eu.stratosphere.core.fs.FileSystem Maven / Gradle / Ivy
/***********************************************************************************************************************
* Copyright (C) 2010-2013 by the Stratosphere project (http://stratosphere.eu)
*
* Licensed 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.
**********************************************************************************************************************/
/**
* This file is based on source code from the Hadoop Project (http://hadoop.apache.org/), licensed by the Apache
* Software Foundation (ASF) under the Apache License, Version 2.0. See the NOTICE file distributed with this work for
* additional information regarding copyright ownership.
*/
package eu.stratosphere.core.fs;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.net.URI;
import java.net.URISyntaxException;
import java.util.HashMap;
import java.util.Map;
import eu.stratosphere.util.ClassUtils;
import eu.stratosphere.util.OperatingSystem;
import eu.stratosphere.util.StringUtils;
/**
* An abstract base class for a fairly generic file system. It
* may be implemented as a distributed file system, or as a local
* one that reflects the locally-connected disk.
*/
public abstract class FileSystem {
private static final String LOCAL_FILESYSTEM_CLASS = "eu.stratosphere.core.fs.local.LocalFileSystem";
private static final String DISTRIBUTED_FILESYSTEM_CLASS = "eu.stratosphere.runtime.fs.hdfs.DistributedFileSystem";
private static final String S3_FILESYSTEM_CLASS = "eu.stratosphere.runtime.fs.s3.S3FileSystem";
/** Object used to protect calls to specific methods.*/
private static final Object SYNCHRONIZATION_OBJECT = new Object();
/**
* Enumeration for write modes.
*
*/
public static enum WriteMode {
/** Creates write path if it does not exist. Does not overwrite existing files and directories. */
NO_OVERWRITE,
/** creates write path if it does not exist. Overwrites existing files and directories. */
OVERWRITE
}
/**
* An auxiliary class to identify a file system by its scheme and its authority.
*/
public static class FSKey {
/**
* The scheme of the file system.
*/
private String scheme;
/**
* The authority of the file system.
*/
private String authority;
/**
* Creates a file system key from a given scheme and an
* authority.
*
* @param scheme
* the scheme of the file system
* @param authority
* the authority of the file system
*/
public FSKey(final String scheme, final String authority) {
this.scheme = scheme;
this.authority = authority;
}
/**
* {@inheritDoc}
*/
@Override
public boolean equals(final Object obj) {
if (obj instanceof FSKey) {
final FSKey key = (FSKey) obj;
if (!this.scheme.equals(key.scheme)) {
return false;
}
if ((this.authority == null) || (key.authority == null)) {
if (this.authority == null && key.authority == null) {
return true;
}
return false;
}
if (!this.authority.equals(key.authority)) {
return false;
}
return true;
}
return false;
}
/**
* {@inheritDoc}
*/
@Override
public int hashCode() {
if (this.scheme != null) {
return this.scheme.hashCode();
}
if (this.authority != null) {
return this.authority.hashCode();
}
return super.hashCode();
}
}
/**
* Data structure mapping file system keys (scheme + authority) to cached file system objects.
*/
private static final Map CACHE = new HashMap();
/**
* Data structure mapping file system schemes to the corresponding implementations
*/
private static final Map FSDIRECTORY = new HashMap();
static {
FSDIRECTORY.put("hdfs", DISTRIBUTED_FILESYSTEM_CLASS);
FSDIRECTORY.put("file", LOCAL_FILESYSTEM_CLASS);
FSDIRECTORY.put("s3", S3_FILESYSTEM_CLASS);
}
/**
* Returns a reference to the {@link FileSystem} instance for accessing the
* local file system.
*
* @return a reference to the {@link FileSystem} instance for accessing the
* local file system.
* @throws IOException
* thrown if a reference to the file system instance could not be obtained
*/
public static FileSystem getLocalFileSystem() throws IOException {
URI localUri;
try {
localUri = OperatingSystem.isWindows() ? new URI("file:/") : new URI("file:///");
} catch (URISyntaxException e) {
throw new IOException("Cannot create URI for local file system");
}
return get(localUri);
}
/**
* Returns a reference to the {@link FileSystem} instance for accessing the
* file system identified by the given {@link URI}.
*
* @param uri
* the {@link URI} identifying the file system
* @return a reference to the {@link FileSystem} instance for accessing the file system identified by the given
* {@link URI}.
