Test (timeout=5000)
   public void testProtoBufRpc() throws Exception {
     TestRpcService client = getClient(addr, conf);
@@ -179,10 +282,39 @@ public void testProtoBufRpc2() throws Exception {
     MetricsRecordBuilder rpcDetailedMetrics = 
         getMetrics(server.getRpcDetailedMetrics().name());
     assertCounterGt("Echo2NumOps", 0L, rpcDetailedMetrics);
+
+    if (testWithLegacy) {
+      testProtobufLegacy();
+    }
+  }
+
+  private void testProtobufLegacy()
+      throws IOException, com.google.protobuf.ServiceException {
+    TestRpcService2Legacy client = getClientLegacy();
+
+    // Test ping method
+    client.ping2(null, TestProtosLegacy.EmptyRequestProto.newBuilder().build());
+
+    // Test echo method
+    TestProtosLegacy.EchoResponseProto echoResponse = client.echo2(null,
+        TestProtosLegacy.EchoRequestProto.newBuilder().setMessage("hello")
+            .build());
+    assertThat(echoResponse.getMessage()).isEqualTo("hello");
+
+    // Ensure RPC metrics are updated
+    MetricsRecordBuilder rpcMetrics = getMetrics(server.getRpcMetrics().name());
+    assertCounterGt("RpcQueueTimeNumOps", 0L, rpcMetrics);
+    assertCounterGt("RpcProcessingTimeNumOps", 0L, rpcMetrics);
+
+    MetricsRecordBuilder rpcDetailedMetrics =
+        getMetrics(server.getRpcDetailedMetrics().name());
+    assertCounterGt("Echo2NumOps", 0L, rpcDetailedMetrics);
   }
 
   @Test (timeout=5000)
   public void testProtoBufRandomException() throws Exception {
+    //No test with legacy
+    assumeFalse(testWithLegacy);
     TestRpcService client = getClient(addr, conf);
 
     try {
@@ -200,6 +332,8 @@ public void testProtoBufRandomException() throws Exception {
   
   @Test(timeout=6000)
   public void testExtraLongRpc() throws Exception {
+    //No test with legacy
+    assumeFalse(testWithLegacy);
     TestRpcService2 client = getClient2();
     final String shortString = StringUtils.repeat("X", 4);
     // short message goes through
@@ -219,6 +353,8 @@ public void testExtraLongRpc() throws Exception {
   @Test(timeout = 12000)
   public void testLogSlowRPC() throws IOException, ServiceException,
       TimeoutException, InterruptedException {
+    //No test with legacy
+    assumeFalse(testWithLegacy);
     TestRpcService2 client = getClient2();
     // make 10 K fast calls
     for (int x = 0; x < 10000; x++) {
@@ -244,6 +380,8 @@ public void testLogSlowRPC() throws IOException, ServiceException,
 
   @Test(timeout = 12000)
   public void testEnsureNoLogIfDisabled() throws IOException, ServiceException {
+    //No test with legacy
+    assumeFalse(testWithLegacy);
     // disable slow RPC  logging
     server.setLogSlowRPC(false);
     TestRpcService2 client = getClient2();

hadoop-common-project/hadoop-common/src/test/java/org/apache/hadoop/ipc/TestProtoBufRpcServerHandoff.java

@@ -145,7 +145,7 @@ public static class TestProtoBufRpcServerHandoffServer
         ServiceException {
       final long startTime = System.currentTimeMillis();
       final ProtobufRpcEngineCallback2 callback =
-          ProtobufRpcEngine2.Server.registerForDeferredResponse();
+          ProtobufRpcEngine2.Server.registerForDeferredResponse2();
       final long sleepTime = request.getSleepTime();
       new Thread() {
         @Override

