Trash.java
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上传日期:2018-01-08
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- /**
- * 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 java.text.*;
- import java.io.*;
- import java.util.Date;
- import org.apache.commons.logging.*;
- import org.apache.hadoop.conf.*;
- import org.apache.hadoop.fs.permission.*;
- import org.apache.hadoop.util.StringUtils;
- /** Provides a <i>trash</i> feature. Files are moved to a user's trash
- * directory, a subdirectory of their home directory named ".Trash". Files are
- * initially moved to a <i>current</i> sub-directory of the trash directory.
- * Within that sub-directory their original path is preserved. Periodically
- * one may checkpoint the current trash and remove older checkpoints. (This
- * design permits trash management without enumeration of the full trash
- * content, without date support in the filesystem, and without clock
- * synchronization.)
- */
- public class Trash extends Configured {
- private static final Log LOG =
- LogFactory.getLog(Trash.class);
- private static final Path CURRENT = new Path("Current");
- private static final Path TRASH = new Path(".Trash/");
- private static final Path HOMES = new Path("/user/");
- private static final FsPermission PERMISSION =
- new FsPermission(FsAction.ALL, FsAction.NONE, FsAction.NONE);
- private static final DateFormat CHECKPOINT = new SimpleDateFormat("yyMMddHHmm");
- private static final int MSECS_PER_MINUTE = 60*1000;
- private final FileSystem fs;
- private final Path trash;
- private final Path current;
- private final long interval;
- /** Construct a trash can accessor.
- * @param conf a Configuration
- */
- public Trash(Configuration conf) throws IOException {
- this(FileSystem.get(conf), conf);
- }
- /**
- * Construct a trash can accessor for the FileSystem provided.
- */
- public Trash(FileSystem fs, Configuration conf) throws IOException {
- super(conf);
- this.fs = fs;
- this.trash = new Path(fs.getHomeDirectory(), TRASH);
- this.current = new Path(trash, CURRENT);
- this.interval = conf.getLong("fs.trash.interval", 60) * MSECS_PER_MINUTE;
- }
- private Trash(Path home, Configuration conf) throws IOException {
- super(conf);
- this.fs = home.getFileSystem(conf);
- this.trash = new Path(home, TRASH);
- this.current = new Path(trash, CURRENT);
- this.interval = conf.getLong("fs.trash.interval", 60) * MSECS_PER_MINUTE;
- }
-
- private Path makeTrashRelativePath(Path basePath, Path rmFilePath) {
- return new Path(basePath + rmFilePath.toUri().getPath());
- }
- /** Move a file or directory to the current trash directory.
- * @return false if the item is already in the trash or trash is disabled
- */
- public boolean moveToTrash(Path path) throws IOException {
- if (interval == 0)
- return false;
- if (!path.isAbsolute()) // make path absolute
- path = new Path(fs.getWorkingDirectory(), path);
- if (!fs.exists(path)) // check that path exists
- throw new FileNotFoundException(path.toString());
- String qpath = path.makeQualified(fs).toString();
- if (qpath.startsWith(trash.toString())) {
- return false; // already in trash
- }
- if (trash.getParent().toString().startsWith(qpath)) {
- throw new IOException("Cannot move "" + path +
- "" to the trash, as it contains the trash");
- }
- Path trashPath = makeTrashRelativePath(current, path);
- Path baseTrashPath = makeTrashRelativePath(current, path.getParent());
-
- IOException cause = null;
- // try twice, in case checkpoint between the mkdirs() & rename()
- for (int i = 0; i < 2; i++) {
- try {
- if (!fs.mkdirs(baseTrashPath, PERMISSION)) { // create current
- LOG.warn("Can't create trash directory: "+baseTrashPath);
- return false;
- }
- } catch (IOException e) {
- LOG.warn("Can't create trash directory: "+baseTrashPath);
- return false;
- }
- try {
- //
- // if the target path in Trash already exists, then append with
- // a number. Start from 1.
