org.elasticsearch.common.io.FileChannelInputStream Maven / Gradle / Ivy
/*
* Licensed to Elasticsearch under one or more contributor
* license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright
* ownership. Elasticsearch 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.elasticsearch.common.io;
import java.io.IOException;
import java.io.InputStream;
import java.nio.ByteBuffer;
import java.nio.channels.FileChannel;
/**
*
*/
public class FileChannelInputStream extends InputStream {
private final FileChannel channel;
private long position;
private long length;
private ByteBuffer bb = null;
private byte[] bs = null; // Invoker's previous array
private byte[] b1 = null;
private long markPosition;
/**
* @param channel The channel to read from
* @param position The position to start reading from
* @param length The length to read
*/
public FileChannelInputStream(FileChannel channel, long position, long length) {
this.channel = channel;
this.position = position;
this.markPosition = position;
this.length = position + length; // easier to work with total length
}
@Override
public int read() throws IOException {
if (b1 == null) {
b1 = new byte[1];
}
int n = read(b1);
if (n == 1) {
return b1[0] & 0xff;
}
return -1;
}
@Override
public int read(byte[] bs, int off, int len) throws IOException {
if (len == 0) {
return 0;
}
if ((length - position) < len) {
len = (int) (length - position);
}
if (len == 0) {
return -1;
}
ByteBuffer bb = ((this.bs == bs) ? this.bb : ByteBuffer.wrap(bs));
bb.limit(Math.min(off + len, bb.capacity()));
bb.position(off);
this.bb = bb;
this.bs = bs;
int read = channel.read(bb, position);
if (read > 0) {
position += read;
}
return read;
}
@Override
public boolean markSupported() {
return true;
}
@Override
public void mark(int readlimit) {
this.markPosition = position;
}
@Override
public void reset() throws IOException {
position = markPosition;
}
}