/**
* 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.Closeable;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.net.URI;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.HashMap;
import java.util.HashSet;
import java.util.IdentityHashMap;
import java.security.PrivilegedExceptionAction;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Set;
import java.util.TreeSet;
import java.util.concurrent.atomic.AtomicLong;
import java.util.regex.Pattern;
import org.apache.commons.logging.*;
import org.apache.hadoop.conf.*;
import org.apache.hadoop.util.*;
import org.apache.hadoop.fs.permission.FsPermission;
import org.apache.hadoop.io.MultipleIOException;
import org.apache.hadoop.security.SecurityUtil;
import org.apache.hadoop.security.UserGroupInformation;
import org.apache.hadoop.security.token.Token;
/****************************************************************
* An abstract base class for a fairly generic filesystem. It
* may be implemented as a distributed filesystem, or as a "local"
* one that reflects the locally-connected disk. The local version
* exists for small Hadoop instances and for testing.
*
* <p>
*
* All user code that may potentially use the Hadoop Distributed
* File System should be written to use a FileSystem object. The
* Hadoop DFS is a multi-machine system that appears as a single
* disk. It's useful because of its fault tolerance and potentially
* very large capacity.
*
* <p>
* The local implementation is {@link LocalFileSystem} and distributed
* implementation is DistributedFileSystem.
*****************************************************************/
public abstract class FileSystem extends Configured implements Closeable {
public static final String FS_DEFAULT_NAME_KEY = "fs.default.name";
public static final Log LOG = LogFactory.getLog(FileSystem.class);
/** FileSystem cache */
static final Cache CACHE = new Cache();
/** The key this instance is stored under in the cache. */
private Cache.Key key;
/** Recording statistics per a FileSystem class */
private static final Map<Class<? extends FileSystem>, Statistics>
statisticsTable =
new IdentityHashMap<Class<? extends FileSystem>, Statistics>();
/**
* The statistics for this file system.
*/
protected Statistics statistics;
/**
* A cache of files that should be deleted when filsystem is closed
* or the JVM is exited.
*/
private Set<Path> deleteOnExit = new TreeSet<Path>();
public static FileSystem get(final URI uri, final Configuration conf,
final String user)
throws IOException, InterruptedException {
UserGroupInformation ugi;
if (user == null) {
ugi = UserGroupInformation.getCurrentUser();
} else {
ugi = UserGroupInformation.createRemoteUser(user);
}
return ugi.doAs(new PrivilegedExceptionAction<FileSystem>() {
public FileSystem run() throws IOException {
return get(uri, conf);
}
});
}
/** Returns the configured filesystem implementation.*/
public static FileSystem get(Configuration conf) throws IOException {
return get(getDefaultUri(conf), conf);
}
/** Get the default filesystem URI from a configuration.
* @param conf the configuration to access
* @return the uri of the default filesystem
*/
public static URI getDefaultUri(Configuration conf) {
return URI.create(fixName(conf.get(FS_DEFAULT_NAME_KEY, "file:///")));
}
/** Set the default filesystem URI in a configuration.
* @param conf the configuration to alter
* @param uri the new default filesystem uri
*/
public static void setDefaultUri(Configuration conf, URI uri) {
conf.set(FS_DEFAULT_NAME_KEY, uri.toString());
}
/** Set the default filesystem URI in a configuration.
* @param conf the configuration to alter
* @param uri the new default filesystem uri
*/
public static void setDefaultUri(Configuration conf, String uri) {
setDefaultUri(conf, URI.create(fixName(uri)));
}
/** Called after a new FileSystem instance is constructed.
* @param name a uri whose authority section names the host, port, etc.
* for this FileSystem
* @param conf the configuration
*/
public void initialize(URI name, Configuration conf) throws IOException {
statistics = getStatistics(name.getScheme(), getClass());
}
/** Returns a URI whose scheme and authority identify this FileSystem.*/
public abstract URI getUri();
/**
* Get the default port for this file system.
* @return the default port or 0 if there isn't one
*/
protected int getDefaultPort() {
return 0;
}
/**
* Get a canonical name for this file system.
* @return a URI string that uniquely identifies this file system
*/
public String getCanonicalServiceName() {
return SecurityUtil.buildDTServiceName(getUri(), getDefaultPort());
}
/** @deprecated call #getUri() instead.*/
public String getName() { return getUri().toString(); }
/** @deprecated call #get(URI,Configuration) instead. */
public static FileSystem getNamed(String name, Configuration conf)
throws IOException {
return get(URI.create(fixName(name)), conf);
}
/** Update old-format filesystem names, for back-compatibility. This should
* eventually be replaced with a checkName() method that throws an exception
* for old-format names. */
private static String fixName(String name) {
// convert old-format name to new-format name
if (name.equals("local")) { // "local" is now "file:///".
LOG.warn("\"local\" is a deprecated filesystem name."
+" Use \"file:///\" instead.");
name = "file:///";
} else if (name.indexOf('/')==-1) { // unqualified is "hdfs://"
LOG.warn("\""+name+"\" is a deprecated filesystem name."
+" Use \"hdfs://"+name+"/\" instead.");
name = "hdfs://"+name;
}
return name;
}
/**
* Get the local file syste
* @param conf the configuration to configure the file system with
* @return a LocalFileSystem
*/
public static LocalFileSystem getLocal(Configuration conf)
throws IOException {
return (LocalFileSystem)get(LocalFileSystem.NAME, conf);
}
/** Returns the FileSystem for this URI's scheme and authority. The scheme
* of the URI determines a configuration property name,
* <tt>fs.<i>scheme</i>.class</tt> whose value names the FileSystem class.
* The entire URI is passed to the FileSystem instance's initialize method.
*/
public static FileSystem get(URI uri, Configuration conf) throws IOException {
String scheme = uri.getScheme();
String authority = uri.getAuthority();
if (scheme == null) { // no scheme: use default FS
return get(conf);
}
if (authority == null) { // no authority
URI defaultUri = getDefaultUri(conf);
if (scheme.equals(defaultUri.getScheme()) // if scheme matches default
&& defaultUri.getAuthority() != null) { // & default has authority
return get(defaultUri, conf); // return default
}
}
String disableCacheName = String.format("fs.%s.impl.disable.cache", scheme);
if (conf.getBoolean(disableCacheName, false)) {
return createFileSystem(uri, conf);
}
return CACHE.get(uri, conf);
}
/** Returns the FileSystem for this URI's scheme and authority. The scheme
* of the URI determines a configuration property name,
* <tt>fs.<i>scheme</i>.class</tt> whose value names the FileSystem class.