* @throws IOException
* thrown if a reference to the file system instance could not be obtained
*/
public static FileSystem get(URI uri) throws IOException {
FileSystem fs = null;
synchronized (SYNCHRONIZATION_OBJECT) {
if (uri.getScheme() == null) {
try {
uri = new URI("file", null, uri.getPath(), null);
}
catch (URISyntaxException e) {
// we tried to repair it, but could not. report the scheme error
throw new IOException("FileSystem: Scheme is null. file:// or hdfs:// are example schemes. "
+ "Failed for " + uri.toString() + ".");
}
}
final FSKey key = new FSKey(uri.getScheme(), uri.getAuthority());
// See if there is a file system object in the cache
if (CACHE.containsKey(key)) {
return CACHE.get(key);
}
// Try to create a new file system
if (!FSDIRECTORY.containsKey(uri.getScheme())) {
throw new IOException("No file system found with scheme " + uri.getScheme()
+ ". Failed for " + uri.toString() + ".");
}
Class fsClass = null;
try {
fsClass = ClassUtils.getFileSystemByName(FSDIRECTORY.get(uri.getScheme()));
} catch (ClassNotFoundException e1) {
throw new IOException(StringUtils.stringifyException(e1));
}
try {
fs = fsClass.newInstance();
}
catch (InstantiationException e) {
throw new IOException("Could not instantiate file system class: " + e.getMessage(), e);
}
catch (IllegalAccessException e) {
throw new IOException("Could not instantiate file system class: " + e.getMessage(), e);
}
// Initialize new file system object
fs.initialize(uri);
// Add new file system object to cache
CACHE.put(key, fs);
}
return fs;
}
/**
* Returns the path of the file system's current working directory.
*
* @return the path of the file system's current working directory
*/
public abstract Path getWorkingDirectory();
/**
* Returns a URI whose scheme and authority identify this file system.
*
* @return a URI whose scheme and authority identify this file system
*/
public abstract URI getUri();
/**
* Called after a new FileSystem instance is constructed.
*
* @param name
* a {@link URI} whose authority section names the host, port, etc. for this file system
*/
public abstract void initialize(URI name) throws IOException;
/**
* 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;
/**
* 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 abstract BlockLocation[] getFileBlockLocations(FileStatus file, long start, long len) throws IOException;
/**
* 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 abstract FSDataInputStream open(Path f) throws IOException;
/**
* Return the number of bytes that large input files should be optimally be split into to minimize I/O time.
*
* @return the number of bytes that large input files should be optimally be split into to minimize I/O time
*/
public long getDefaultBlockSize() {
return 32 * 1024 * 1024; // 32 MB;
}
/**
* 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;
/**
* Check if exists.
*
* @param f
* source file
*/
public boolean exists(final Path f) throws IOException {
try {
return (getFileStatus(f) != null);
} catch (FileNotFoundException e) {
return false;
}
}
/**
* 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, false otherwise
* @throws IOException
*/
public abstract boolean delete(Path f, boolean recursive) throws IOException;
/**
* 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.
*
* @param f
* the directory/directories to be created
* @return true if at least one new directory has been created, false otherwise
* @throws IOException
* thrown if an I/O error occurs while creating the directory
*/
public abstract boolean mkdirs(Path f) throws IOException;
/**
* 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.
* @param blockSize
* @throws IOException
*/
public abstract FSDataOutputStream create(Path f, boolean overwrite, int bufferSize, short replication,
long blockSize) throws IOException;
/**
* 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.
* @throws IOException
*/
public abstract FSDataOutputStream create(Path f, boolean overwrite) throws IOException;
/**
* Renames the file/directory src to dst.
*
* @param src
* the file/directory to rename
* @param dst
* the new name of the file/directory
* @return true if the renaming was successful, false otherwise
* @throws IOException
*/
public abstract boolean rename(Path src, Path dst) throws IOException;
/**
* Initializes output directories on local file systems according to the given write mode.
*
* WriteMode.CREATE & parallel output:
* - A directory is created if the output path does not exist.
* - An existing directory is reused, files contained in the directory are NOT deleted.
* - An existing file raises an exception.
*
* WriteMode.CREATE & NONE parallel output:
* - An existing file or directory raises an exception.
*
* WriteMode.OVERWRITE & parallel output:
* - A directory is created if the output path does not exist.
* - An existing directory is reused, files contained in the directory are NOT deleted.
* - An existing file is deleted and replaced by a new directory.
*
* WriteMode.OVERWRITE & NONE parallel output:
* - An existing file or directory (and all its content) is deleted
*
* Files contained in an existing directory are not deleted, because multiple instances of a
* DataSinkTask might call this function at the same time and hence might perform concurrent
* delete operations on the file system (possibly deleting output files of concurrently running tasks).
* Since concurrent DataSinkTasks are not aware of each other, coordination of delete and create
* operations would be difficult.
*
* @param outPath Output path that should be prepared.
* @param writeMode Write mode to consider.
* @param createDirectory True, to initialize a directory at the given path, false otherwise.
* @return True, if the path was successfully prepared, false otherwise.
