svn merge -c 1291602 from trunk for HADOOP-8084.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-0.23-PB@1291970 13f79535-47bb-0310-9956-ffa450edef68

hadoop-common-project/hadoop-common/CHANGES.txt

@@ -47,6 +47,9 @@ Release 0.23-PB - Unreleased
 
     HADOOP-8070. Add a standalone benchmark for RPC call performance. (todd)
 
+    HADOOP-8084. Updates ProtoBufRpc engine to not do an unnecessary copy 
+    for RPC request/response. (ddas)
+
   BUG FIXES
 
     HADOOP-7695. RPC.stopProxy can throw unintended exception while logging

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

@@ -34,6 +34,7 @@ import org.apache.commons.logging.LogFactory;
 import org.apache.hadoop.classification.InterfaceAudience;
 import org.apache.hadoop.classification.InterfaceStability;
 import org.apache.hadoop.conf.Configuration;
+import org.apache.hadoop.io.DataOutputOutputStream;
 import org.apache.hadoop.io.Writable;
 import org.apache.hadoop.ipc.Client.ConnectionId;
 import org.apache.hadoop.ipc.RPC.RpcInvoker;
@@ -45,6 +46,7 @@ import org.apache.hadoop.ipc.protobuf.HadoopRpcProtos.HadoopRpcResponseProto.Res
 import org.apache.hadoop.security.UserGroupInformation;
 import org.apache.hadoop.security.token.SecretManager;
 import org.apache.hadoop.security.token.TokenIdentifier;
+import org.apache.hadoop.util.ProtoUtil;
 import org.apache.hadoop.util.StringUtils;
 
 import com.google.common.annotations.VisibleForTesting;
@@ -268,13 +270,13 @@ public class ProtobufRpcEngine implements RpcEngine {
 
     @Override
     public void write(DataOutput out) throws IOException {
-      out.writeInt(message.toByteArray().length);
-      out.write(message.toByteArray());
+      ((Message)message).writeDelimitedTo(
+          DataOutputOutputStream.constructOutputStream(out));
     }
 
     @Override
     public void readFields(DataInput in) throws IOException {
-      int length = in.readInt();
+      int length = ProtoUtil.readRawVarint32(in);
       byte[] bytes = new byte[length];
       in.readFully(bytes);
       message = HadoopRpcRequestProto.parseFrom(bytes);
@@ -297,13 +299,13 @@ public class ProtobufRpcEngine implements RpcEngine {
 
     @Override
     public void write(DataOutput out) throws IOException {
-      out.writeInt(message.toByteArray().length);
-      out.write(message.toByteArray());
+      ((Message)message).writeDelimitedTo(
+          DataOutputOutputStream.constructOutputStream(out));      
     }
 
     @Override
     public void readFields(DataInput in) throws IOException {
-      int length = in.readInt();
+      int length = ProtoUtil.readRawVarint32(in);
       byte[] bytes = new byte[length];
       in.readFully(bytes);
       message = HadoopRpcResponseProto.parseFrom(bytes);