* The entire URI is passed to the FileSystem instance's initialize method.
* This always returns a new FileSystem object.
*/
public static FileSystem newInstance(URI uri, Configuration conf) throws IOException {
String scheme = uri.getScheme();
String authority = uri.getAuthority();
if (scheme == null) { // no scheme: use default FS
return newInstance(conf);
}
if (authority == null) { // no authority
URI defaultUri = getDefaultUri(conf);
if (scheme.equals(defaultUri.getScheme()) // if scheme matches default
&& defaultUri.getAuthority() != null) { // & default has authority
return newInstance(defaultUri, conf); // return default
}
}
return CACHE.getUnique(uri, conf);
}
/** Returns a unique configured filesystem implementation.
* This always returns a new FileSystem object. */
public static FileSystem newInstance(Configuration conf) throws IOException {
return newInstance(getDefaultUri(conf), conf);
}
/**
* Get a unique local file system object
* @param conf the configuration to configure the file system with
* @return a LocalFileSystem
* This always returns a new FileSystem object.
*/
public static LocalFileSystem newInstanceLocal(Configuration conf)
throws IOException {
return (LocalFileSystem)newInstance(LocalFileSystem.NAME, conf);
}
/**
* Close all cached filesystems. Be sure those filesystems are not
* used anymore.
*
* @throws IOException
*/
public static void closeAll() throws IOException {
LOG.debug("Starting clear of FileSystem cache with " + CACHE.size() +
" elements.");
CACHE.closeAll(null, false);
LOG.debug("Done clearing cache");
}
/**
* Close all cached filesystems for a given UGI. Be sure those filesystems
* are not used anymore.
* @param ugi
* @throws IOException
*/
public static void closeAllForUGI(UserGroupInformation ugi)
throws IOException {
CACHE.closeAll(ugi, false);
}
/** Make sure that a path specifies a FileSystem. */
public Path makeQualified(Path path) {
checkPath(path);
return path.makeQualified(this);
}
/** create a file with the provided permission
* The permission of the file is set to be the provided permission as in
* setPermission, not permission&~umask
*
* It is implemented using two RPCs. It is understood that it is inefficient,
* but the implementation is thread-safe. The other option is to change the
* value of umask in configuration to be 0, but it is not thread-safe.
*
* @param fs file system handle
* @param file the name of the file to be created
* @param permission the permission of the file
* @return an output stream
* @throws IOException
*/
public static FSDataOutputStream create(FileSystem fs,
Path file, FsPermission permission) throws IOException {
// create the file with default permission
FSDataOutputStream out = fs.create(file);
// set its permission to the supplied one
fs.setPermission(file, permission);
return out;
}
/** create a directory with the provided permission
* The permission of the directory is set to be the provided permission as in
* setPermission, not permission&~umask
*
* @see #create(FileSystem, Path, FsPermission)
*
* @param fs file system handle
* @param dir the name of the directory to be created
* @param permission the permission of the directory
* @return true if the directory creation succeeds; false otherwise
* @throws IOException
*/
public static boolean mkdirs(FileSystem fs, Path dir, FsPermission permission)
throws IOException {
// create the directory using the default permission
boolean result = fs.mkdirs(dir);
// set its permission to be the supplied one
fs.setPermission(dir, permission);
return result;
}
///////////////////////////////////////////////////////////////
// FileSystem
///////////////////////////////////////////////////////////////
protected FileSystem() {
super(null);
}
/** Check that a Path belongs to this FileSystem. */
protected void checkPath(Path path) {
URI uri = path.toUri();
if (uri.getScheme() == null) // fs is relative
return;
String thisScheme = this.getUri().getScheme();
String thatScheme = uri.getScheme();
String thisAuthority = this.getUri().getAuthority();
String thatAuthority = uri.getAuthority();
//authority and scheme are not case sensitive
if (thisScheme.equalsIgnoreCase(thatScheme)) {// schemes match
if (thisAuthority == thatAuthority || // & authorities match
(thisAuthority != null &&
thisAuthority.equalsIgnoreCase(thatAuthority)))
return;
if (thatAuthority == null && // path's authority is null
thisAuthority != null) { // fs has an authority
URI defaultUri = getDefaultUri(getConf()); // & is the conf default
if (thisScheme.equalsIgnoreCase(defaultUri.getScheme()) &&
thisAuthority.equalsIgnoreCase(defaultUri.getAuthority()))
return;
try { // or the default fs's uri
defaultUri = get(getConf()).getUri();
} catch (IOException e) {
throw new RuntimeException(e);
}
if (thisScheme.equalsIgnoreCase(defaultUri.getScheme()) &&
thisAuthority.equalsIgnoreCase(defaultUri.getAuthority()))
return;
}
}
throw new IllegalArgumentException("Wrong FS: "+path+
", expected: "+this.getUri());
}
/**
* Return an array containing hostnames, offset and size of
* portions of the given file. For a nonexistent
* file or regions, null will be returned.
*
* This call is most helpful with DFS, where it returns
* hostnames of machines that contain the given file.
*
* The FileSystem will simply return an elt containing 'localhost'.
*/
public BlockLocation[] getFileBlockLocations(FileStatus file,
long start, long len) throws IOException {
if (file == null) {
return null;
}
if ( (start<0) || (len < 0) ) {
throw new IllegalArgumentException("Invalid start or len parameter");
}
if (file.getLen() < start) {
return new BlockLocation[0];
}
String[] name = { "localhost:50010" };
String[] host = { "localhost" };
return new BlockLocation[] { new BlockLocation(name, host, 0, file.getLen()) };
}
/**
* Opens an FSDataInputStream at the indicated Path.
* @param f the file name to open
* @param bufferSize the size of the buffer to be used.
*/
public abstract FSDataInputStream open(Path f, int bufferSize)
throws IOException;
/**
* Opens an FSDataInputStream at the indicated Path.
* @param f the file to open
*/
public FSDataInputStream open(Path f) throws IOException {
return open(f, getConf().getInt("io.file.buffer.size", 4096));
}
/**
* Opens an FSDataOutputStream at the indicated Path.
