/*
* Copyright 2010 LinkedIn Corp.
*
* Licensed 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 azkaban.utils;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
import com.google.common.base.Joiner;
import com.google.common.collect.Iterators;
/**
* A circular buffer of items of a given length. It will grow up to the give
* size as items are appended, then it will begin to overwrite older items.
*
* @param <T> The type of the item contained.
*/
public class CircularBuffer<T> implements Iterable<T> {
private final List<T> lines;
private final int size;
private int start;
public CircularBuffer(int size) {
this.lines = new ArrayList<T>();
this.size = size;
this.start = 0;
}
public void append(T line) {
if (lines.size() < size) {
lines.add(line);
} else {
lines.set(start, line);
start = (start + 1) % size;
}
}
@Override
public String toString() {
return "[" + Joiner.on(", ").join(lines) + "]";
}
@Override
public Iterator<T> iterator() {
if (start == 0)
return lines.iterator();
else
return Iterators.concat(lines.subList(start, lines.size()).iterator(),
lines.subList(0, start).iterator());
}
public int getMaxSize() {
return this.size;
}
public int getSize() {
return this.lines.size();
}
}