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HADOOP-9416. Add new symlink resolution methods in FileSystem and FileSystemLinkResolver. (awang via cmccabe) 

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1499602 13f79535-47bb-0310-9956-ffa450edef68
This commit is contained in:
Colin McCabe 2013-07-03 23:29:08 +00:00
parent cf4d0cf189
commit 33fe54a25f
9 changed files with 244 additions and 45 deletions
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3
hadoop-common-project/hadoop-common/CHANGES.txt
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@ -309,6 +309,9 @@ Release 2.2.0 - UNRELEASED
HADOOP-9414. Refactor out FSLinkResolver and relevant helper methods.
(Andrew Wang via Colin Patrick McCabe)
HADOOP-9416. Add new symlink resolution methods in FileSystem and
FileSystemLinkResolver. (Andrew Wang via Colin Patrick McCabe)
OPTIMIZATIONS
BUG FIXES

44
hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/fs/FSLinkResolver.java
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@ -20,30 +20,20 @@ package org.apache.hadoop.fs;
import java.io.IOException;
import java.net.URI;
import org.apache.hadoop.classification.InterfaceAudience;
import org.apache.hadoop.classification.InterfaceStability;
/**
* Class used to perform an operation on and resolve symlinks in a
* path. The operation may potentially span multiple file systems.
* Used primarily by {@link FileContext} to operate on and resolve
* symlinks in a path. Operations can potentially span multiple
* {@link AbstractFileSystem}s.
*
* @see FileSystemLinkResolver
*/
@InterfaceAudience.Private
@InterfaceStability.Evolving
public abstract class FSLinkResolver<T> {
private static final int MAX_PATH_LINKS = 32;
/**
* See {@link #qualifySymlinkTarget(URI, Path, Path)}
*/
public static Path qualifySymlinkTarget(final AbstractFileSystem pathFS,
Path pathWithLink, Path target) {
return qualifySymlinkTarget(pathFS.getUri(), pathWithLink, target);
}
/**
* See {@link #qualifySymlinkTarget(URI, Path, Path)}
*/
public static Path qualifySymlinkTarget(final FileSystem pathFS,
Path pathWithLink, Path target) {
return qualifySymlinkTarget(pathFS.getUri(), pathWithLink, target);
}
/**
* Return a fully-qualified version of the given symlink target if it
* has no scheme and authority. Partially and fully-qualified paths
@ -53,7 +43,7 @@ public abstract class FSLinkResolver<T> {
* @param target The symlink's absolute target
* @return Fully qualified version of the target.
*/
private static Path qualifySymlinkTarget(final URI pathURI,
public static Path qualifySymlinkTarget(final URI pathURI,
Path pathWithLink, Path target) {
// NB: makeQualified uses the target's scheme and authority, if
// specified, and the scheme and authority of pathURI, if not.
@ -64,8 +54,6 @@ public abstract class FSLinkResolver<T> {
pathWithLink.getParent()) : target;
}
// FileContext / AbstractFileSystem resolution methods
/**
* Generic helper function overridden on instantiation to perform a
* specific operation on the given file system using the given path
@ -77,10 +65,8 @@ public abstract class FSLinkResolver<T> {
* not be resolved
* @throws IOException an I/O error occurred
*/
public T next(final AbstractFileSystem fs, final Path p)
throws IOException, UnresolvedLinkException {
throw new AssertionError("Should not be called without first overriding!");
}
abstract public T next(final AbstractFileSystem fs, final Path p)
throws IOException, UnresolvedLinkException;
/**
* Performs the operation specified by the next function, calling it
@ -104,12 +90,12 @@ public abstract class FSLinkResolver<T> {
in = next(fs, p);
isLink = false;
} catch (UnresolvedLinkException e) {
if (count++ > MAX_PATH_LINKS) {
if (count++ > FsConstants.MAX_PATH_LINKS) {
throw new IOException("Possible cyclic loop while " +
"following symbolic link " + path);
}
// Resolve the first unresolved path component
p = FSLinkResolver.qualifySymlinkTarget(fs, p, fs.getLinkTarget(p));
p = qualifySymlinkTarget(fs.getUri(), p, fs.getLinkTarget(p));
fs = fc.getFSofPath(p);
}
}