* Files are overwritten by default.
*/
public FSDataOutputStream create(Path f) throws IOException {
return create(f, true);
}
/**
* Opens an FSDataOutputStream at the indicated Path.
*/
public FSDataOutputStream create(Path f, boolean overwrite)
throws IOException {
return create(f, overwrite,
getConf().getInt("io.file.buffer.size", 4096),
getDefaultReplication(),
getDefaultBlockSize());
}
/**
* Create an FSDataOutputStream at the indicated Path with write-progress
* reporting.
* Files are overwritten by default.
*/
public FSDataOutputStream create(Path f, Progressable progress) throws IOException {
return create(f, true,
getConf().getInt("io.file.buffer.size", 4096),
getDefaultReplication(),
getDefaultBlockSize(), progress);
}
/**
* Opens an FSDataOutputStream at the indicated Path.
* Files are overwritten by default.
*/
public FSDataOutputStream create(Path f, short replication)
throws IOException {
return create(f, true,
getConf().getInt("io.file.buffer.size", 4096),
replication,
getDefaultBlockSize());
}
/**
* Opens an FSDataOutputStream at the indicated Path with write-progress
* reporting.
* Files are overwritten by default.
*/
public FSDataOutputStream create(Path f, short replication, Progressable progress)
throws IOException {
return create(f, true,
getConf().getInt("io.file.buffer.size", 4096),
replication,
getDefaultBlockSize(), progress);
}
/**
* Opens an FSDataOutputStream at the indicated Path.
* @param f the file name to open
* @param overwrite if a file with this name already exists, then if true,
* the file will be overwritten, and if false an error will be thrown.
* @param bufferSize the size of the buffer to be used.
*/
public FSDataOutputStream create(Path f,
boolean overwrite,
int bufferSize
) throws IOException {
return create(f, overwrite, bufferSize,
getDefaultReplication(),
getDefaultBlockSize());
}
/**
* Opens an FSDataOutputStream at the indicated Path with write-progress
* reporting.
* @param f the file name to open
* @param overwrite if a file with this name already exists, then if true,
* the file will be overwritten, and if false an error will be thrown.
* @param bufferSize the size of the buffer to be used.
*/
public FSDataOutputStream create(Path f,
boolean overwrite,
int bufferSize,
Progressable progress
) throws IOException {
return create(f, overwrite, bufferSize,
getDefaultReplication(),
getDefaultBlockSize(), progress);
}
/**
* Opens an FSDataOutputStream at the indicated Path.
* @param f the file name to open
* @param overwrite if a file with this name already exists, then if true,
* the file will be overwritten, and if false an error will be thrown.
* @param bufferSize the size of the buffer to be used.
* @param replication required block replication for the file.
*/
public FSDataOutputStream create(Path f,
boolean overwrite,
int bufferSize,
short replication,
long blockSize
) throws IOException {
return create(f, overwrite, bufferSize, replication, blockSize, null);
}
/**
* Opens an FSDataOutputStream at the indicated Path with write-progress
* reporting.
* @param f the file name to open
* @param overwrite if a file with this name already exists, then if true,
* the file will be overwritten, and if false an error will be thrown.
* @param bufferSize the size of the buffer to be used.
* @param replication required block replication for the file.
*/
public FSDataOutputStream create(Path f,
boolean overwrite,
int bufferSize,
short replication,
long blockSize,
Progressable progress
) throws IOException {
return this.create(f, FsPermission.getDefault(),
overwrite, bufferSize, replication, blockSize, progress);
}
/**
* Opens an FSDataOutputStream at the indicated Path with write-progress
* reporting.
* @param f the file name to open
* @param permission
* @param overwrite if a file with this name already exists, then if true,
* the file will be overwritten, and if false an error will be thrown.
* @param bufferSize the size of the buffer to be used.
* @param replication required block replication for the file.
* @param blockSize
* @param progress
* @throws IOException
* @see #setPermission(Path, FsPermission)
*/
public abstract FSDataOutputStream create(Path f,
FsPermission permission,
boolean overwrite,
int bufferSize,
short replication,
long blockSize,
Progressable progress) throws IOException;
/**
* Creates the given Path as a brand-new zero-length file. If
* create fails, or if it already existed, return false.
*/
public boolean createNewFile(Path f) throws IOException {
if (exists(f)) {
return false;
} else {
create(f, false, getConf().getInt("io.file.buffer.size", 4096)).close();
return true;
}
}
/**
* Append to an existing file (optional operation).
* Same as append(f, getConf().getInt("io.file.buffer.size", 4096), null)
* @param f the existing file to be appended.
* @throws IOException
*/
public FSDataOutputStream append(Path f) throws IOException {
return append(f, getConf().getInt("io.file.buffer.size", 4096), null);
}
/**
* Append to an existing file (optional operation).
* Same as append(f, bufferSize, null).
* @param f the existing file to be appended.
* @param bufferSize the size of the buffer to be used.
* @throws IOException
*/
public FSDataOutputStream append(Path f, int bufferSize) throws IOException {
return append(f, bufferSize, null);
}
/**
* Append to an existing file (optional operation).
* @param f the existing file to be appended.
* @param bufferSize the size of the buffer to be used.
* @param progress for reporting progress if it is not null.
* @throws IOException
*/
public abstract FSDataOutputStream append(Path f, int bufferSize,
Progressable progress) throws IOException;
/**
* Get replication.
*
* @deprecated Use getFileStatus() instead
* @param src file name
* @return file replication
* @throws IOException
*/
@Deprecated
public short getReplication(Path src) throws IOException {
return getFileStatus(src).getReplication();
}
/**
* Set replication for an existing file.
*
* @param src file name
* @param replication new replication
* @throws IOException
* @return true if successful;
* false if file does not exist or is a directory
*/
public boolean setReplication(Path src, short replication)
throws IOException {
return true;
}
/**
* Renames Path src to Path dst. Can take place on local fs
* or remote DFS.
*/
public abstract boolean rename(Path src, Path dst) throws IOException;
/** Delete a file. */
/** @deprecated Use delete(Path, boolean) instead */ @Deprecated
public abstract boolean delete(Path f) throws IOException;
/** Delete a file.
*
* @param f the path to delete.
* @param recursive if path is a directory and set to
* true, the directory is deleted else throws an exception. In
* case of a file the recursive can be set to either true or false.
