/* * 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 com.google.common.base.Joiner; import com.google.common.collect.Iterators; import java.util.ArrayList; import java.util.Iterator; import java.util.List; /** * 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(final int size) { this.lines = new ArrayList<>(); this.size = size; this.start = 0; } public void append(final T line) { if (this.lines.size() < this.size) { this.lines.add(line); } else { this.lines.set(this.start, line); this.start = (this.start + 1) % this.size; } } @Override public String toString() { return "[" + Joiner.on(", ").join(this.lines) + "]"; } @Override public Iterator<T> iterator() { if (this.start == 0) { return this.lines.iterator(); } else { return Iterators.concat(this.lines.subList(this.start, this.lines.size()).iterator(), this.lines.subList(0, this.start).iterator()); } } public int getMaxSize() { return this.size; } public int getSize() { return this.lines.size(); } }