hadoop-hdfs-project/hadoop-hdfs/src/contrib/libhdfs3/src/client/DataTransferProtocol.h

/**
 * 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.
 */

#ifndef _HDFS_LIBHDFS_3_CLIENT_DATATRANSFERPROTOCOL_H_
#define _HDFS_LIBHDFS_3_CLIENT_DATATRANSFERPROTOCOL_H_

#include "client/Token.h"
#include "server/DatanodeInfo.h"
#include "server/ExtendedBlock.h"

#include <vector>

namespace hdfs {
namespace internal {

/**
 * Transfer data to/from datanode using a streaming protocol.
 */
class DataTransferProtocol {
public:
    virtual ~DataTransferProtocol() {
    }
    /**
     * Read a block.
     *
     * @param blk the block being read.
     * @param blockToken security token for accessing the block.
     * @param clientName client's name.
     * @param blockOffset offset of the block.
     * @param length maximum number of bytes for this read.
     */
    virtual void readBlock(const ExtendedBlock & blk,
                           const Token & blockToken, const char * clientName,
                           int64_t blockOffset, int64_t length) = 0;

    /**
     * Write a block to a datanode pipeline.
     *
     * @param blk the block being written.
     * @param blockToken security token for accessing the block.
     * @param clientName client's name.
     * @param targets target datanodes in the pipeline.
     * @param source source datanode.
     * @param stage pipeline stage.
     * @param pipelineSize the size of the pipeline.
     * @param minBytesRcvd minimum number of bytes received.
     * @param maxBytesRcvd maximum number of bytes received.
     * @param latestGenerationStamp the latest generation stamp of the block.
     */
    virtual void writeBlock(const ExtendedBlock & blk,
                            const Token & blockToken, const char * clientName,
                            const std::vector<DatanodeInfo> & targets, int stage,
                            int pipelineSize, int64_t minBytesRcvd, int64_t maxBytesRcvd,
                            int64_t latestGenerationStamp, int checksumType,
                            int bytesPerChecksum) = 0;

    /**
     * Transfer a block to another datanode.
     * The block stage must be
     * either {@link BlockConstructionStage#TRANSFER_RBW}
     * or {@link BlockConstructionStage#TRANSFER_FINALIZED}.
     *
     * @param blk the block being transferred.
     * @param blockToken security token for accessing the block.
     * @param clientName client's name.
     * @param targets target datanodes.
     */
    virtual void transferBlock(const ExtendedBlock & blk,
                               const Token & blockToken, const char * clientName,
                               const std::vector<DatanodeInfo> & targets) = 0;

    /**
     * Get block checksum (MD5 of CRC32).
     *
     * @param blk a block.
     * @param blockToken security token for accessing the block.
     * @throw HdfsIOException
     */
    virtual void blockChecksum(const ExtendedBlock & blk,
                               const Token & blockToken) = 0;
};

}
}

#endif /* _HDFS_LIBHDFS_3_CLIENT_DATATRANSFERPROTOCOL_H_ */