* @return true if delete is successful else false.
* @throws IOException
*/
public abstract boolean delete(Path f, boolean recursive) throws IOException;
/**
* Mark a path to be deleted when FileSystem is closed.
* When the JVM shuts down,
* all FileSystem objects will be closed automatically.
* Then,
* the marked path will be deleted as a result of closing the FileSystem.
*
* The path has to exist in the file system.
*
* @param f the path to delete.
* @return true if deleteOnExit is successful, otherwise false.
* @throws IOException
*/
public boolean deleteOnExit(Path f) throws IOException {
if (!exists(f)) {
return false;
}
synchronized (deleteOnExit) {
deleteOnExit.add(f);
}
return true;
}
/**
* Delete all files that were marked as delete-on-exit. This recursively
* deletes all files in the specified paths.
*/
protected void processDeleteOnExit() {
synchronized (deleteOnExit) {
for (Iterator<Path> iter = deleteOnExit.iterator(); iter.hasNext();) {
Path path = iter.next();
try {
delete(path, true);
}
catch (IOException e) {
LOG.info("Ignoring failure to deleteOnExit for path " + path);
}
iter.remove();
}
}
}
/** Check if exists.
* @param f source file
*/
public boolean exists(Path f) throws IOException {
try {
return getFileStatus(f) != null;
} catch (FileNotFoundException e) {
return false;
}
}
/** True iff the named path is a directory. */
/** @deprecated Use getFileStatus() instead */ @Deprecated
public boolean isDirectory(Path f) throws IOException {
try {
return getFileStatus(f).isDir();
} catch (FileNotFoundException e) {
return false; // f does not exist
}
}
/** True iff the named path is a regular file. */
public boolean isFile(Path f) throws IOException {
try {
return !getFileStatus(f).isDir();
} catch (FileNotFoundException e) {
return false; // f does not exist
}
}
/** The number of bytes in a file. */
/** @deprecated Use getFileStatus() instead */ @Deprecated
public long getLength(Path f) throws IOException {
return getFileStatus(f).getLen();
}
/** Return the {@link ContentSummary} of a given {@link Path}. */
public ContentSummary getContentSummary(Path f) throws IOException {
FileStatus status = getFileStatus(f);
if (!status.isDir()) {
// f is a file
return new ContentSummary(status.getLen(), 1, 0);
}
// f is a directory
long[] summary = {0, 0, 1};
for(FileStatus s : listStatus(f)) {
ContentSummary c = s.isDir() ? getContentSummary(s.getPath()) :
new ContentSummary(s.getLen(), 1, 0);
summary[0] += c.getLength();
summary[1] += c.getFileCount();
summary[2] += c.getDirectoryCount();
}
return new ContentSummary(summary[0], summary[1], summary[2]);
}
final private static PathFilter DEFAULT_FILTER = new PathFilter() {
public boolean accept(Path file) {
return true;
}
};
/**
* List the statuses of the files/directories in the given path if the path is
* a directory.
*
* @param f
* given path
* @return the statuses of the files/directories in the given patch
* @throws IOException
*/
public abstract FileStatus[] listStatus(Path f) throws IOException;
/*
* Filter files/directories in the given path using the user-supplied path
* filter. Results are added to the given array <code>results</code>.
*/
private void listStatus(ArrayList<FileStatus> results, Path f,
PathFilter filter) throws IOException {
FileStatus listing[] = listStatus(f);
if (listing != null) {
for (int i = 0; i < listing.length; i++) {
if (filter.accept(listing[i].getPath())) {
results.add(listing[i]);
}
}
}
}
/**
* Filter files/directories in the given path using the user-supplied path
* filter.
*
* @param f
* a path name
* @param filter
* the user-supplied path filter
* @return an array of FileStatus objects for the files under the given path
* after applying the filter
* @throws IOException
* if encounter any problem while fetching the status
*/
public FileStatus[] listStatus(Path f, PathFilter filter) throws IOException {
ArrayList<FileStatus> results = new ArrayList<FileStatus>();
listStatus(results, f, filter);
return results.toArray(new FileStatus[results.size()]);
}
/**
* Filter files/directories in the given list of paths using default
* path filter.
*
* @param files
* a list of paths
* @return a list of statuses for the files under the given paths after
* applying the filter default Path filter
* @exception IOException
*/
public FileStatus[] listStatus(Path[] files)
throws IOException {
return listStatus(files, DEFAULT_FILTER);
}
/**
* Filter files/directories in the given list of paths using user-supplied
* path filter.
*
* @param files
* a list of paths
* @param filter
* the user-supplied path filter
* @return a list of statuses for the files under the given paths after
* applying the filter
* @exception IOException
*/
public FileStatus[] listStatus(Path[] files, PathFilter filter)
throws IOException {
ArrayList<FileStatus> results = new ArrayList<FileStatus>();
for (int i = 0; i < files.length; i++) {
listStatus(results, files[i], filter);
}
return results.toArray(new FileStatus[results.size()]);
}
/**
* <p>Return all the files that match filePattern and are not checksum
* files. Results are sorted by their names.
*
* <p>
* A filename pattern is composed of <i>regular</i> characters and
* <i>special pattern matching</i> characters, which are:
*
* <dl>
* <dd>
* <dl>
* <p>
* <dt> <tt> ? </tt>
* <dd> Matches any single character.
*
* <p>
* <dt> <tt> * </tt>
* <dd> Matches zero or more characters.
*
* <p>
* <dt> <tt> [<i>abc</i>] </tt>
* <dd> Matches a single character from character set
* <tt>{<i>a,b,c</i>}</tt>.
*
* <p>
* <dt> <tt> [<i>a</i>-<i>b</i>] </tt>
* <dd> Matches a single character from the character range
* <tt>{<i>a...b</i>}</tt>. Note that character <tt><i>a</i></tt> must be
* lexicographically less than or equal to character <tt><i>b</i></tt>.
*
* <p>
* <dt> <tt> [^<i>a</i>] </tt>
* <dd> Matches a single character that is not from character set or range
* <tt>{<i>a</i>}</tt>. Note that the <tt>^</tt> character must occur
* immediately to the right of the opening bracket.
*
* <p>
* <dt> <tt> \<i>c</i> </tt>
* <dd> Removes (escapes) any special meaning of character <i>c</i>.
