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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.hbase.io;
import java.io.InputStream;
import java.nio.ByteBuffer;
import org.apache.hadoop.hbase.util.ByteBufferUtils;
import org.apache.yetus.audience.InterfaceAudience;
/**
* Not thread safe!
*
* Please note that the reads will cause position movement on wrapped ByteBuffer.
*/
@InterfaceAudience.Private
public class ByteBufferInputStream extends InputStream {
private ByteBuffer buf;
public ByteBufferInputStream(ByteBuffer buf) {
this.buf = buf;
}
/**
* Reads the next byte of data from this input stream. The value byte is returned as an
* int in the range 0 to 255. If no byte is available
* because the end of the stream has been reached, the value -1 is returned.
* @return the next byte of data, or -1 if the end of the stream has been reached.
*/
@Override
public int read() {
if (this.buf.hasRemaining()) {
return (this.buf.get() & 0xff);
}
return -1;
}
/**
* Reads up to next len bytes of data from buffer into passed array(starting from
* given offset).
* @param b the array into which the data is read.
* @param off the start offset in the destination array b
* @param len the maximum number of bytes to read.
* @return the total number of bytes actually read into the buffer, or -1 if not even
* 1 byte can be read because the end of the stream has been reached.
*/
@Override
public int read(byte[] b, int off, int len) {
int avail = available();
if (avail <= 0) {
return -1;
}
if (len > avail) {
len = avail;
}
if (len <= 0) {
return 0;
}
ByteBufferUtils.copyFromBufferToArray(b, this.buf, this.buf.position(), off, len);
this.buf.position(this.buf.position() + len); // we should advance the buffer position
return len;
}
/**
* Skips n bytes of input from this input stream. Fewer bytes might be skipped if the
* end of the input stream is reached. The actual number k of bytes to be skipped is
* equal to the smaller of n and remaining bytes in the stream.
* @param n the number of bytes to be skipped.
* @return the actual number of bytes skipped.
*/
@Override
public long skip(long n) {
long k = Math.min(n, available());
if (k < 0) {
k = 0;
}
this.buf.position((int) (this.buf.position() + k));
return k;
}
/**
* @return the number of remaining bytes that can be read (or skipped over) from this input
* stream.
*/
@Override
public int available() {
return this.buf.remaining();
}
}