| /* |
| * 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.solr.logging; |
| |
| import java.util.ArrayList; |
| import java.util.Iterator; |
| import java.util.List; |
| |
| /** |
| * FIFO Circular List. |
| * |
| * Once the size is reached, it will overwrite previous entries |
| * |
| */ |
| public class CircularList<T> implements Iterable<T> |
| { |
| private T[] data; |
| private int head=0; |
| private int tail=0; |
| private int size=0; |
| |
| @SuppressWarnings("unchecked") |
| public CircularList(int size) { |
| data = (T[])new Object[size]; |
| } |
| |
| @SuppressWarnings("unchecked") |
| public synchronized void resize(int newsize) { |
| if(newsize==this.size) return; |
| |
| T[] vals = (T[])new Object[newsize]; |
| int i = 0; |
| if(newsize>size) { |
| for(i=0; i<size; i++) { |
| vals[i] = data[convert(i)]; |
| } |
| } |
| else { |
| int off=size-newsize; |
| for(i=0; i<newsize; i++) { |
| vals[i] = data[convert(i+off)]; |
| } |
| } |
| data = vals; |
| head = 0; |
| tail = i; |
| } |
| |
| private int convert(int index) { |
| return (index + head) % data.length; |
| } |
| |
| public boolean isEmpty() { |
| return head == tail; // or size == 0 |
| } |
| |
| public int size() { |
| return size; |
| } |
| |
| public int getBufferSize() { |
| return data.length; |
| } |
| |
| private void checkIndex(int index) { |
| if (index >= size || index < 0) |
| throw new IndexOutOfBoundsException("Index: "+index+", Size: "+size); |
| } |
| |
| public T get(int index) { |
| checkIndex(index); |
| return data[convert(index)]; |
| } |
| |
| public synchronized void add(T o) { |
| data[tail] = o; |
| tail = (tail+1)%data.length; |
| if( size == data.length ) { |
| head = (head+1)%data.length; |
| } |
| size++; |
| if( size > data.length ) { |
| size = data.length; |
| } |
| } |
| |
| public synchronized void clear() { |
| for( int i=0; i<data.length; i++ ) { |
| data[i] = null; // for GC |
| } |
| head = tail = size = 0; |
| } |
| |
| public List<T> toList() |
| { |
| ArrayList<T> list = new ArrayList<>( size ); |
| for( int i=0; i<size; i++ ) { |
| list.add( data[convert(i)] ); |
| } |
| return list; |
| } |
| |
| @Override |
| public String toString() |
| { |
| StringBuilder str = new StringBuilder(); |
| str.append( "[" ); |
| for( int i=0; i<size; i++ ) { |
| if( i > 0 ) { |
| str.append( "," ); |
| } |
| str.append( data[convert(i)] ); |
| } |
| str.append( "]" ); |
| return str.toString(); |
| } |
| |
| @Override |
| public Iterator<T> iterator() { |
| return new Iterator<T>() { |
| int idx = 0; |
| |
| @Override |
| public boolean hasNext() { |
| return idx<size; |
| } |
| |
| @Override |
| public T next() { |
| return get( idx++ ); |
| } |
| |
| @Override |
| public void remove() { |
| throw new UnsupportedOperationException(); |
| } |
| }; |
| } |
| } |