/**
* 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.server.namenode.snapshot;
import java.io.DataInput;
import java.io.DataOutput;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Collections;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.concurrent.atomic.AtomicInteger;
import org.apache.hadoop.hdfs.DFSUtil;
import org.apache.hadoop.hdfs.protocol.SnapshotException;
import org.apache.hadoop.hdfs.protocol.SnapshottableDirectoryStatus;
import org.apache.hadoop.hdfs.server.namenode.FSDirectory;
import org.apache.hadoop.hdfs.server.namenode.FSImageFormat;
import org.apache.hadoop.hdfs.server.namenode.FSNamesystem;
import org.apache.hadoop.hdfs.server.namenode.INode;
import org.apache.hadoop.hdfs.server.namenode.INode.BlocksMapUpdateInfo;
import org.apache.hadoop.hdfs.server.namenode.INodeDirectory;
import org.apache.hadoop.hdfs.server.namenode.INodesInPath;
import org.apache.hadoop.hdfs.server.namenode.snapshot.INodeDirectorySnapshottable.SnapshotDiffInfo;
/**
* Manage snapshottable directories and their snapshots.
*
* This class includes operations that create, access, modify snapshots and/or
* snapshot-related data. In general, the locking structure of snapshot
* operations is: <br>
*
* 1. Lock the {@link FSNamesystem} lock in {@link FSNamesystem} before calling
* into {@link SnapshotManager} methods.<br>
* 2. Lock the {@link FSDirectory} lock for the {@link SnapshotManager} methods
* if necessary.
*/
public class SnapshotManager implements SnapshotStats {
private boolean allowNestedSnapshots = false;
private final FSDirectory fsdir;
private static final int SNAPSHOT_ID_BIT_WIDTH = 24;
private final AtomicInteger numSnapshots = new AtomicInteger();
private int snapshotCounter = 0;
/** All snapshottable directories in the namesystem. */
private final Map<Long, INodeDirectorySnapshottable> snapshottables
= new HashMap<Long, INodeDirectorySnapshottable>();
public SnapshotManager(final FSDirectory fsdir) {
this.fsdir = fsdir;
}
/** Used in tests only */
void setAllowNestedSnapshots(boolean allowNestedSnapshots) {
this.allowNestedSnapshots = allowNestedSnapshots;
}
private void checkNestedSnapshottable(INodeDirectory dir, String path)
throws SnapshotException {
if (allowNestedSnapshots) {
return;
}
for(INodeDirectorySnapshottable s : snapshottables.values()) {
if (s.isAncestorDirectory(dir)) {
throw new SnapshotException(
"Nested snapshottable directories not allowed: path=" + path
+ ", the subdirectory " + s.getFullPathName()
+ " is already a snapshottable directory.");
}
if (dir.isAncestorDirectory(s)) {
throw new SnapshotException(
"Nested snapshottable directories not allowed: path=" + path
+ ", the ancestor " + s.getFullPathName()
+ " is already a snapshottable directory.");
}
}
}
/**
* Set the given directory as a snapshottable directory.
* If the path is already a snapshottable directory, update the quota.
*/
public void setSnapshottable(final String path, boolean checkNestedSnapshottable)
throws IOException {
final INodesInPath iip = fsdir.getINodesInPath4Write(path);
final INodeDirectory d = INodeDirectory.valueOf(iip.getLastINode(), path);
if (checkNestedSnapshottable) {
checkNestedSnapshottable(d, path);
}
final INodeDirectorySnapshottable s;
if (d.isSnapshottable()) {
//The directory is already a snapshottable directory.
s = (INodeDirectorySnapshottable)d;
s.setSnapshotQuota(INodeDirectorySnapshottable.SNAPSHOT_LIMIT);
} else {
s = d.replaceSelf4INodeDirectorySnapshottable(iip.getLatestSnapshot(),
fsdir.getINodeMap());
}
addSnapshottable(s);
}
/** Add the given snapshottable directory to {@link #snapshottables}. */
public void addSnapshottable(INodeDirectorySnapshottable dir) {
snapshottables.put(dir.getId(), dir);
}
/** Remove the given snapshottable directory from {@link #snapshottables}. */
private void removeSnapshottable(INodeDirectorySnapshottable s) {
snapshottables.remove(s.getId());
}
/** Remove snapshottable directories from {@link #snapshottables} */
public void removeSnapshottable(List<INodeDirectorySnapshottable> toRemove) {
if (toRemove != null) {
for (INodeDirectorySnapshottable s : toRemove) {
removeSnapshottable(s);
}
}
}
/**
* Set the given snapshottable directory to non-snapshottable.
