hadoop/hadoop-hdfs-project/hadoop-hdfs/src/main/proto/DatanodeProtocol.proto

/**
 * 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.
 */

// This file contains protocol buffers that are used throughout HDFS -- i.e.
// by the client, server, and data transfer protocols.

option java_package = "org.apache.hadoop.hdfs.protocol.proto";
option java_outer_classname = "DatanodeProtocolProtos";
option java_generic_services = true;
option java_generate_equals_and_hash = true;

import "hdfs.proto";

/**
 * Information to identify a datanode to a namenode
 */
message DatanodeRegistrationProto {
  required DatanodeIDProto datanodeID = 1;    // Datanode information
  required StorageInfoProto storageInfo = 2;  // Node information
  required ExportedBlockKeysProto keys = 3;   // Block keys
}

/**
 * Commands sent from namenode to the datanodes
 */
message DatanodeCommandProto {
  enum Type {
    BalancerBandwidthCommand = 0;
    BlockCommand = 1;
    BlockRecoveryCommand = 2;
    FinalizeCommand = 3;
    KeyUpdateCommand = 4;
    RegisterCommand = 5;
    UpgradeCommand = 6;
  }

  required Type cmdType = 1;    // Type of the command

  // One of the following command is available when the corresponding
  // cmdType is set
  optional BalancerBandwidthCommandProto balancerCmd = 2;
  optional BlockCommandProto blkCmd = 3;
  optional BlockRecoveryCommandProto recoveryCmd = 4;
  optional FinalizeCommandProto finalizeCmd = 5;
  optional KeyUpdateCommandProto keyUpdateCmd = 6;
  optional RegisterCommandProto registerCmd = 7;
  optional UpgradeCommandProto upgradeCmd = 8;
}

/**
 * Command sent from namenode to datanode to set the
 * maximum bandwidth to be used for balancing.
 */
message BalancerBandwidthCommandProto {

  // Maximum bandwidth to be used by datanode for balancing
  required uint64 bandwidth = 1;
}

/**
 * Command to instruct datanodes to perform certain action
 * on the given set of blocks.
 */
message BlockCommandProto {
  enum Action {  
    TRANSFER = 1;   // Transfer blocks to another datanode
    INVALIDATE = 2; // Invalidate blocks
  }
  required Action action = 1;
  required string blockPoolId = 2;
  repeated BlockProto blocks = 3;
  repeated DatanodeInfosProto targets = 4;
}

/**
 * List of blocks to be recovered by the datanode
 */
message BlockRecoveryCommandProto {
  repeated RecoveringBlockProto blocks = 1;
}

/**
 * Finalize the upgrade at the datanode
 */
message FinalizeCommandProto {
  required string blockPoolId = 1; // Block pool to be finalized
}

/**
 * Update the block keys at the datanode
 */
message KeyUpdateCommandProto {
  required ExportedBlockKeysProto keys = 1;
}

/**
 * Instruct datanode to register with the namenode
 */
message RegisterCommandProto {
  // void
}

/**
 * Generic distributed upgrade Command
 */
message UpgradeCommandProto {
  enum Action {
    UNKNOWN = 0;          // Unknown action
    REPORT_STATUS = 100;  // Report upgrade status
    START_UPGRADE = 101;  // Start upgrade
  }
  required Action action = 1;  // Upgrade action
  required uint32 version = 2; // Version of the upgrade
  required uint32 upgradeStatus = 3; // % completed in range 0 & 100
}

/**
 * registration - Information of the datanode registering with the namenode
 */
message RegisterDatanodeRequestProto {
  required DatanodeRegistrationProto registration = 1; // Datanode info
}

/**
 * registration - Update registration of the datanode that successfully 
 *                registered. StorageInfo will be updated to include new 
 *                storage ID if the datanode did not have one in the request.
 */
message RegisterDatanodeResponseProto {
  required DatanodeRegistrationProto registration = 1; // Datanode info
}

/**
 * registration - datanode registration information
 * capacity - total storage capacity available at the datanode
 * dfsUsed - storage used by HDFS
 * remaining - remaining storage available for HDFS
 * blockPoolUsed - storage used by the block pool
 * xmitsInProgress - number of transfers from this datanode to others
 * xceiverCount - number of active transceiver threads
 * failedVolumes - number of failed volumes
 */
message HeartbeatRequestProto {
  required DatanodeRegistrationProto registration = 1; // Datanode info
  required uint64 capacity = 2;
  required uint64 dfsUsed = 3;
  required uint64 remaining = 4;
  required uint64 blockPoolUsed = 5;
  required uint32 xmitsInProgress = 6;
  required uint32 xceiverCount = 7;
  required uint32 failedVolumes = 8;
}

/**
 * cmds - Commands from namenode to datanode.
 */
message HeartbeatResponseProto {
  repeated DatanodeCommandProto cmds = 1; // Returned commands can be null
}

