/*
* Copyright © 2014 Cask Data, Inc.
*
* 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.
*/
package co.cask.tigon.io;
import org.apache.hadoop.fs.Seekable;
import java.io.FileInputStream;
import java.io.FilterInputStream;
import java.io.IOException;
import java.io.InputStream;
/**
* Abstract base class for {@link java.io.InputStream} that implements the
* {@link org.apache.hadoop.fs.Seekable} interface.
*/
public abstract class SeekableInputStream extends FilterInputStream implements Seekable {
/**
* Creates a {@link SeekableInputStream} from the given {@link java.io.InputStream}. Exception will be
* thrown if failed to do so.
*
* @throws java.io.IOException If the given input stream is not seekable.
*/
public static SeekableInputStream create(InputStream input) throws IOException {
if (input instanceof SeekableInputStream) {
return (SeekableInputStream) input;
}
if (input instanceof FileInputStream) {
return create((FileInputStream) input);
}
if (input instanceof Seekable) {
final Seekable seekable = (Seekable) input;
return new SeekableInputStream(input) {
@Override
public void seek(long pos) throws IOException {
seekable.seek(pos);
}
@Override
public long getPos() throws IOException {
return seekable.getPos();
}
@Override
public boolean seekToNewSource(long targetPos) throws IOException {
return seekable.seekToNewSource(targetPos);
}
};
}
throw new IOException("Failed to create SeekableInputStream from " + input.getClass());
}
/**
* Creates a {@link SeekableInputStream} from the given {@link java.io.FileInputStream}.
*/
private static SeekableInputStream create(final FileInputStream input) {
return new SeekableInputStream(input) {
@Override
public void seek(long pos) throws IOException {
input.getChannel().position(pos);
}
@Override
public long getPos() throws IOException {
return input.getChannel().position();
}
@Override
public boolean seekToNewSource(long targetPos) throws IOException {
return false;
}
};
}
protected SeekableInputStream(InputStream in) {
super(in);
}
}