*
* <p>
* <dt> <tt> {ab,cd} </tt>
* <dd> Matches a string from the string set <tt>{<i>ab, cd</i>} </tt>
*
* <p>
* <dt> <tt> {ab,c{de,fh}} </tt>
* <dd> Matches a string from the string set <tt>{<i>ab, cde, cfh</i>}</tt>
*
* </dl>
* </dd>
* </dl>
*
* @param pathPattern a regular expression specifying a pth pattern
* @return an array of paths that match the path pattern
* @throws IOException
*/
public FileStatus[] globStatus(Path pathPattern) throws IOException {
return globStatus(pathPattern, DEFAULT_FILTER);
}
/**
* Return an array of FileStatus objects whose path names match pathPattern
* and is accepted by the user-supplied path filter. Results are sorted by
* their path names.
* Return null if pathPattern has no glob and the path does not exist.
* Return an empty array if pathPattern has a glob and no path matches it.
*
* @param pathPattern
* a regular expression specifying the path pattern
* @param filter
* a user-supplied path filter
* @return an array of FileStatus objects
* @throws IOException if any I/O error occurs when fetching file status
*/
public FileStatus[] globStatus(Path pathPattern, PathFilter filter)
throws IOException {
String filename = pathPattern.toUri().getPath();
List<String> filePatterns = GlobExpander.expand(filename);
if (filePatterns.size() == 1) {
return globStatusInternal(pathPattern, filter);
} else {
List<FileStatus> results = new ArrayList<FileStatus>();
for (String filePattern : filePatterns) {
FileStatus[] files = globStatusInternal(new Path(filePattern), filter);
for (FileStatus file : files) {
results.add(file);
}
}
return results.toArray(new FileStatus[results.size()]);
}
}
private FileStatus[] globStatusInternal(Path pathPattern, PathFilter filter)
throws IOException {
Path[] parents = new Path[1];
int level = 0;
String filename = pathPattern.toUri().getPath();
// path has only zero component
if ("".equals(filename) || Path.SEPARATOR.equals(filename)) {
return getFileStatus(new Path[]{pathPattern});
}
// path has at least one component
String[] components = filename.split(Path.SEPARATOR);
// get the first component
if (pathPattern.isAbsolute()) {
parents[0] = new Path(Path.SEPARATOR);
level = 1;
} else {
parents[0] = new Path(Path.CUR_DIR);
}
// glob the paths that match the parent path, i.e., [0, components.length-1]
boolean[] hasGlob = new boolean[]{false};
Path[] parentPaths = globPathsLevel(parents, components, level, hasGlob);
FileStatus[] results;
if (parentPaths == null || parentPaths.length == 0) {
results = null;
} else {
// Now work on the last component of the path
GlobFilter fp = new GlobFilter(components[components.length - 1], filter);
if (fp.hasPattern()) { // last component has a pattern
// list parent directories and then glob the results
results = listStatus(parentPaths, fp);
hasGlob[0] = true;
} else { // last component does not have a pattern
// get all the path names
ArrayList<Path> filteredPaths = new ArrayList<Path>(parentPaths.length);
for (int i = 0; i < parentPaths.length; i++) {
parentPaths[i] = new Path(parentPaths[i],
components[components.length - 1]);
if (fp.accept(parentPaths[i])) {
filteredPaths.add(parentPaths[i]);
}
}
// get all their statuses
results = getFileStatus(
filteredPaths.toArray(new Path[filteredPaths.size()]));
}
}
// Decide if the pathPattern contains a glob or not
if (results == null) {
if (hasGlob[0]) {
results = new FileStatus[0];
}
} else {
if (results.length == 0 ) {
if (!hasGlob[0]) {
results = null;
}
} else {
Arrays.sort(results);
}
}
return results;
}
/*
* For a path of N components, return a list of paths that match the
* components [<code>level</code>, <code>N-1</code>].
*/
private Path[] globPathsLevel(Path[] parents, String[] filePattern,
int level, boolean[] hasGlob) throws IOException {
if (level == filePattern.length - 1)
return parents;
if (parents == null || parents.length == 0) {
return null;
}
GlobFilter fp = new GlobFilter(filePattern[level]);
if (fp.hasPattern()) {
parents = FileUtil.stat2Paths(listStatus(parents, fp));
hasGlob[0] = true;
} else {
for (int i = 0; i < parents.length; i++) {
parents[i] = new Path(parents[i], filePattern[level]);
}
}
return globPathsLevel(parents, filePattern, level + 1, hasGlob);
}
/* A class that could decide if a string matches the glob or not */
private static class GlobFilter implements PathFilter {
private PathFilter userFilter = DEFAULT_FILTER;
private Pattern regex;
private boolean hasPattern = false;
/** Default pattern character: Escape any special meaning. */
private static final char PAT_ESCAPE = '\\';
/** Default pattern character: Any single character. */
private static final char PAT_ANY = '.';
/** Default pattern character: Character set close. */
private static final char PAT_SET_CLOSE = ']';
GlobFilter(String filePattern) throws IOException {
setRegex(filePattern);
}
GlobFilter(String filePattern, PathFilter filter) throws IOException {
userFilter = filter;
setRegex(filePattern);
}
private boolean isJavaRegexSpecialChar(char pChar) {
return pChar == '.' || pChar == '$' || pChar == '(' || pChar == ')' ||
pChar == '|' || pChar == '+';
}
void setRegex(String filePattern) throws IOException {
int len;
int setOpen;
int curlyOpen;
boolean setRange;
StringBuilder fileRegex = new StringBuilder();
// Validate the pattern
len = filePattern.length();
if (len == 0)
return;
setOpen = 0;
setRange = false;
curlyOpen = 0;
for (int i = 0; i < len; i++) {
char pCh;
// Examine a single pattern character
pCh = filePattern.charAt(i);
if (pCh == PAT_ESCAPE) {
fileRegex.append(pCh);
i++;
if (i >= len)
error("An escaped character does not present", filePattern, i);
pCh = filePattern.charAt(i);
} else if (isJavaRegexSpecialChar(pCh)) {
fileRegex.append(PAT_ESCAPE);
} else if (pCh == '*') {
fileRegex.append(PAT_ANY);
hasPattern = true;
} else if (pCh == '?') {
pCh = PAT_ANY;
hasPattern = true;
} else if (pCh == '{') {
fileRegex.append('(');
pCh = '(';
curlyOpen++;
hasPattern = true;
} else if (pCh == ',' && curlyOpen > 0) {
fileRegex.append(")|");
pCh = '(';
} else if (pCh == '}' && curlyOpen > 0) {
// End of a group
curlyOpen--;
fileRegex.append(")");
pCh = ')';
} else if (pCh == '[' && setOpen == 0) {
setOpen++;
hasPattern = true;
} else if (pCh == '^' && setOpen > 0) {
} else if (pCh == '-' && setOpen > 0) {
// Character set range
setRange = true;
} else if (pCh == PAT_SET_CLOSE && setRange) {
// Incomplete character set range
error("Incomplete character set range", filePattern, i);
} else if (pCh == PAT_SET_CLOSE && setOpen > 0) {
// End of a character set
if (setOpen < 2)
error("Unexpected end of set", filePattern, i);
setOpen = 0;
} else if (setOpen > 0) {
// Normal character, or the end of a character set range
setOpen++;
setRange = false;
}
fileRegex.append(pCh);
}
// Check for a well-formed pattern
if (setOpen > 0 || setRange || curlyOpen > 0) {
// Incomplete character set or character range
error("Expecting set closure character or end of range, or }",
filePattern, len);
}
regex = Pattern.compile(fileRegex.toString());
}
boolean hasPattern() {
return hasPattern;
}
public boolean accept(Path path) {
return regex.matcher(path.getName()).matches() && userFilter.accept(path);
}
private void error(String s, String pattern, int pos) throws IOException {
throw new IOException("Illegal file pattern: "
+s+ " for glob "+ pattern + " at " + pos);
}
}
/** Return the current user's home directory in this filesystem.
