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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.qpid.amqp_1_0.transport;
import java.nio.ByteBuffer;
public class CircularBytesBuffer
{
private final byte[] _buffer;
private final int _mask;
private final ByteBuffer _inputBuffer;
private final ByteBuffer _outputBuffer;
private volatile int _start;
private volatile int _size;
public CircularBytesBuffer(int size)
{
size = calculateSize(size);
_buffer = new byte[size];
_mask = size - 1;
_inputBuffer = ByteBuffer.wrap(_buffer);
_outputBuffer = ByteBuffer.wrap(_buffer);
}
public int size()
{
return _size;
}
public boolean isFull()
{
return _size == _buffer.length;
}
public boolean isEmpty()
{
return _size == 0;
}
public void put(ByteBuffer buffer)
{
if(!isFull())
{
int start;
int size;
synchronized(this)
{
start = _start;
size = _size;
}
int pos = (start + size) & _mask;
int length = ((_buffer.length - pos) > size ? start : _buffer.length) - pos;
int remaining = length > buffer.remaining() ? buffer.remaining() : length;
buffer.get(_buffer, pos, remaining);
synchronized(this)
{
_size += remaining;
}
// We may still have space left if we have to wrap from the end to the start of the buffer
if(buffer.hasRemaining())
{
put(buffer);
}
}
}
public synchronized void put(BytesProcessor processor)
{
if(!isFull())
{
int start;
int size;
synchronized(this)
{
start = _start;
size = _size;
}
int pos = (start + size) & _mask;
int length = ((_buffer.length - pos) > size ? start : _buffer.length) - pos;
_outputBuffer.position(pos);
_outputBuffer.limit(pos+length);
processor.processBytes(_outputBuffer);
synchronized (this)
{
_size += length - _outputBuffer.remaining();
}
if(_outputBuffer.remaining() == 0)
{
put(processor);
}
}
}
public synchronized void get(BytesProcessor processor)
{
if(!isEmpty())
{
int start;
int size;
synchronized(this)
{
start = _start;
size = _size;
}
int length = start + size > _buffer.length ? _buffer.length - start : size;
_inputBuffer.position(start);
_inputBuffer.limit(start+length);
processor.processBytes(_inputBuffer);
final int consumed = length - _inputBuffer.remaining();
synchronized(this)
{
_start += consumed;
_size -= consumed;
}
if(!_inputBuffer.hasRemaining())
{
get(processor);
}
}
}
private int calculateSize(int size)
{
int n = 0;
int s = size;
do
{
s>>=1;
n++;
}
while(s > 0);
s = 1 << n;
if(s < size)
{
s<<= 1;
}
return s;
}
}
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