hadoop-common-project/hadoop-common/src/test/proto/test_legacy.proto

@@ -0,0 +1,101 @@
+/**
+ * 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.
+ */
+option java_package = "org.apache.hadoop.ipc.protobuf";
+option java_outer_classname = "TestProtosLegacy";
+option java_generate_equals_and_hash = true;
+package hadoop.common;
+
+message EmptyRequestProto {
+}
+
+message EmptyResponseProto {
+}
+
+message EchoRequestProto {
+  required string message = 1;
+}
+
+message EchoResponseProto {
+  required string message = 1;
+}
+
+message OptRequestProto {
+  optional string message = 1;
+}
+
+message OptResponseProto {
+  optional string message = 1;
+}
+
+message SleepRequestProto{
+  required int32 milliSeconds = 1;
+}
+
+message SleepResponseProto{
+}
+
+message SlowPingRequestProto {
+  required bool shouldSlow = 1;
+}
+
+message EchoRequestProto2 {
+  repeated string message = 1;
+}
+
+message EchoResponseProto2 {
+  repeated string message = 1;
+}
+
+message AddRequestProto {
+  required int32 param1 = 1;
+  required int32 param2 = 2;
+}
+
+message AddRequestProto2 {
+  repeated int32 params = 1;
+}
+
+message AddResponseProto {
+  required int32 result = 1;
+}
+
+message ExchangeRequestProto {
+  repeated int32 values = 1;
+}
+
+message ExchangeResponseProto {
+  repeated int32 values = 1;
+}
+
+message AuthMethodResponseProto {
+  required int32 code = 1;
+  required string mechanismName = 2;
+}
+
+message UserResponseProto {
+  required string user = 1;
+}
+
+message SleepRequestProto2 {
+  optional int64 sleep_time = 1;
+}
+
+message SleepResponseProto2 {
+  optional int64 receive_time = 1;
+  optional int64 response_time = 2;
+}

hadoop-common-project/hadoop-common/src/test/proto/test_rpc_service_legacy.proto

@@ -0,0 +1,79 @@
+/**
+ * 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.
+ */
+syntax = "proto2";
+option java_package = "org.apache.hadoop.ipc.protobuf";
+option java_outer_classname = "TestRpcServiceProtosLegacy";
+option java_generic_services = true;
+option java_generate_equals_and_hash = true;
+package hadoop.common;
+
+import "test_legacy.proto";
+
+
+/**
+ * A protobuf service for use in tests
+ */
+service TestProtobufRpcProto {
+  rpc ping(EmptyRequestProto) returns (EmptyResponseProto);
+  rpc echo(EchoRequestProto) returns (EchoResponseProto);
+  rpc error(EmptyRequestProto) returns (EmptyResponseProto);
+  rpc error2(EmptyRequestProto) returns (EmptyResponseProto);
+  rpc slowPing(SlowPingRequestProto) returns (EmptyResponseProto);
+  rpc echo2(EchoRequestProto2) returns (EchoResponseProto2);
+  rpc add(AddRequestProto) returns (AddResponseProto);
+  rpc add2(AddRequestProto2) returns (AddResponseProto);
+  rpc testServerGet(EmptyRequestProto) returns (EmptyResponseProto);
+  rpc exchange(ExchangeRequestProto) returns (ExchangeResponseProto);
+  rpc sleep(SleepRequestProto) returns (EmptyResponseProto);
+  rpc lockAndSleep(SleepRequestProto) returns (EmptyResponseProto);
+  rpc getAuthMethod(EmptyRequestProto) returns (AuthMethodResponseProto);
+  rpc getAuthUser(EmptyRequestProto) returns (UserResponseProto);
+  rpc echoPostponed(EchoRequestProto) returns (EchoResponseProto);
+  rpc sendPostponed(EmptyRequestProto) returns (EmptyResponseProto);
+  rpc getCurrentUser(EmptyRequestProto) returns (UserResponseProto);
+  rpc getServerRemoteUser(EmptyRequestProto) returns (UserResponseProto);
+}
+
+service TestProtobufRpc2Proto {
+  rpc ping2(EmptyRequestProto) returns (EmptyResponseProto);
+  rpc echo2(EchoRequestProto) returns (EchoResponseProto);
+  rpc sleep(SleepRequestProto) returns (SleepResponseProto);
+}
+
+service OldProtobufRpcProto {
+  rpc ping(EmptyRequestProto) returns (EmptyResponseProto);
+  rpc echo(EmptyRequestProto) returns (EmptyResponseProto);
+}
+
+service NewProtobufRpcProto {
+  rpc ping(EmptyRequestProto) returns (EmptyResponseProto);
+  rpc echo(OptRequestProto) returns (OptResponseProto);
+}
+
+service NewerProtobufRpcProto {
+  rpc ping(EmptyRequestProto) returns (EmptyResponseProto);
+  rpc echo(EmptyRequestProto) returns (EmptyResponseProto);
+}
+
+service CustomProto {
+  rpc ping(EmptyRequestProto) returns (EmptyResponseProto);
+}
+
+service TestProtobufRpcHandoffProto {
+  rpc sleep(SleepRequestProto2) returns (SleepResponseProto2);
+}