3
hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/fs/FileContext.java
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@ -1128,7 +1128,8 @@ public final class FileContext {
throws IOException, UnresolvedLinkException {
FileStatus fi = fs.getFileLinkStatus(p);
if (fi.isSymlink()) {
fi.setSymlink(qualifySymlinkTarget(fs, p, fi.getSymlink()));
fi.setSymlink(FSLinkResolver.qualifySymlinkTarget(fs.getUri(), p,
fi.getSymlink()));
}
return fi;
}

78
hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/fs/FileSystem.java
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@ -53,6 +53,7 @@ import org.apache.hadoop.fs.permission.FsPermission;
import org.apache.hadoop.io.MultipleIOException;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.net.NetUtils;
import org.apache.hadoop.security.AccessControlException;
import org.apache.hadoop.security.Credentials;
import org.apache.hadoop.security.SecurityUtil;
import org.apache.hadoop.security.UserGroupInformation;
@ -262,6 +263,16 @@ public abstract class FileSystem extends Configured implements Closeable {
return 0;
}
protected static FileSystem getFSofPath(final Path absOrFqPath,
final Configuration conf)
throws UnsupportedFileSystemException, IOException {
absOrFqPath.checkNotSchemeWithRelative();
absOrFqPath.checkNotRelative();
// Uses the default file system if not fully qualified
return get(absOrFqPath.toUri(), conf);
}
/**
* Get a canonical service name for this file system. The token cache is
* the only user of the canonical service name, and uses it to lookup this
@ -811,7 +822,9 @@ public abstract class FileSystem extends Configured implements Closeable {
public FSDataOutputStream create(Path f, short replication,
Progressable progress) throws IOException {
return create(f, true,
getConf().getInt("io.file.buffer.size", 4096),
getConf().getInt(
CommonConfigurationKeysPublic.IO_FILE_BUFFER_SIZE_KEY,
CommonConfigurationKeysPublic.IO_FILE_BUFFER_SIZE_DEFAULT),
replication,
getDefaultBlockSize(f), progress);
}
@ -1243,7 +1256,7 @@ public abstract class FileSystem extends Configured implements Closeable {
protected void rename(final Path src, final Path dst,
final Rename... options) throws IOException {
// Default implementation
final FileStatus srcStatus = getFileStatus(src);
final FileStatus srcStatus = getFileLinkStatus(src);
if (srcStatus == null) {
throw new FileNotFoundException("rename source " + src + " not found.");
}
@ -1259,7 +1272,7 @@ public abstract class FileSystem extends Configured implements Closeable {
FileStatus dstStatus;
try {
dstStatus = getFileStatus(dst);
dstStatus = getFileLinkStatus(dst);
} catch (IOException e) {
dstStatus = null;
}
@ -2173,6 +2186,65 @@ public abstract class FileSystem extends Configured implements Closeable {
*/
public abstract FileStatus getFileStatus(Path f) throws IOException;
/**
* See {@link FileContext#fixRelativePart}
*/
protected Path fixRelativePart(Path p) {
if (p.isUriPathAbsolute()) {
return p;
} else {
return new Path(getWorkingDirectory(), p);
}
}
/**
* See {@link FileContext#createSymlink(Path, Path, boolean)}
*/
public void createSymlink(final Path target, final Path link,
final boolean createParent) throws AccessControlException,
FileAlreadyExistsException, FileNotFoundException,
ParentNotDirectoryException, UnsupportedFileSystemException,
IOException {
// Supporting filesystems should override this method
throw new UnsupportedOperationException(
"Filesystem does not support symlinks!");
}
/**
* See {@link FileContext#getFileLinkStatus(Path)}
*/
public FileStatus getFileLinkStatus(final Path f)
throws AccessControlException, FileNotFoundException,
UnsupportedFileSystemException, IOException {
// Supporting filesystems should override this method
return getFileStatus(f);
}
/**
* See {@link AbstractFileSystem#supportsSymlinks()}
*/
public boolean supportsSymlinks() {
return false;
}
/**
* See {@link FileContext#getLinkTarget(Path)}
*/
public Path getLinkTarget(Path f) throws IOException {
// Supporting filesystems should override this method
throw new UnsupportedOperationException(
"Filesystem does not support symlinks!");
}
/**
* See {@link AbstractFileSystem#getLinkTarget(Path)}
*/
protected Path resolveLink(Path f) throws IOException {
// Supporting filesystems should override this method
throw new UnsupportedOperationException(
"Filesystem does not support symlinks!");
}
/**
* Get the checksum of a file.
*