/**
 * registration - datanode registration information
 * blockPoolID  - block pool ID of the reported blocks
 * blocks       - each block is represented as two longs in the array.
 *                first long represents block ID
 *                second long represents length
 */
message BlockReportRequestProto {
  required DatanodeRegistrationProto registration = 1;
  required string blockPoolId = 2;
  repeated uint64 blocks = 3 [packed=true];
}

/**
 * cmd - Command from namenode to the datanode
 */
message BlockReportResponseProto {
  required DatanodeCommandProto cmd = 1;
} 

/**
 * Data structure to send received or deleted block information
 * from datanode to namenode.
 *
 * deleteHint set to "-" indicates block deletion.
 * other deleteHint indicates block addition.
 */
message ReceivedDeletedBlockInfoProto {
  required BlockProto block = 1;
  optional string deleteHint = 2;
}

/**
 * registration - datanode registration information
 * blockPoolID  - block pool ID of the reported blocks
 * blocks       - Received/deleted block list
 */
message BlockReceivedAndDeletedRequestProto {
  required DatanodeRegistrationProto registration = 1;
  required string blockPoolId = 2;
  repeated ReceivedDeletedBlockInfoProto blocks = 3;
}

/**
 * void response
 */
message BlockReceivedAndDeletedResponseProto {
}

/**
 * registartion - Datanode reporting the error
 * errorCode - error code indicating the error
 * msg - Free text description of the error
 */
message ErrorReportRequestProto {
  enum ErrorCode {
    NOTIFY = 0;           // Error report to be logged at the namenode
    DISK_ERROR = 1;       // DN has disk errors but still has valid volumes
    INVALID_BLOCK = 2;    // Command from namenode has invalid block ID
    FATAL_DISK_ERROR = 3; // No valid volumes left on datanode
  }
  required DatanodeRegistrationProto registartion = 1; // Registartion info
  required uint32 errorCode = 2;  // Error code
  required string msg = 3;        // Error message
}

/**
 * void response
 */
message ErrorReportResponseProto {
}

/**
 * cmd - Upgrade command sent from datanode to namenode
 */
message ProcessUpgradeRequestProto {
  optional UpgradeCommandProto cmd = 1;
}

/**
 * cmd - Upgrade command sent from namenode to datanode
 */
message ProcessUpgradeResponseProto {
  optional UpgradeCommandProto cmd = 1;
}

/**
 * blocks - list of blocks that are reported as corrupt
 */
message ReportBadBlocksRequestProto {
  repeated LocatedBlockProto blocks = 1;
}

/**
 * void response
 */
message ReportBadBlocksResponseProto {
}

/**
 * Commit block synchronization request during lease recovery
 */
message CommitBlockSynchronizationRequestProto {
  required ExtendedBlockProto block = 1;
  required uint64 newGenStamp = 2;
  required uint64 newLength = 3;
  required bool closeFile = 4;
  required bool deleteBlock = 5;
  repeated DatanodeIDProto newTaragets = 6;
}

/**
 * void response
 */
message CommitBlockSynchronizationResponseProto {
}

/**
 * Protocol used from datanode to the namenode
 * See the request and response for details of rpc call.
 */
service DatanodeProtocolService {
  /**
   * Register a datanode at a namenode
   */
  rpc registerDatanode(RegisterDatanodeRequestProto)
      returns(RegisterDatanodeResponseProto);

  /**
   * Send heartbeat from datanode to namenode
   */
  rpc sendHeartbeat(HeartbeatRequestProto) returns(HeartbeatResponseProto);

  /**
   * Report blocks at a given datanode to the namenode
   */
  rpc blockReport(BlockReportRequestProto) returns(BlockReportResponseProto);

  /**
   * Report from datanode about recently received or deleted block
   */
  rpc blockReceivedAndDeleted(BlockReceivedAndDeletedRequestProto) 
      returns(BlockReceivedAndDeletedResponseProto);

  /**
   * Report from a datanode of an error to the active namenode.
   * Used for debugging.
   */
  rpc errorReport(ErrorReportRequestProto) returns(ErrorReportResponseProto);
  
  /**
   * Request the version
   */
  rpc versionRequest(VersionRequestProto) returns(VersionResponseProto);

  /**
   * Generic way to send commands from datanode to namenode during
   * distributed upgrade process.
   */
  rpc processUpgrade(ProcessUpgradeRequestProto) returns(ProcessUpgradeResponseProto);

  /**
   * Report corrupt blocks at the specified location
   */
  rpc reportBadBlocks(ReportBadBlocksRequestProto) returns(ReportBadBlocksResponseProto);

  /**
   * Commit block synchronization during lease recovery.
   */
  rpc commitBlockSynchronization(CommitBlockSynchronizationRequestProto)
      returns(CommitBlockSynchronizationResponseProto);
}