- //
- String orig = trashPath.toString();
- for (int j = 1; fs.exists(trashPath); j++) {
- trashPath = new Path(orig + "." + j);
- }
- if (fs.rename(path, trashPath)) // move to current trash
- return true;
- } catch (IOException e) {
- cause = e;
- }
- }
- throw (IOException)
- new IOException("Failed to move to trash: "+path).initCause(cause);
- }
- /** Create a trash checkpoint. */
- public void checkpoint() throws IOException {
- if (!fs.exists(current)) // no trash, no checkpoint
- return;
- Path checkpoint;
- synchronized (CHECKPOINT) {
- checkpoint = new Path(trash, CHECKPOINT.format(new Date()));
- }
- if (fs.rename(current, checkpoint)) {
- LOG.info("Created trash checkpoint: "+checkpoint.toUri().getPath());
- } else {
- throw new IOException("Failed to checkpoint trash: "+checkpoint);
- }
- }
- /** Delete old checkpoints. */
- public void expunge() throws IOException {
- FileStatus[] dirs = fs.listStatus(trash); // scan trash sub-directories
- if( dirs == null){
- return;
- }
- long now = System.currentTimeMillis();
- for (int i = 0; i < dirs.length; i++) {
- Path path = dirs[i].getPath();
- String dir = path.toUri().getPath();
- String name = path.getName();
- if (name.equals(CURRENT.getName())) // skip current
- continue;
- long time;
- try {
- synchronized (CHECKPOINT) {
- time = CHECKPOINT.parse(name).getTime();
- }
- } catch (ParseException e) {
- LOG.warn("Unexpected item in trash: "+dir+". Ignoring.");
- continue;
- }
- if ((now - interval) > time) {
- if (fs.delete(path, true)) {
- LOG.info("Deleted trash checkpoint: "+dir);
- } else {
- LOG.warn("Couldn't delete checkpoint: "+dir+" Ignoring.");
- }
- }
- }
- }
- //
- // get the current working directory
- //
- Path getCurrentTrashDir() {
- return current;
- }
- /** Return a {@link Runnable} that periodically empties the trash of all
- * users, intended to be run by the superuser. Only one checkpoint is kept
- * at a time.
- */
- public Runnable getEmptier() throws IOException {
- return new Emptier(getConf());
- }
- private static class Emptier implements Runnable {
- private Configuration conf;
- private FileSystem fs;
- private long interval;
- public Emptier(Configuration conf) throws IOException {
- this.conf = conf;
- this.interval = conf.getLong("fs.trash.interval", 60) * MSECS_PER_MINUTE;
- this.fs = FileSystem.get(conf);
- }
- public void run() {
- if (interval == 0)
- return; // trash disabled
- long now = System.currentTimeMillis();
- long end;
- while (true) {
- end = ceiling(now, interval);
- try { // sleep for interval
- Thread.sleep(end - now);
- } catch (InterruptedException e) {
- return; // exit on interrupt
- }
-
- try {
- now = System.currentTimeMillis();
- if (now >= end) {
- FileStatus[] homes = null;
- try {
- homes = fs.listStatus(HOMES); // list all home dirs
- } catch (IOException e) {
- LOG.warn("Trash can't list homes: "+e+" Sleeping.");
- continue;
- }
- if (homes == null)
- continue;
- for (FileStatus home : homes) { // dump each trash
- if (!home.isDir())
- continue;
- try {
- Trash trash = new Trash(home.getPath(), conf);
- trash.expunge();
- trash.checkpoint();
- } catch (IOException e) {
- LOG.warn("Trash caught: "+e+". Skipping "+home.getPath()+".");
- }
- }
- }
- } catch (Exception e) {
- LOG.warn("RuntimeException during Trash.Emptier.run() " +
- StringUtils.stringifyException(e));
- }
- }
- }
- private long ceiling(long time, long interval) {
- return floor(time, interval) + interval;
- }
- private long floor(long time, long interval) {
- return (time / interval) * interval;
- }
- }
- /** Run an emptier.*/
- public static void main(String[] args) throws Exception {
- new Trash(new Configuration()).getEmptier().run();
- }
- }