hadoop/hadoop-hdfs-project/hadoop-hdfs/src/main/proto/fsimage.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.
 */

option java_package = "org.apache.hadoop.hdfs.server.namenode";
option java_outer_classname = "FsImageProto";

package hadoop.hdfs.fsimage;

import "hdfs.proto";

/**
 * This file defines the on-disk layout of the file system image. The
 * layout is defined by the following EBNF grammar, in which angle
 * brackets mark protobuf definitions. (e.g., <FileSummary>)
 *
 * FILE := MAGIC SECTION* <FileSummary> FileSummaryLength
 * MAGIC := 'HDFSIMG1'
 * SECTION := <NameSystemSection> | ...
 * FileSummaryLength := 4 byte int
 *
 * Some notes:
 *
 * The codec field in FileSummary describes the compression codec used
 * for all sections. The fileheader is always uncompressed.
 *
 * All protobuf messages are serialized in delimited form, which means
 * that there always will be an integer indicates the size of the
 * protobuf message.
 *
 */

message FileSummary {
  // The version of the above EBNF grammars.
  required uint32 ondiskVersion = 1;
  // layoutVersion describes which features are available in the
  // FSImage.
  required uint32 layoutVersion = 2;
  optional string codec         = 3;
  // index for each section
  message Section {
    optional string name = 1;
    optional uint64 length = 2;
    optional uint64 offset = 3;
  }
  repeated Section sections = 4;
}

/**
 * Name: NS_INFO
 */
message NameSystemSection {
  optional uint32 namespaceId = 1;
  optional uint64 genstampV1 = 2;
  optional uint64 genstampV2 = 3;
  optional uint64 genstampV1Limit = 4;
  optional uint64 lastAllocatedBlockId = 5;
  optional uint64 transactionId = 6;
}

/**
 * Name: INODE
 */
message INodeSection {
  message Permission {
    optional string user = 1;
    optional string group = 2;
    optional uint32 permission = 3;
  }

  /**
   * under-construction feature for INodeFile
   */
  message FileUnderConstructionFeature {
    optional string clientName = 1;
    optional string clientMachine = 2;
  }

  message INodeFile {
    optional uint32 replication = 1;
    optional uint64 modificationTime = 2;
    optional uint64 accessTime = 3;
    optional uint64 preferredBlockSize = 4;
    optional Permission permission = 5;
    repeated BlockProto blocks = 6;
    optional FileUnderConstructionFeature fileUC = 7;
  }

  message INodeDirectory {
    optional uint64 modificationTime = 1;
    // namespace quota
    optional uint64 nsQuota = 2;
    // diskspace quota
    optional uint64 dsQuota = 3;
    optional Permission permission = 4;
  }

  message INodeSymlink {
    optional Permission permission = 1;
    optional bytes target = 2;
  }

  message INode {
    enum Type {
      FILE = 1;
      DIRECTORY = 2;
      SYMLINK = 3;
    };
    required Type type = 1;
    required uint64 id = 2;
    optional bytes name = 3;
    
    optional INodeFile file = 4;
    optional INodeDirectory directory = 5;
    optional INodeSymlink symlink = 6;
  }

  optional uint64 lastInodeId = 1;
  optional uint64 numInodes = 2;
  // repeated INodes..
}

/**
 * This section records information about under-construction files for
 * reconstructing the lease map.
 * NAME: FILES_UNDERCONSTRUCTION
 */
message FilesUnderConstructionSection {
  message FileUnderConstructionEntry {
    optional uint64 inodeId = 1;
    optional string fullPath = 2;
  }
  // repeated FileUnderConstructionEntry...
}

/**
 * This section records the children of each directories
 * NAME: INODE_DIR
 */
message INodeDirectorySection {
  message DirEntry {
    optional uint64 parent = 1;
    repeated uint64 children = 2;
  }
  // repeated DirEntry, ended at the boundary of the section.
}