| /* |
| * 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.hadoop.hbase.util; |
| |
| import java.util.ArrayList; |
| import java.util.Collection; |
| import java.util.Collections; |
| import java.util.Comparator; |
| import java.util.Iterator; |
| import java.util.List; |
| import java.util.ListIterator; |
| import java.util.RandomAccess; |
| |
| /** |
| * Simple sorted list implementation that uses {@link java.util.ArrayList} as |
| * the underlying collection so we can support RandomAccess. All mutations |
| * create a new copy of the <code>ArrayList</code> instance, so can be |
| * expensive. This class is only intended for use on small, very rarely |
| * written collections that expect highly concurrent reads. |
| * <p> |
| * Read operations are performed on a reference to the internal list at the |
| * time of invocation, so will not see any mutations to the collection during |
| * their operation. Iterating over list elements manually using the |
| * RandomAccess pattern involves multiple operations. For this to be safe get |
| * a reference to the internal list first using get(). |
| * <p> |
| * If constructed with a {@link java.util.Comparator}, the list will be sorted |
| * using the comparator. Adding or changing an element using an index will |
| * trigger a resort. |
| * <p> |
| * Iterators are read-only. They cannot be used to remove elements. |
| */ |
| @edu.umd.cs.findbugs.annotations.SuppressWarnings(value="UG_SYNC_SET_UNSYNC_GET", |
| justification="TODO: synchronization in here needs review!!!") |
| public class SortedList<E> implements List<E>, RandomAccess { |
| private volatile List<E> list; |
| private final Comparator<? super E> comparator; |
| |
| /** |
| * Constructs an empty list with the default initial capacity that will be |
| * sorted using the given comparator. |
| * |
| * @param comparator the comparator |
| */ |
| public SortedList(Comparator<? super E> comparator) { |
| this.list = Collections.emptyList(); |
| this.comparator = comparator; |
| } |
| |
| /** |
| * Constructs a list containing the elements of the given collection, in the |
| * order returned by the collection's iterator, that will be sorted with the |
| * given comparator. |
| * |
| * @param c the collection |
| * @param comparator the comparator |
| */ |
| public SortedList(Collection<? extends E> c, Comparator<? super E> comparator) { |
| this.list = Collections.unmodifiableList(new ArrayList<E>(c)); |
| this.comparator = comparator; |
| } |
| |
| /** |
| * Returns a reference to the unmodifiable list currently backing the SortedList. |
| * Changes to the SortedList will not be reflected in this list. Use this |
| * method to get a reference for iterating over using the RandomAccess |
| * pattern. |
| */ |
| public List<E> get() { // FindBugs: UG_SYNC_SET_UNSYNC_GET complaint. Fix!! |
| return list; |
| } |
| |
| @Override |
| public int size() { |
| return list.size(); |
| } |
| |
| @Override |
| public boolean isEmpty() { |
| return list.isEmpty(); |
| } |
| |
| @Override |
| public boolean contains(Object o) { |
| return list.contains(o); |
| } |
| |
| @Override |
| public Iterator<E> iterator() { |
| return list.iterator(); |
| } |
| |
| @Override |
| public Object[] toArray() { |
| return list.toArray(); |
| } |
| |
| @Override |
| public <T> T[] toArray(T[] a) { |
| return list.toArray(a); |
| } |
| |
| @Override |
| public synchronized boolean add(E e) { |
| ArrayList<E> newList = new ArrayList<E>(list); |
| boolean changed = newList.add(e); |
| if (changed) { |
| Collections.sort(newList, comparator); |
| } |
| list = Collections.unmodifiableList(newList); |
| return changed; |
| } |
| |
| @Override |
| public synchronized boolean remove(Object o) { |
| ArrayList<E> newList = new ArrayList<E>(list); |
| // Removals in ArrayList won't break sorting |
| boolean changed = newList.remove(o); |
| list = Collections.unmodifiableList(newList); |
| return changed; |
| } |
| |
| @Override |
| public boolean containsAll(Collection<?> c) { |
| return list.containsAll(c); |
| } |
| |
| @Override |
| public synchronized boolean addAll(Collection<? extends E> c) { |
| ArrayList<E> newList = new ArrayList<E>(list); |
| boolean changed = newList.addAll(c); |
| if (changed) { |
| Collections.sort(newList, comparator); |
| } |
| list = Collections.unmodifiableList(newList); |
| return changed; |
| } |
| |
| @Override |
| public synchronized boolean addAll(int index, Collection<? extends E> c) { |
| ArrayList<E> newList = new ArrayList<E>(list); |
| boolean changed = newList.addAll(index, c); |
| if (changed) { |
| Collections.sort(newList, comparator); |
| } |
| list = Collections.unmodifiableList(newList); |
| return changed; |
| } |
| |
| @Override |
| public synchronized boolean removeAll(Collection<?> c) { |
| ArrayList<E> newList = new ArrayList<E>(list); |
| // Removals in ArrayList won't break sorting |
| boolean changed = newList.removeAll(c); |
| list = Collections.unmodifiableList(newList); |
| return changed; |
| } |
| |
| @Override |
| public synchronized boolean retainAll(Collection<?> c) { |
| ArrayList<E> newList = new ArrayList<E>(list); |
| // Removals in ArrayList won't break sorting |
| boolean changed = newList.retainAll(c); |
| list = Collections.unmodifiableList(newList); |
| return changed; |
| } |
| |
| @Override |
| public synchronized void clear() { |
| list = Collections.emptyList(); |
| } |
| |
| @Override |
| public synchronized E get(int index) { |
| return list.get(index); |
| } |
| |
| @Override |
| public synchronized E set(int index, E element) { |
| ArrayList<E> newList = new ArrayList<E>(list); |
| E result = newList.set(index, element); |
| Collections.sort(list, comparator); |
| list = Collections.unmodifiableList(newList); |
| return result; |
| } |
| |
| @Override |
| public synchronized void add(int index, E element) { |
| ArrayList<E> newList = new ArrayList<E>(list); |
| newList.add(index, element); |
| Collections.sort(list, comparator); |
| list = Collections.unmodifiableList(newList); |
| } |
| |
| @Override |
| public synchronized E remove(int index) { |
| ArrayList<E> newList = new ArrayList<E>(list); |
| // Removals in ArrayList won't break sorting |
| E result = newList.remove(index); |
| list = Collections.unmodifiableList(newList); |
| return result; |
| } |
| |
| @Override |
| public int indexOf(Object o) { |
| return list.indexOf(o); |
| } |
| |
| @Override |
| public int lastIndexOf(Object o) { |
| return list.lastIndexOf(o); |
| } |
| |
| @Override |
| public ListIterator<E> listIterator() { |
| return list.listIterator(); |
| } |
| |
| @Override |
| public ListIterator<E> listIterator(int index) { |
| return list.listIterator(index); |
| } |
| |
| @Override |
| public List<E> subList(int fromIndex, int toIndex) { |
| return list.subList(fromIndex, toIndex); |
| } |
| } |