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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.server.util;
import java.util.Iterator;
import org.apache.log4j.Logger;
public class CircularBuffer implements Iterable
{
private static final Logger _logger = Logger.getLogger(CircularBuffer.class);
private final Object[] _log;
private int _size;
private int _index;
public CircularBuffer(int size)
{
_log = new Object[size];
}
public void add(Object o)
{
_log[_index++] = o;
_size = Math.min(_size+1, _log.length);
if(_index >= _log.length)
{
_index = 0;
}
}
public Object get(int i)
{
if(i >= _log.length)
{
throw new ArrayIndexOutOfBoundsException(i);
}
return _log[index(i)];
}
public int size() {
return _size;
}
public Iterator iterator()
{
return new Iterator()
{
private int i = 0;
public boolean hasNext()
{
return i < _size;
}
public Object next()
{
return get(i++);
}
public void remove()
{
throw new UnsupportedOperationException();
}
};
}
public String toString()
{
StringBuilder s = new StringBuilder();
boolean first = true;
for(Object o : this)
{
if(!first)
{
s.append(", ");
}
else
{
first = false;
}
s.append(o);
}
return s.toString();
}
public void dump()
{
for(Object o : this)
{
_logger.info(o);
}
}
int index(int i)
{
return _size == _log.length ? (_index + i) % _log.length : i;
}
public static void main(String[] artgv)
{
String[] items = new String[]{
"A","B","C","D","E","F","G","H","I","J","K"
};
CircularBuffer buffer = new CircularBuffer(5);
for(String s : items)
{
buffer.add(s);
_logger.info(buffer);
}
}
}
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