* The default implementation returns "/user/$USER/".
*/
public Path getHomeDirectory() {
return new Path("/user/"+System.getProperty("user.name"))
.makeQualified(this);
}
/**
* Get a new delegation token for this file system.
* @param renewer the account name that is allowed to renew the token.
* @return a new delegation token
* @throws IOException
*/
public Token<?> getDelegationToken(String renewer) throws IOException {
return null;
}
/**
* Set the current working directory for the given file system. All relative
* paths will be resolved relative to it.
*
* @param new_dir
*/
public abstract void setWorkingDirectory(Path new_dir);
/**
* Get the current working directory for the given file system
* @return the directory pathname
*/
public abstract Path getWorkingDirectory();
/**
* Call {@link #mkdirs(Path, FsPermission)} with default permission.
*/
public boolean mkdirs(Path f) throws IOException {
return mkdirs(f, FsPermission.getDefault());
}
/**
* Make the given file and all non-existent parents into
* directories. Has the semantics of Unix 'mkdir -p'.
* Existence of the directory hierarchy is not an error.
*/
public abstract boolean mkdirs(Path f, FsPermission permission
) throws IOException;
/**
* The src file is on the local disk. Add it to FS at
* the given dst name and the source is kept intact afterwards
*/
public void copyFromLocalFile(Path src, Path dst)
throws IOException {
copyFromLocalFile(false, src, dst);
}
/**
* The src files is on the local disk. Add it to FS at
* the given dst name, removing the source afterwards.
*/
public void moveFromLocalFile(Path[] srcs, Path dst)
throws IOException {
copyFromLocalFile(true, true, srcs, dst);
}
/**
* The src file is on the local disk. Add it to FS at
* the given dst name, removing the source afterwards.
*/
public void moveFromLocalFile(Path src, Path dst)
throws IOException {
copyFromLocalFile(true, src, dst);
}
/**
* The src file is on the local disk. Add it to FS at
* the given dst name.
* delSrc indicates if the source should be removed
*/
public void copyFromLocalFile(boolean delSrc, Path src, Path dst)
throws IOException {
copyFromLocalFile(delSrc, true, src, dst);
}
/**
* The src files are on the local disk. Add it to FS at
* the given dst name.
* delSrc indicates if the source should be removed
*/
public void copyFromLocalFile(boolean delSrc, boolean overwrite,
Path[] srcs, Path dst)
throws IOException {
Configuration conf = getConf();
FileUtil.copy(getLocal(conf), srcs, this, dst, delSrc, overwrite, conf);
}
/**
* The src file is on the local disk. Add it to FS at
* the given dst name.
* delSrc indicates if the source should be removed
*/
public void copyFromLocalFile(boolean delSrc, boolean overwrite,
Path src, Path dst)
throws IOException {
Configuration conf = getConf();
FileUtil.copy(getLocal(conf), src, this, dst, delSrc, overwrite, conf);
}
/**
* The src file is under FS, and the dst is on the local disk.
* Copy it from FS control to the local dst name.
*/
public void copyToLocalFile(Path src, Path dst) throws IOException {
copyToLocalFile(false, src, dst);
}
/**
* The src file is under FS, and the dst is on the local disk.
* Copy it from FS control to the local dst name.
* Remove the source afterwards
*/
public void moveToLocalFile(Path src, Path dst) throws IOException {
copyToLocalFile(true, src, dst);
}
/**
* The src file is under FS, and the dst is on the local disk.
* Copy it from FS control to the local dst name.
* delSrc indicates if the src will be removed or not.
*/
public void copyToLocalFile(boolean delSrc, Path src, Path dst)
throws IOException {
FileUtil.copy(this, src, getLocal(getConf()), dst, delSrc, getConf());
}
/**
* Returns a local File that the user can write output to. The caller
* provides both the eventual FS target name and the local working
* file. If the FS is local, we write directly into the target. If
* the FS is remote, we write into the tmp local area.
*/
public Path startLocalOutput(Path fsOutputFile, Path tmpLocalFile)
throws IOException {
return tmpLocalFile;
}
/**
* Called when we're all done writing to the target. A local FS will
* do nothing, because we've written to exactly the right place. A remote
* FS will copy the contents of tmpLocalFile to the correct target at
* fsOutputFile.
*/
public void completeLocalOutput(Path fsOutputFile, Path tmpLocalFile)
throws IOException {
moveFromLocalFile(tmpLocalFile, fsOutputFile);
}
/**
* No more filesystem operations are needed. Will
* release any held locks.
