org.apache.hadoop.fs.FSInputStream Maven / Gradle / Ivy
/**
* 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.*;
import java.nio.ByteBuffer;
import org.apache.hadoop.classification.InterfaceAudience;
import org.apache.hadoop.classification.InterfaceStability;
import org.apache.hadoop.fs.ZeroCopyUnavailableException;
/****************************************************************
* FSInputStream is a generic old InputStream with a little bit
* of RAF-style seek ability.
*
*****************************************************************/
@InterfaceAudience.LimitedPrivate({"HDFS"})
@InterfaceStability.Unstable
public abstract class FSInputStream extends InputStream
implements Seekable, PositionedReadable {
/**
* Seek to the given offset from the start of the file.
* The next read() will be from that location. Can't
* seek past the end of the file.
*/
@Override
public abstract void seek(long pos) throws IOException;
/**
* Return the current offset from the start of the file
*/
@Override
public abstract long getPos() throws IOException;
/**
* Seeks a different copy of the data. Returns true if
* found a new source, false otherwise.
*/
@Override
public abstract boolean seekToNewSource(long targetPos) throws IOException;
@Override
public int read(long position, byte[] buffer, int offset, int length)
throws IOException {
synchronized (this) {
long oldPos = getPos();
int nread = -1;
try {
seek(position);
nread = read(buffer, offset, length);
} finally {
seek(oldPos);
}
return nread;
}
}
@Override
public void readFully(long position, byte[] buffer, int offset, int length)
throws IOException {
int nread = 0;
while (nread < length) {
int nbytes = read(position+nread, buffer, offset+nread, length-nread);
if (nbytes < 0) {
throw new EOFException("End of file reached before reading fully.");
}
nread += nbytes;
}
}
@Override
public void readFully(long position, byte[] buffer)
throws IOException {
readFully(position, buffer, 0, buffer.length);
}
}