99
hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/fs/FileSystemLinkResolver.java Normal file
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@ -0,0 +1,99 @@
/**
* 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.io.IOException;
import org.apache.hadoop.classification.InterfaceAudience;
import org.apache.hadoop.classification.InterfaceStability;
/**
* FileSystem-specific class used to operate on and resolve symlinks in a path.
* Operation can potentially span multiple {@link FileSystem}s.
*
* @see FSLinkResolver
*/
@InterfaceAudience.Private
@InterfaceStability.Evolving
public abstract class FileSystemLinkResolver<T> {
/**
* FileSystem subclass-specific implementation of superclass method.
* Overridden on instantiation to perform the actual method call, which throws
* an UnresolvedLinkException if called on an unresolved {@link Path}.
* @param p Path on which to perform an operation
* @return Generic type returned by operation
* @throws IOException
* @throws UnresolvedLinkException
*/
abstract public T doCall(final Path p) throws IOException,
UnresolvedLinkException;
/**
* Calls the abstract FileSystem call equivalent to the specialized subclass
* implementation in {@link #doCall(Path)}. This is used when retrying the
* call with a newly resolved Path and corresponding new FileSystem.
*
* @param fs
* FileSystem with which to retry call
* @param p
* Resolved Target of path
* @return Generic type determined by implementation
* @throws IOException
*/
abstract public T next(final FileSystem fs, final Path p) throws IOException;
/**
* Attempt calling overridden {@link #doCall(Path)} method with
* specified {@link FileSystem} and {@link Path}. If the call fails with an
* UnresolvedLinkException, it will try to resolve the path and retry the call
* by calling {@link #next(FileSystem, Path)}.
* @param filesys FileSystem with which to try call
* @param path Path with which to try call
* @return Generic type determined by implementation
* @throws IOException
*/
public T resolve(final FileSystem filesys, final Path path)
throws IOException {
int count = 0;
T in = null;
Path p = path;
FileSystem fs = FileSystem.getFSofPath(p, filesys.getConf());
for (boolean isLink = true; isLink;) {
try {
in = doCall(p);
isLink = false;
} catch (UnresolvedLinkException e) {
if (count++ > FsConstants.MAX_PATH_LINKS) {
throw new IOException("Possible cyclic loop while " +
"following symbolic link " + path);
}
// Resolve the first unresolved path component
p = FSLinkResolver.qualifySymlinkTarget(fs.getUri(), p,
filesys.resolveLink(p));
fs = FileSystem.getFSofPath(p, filesys.getConf());
// Have to call next if it's a new FS
if (!fs.equals(filesys)) {
return next(fs, p);
}
// Else, we keep resolving with this filesystem
}
}
// Successful call, path was fully resolved
return in;
}
}

