hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/protocolPB/JournalProtocolTranslatorPB.java

/**
 * 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.hdfs.protocolPB;

import java.io.Closeable;
import java.io.IOException;
import java.net.InetSocketAddress;

import org.apache.hadoop.classification.InterfaceAudience;
import org.apache.hadoop.classification.InterfaceStability;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.hdfs.protocol.proto.JournalProtocolProtos.JournalRequestProto;
import org.apache.hadoop.hdfs.protocol.proto.JournalProtocolProtos.StartLogSegmentRequestProto;
import org.apache.hadoop.hdfs.protocolR23Compatible.ProtocolSignatureWritable;
import org.apache.hadoop.hdfs.server.protocol.JournalProtocol;
import org.apache.hadoop.hdfs.server.protocol.NamenodeRegistration;
import org.apache.hadoop.ipc.ProtobufRpcEngine;
import org.apache.hadoop.ipc.ProtobufHelper;
import org.apache.hadoop.ipc.ProtocolMetaInterface;
import org.apache.hadoop.ipc.ProtocolSignature;
import org.apache.hadoop.ipc.RPC;
import org.apache.hadoop.ipc.RpcClientUtil;
import org.apache.hadoop.ipc.RpcPayloadHeader.RpcKind;

import com.google.protobuf.RpcController;
import com.google.protobuf.ServiceException;

/**
 * This class is the client side translator to translate the requests made on
 * {@link JournalProtocol} interfaces to the RPC server implementing
 * {@link JournalProtocolPB}.
 */
@InterfaceAudience.Private
@InterfaceStability.Stable
public class JournalProtocolTranslatorPB implements ProtocolMetaInterface,
    JournalProtocol, Closeable {
  /** RpcController is not used and hence is set to null */
  private final static RpcController NULL_CONTROLLER = null;
  private final JournalProtocolPB rpcProxy;

  public JournalProtocolTranslatorPB(InetSocketAddress nameNodeAddr,
      Configuration conf) throws IOException {
    RPC.setProtocolEngine(conf, JournalProtocolPB.class, ProtobufRpcEngine.class);
    rpcProxy = RPC.getProxy(JournalProtocolPB.class,
        RPC.getProtocolVersion(JournalProtocolPB.class), nameNodeAddr, conf);
  }

  @Override
  public void close() {
    RPC.stopProxy(rpcProxy);
  }

  @Override
  public long getProtocolVersion(String protocolName, long clientVersion)
      throws IOException {
    return rpcProxy.getProtocolVersion(protocolName, clientVersion);
  }

  @Override
  public ProtocolSignature getProtocolSignature(String protocol,
      long clientVersion, int clientMethodsHash) throws IOException {
    return ProtocolSignatureWritable.convert(rpcProxy.getProtocolSignature2(
        protocol, clientVersion, clientMethodsHash));
  }

  @Override
  public void journal(NamenodeRegistration reg, long firstTxnId,
      int numTxns, byte[] records) throws IOException {
    JournalRequestProto req = JournalRequestProto.newBuilder()
        .setRegistration(PBHelper.convert(reg))
        .setFirstTxnId(firstTxnId)
        .setNumTxns(numTxns)
        .setRecords(PBHelper.getByteString(records))
        .build();
    try {
      rpcProxy.journal(NULL_CONTROLLER, req);
    } catch (ServiceException e) {
      throw ProtobufHelper.getRemoteException(e);
    }
  }

  @Override
  public void startLogSegment(NamenodeRegistration registration, long txid)
      throws IOException {
    StartLogSegmentRequestProto req = StartLogSegmentRequestProto.newBuilder()
        .setRegistration(PBHelper.convert(registration))
        .setTxid(txid)
        .build();
    try {
      rpcProxy.startLogSegment(NULL_CONTROLLER, req);
    } catch (ServiceException e) {
      throw ProtobufHelper.getRemoteException(e);
    }
  }

  @Override
  public boolean isMethodSupported(String methodName) throws IOException {
    return RpcClientUtil.isMethodSupported(rpcProxy, JournalProtocolPB.class,
        RpcKind.RPC_PROTOCOL_BUFFER,
        RPC.getProtocolVersion(JournalProtocolPB.class), methodName);
  }
}