src/hdfs/org/apache/hadoop/hdfs/protocol/HdfsFileStatus.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.protocol;

import java.io.DataInput;
import java.io.DataOutput;
import java.io.IOException;

import org.apache.hadoop.fs.Path;
import org.apache.hadoop.fs.permission.FsPermission;
import org.apache.hadoop.hdfs.DFSUtil;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.io.Writable;
import org.apache.hadoop.io.WritableFactories;
import org.apache.hadoop.io.WritableFactory;

/** Interface that represents the over the wire information for a file.
 */
public class HdfsFileStatus implements Writable {
  static {                                      // register a ctor
    WritableFactories.setFactory
      (HdfsFileStatus.class,
       new WritableFactory() {
         public Writable newInstance() { return new HdfsFileStatus(); }
       });
  }

  private byte[] path;  // local name of the inode that's encoded in java UTF8
  private long length;
  private boolean isdir;
  private short block_replication;
  private long blocksize;
  private long modification_time;
  private long access_time;
  private FsPermission permission;
  private String owner;
  private String group;
  
  public static final byte[] EMPTY_NAME = new byte[0];

  /**
   * default constructor
   */
  public HdfsFileStatus() { this(0, false, 0, 0, 0, 0, null, null, null, null); }
  
  /**
   * Constructor
   * @param length the number of bytes the file has
   * @param isdir if the path is a directory
   * @param block_replication the replication factor
   * @param blocksize the block size
   * @param modification_time modification time
   * @param access_time access time
   * @param permission permission
   * @param owner the owner of the path
   * @param group the group of the path
   * @param path the local name in java UTF8 encoding the same as that in-memory
   */
  public HdfsFileStatus(long length, boolean isdir, int block_replication,
                    long blocksize, long modification_time, long access_time,
                    FsPermission permission, String owner, String group, 
                    byte[] path) {
    this.length = length;
    this.isdir = isdir;
    this.block_replication = (short)block_replication;
    this.blocksize = blocksize;
    this.modification_time = modification_time;
    this.access_time = access_time;
    this.permission = (permission == null) ? 
                      FsPermission.getDefault() : permission;
    this.owner = (owner == null) ? "" : owner;
    this.group = (group == null) ? "" : group;
    this.path = path;
  }

  /**
   * Get the length of this file, in bytes.
   * @return the length of this file, in bytes.
   */
  final public long getLen() {
    return length;
  }

  /**
   * Is this a directory?
   * @return true if this is a directory
   */
  final public boolean isDir() {
    return isdir;
  }

  /**
   * Get the block size of the file.
   * @return the number of bytes
   */
  final public long getBlockSize() {
    return blocksize;
  }

  /**
   * Get the replication factor of a file.
   * @return the replication factor of a file.
   */
  final public short getReplication() {
    return block_replication;
  }

  /**
   * Get the modification time of the file.
   * @return the modification time of file in milliseconds since January 1, 1970 UTC.
   */
  final public long getModificationTime() {
    return modification_time;
  }

  /**
   * Get the access time of the file.
   * @return the access time of file in milliseconds since January 1, 1970 UTC.
   */
  final public long getAccessTime() {
    return access_time;
  }

  /**
   * Get FsPermission associated with the file.
   * @return permssion
   */
  final public FsPermission getPermission() {
    return permission;
  }
  
  /**
   * Get the owner of the file.
   * @return owner of the file
   */
  final public String getOwner() {
    return owner;
  }
  
  /**
   * Get the group associated with the file.
   * @return group for the file. 
   */
  final public String getGroup() {
    return group;
  }
  
  /**
   * Check if the local name is empty
   * @return true if the name is empty
   */
  final public boolean isEmptyLocalName() {
    return path.length == 0;
  }

  /**
   * Get the string representation of the local name
   * @return the local name in string
   */
  final public String getLocalName() {
    return DFSUtil.bytes2String(path);
  }
  
  /**
   * Get the Java UTF8 representation of the local name
   * @return the local name in java UTF8
   */
  final public byte[] getLocalNameInBytes() {
    return path;
  }
  
  /**
   * Get the string representation of the full path name
   * @param parent the parent path
   * @return the full path in string
   */
  final public String getFullName(final String parent) {
    if (isEmptyLocalName()) {
      return parent;
    }
    
    StringBuilder fullName = new StringBuilder(parent);
    if (!parent.endsWith(Path.SEPARATOR)) {
      fullName.append(Path.SEPARATOR);
    }
    fullName.append(getLocalName());
    return fullName.toString();
  }

  /**
   * Get the full path
   * @param parent the parent path
   * @return the full path
   */
  final public Path getFullPath(final Path parent) {
    if (isEmptyLocalName()) {
      return parent;
    }
    
    return new Path(parent, getLocalName());
  }

  //////////////////////////////////////////////////
  // Writable
  //////////////////////////////////////////////////
  public void write(DataOutput out) throws IOException {
    out.writeInt(path.length);
    out.write(path);
    out.writeLong(length);
    out.writeBoolean(isdir);
    out.writeShort(block_replication);
    out.writeLong(blocksize);
    out.writeLong(modification_time);
    out.writeLong(access_time);
    permission.write(out);
    Text.writeString(out, owner);
    Text.writeString(out, group);
  }

  public void readFields(DataInput in) throws IOException {
    int numOfBytes = in.readInt();
    if (numOfBytes == 0) {
      this.path = EMPTY_NAME;
    } else {
      this.path = new byte[numOfBytes];
      in.readFully(path);
    }
    this.length = in.readLong();
    this.isdir = in.readBoolean();
    this.block_replication = in.readShort();
    blocksize = in.readLong();
    modification_time = in.readLong();
    access_time = in.readLong();
    permission.readFields(in);
    owner = Text.readString(in);
    group = Text.readString(in);
  }
}