| /* 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.classification.InterfaceAudience; |
| import org.apache.hadoop.classification.InterfaceStability; |
| import org.apache.hadoop.io.Writable; |
| import org.apache.hadoop.io.WritableFactories; |
| import org.apache.hadoop.io.WritableFactory; |
| |
| /** |
| * This class defines a partial listing of a directory to support |
| * iterative directory listing. |
| */ |
| @InterfaceAudience.Private |
| @InterfaceStability.Evolving |
| public class DirectoryListing implements Writable { |
| static { // register a ctor |
| WritableFactories.setFactory |
| (DirectoryListing.class, |
| new WritableFactory() { |
| public Writable newInstance() { return new DirectoryListing(); } |
| }); |
| } |
| |
| private HdfsFileStatus[] partialListing; |
| private int remainingEntries; |
| |
| /** |
| * default constructor |
| */ |
| public DirectoryListing() { |
| } |
| |
| /** |
| * constructor |
| * @param partialListing a partial listing of a directory |
| * @param remainingEntries number of entries that are left to be listed |
| */ |
| public DirectoryListing(HdfsFileStatus[] partialListing, |
| int remainingEntries) { |
| if (partialListing == null) { |
| throw new IllegalArgumentException("partial listing should not be null"); |
| } |
| if (partialListing.length == 0 && remainingEntries != 0) { |
| throw new IllegalArgumentException("Partial listing is empty but " + |
| "the number of remaining entries is not zero"); |
| } |
| this.partialListing = partialListing; |
| this.remainingEntries = remainingEntries; |
| } |
| |
| /** |
| * Get the partial listing of file status |
| * @return the partial listing of file status |
| */ |
| public HdfsFileStatus[] getPartialListing() { |
| return partialListing; |
| } |
| |
| /** |
| * Get the number of remaining entries that are left to be listed |
| * @return the number of remaining entries that are left to be listed |
| */ |
| public int getRemainingEntries() { |
| return remainingEntries; |
| } |
| |
| /** |
| * Check if there are more entries that are left to be listed |
| * @return true if there are more entries that are left to be listed; |
| * return false otherwise. |
| */ |
| public boolean hasMore() { |
| return remainingEntries != 0; |
| } |
| |
| /** |
| * Get the last name in this list |
| * @return the last name in the list if it is not empty; otherwise return null |
| */ |
| public byte[] getLastName() { |
| if (partialListing.length == 0) { |
| return null; |
| } |
| return partialListing[partialListing.length-1].getLocalNameInBytes(); |
| } |
| |
| // Writable interface |
| @Override |
| public void readFields(DataInput in) throws IOException { |
| int numEntries = in.readInt(); |
| partialListing = new HdfsFileStatus[numEntries]; |
| if (numEntries !=0 ) { |
| boolean hasLocation = in.readBoolean(); |
| for (int i=0; i<numEntries; i++) { |
| if (hasLocation) { |
| partialListing[i] = new HdfsLocatedFileStatus(); |
| } else { |
| partialListing[i] = new HdfsFileStatus(); |
| } |
| partialListing[i].readFields(in); |
| } |
| } |
| remainingEntries = in.readInt(); |
| } |
| |
| @Override |
| public void write(DataOutput out) throws IOException { |
| out.writeInt(partialListing.length); |
| if (partialListing.length != 0) { |
| if (partialListing[0] instanceof HdfsLocatedFileStatus) { |
| out.writeBoolean(true); |
| } else { |
| out.writeBoolean(false); |
| } |
| for (HdfsFileStatus fileStatus : partialListing) { |
| fileStatus.write(out); |
| } |
| } |
| out.writeInt(remainingEntries); |
| } |
| } |