*
* @throws SnapshotException if there are snapshots in the directory.
*/
public void resetSnapshottable(final String path) throws IOException {
final INodesInPath iip = fsdir.getINodesInPath4Write(path);
final INodeDirectory d = INodeDirectory.valueOf(iip.getLastINode(), path);
if (!d.isSnapshottable()) {
// the directory is already non-snapshottable
return;
}
final INodeDirectorySnapshottable s = (INodeDirectorySnapshottable) d;
if (s.getNumSnapshots() > 0) {
throw new SnapshotException("The directory " + path + " has snapshot(s). "
+ "Please redo the operation after removing all the snapshots.");
}
if (s == fsdir.getRoot()) {
s.setSnapshotQuota(0);
} else {
s.replaceSelf(iip.getLatestSnapshot(), fsdir.getINodeMap());
}
removeSnapshottable(s);
}
/**
* Find the source root directory where the snapshot will be taken
* for a given path.
*
* @param path The directory path where the snapshot will be taken.
* @return Snapshottable directory.
* @throws IOException
* Throw IOException when the given path does not lead to an
* existing snapshottable directory.
*/
public INodeDirectorySnapshottable getSnapshottableRoot(final String path
) throws IOException {
final INodesInPath i = fsdir.getINodesInPath4Write(path);
return INodeDirectorySnapshottable.valueOf(i.getLastINode(), path);
}
/**
* Create a snapshot of the given path.
* It is assumed that the caller will perform synchronization.
*
* @param path
* The directory path where the snapshot will be taken.
* @param snapshotName
* The name of the snapshot.
* @throws IOException
* Throw IOException when 1) the given path does not lead to an
* existing snapshottable directory, and/or 2) there exists a
* snapshot with the given name for the directory, and/or 3)
* snapshot number exceeds quota
*/
public String createSnapshot(final String path, String snapshotName
) throws IOException {
INodeDirectorySnapshottable srcRoot = getSnapshottableRoot(path);
if (snapshotCounter == getMaxSnapshotID()) {
// We have reached the maximum allowable snapshot ID and since we don't
// handle rollover we will fail all subsequent snapshot creation
// requests.
//
throw new SnapshotException(
"Failed to create the snapshot. The FileSystem has run out of " +
"snapshot IDs and ID rollover is not supported.");
}
srcRoot.addSnapshot(snapshotCounter, snapshotName);
//create success, update id
snapshotCounter++;
numSnapshots.getAndIncrement();
return Snapshot.getSnapshotPath(path, snapshotName);
}
/**
* Delete a snapshot for a snapshottable directory
* @param path Path to the directory where the snapshot was taken
* @param snapshotName Name of the snapshot to be deleted
* @param collectedBlocks Used to collect information to update blocksMap
* @throws IOException
*/
public void deleteSnapshot(final String path, final String snapshotName,
BlocksMapUpdateInfo collectedBlocks, final List<INode> removedINodes)
throws IOException {
// parse the path, and check if the path is a snapshot path
// the INodeDirectorySnapshottable#valueOf method will throw Exception
// if the path is not for a snapshottable directory
INodeDirectorySnapshottable srcRoot = getSnapshottableRoot(path);
srcRoot.removeSnapshot(snapshotName, collectedBlocks, removedINodes);
numSnapshots.getAndDecrement();
}
/**
* Rename the given snapshot
* @param path
* The directory path where the snapshot was taken
* @param oldSnapshotName
* Old name of the snapshot
* @param newSnapshotName
* New name of the snapshot
* @throws IOException
* Throw IOException when 1) the given path does not lead to an
* existing snapshottable directory, and/or 2) the snapshot with the
* old name does not exist for the directory, and/or 3) there exists
* a snapshot with the new name for the directory
*/
public void renameSnapshot(final String path, final String oldSnapshotName,
final String newSnapshotName) throws IOException {
// Find the source root directory path where the snapshot was taken.
