org.apache.hadoop.io.file.tfile.BoundedRangeFileInputStream Maven / Gradle / Ivy
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/**
* 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.io.file.tfile;
import java.io.IOException;
import java.io.InputStream;
import org.apache.hadoop.fs.FSDataInputStream;
/**
* BoundedRangeFIleInputStream abstracts a contiguous region of a Hadoop
* FSDataInputStream as a regular input stream. One can create multiple
* BoundedRangeFileInputStream on top of the same FSDataInputStream and they
* would not interfere with each other.
*/
class BoundedRangeFileInputStream extends InputStream {
private FSDataInputStream in;
private long pos;
private long end;
private long mark;
private final byte[] oneByte = new byte[1];
/**
* Constructor
*
* @param in
* The FSDataInputStream we connect to.
* @param offset
* Begining offset of the region.
* @param length
* Length of the region.
*
* The actual length of the region may be smaller if (off_begin +
* length) goes beyond the end of FS input stream.
*/
public BoundedRangeFileInputStream(FSDataInputStream in, long offset,
long length) {
if (offset < 0 || length < 0) {
throw new IndexOutOfBoundsException("Invalid offset/length: " + offset
+ "/" + length);
}
this.in = in;
this.pos = offset;
this.end = offset + length;
this.mark = -1;
}
@Override
public int available() throws IOException {
int avail = in.available();
if (pos + avail > end) {
avail = (int) (end - pos);
}
return avail;
}
@Override
public int read() throws IOException {
int ret = read(oneByte);
if (ret == 1) return oneByte[0] & 0xff;
return -1;
}
@Override
public int read(byte[] b) throws IOException {
return read(b, 0, b.length);
}
@Override
public int read(byte[] b, int off, int len) throws IOException {
if ((off | len | (off + len) | (b.length - (off + len))) < 0) {
throw new IndexOutOfBoundsException();
}
int n = (int) Math.min(Integer.MAX_VALUE, Math.min(len, (end - pos)));
if (n == 0) return -1;
int ret = 0;
synchronized (in) {
in.seek(pos);
ret = in.read(b, off, n);
}
if (ret < 0) {
end = pos;
return -1;
}
pos += ret;
return ret;
}
@Override
/*
* We may skip beyond the end of the file.
*/
public long skip(long n) throws IOException {
long len = Math.min(n, end - pos);
pos += len;
return len;
}
@Override
public synchronized void mark(int readlimit) {
mark = pos;
}
@Override
public synchronized void reset() throws IOException {
if (mark < 0) throw new IOException("Resetting to invalid mark");
pos = mark;
}
@Override
public boolean markSupported() {
return true;
}
@Override
public void close() {
// Invalidate the state of the stream.
in = null;
pos = end;
mark = -1;
}
}