*/
public void close() throws IOException {
// delete all files that were marked as delete-on-exit.
processDeleteOnExit();
CACHE.remove(this.key, this);
LOG.debug("Removing filesystem for " + getUri());
}
/** Return the total size of all files in the filesystem.*/
public long getUsed() throws IOException{
long used = 0;
FileStatus[] files = listStatus(new Path("/"));
for(FileStatus file:files){
used += file.getLen();
}
return used;
}
/**
* Get the block size for a particular file.
* @param f the filename
* @return the number of bytes in a block
*/
/** @deprecated Use getFileStatus() instead */ @Deprecated
public long getBlockSize(Path f) throws IOException {
return getFileStatus(f).getBlockSize();
}
/** Return the number of bytes that large input files should be optimally
* be split into to minimize i/o time. */
public long getDefaultBlockSize() {
// default to 32MB: large enough to minimize the impact of seeks
return getConf().getLong("fs.local.block.size", 32 * 1024 * 1024);
}
/**
* Get the default replication.
*/
public short getDefaultReplication() { return 1; }
/**
* Return a file status object that represents the path.
* @param f The path we want information from
* @return a FileStatus object
* @throws FileNotFoundException when the path does not exist;
* IOException see specific implementation
*/
public abstract FileStatus getFileStatus(Path f) throws IOException;
/**
* Get the checksum of a file.
*
* @param f The file path
* @return The file checksum. The default return value is null,
* which indicates that no checksum algorithm is implemented
* in the corresponding FileSystem.
*/
public FileChecksum getFileChecksum(Path f) throws IOException {
return null;
}
/**
* Set the verify checksum flag. This is only applicable if the
* corresponding FileSystem supports checksum. By default doesn't do anything.
* @param verifyChecksum
*/
public void setVerifyChecksum(boolean verifyChecksum) {
//doesn't do anything
}
/**
* Return a list of file status objects that corresponds to the list of paths
* excluding those non-existent paths.
*
* @param paths
* the list of paths we want information from
* @return a list of FileStatus objects
* @throws IOException
* see specific implementation
*/
private FileStatus[] getFileStatus(Path[] paths) throws IOException {
if (paths == null) {
return null;
}
ArrayList<FileStatus> results = new ArrayList<FileStatus>(paths.length);
for (int i = 0; i < paths.length; i++) {
try {
results.add(getFileStatus(paths[i]));
} catch (FileNotFoundException e) { // do nothing
}
}
return results.toArray(new FileStatus[results.size()]);
}
/**
* Returns a status object describing the use and capacity of the
* file system. If the file system has multiple partitions, the
* use and capacity of the root partition is reflected.
*
* @return a FsStatus object
* @throws IOException
* see specific implementation
*/
public FsStatus getStatus() throws IOException {
return getStatus(null);
}
/**
* Returns a status object describing the use and capacity of the
* file system. If the file system has multiple partitions, the
* use and capacity of the partition pointed to by the specified
* path is reflected.
* @param p Path for which status should be obtained. null means
* the default partition.
* @return a FsStatus object
* @throws IOException
* see specific implementation
*/
public FsStatus getStatus(Path p) throws IOException {
return new FsStatus(Long.MAX_VALUE, 0, Long.MAX_VALUE);
}
/**
* Set permission of a path.
* @param p
* @param permission
*/
public void setPermission(Path p, FsPermission permission
) throws IOException {
}
/**
* Set owner of a path (i.e. a file or a directory).
* The parameters username and groupname cannot both be null.
* @param p The path
* @param username If it is null, the original username remains unchanged.
* @param groupname If it is null, the original groupname remains unchanged.
*/
public void setOwner(Path p, String username, String groupname
) throws IOException {
}
/**
* Set access time of a file
* @param p The path
* @param mtime Set the modification time of this file.
* The number of milliseconds since Jan 1, 1970.
* A value of -1 means that this call should not set modification time.
* @param atime Set the access time of this file.
* The number of milliseconds since Jan 1, 1970.
* A value of -1 means that this call should not set access time.
*/
public void setTimes(Path p, long mtime, long atime
) throws IOException {
}
private static FileSystem createFileSystem(URI uri, Configuration conf
) throws IOException {
Class<?> clazz = conf.getClass("fs." + uri.getScheme() + ".impl", null);
LOG.debug("Creating filesystem for " + uri);
if (clazz == null) {
throw new IOException("No FileSystem for scheme: " + uri.getScheme());
}
FileSystem fs = (FileSystem)ReflectionUtils.newInstance(clazz, conf);
fs.initialize(uri, conf);
return fs;
}
/** Caching FileSystem objects */
static class Cache {
private final ClientFinalizer clientFinalizer = new ClientFinalizer();
private final Map<Key, FileSystem> map = new HashMap<Key, FileSystem>();
private final Set<Key> toAutoClose = new HashSet<Key>();
/** A variable that makes all objects in the cache unique */
private static AtomicLong unique = new AtomicLong(1);
FileSystem get(URI uri, Configuration conf) throws IOException{
Key key = new Key(uri, conf);
return getInternal(uri, conf, key);
}
/** The objects inserted into the cache using this method are all unique */
synchronized FileSystem getUnique(URI uri, Configuration conf) throws IOException{
Key key = new Key(uri, conf, unique.getAndIncrement());
return getInternal(uri, conf, key);
}
private FileSystem getInternal(URI uri, Configuration conf, Key key) throws IOException{
FileSystem fs = null;
synchronized (this) {
fs = map.get(key);
}
if (fs != null) {
return fs;
}
fs = createFileSystem(uri, conf);
synchronized (this) { // refetch the lock again
FileSystem oldfs = map.get(key);
if (oldfs != null) { // a file system is created while lock is releasing
fs.close(); // close the new file system
return oldfs; // return the old file system
}
// now insert the new file system into the map
if (map.isEmpty() && !clientFinalizer.isAlive()) {
Runtime.getRuntime().addShutdownHook(clientFinalizer);
}
fs.key = key;
map.put(key, fs);
if (conf.getBoolean("fs.automatic.close", true)) {
toAutoClose.add(key);
}
return fs;
}
}
synchronized void remove(Key key, FileSystem fs) {
if (map.containsKey(key) && fs == map.get(key)) {
map.remove(key);
toAutoClose.remove(key);
if (map.isEmpty() && !clientFinalizer.isAlive()) {
if (!Runtime.getRuntime().removeShutdownHook(clientFinalizer)) {
LOG.info("Could not cancel cleanup thread, though no " +
"FileSystems are open");
}
}
}
}
private class ClientFinalizer extends Thread {
public synchronized void run() {
try {
closeAll(null, true);
} catch (IOException e) {
LOG.info("FileSystem.Cache.closeAll() threw an exception:\n" + e);
}
}
}
/**
* Close all of the file systems in the cache.