27
hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/fs/FilterFileSystem.java
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@ -28,6 +28,7 @@ import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.permission.FsPermission;
import org.apache.hadoop.fs.ContentSummary;
import org.apache.hadoop.fs.Options.ChecksumOpt;
import org.apache.hadoop.security.AccessControlException;
import org.apache.hadoop.util.Progressable;
/****************************************************************
@ -397,6 +398,32 @@ public class FilterFileSystem extends FileSystem {
return fs.getFileStatus(f);
}
public void createSymlink(final Path target, final Path link,
final boolean createParent) throws AccessControlException,
FileAlreadyExistsException, FileNotFoundException,
ParentNotDirectoryException, UnsupportedFileSystemException,
IOException {
fs.createSymlink(target, link, createParent);
}
public FileStatus getFileLinkStatus(final Path f)
throws AccessControlException, FileNotFoundException,
UnsupportedFileSystemException, IOException {
return fs.getFileLinkStatus(f);
}
public boolean supportsSymlinks() {
return fs.supportsSymlinks();
}
public Path getLinkTarget(Path f) throws IOException {
return fs.getLinkTarget(f);
}
protected Path resolveLink(Path f) throws IOException {
return fs.resolveLink(f);
}
@Override
public FileChecksum getFileChecksum(Path f) throws IOException {
return fs.getFileChecksum(f);

2
hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/fs/FsConstants.java
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@ -34,6 +34,8 @@ public interface FsConstants {
// URI scheme for FTP
public static final String FTP_SCHEME = "ftp";
// Maximum number of symlinks to recursively resolve in a path
static final int MAX_PATH_LINKS = 32;
/**
* ViewFs: viewFs file system (ie the mount file system on client side)

28
hadoop-common-project/hadoop-common/src/test/java/org/apache/hadoop/fs/FileSystemTestWrapper.java
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@ -133,8 +133,11 @@ public final class FileSystemTestWrapper extends FSTestWrapper {
}
public boolean isSymlink(Path p) throws IOException {
throw new UnsupportedFileSystemException(
"FileSystem does not support symlinks");
try {
return fs.getFileLinkStatus(p).isSymlink();
} catch (FileNotFoundException e) {
return false;
}
}
public void writeFile(Path path, byte b[]) throws IOException {
@ -182,8 +185,16 @@ public final class FileSystemTestWrapper extends FSTestWrapper {
public void checkFileLinkStatus(String path, fileType expectedType)
throws IOException {
throw new UnsupportedFileSystemException(
"FileSystem does not support symlinks");
FileStatus s = fs.getFileLinkStatus(new Path(path));
Assert.assertNotNull(s);
if (expectedType == fileType.isDir) {
Assert.assertTrue(s.isDirectory());
} else if (expectedType == fileType.isFile) {
Assert.assertTrue(s.isFile());
} else if (expectedType == fileType.isSymlink) {
Assert.assertTrue(s.isSymlink());
}
Assert.assertEquals(fs.makeQualified(new Path(path)), s.getPath());
}
//
@ -215,8 +226,7 @@ public final class FileSystemTestWrapper extends FSTestWrapper {
@Override
public FileStatus getFileLinkStatus(Path f) throws AccessControlException,
FileNotFoundException, UnsupportedFileSystemException, IOException {
throw new UnsupportedFileSystemException(
"FileSystem does not support symlinks");
return fs.getFileLinkStatus(f);
}
@Override
@ -224,8 +234,7 @@ public final class FileSystemTestWrapper extends FSTestWrapper {
throws AccessControlException, FileAlreadyExistsException,
FileNotFoundException, ParentNotDirectoryException,
UnsupportedFileSystemException, IOException {
throw new UnsupportedFileSystemException(
"FileSystem does not support symlinks");
fs.createSymlink(target, link, createParent);
}
@Override
@ -297,8 +306,7 @@ public final class FileSystemTestWrapper extends FSTestWrapper {
@Override
public Path getLinkTarget(Path f) throws AccessControlException,
FileNotFoundException, UnsupportedFileSystemException, IOException {
throw new UnsupportedFileSystemException(
"FileSystem does not support symlinks");
return fs.getLinkTarget(f);
}
@Override

1
hadoop-common-project/hadoop-common/src/test/java/org/apache/hadoop/fs/TestFilterFileSystem.java
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@ -209,6 +209,7 @@ public class TestFilterFileSystem {
public String getScheme() {
return "dontcheck";
}
public Path fixRelativePart(Path p) { return null; }
}
@Test