/**
* 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.tools.snapshot;
import java.io.IOException;
import org.apache.hadoop.classification.InterfaceAudience;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.hdfs.DistributedFileSystem;
import org.apache.hadoop.hdfs.protocol.HdfsConstants;
import org.apache.hadoop.hdfs.protocol.SnapshotDiffReport;
/**
* A tool used to get the difference report between two snapshots, or between
* a snapshot and the current status of a directory.
* <pre>
* Usage: SnapshotDiff snapshotDir from to
* For from/to, users can use "." to present the current status, and use
* ".snapshot/snapshot_name" to present a snapshot, where ".snapshot/" can be
* omitted.
* </pre>
*/
@InterfaceAudience.Private
public class SnapshotDiff {
private static String getSnapshotName(String name) {
if (Path.CUR_DIR.equals(name)) { // current directory
return "";
}
final int i;
if (name.startsWith(HdfsConstants.DOT_SNAPSHOT_DIR + Path.SEPARATOR)) {
i = 0;
} else if (name.startsWith(
HdfsConstants.SEPARATOR_DOT_SNAPSHOT_DIR + Path.SEPARATOR)) {
i = 1;
} else {
return name;
}
// get the snapshot name
return name.substring(i + HdfsConstants.DOT_SNAPSHOT_DIR.length() + 1);
}
public static void main(String[] argv) throws IOException {
String description = "SnapshotDiff <snapshotDir> <from> <to>:\n" +
"\tGet the difference between two snapshots, \n" +
"\tor between a snapshot and the current tree of a directory.\n" +
"\tFor <from>/<to>, users can use \".\" to present the current status,\n" +
"\tand use \".snapshot/snapshot_name\" to present a snapshot,\n" +
"\twhere \".snapshot/\" can be omitted\n";
if(argv.length != 3) {
System.err.println("Usage: \n" + description);
System.exit(1);
}
Configuration conf = new Configuration();
FileSystem fs = FileSystem.get(conf);
if (! (fs instanceof DistributedFileSystem)) {
System.err.println(
"SnapshotDiff can only be used in DistributedFileSystem");
System.exit(1);
}
DistributedFileSystem dfs = (DistributedFileSystem) fs;
Path snapshotRoot = new Path(argv[0]);
String fromSnapshot = getSnapshotName(argv[1]);
String toSnapshot = getSnapshotName(argv[2]);
try {
SnapshotDiffReport diffReport = dfs.getSnapshotDiffReport(snapshotRoot,
fromSnapshot, toSnapshot);
System.out.println(diffReport.toString());
} catch (IOException e) {
String[] content = e.getLocalizedMessage().split("\n");
System.err.println("snapshotDiff: " + content[0]);
}
}
}