// All the check for path has been included in the valueOf method.
final INodeDirectorySnapshottable srcRoot
= INodeDirectorySnapshottable.valueOf(fsdir.getINode(path), path);
// Note that renameSnapshot and createSnapshot are synchronized externally
// through FSNamesystem's write lock
srcRoot.renameSnapshot(path, oldSnapshotName, newSnapshotName);
}
@Override
public int getNumSnapshottableDirs() {
return snapshottables.size();
}
@Override
public int getNumSnapshots() {
return numSnapshots.get();
}
/**
* Write {@link #snapshotCounter}, {@link #numSnapshots},
* and all snapshots to the DataOutput.
*/
public void write(DataOutput out) throws IOException {
out.writeInt(snapshotCounter);
out.writeInt(numSnapshots.get());
// write all snapshots.
for(INodeDirectorySnapshottable snapshottableDir : snapshottables.values()) {
for(Snapshot s : snapshottableDir.getSnapshotsByNames()) {
s.write(out);
}
}
}
/**
* Read values of {@link #snapshotCounter}, {@link #numSnapshots}, and
* all snapshots from the DataInput
*/
public Map<Integer, Snapshot> read(DataInput in, FSImageFormat.Loader loader
) throws IOException {
snapshotCounter = in.readInt();
numSnapshots.set(in.readInt());
// read snapshots
final Map<Integer, Snapshot> snapshotMap = new HashMap<Integer, Snapshot>();
for(int i = 0; i < numSnapshots.get(); i++) {
final Snapshot s = Snapshot.read(in, loader);
snapshotMap.put(s.getId(), s);
}
return snapshotMap;
}
/**
* List all the snapshottable directories that are owned by the current user.
* @param userName Current user name.
* @return Snapshottable directories that are owned by the current user,
* represented as an array of {@link SnapshottableDirectoryStatus}. If
* {@code userName} is null, return all the snapshottable dirs.
*/
public SnapshottableDirectoryStatus[] getSnapshottableDirListing(
String userName) {
if (snapshottables.isEmpty()) {
return null;
}
List<SnapshottableDirectoryStatus> statusList =
new ArrayList<SnapshottableDirectoryStatus>();
for (INodeDirectorySnapshottable dir : snapshottables.values()) {
if (userName == null || userName.equals(dir.getUserName())) {
SnapshottableDirectoryStatus status = new SnapshottableDirectoryStatus(
dir.getModificationTime(), dir.getAccessTime(),
dir.getFsPermission(), dir.getUserName(), dir.getGroupName(),
dir.getLocalNameBytes(), dir.getId(), dir.getChildrenNum(null),
dir.getNumSnapshots(),
dir.getSnapshotQuota(), dir.getParent() == null ?
DFSUtil.EMPTY_BYTES :
DFSUtil.string2Bytes(dir.getParent().getFullPathName()));
statusList.add(status);
}
}
Collections.sort(statusList, SnapshottableDirectoryStatus.COMPARATOR);
return statusList.toArray(
new SnapshottableDirectoryStatus[statusList.size()]);
}
/**
* Compute the difference between two snapshots of a directory, or between a
* snapshot of the directory and its current tree.
*/
public SnapshotDiffInfo diff(final String path, final String from,
final String to) throws IOException {
if ((from == null || from.isEmpty())
&& (to == null || to.isEmpty())) {
// both fromSnapshot and toSnapshot indicate the current tree
return null;
}
// Find the source root directory path where the snapshots were taken.
// All the check for path has been included in the valueOf method.
INodesInPath inodesInPath = fsdir.getINodesInPath4Write(path.toString());
final INodeDirectorySnapshottable snapshotRoot = INodeDirectorySnapshottable
.valueOf(inodesInPath.getLastINode(), path);
return snapshotRoot.computeDiff(from, to);
}
/**
* Returns the maximum allowable snapshot ID based on the bit width of the
* snapshot ID.
*
* @return maximum allowable snapshot ID.
*/
public int getMaxSnapshotID() {
return ((1 << SNAPSHOT_ID_BIT_WIDTH) - 1);
}
}