* @param ugi Only close filesystems with this UGI - may be null to indicate ignoring UGI
* @param onlyAutomatic only close filesystems marked for automatic close
*/
synchronized void closeAll(UserGroupInformation ugi, boolean onlyAutomatic) throws IOException {
List<FileSystem> targetFSList = new ArrayList<FileSystem>();
//Make a pass over the list and collect the filesystems to close
//we cannot close inline since close() removes the entry from the Map
for (Map.Entry<Key, FileSystem> entry : map.entrySet()) {
final Key key = entry.getKey();
final FileSystem fs = entry.getValue();
if (fs == null) continue;
if (ugi != null && !ugi.equals(key.ugi)) continue;
if (onlyAutomatic && !toAutoClose.contains(key)) {
continue;
}
targetFSList.add(fs);
}
List<IOException> exceptions = new ArrayList<IOException>();
//now make a pass over the target list and close each
for (FileSystem fs : targetFSList) {
try {
fs.close();
}
catch(IOException ioe) {
exceptions.add(ioe);
}
}
if (!exceptions.isEmpty()) {
throw MultipleIOException.createIOException(exceptions);
}
}
synchronized void closeAll(UserGroupInformation ugi) throws IOException {
List<FileSystem> targetFSList = new ArrayList<FileSystem>();
//Make a pass over the list and collect the filesystems to close
//we cannot close inline since close() removes the entry from the Map
for (Map.Entry<Key, FileSystem> entry : map.entrySet()) {
final Key key = entry.getKey();
final FileSystem fs = entry.getValue();
if (ugi.equals(key.ugi) && fs != null) {
targetFSList.add(fs);
}
}
List<IOException> exceptions = new ArrayList<IOException>();
//now make a pass over the target list and close each
for (FileSystem fs : targetFSList) {
try {
fs.close();
}
catch(IOException ioe) {
exceptions.add(ioe);
}
}
if (!exceptions.isEmpty()) {
throw MultipleIOException.createIOException(exceptions);
}
}
/** FileSystem.Cache.Key */
static class Key {
final String scheme;
final String authority;
final long unique;
final UserGroupInformation ugi;
Key(URI uri, Configuration conf) throws IOException {
this(uri, conf, 0);
}
Key(URI uri, Configuration conf, long unique) throws IOException {
scheme = uri.getScheme()==null?"":uri.getScheme().toLowerCase();
authority = uri.getAuthority()==null?"":uri.getAuthority().toLowerCase();
this.unique = unique;
this.ugi = UserGroupInformation.getCurrentUser();
}
/** {@inheritDoc} */
public int hashCode() {
return (scheme + authority).hashCode() + (int)unique + ugi.hashCode();
}
static boolean isEqual(Object a, Object b) {
return a == b || (a != null && a.equals(b));
}
/** {@inheritDoc} */
public boolean equals(Object obj) {
if (obj == this) {
return true;
}
if (obj != null && obj instanceof Key) {
Key that = (Key)obj;
return isEqual(this.scheme, that.scheme)
&& isEqual(this.authority, that.authority)
&& isEqual(this.ugi, that.ugi)
&& (this.unique == that.unique);
}
return false;
}
/** {@inheritDoc} */
public String toString() {
return "("+ugi.toString() + ")@" + scheme + "://" + authority;
}
}
/**
* Get the number of file systems in the cache.
* @return the number of cached file systems
*/
int size() {
return map.size();
}
}
public static final class Statistics {
private final String scheme;
private AtomicLong bytesRead = new AtomicLong();
private AtomicLong bytesWritten = new AtomicLong();
public Statistics(String scheme) {
this.scheme = scheme;
}
/**
* Increment the bytes read in the statistics
* @param newBytes the additional bytes read
*/
public void incrementBytesRead(long newBytes) {
bytesRead.getAndAdd(newBytes);
}
/**
* Increment the bytes written in the statistics
* @param newBytes the additional bytes written
*/
public void incrementBytesWritten(long newBytes) {
bytesWritten.getAndAdd(newBytes);
}
/**
* Get the total number of bytes read
* @return the number of bytes
*/
public long getBytesRead() {
return bytesRead.get();
}
/**
* Get the total number of bytes written
* @return the number of bytes
*/
public long getBytesWritten() {
return bytesWritten.get();
}
public String toString() {
return bytesRead + " bytes read and " + bytesWritten +
" bytes written";
}
/**
* Reset the counts of bytes to 0.
*/
public void reset() {
bytesWritten.set(0);
bytesRead.set(0);
}
/**
* Get the uri scheme associated with this statistics object.
* @return the schema associated with this set of statistics
*/
public String getScheme() {
return scheme;
}
}
/**
* Get the Map of Statistics object indexed by URI Scheme.
* @return a Map having a key as URI scheme and value as Statistics object
* @deprecated use {@link #getAllStatistics} instead
*/
public static synchronized Map<String, Statistics> getStatistics() {
Map<String, Statistics> result = new HashMap<String, Statistics>();
for(Statistics stat: statisticsTable.values()) {
result.put(stat.getScheme(), stat);
}
return result;
}
/**
* Return the FileSystem classes that have Statistics
*/
public static synchronized List<Statistics> getAllStatistics() {
return new ArrayList<Statistics>(statisticsTable.values());
}
/**
* Get the statistics for a particular file system
* @param cls the class to lookup
* @return a statistics object
*/
public static synchronized
Statistics getStatistics(String scheme, Class<? extends FileSystem> cls) {
Statistics result = statisticsTable.get(cls);
if (result == null) {
result = new Statistics(scheme);
statisticsTable.put(cls, result);
}
return result;
}
public static synchronized void clearStatistics() {
for(Statistics stat: statisticsTable.values()) {
stat.reset();
}
}
public static synchronized
void printStatistics() throws IOException {
for (Map.Entry<Class<? extends FileSystem>, Statistics> pair:
statisticsTable.entrySet()) {
System.out.println(" FileSystem " + pair.getKey().getName() +
": " + pair.getValue());
}
}
}