org.apache.hadoop.fs.PartialListing Maven / Gradle / Ivy
/*
* 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.fs;
import org.apache.hadoop.thirdparty.com.google.common.base.Preconditions;
import org.apache.commons.lang3.builder.ToStringBuilder;
import org.apache.hadoop.classification.InterfaceAudience;
import org.apache.hadoop.classification.InterfaceStability;
import org.apache.hadoop.ipc.RemoteException;
import java.io.IOException;
import java.util.List;
/**
* A partial listing of the children of a parent directory. Since it is a
* partial listing, multiple PartialListing may need to be combined to obtain
* the full listing of a parent directory.
*
* ListingBatch behaves similar to a Future, in that getting the result via
* {@link #get()} will throw an Exception if there was a failure.
*/
@InterfaceAudience.Public
@InterfaceStability.Unstable
public class PartialListing {
private final Path listedPath;
private final List partialListing;
private final RemoteException exception;
public PartialListing(Path listedPath, List partialListing) {
this(listedPath, partialListing, null);
}
public PartialListing(Path listedPath, RemoteException exception) {
this(listedPath, null, exception);
}
private PartialListing(Path listedPath, List partialListing,
RemoteException exception) {
Preconditions.checkArgument(partialListing == null ^ exception == null);
this.partialListing = partialListing;
this.listedPath = listedPath;
this.exception = exception;
}
/**
* Partial listing of the path being listed. In the case where the path is
* a file. The list will be a singleton with the file itself.
*
* @return Partial listing of the path being listed.
* @throws IOException if there was an exception getting the listing.
*/
public List get() throws IOException {
if (exception != null) {
throw exception.unwrapRemoteException();
}
return partialListing;
}
/**
* Path being listed.
*
* @return the path being listed.
*/
public Path getListedPath() {
return listedPath;
}
@Override
public String toString() {
return new ToStringBuilder(this)
.append("listedPath", listedPath)
.append("partialListing", partialListing)
.append("exception", exception)
.toString();
}
}