| /* |
| * 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.cassandra.utils; |
| |
| import java.util.concurrent.locks.ReadWriteLock; |
| import java.util.concurrent.locks.ReentrantReadWriteLock; |
| |
| // simple thread-unsafe skiplist that permits indexing/removal by position, insertion at the end |
| // (though easily extended to insertion at any position, not necessary here) |
| // we use it for sampling items by position for visiting writes in the pool of pending writes |
| public class LockedDynamicList<E> extends DynamicList<E> |
| { |
| |
| private final ReadWriteLock lock = new ReentrantReadWriteLock(); |
| |
| public LockedDynamicList(int maxExpectedSize) |
| { |
| super(maxExpectedSize); |
| } |
| |
| // add the value to the end of the list, and return the associated Node that permits efficient removal |
| // regardless of its future position in the list from other modifications |
| public Node<E> append(E value, int maxSize) |
| { |
| lock.writeLock().lock(); |
| try |
| { |
| return super.append(value, maxSize); |
| } |
| finally |
| { |
| lock.writeLock().unlock(); |
| } |
| } |
| |
| // remove the provided node and its associated value from the list |
| public void remove(Node<E> node) |
| { |
| lock.writeLock().lock(); |
| try |
| { |
| super.remove(node); |
| } |
| finally |
| { |
| lock.writeLock().unlock(); |
| } |
| } |
| |
| // retrieve the item at the provided index, or return null if the index is past the end of the list |
| public E get(int index) |
| { |
| lock.readLock().lock(); |
| try |
| { |
| return super.get(index); |
| } |
| finally |
| { |
| lock.readLock().unlock(); |
| } |
| } |
| |
| public int size() |
| { |
| lock.readLock().lock(); |
| try |
| { |
| return super.size(); |
| } |
| finally |
| { |
| lock.readLock().unlock(); |
| } |
| } |
| } |