/*
* 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 com.aliyun.odps.volume;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.util.ArrayList;
/**
* VolumeFileSystem have volume partition dir as root, so all paths are
* relative to partition dir.
* <p>Only available at job runtime.
*/
public abstract class FileSystem {
/**
* 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;
/**
* Create an FSDataOutputStream at the indicated Path.
* Files are overwritten by default.
*
* @param f
* the file to create
*/
public FSDataOutputStream create(Path f) throws IOException {
return create(f, true);
}
/**
* Create an FSDataOutputStream at the indicated Path.
*
* @param f
* the file to create
* @param overwrite
* if a file with this name already exists, then if true,
* the file will be overwritten, and if false an exception will be thrown.
*/
public abstract FSDataOutputStream create(Path f, boolean overwrite)
throws IOException;
/**
* Create an FSDataOutputStream at the indicated Path.
*
* @param f
* the file name to create
* @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 abstract FSDataOutputStream create(Path f,
boolean overwrite,
int bufferSize
) throws IOException;
/**
* Creates the given Path as a brand-new zero-length file. If
* create fails, or if it already existed, return false.
*
* @param f
* path to use for create
*/
public boolean createNewFile(Path f) throws IOException {
if (exists(f)) {
return false;
} else {
create(f, false).close();
return true;
}
}
/**
* Append to an existing file (optional operation).
*
* @param f
* the existing file to be appended.
* @throws IOException
*/
public abstract FSDataOutputStream append(Path f) throws IOException;
/**
* 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 abstract FSDataOutputStream append(Path f, int bufferSize) throws IOException;
/**
* Renames Path src to Path dst. Can take place on local fs
* or remote DFS.
*
* @param src
* path to be renamed
* @param dst
* new path after rename
* @return true if rename is successful
* @throws IOException
* on failure
*/
public abstract boolean rename(Path src, Path dst) throws IOException;
/**
* Delete a file.
* Always recursive delete.
*
* @param f
* the path to delete.
* @return true if delete is successful else false.
* @throws IOException
*/
public abstract boolean delete(Path f) throws IOException;
/**
* Non-recursive delete not supported, just for compatible with hadoop.
*/
public boolean delete(Path f, boolean recursive) throws IOException {
if (!recursive) {
throw new RuntimeException("Non-recursive delete not implemented...");
} else {
return delete(f);
}
}
/**
* 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.
* Note: Avoid using this method. Instead reuse the FileStatus
* returned by getFileStatus() or listStatus() methods.
*
* @param f
* path to check
*/
public boolean isDirectory(Path f) throws IOException {
try {
return getFileStatus(f).isDirectory();
} catch (FileNotFoundException e) {
return false; // f does not exist
}
}
/**
* True iff the named path is a regular file.
* Note: Avoid using this method. Instead reuse the FileStatus
* returned by getFileStatus() or listStatus() methods.
*
* @param f
* path to check
*/
public boolean isFile(Path f) throws IOException {
try {
return getFileStatus(f).isFile();
} catch (FileNotFoundException e) {
return false; // f does not exist
}
}
final private static PathFilter DEFAULT_FILTER = new PathFilter() {
@Override
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 FileNotFoundException
* when the path does not exist;
* IOException see specific implementation
*/
public abstract FileStatus[] listStatus(Path f) throws FileNotFoundException,
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 FileNotFoundException, IOException {
FileStatus listing[] = listStatus(f);
if (listing == null) {
throw new IOException("Error accessing " + f);
}
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 FileNotFoundException
* when the path does not exist;
* IOException see specific implementation
*/
public FileStatus[] listStatus(Path f, PathFilter filter)
throws FileNotFoundException, 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
* @throws FileNotFoundException
* when the path does not exist;
* IOException see specific implementation
*/
public FileStatus[] listStatus(Path[] files)
throws FileNotFoundException, 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
* @throws FileNotFoundException
* when the path does not exist;
* IOException see specific implementation
*/
public FileStatus[] listStatus(Path[] files, PathFilter filter)
throws FileNotFoundException, 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()]);
}
/**
* 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
* path to create
*/
public abstract boolean mkdirs(Path f) 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;
}