* @throws IOException
*/
public boolean initOutPathLocalFS(Path outPath, WriteMode writeMode, boolean createDirectory) throws IOException {
if(this.isDistributedFS()) {
return false;
}
// check if path exists
if(this.exists(outPath)) {
// path exists, check write mode
switch(writeMode) {
case NO_OVERWRITE:
if(this.getFileStatus(outPath).isDir()) {
return true;
} else {
// file may not be overwritten
throw new IOException("File or directory already exists. Existing files and directories are not overwritten in " +
WriteMode.NO_OVERWRITE.name() + " mode. Use " + WriteMode.OVERWRITE.name() +
" mode to overwrite existing files and directories.");
}
case OVERWRITE:
if(this.getFileStatus(outPath).isDir()) {
if(createDirectory) {
// directory exists and does not need to be created
return true;
} else {
// we will write in a single file, delete directory (there is also no other thread trying to delete the directory).
try {
this.delete(outPath, true);
} catch(IOException ioe) {
throw new IOException("Could not prepare output path. ",ioe);
}
}
} else {
// delete file
try {
this.delete(outPath, false);
} catch(IOException ioe) {
// Some other thread might already have deleted the file.
// If - for some other reason - the file could not be deleted,
// the error will be handled later.
}
}
break;
default:
throw new IllegalArgumentException("Invalid write mode: "+writeMode);
}
}
if(createDirectory) {
// Output directory needs to be created
try {
if(!this.exists(outPath)) {
this.mkdirs(outPath);
}
} catch(IOException ioe) {
// Some other thread might already have created the directory.
// If - for some other reason - the directory could not be created
// and the path does not exist, this will be handled later.
}
// double check that the output directory exists
return this.exists(outPath) && this.getFileStatus(outPath).isDir();
} else {
// check that the output path does not exist and an output file can be created by the output format.
return !this.exists(outPath);
}
}
/**
* Initializes output directories on distributed file systems according to the given write mode.
*
* WriteMode.CREATE & parallel output:
* - A directory is created if the output path does not exist.
* - An existing file or directory raises an exception.
*
* WriteMode.CREATE & NONE parallel output:
* - An existing file or directory raises an exception.
*
* WriteMode.OVERWRITE & parallel output:
* - A directory is created if the output path does not exist.
* - An existing directory and its content is deleted and a new directory is created.
* - An existing file is deleted and replaced by a new directory.
*
* WriteMode.OVERWRITE & NONE parallel output:
* - An existing file or directory is deleted and replaced by a new directory.
*
* @param outPath Output path that should be prepared.
* @param writeMode Write mode to consider.
* @param createDirectory True, to initialize a directory at the given path, false otherwise.
* @return True, if the path was successfully prepared, false otherwise.
* @throws IOException
*/
public boolean initOutPathDistFS(Path outPath, WriteMode writeMode, boolean createDirectory) throws IOException {
if(!this.isDistributedFS()) {
return false;
}
// check if path exists
if(this.exists(outPath)) {
// path exists, check write mode
switch(writeMode) {
case NO_OVERWRITE:
// file or directory may not be overwritten
throw new IOException("File or directory already exists. Existing files and directories are not overwritten in " +
WriteMode.NO_OVERWRITE.name() + " mode. Use " + WriteMode.OVERWRITE.name() +
" mode to overwrite existing files and directories.");
case OVERWRITE:
// output path exists. We delete it and all contained files in case of a directory.
try {
this.delete(outPath, true);
} catch(IOException ioe) {
// Some other thread might already have deleted the path.
// If - for some other reason - the path could not be deleted,
// this will be handled later.
}
break;
default:
throw new IllegalArgumentException("Invalid write mode: "+writeMode);
}
}
if(createDirectory) {
// Output directory needs to be created
try {
if(!this.exists(outPath)) {
this.mkdirs(outPath);
}
} catch(IOException ioe) {
// Some other thread might already have created the directory.
// If - for some other reason - the directory could not be created
// and the path does not exist, this will be handled later.
}
// double check that the output directory exists
return this.exists(outPath) && this.getFileStatus(outPath).isDir();
} else {
// check that the output path does not exist and an output file can be created by the output format.
return !this.exists(outPath);
}
}
/**
* Returns true if this is a distributed file system, false otherwise.
*
* @return True if this is a distributed file system, false otherwise.
*/
public abstract boolean isDistributedFS();
/**
* Returns the number of blocks this file/directory consists of
* assuming the file system's standard block size.
*
* @param file
* the file
* @return the number of block's the file/directory consists of
* @throws IOException
*/
public int getNumberOfBlocks(final FileStatus file) throws IOException {
int numberOfBlocks = 0;
if (file == null) {
return 0;
}
// For a file, this is easy
if (!file.isDir()) {
return getNumberOfBlocks(file.getLen(), file.getBlockSize());
}
// file is a directory
final FileStatus[] files = this.listStatus(file.getPath());
for (int i = 0; i < files.length; i++) {
if (!files[i].isDir()) {
numberOfBlocks += getNumberOfBlocks(files[i].getLen(), files[i].getBlockSize());
}
}
return numberOfBlocks;
}
private int getNumberOfBlocks(final long length, final long blocksize) {
if (blocksize != 0) {
int numberOfBlocks;
numberOfBlocks = (int) (length / blocksize);
if ((length % blocksize) != 0) {
numberOfBlocks++;
}
return numberOfBlocks;
} else {
return 1;
}
}
}
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