org.apache.commons.collections4.queue.SynchronizedQueue Maven / Gradle / Ivy
/*
* 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.commons.collections4.queue;
import java.util.Queue;
import org.apache.commons.collections4.collection.SynchronizedCollection;
/**
* Decorates another {@link Queue} to synchronize its behaviour for a multi-threaded environment.
*
* Methods are synchronized, then forwarded to the decorated queue. Iterators must be separately synchronized around the
* loop.
*
* @param the type of the elements in the collection
* @since 4.2
*/
public class SynchronizedQueue extends SynchronizedCollection implements Queue {
/** Serialization version */
private static final long serialVersionUID = 1L;
/**
* Factory method to create a synchronized queue.
*
* @param
* the type of the elements in the queue
* @param queue
* the queue to decorate, must not be null
* @return a new synchronized Queue
* @throws NullPointerException
* if queue is null
*/
public static SynchronizedQueue synchronizedQueue(final Queue queue) {
return new SynchronizedQueue<>(queue);
}
// -----------------------------------------------------------------------
/**
* Constructor that wraps (not copies).
*
* @param queue
* the queue to decorate, must not be null
* @throws NullPointerException
* if queue is null
*/
protected SynchronizedQueue(final Queue queue) {
super(queue);
}
/**
* Constructor that wraps (not copies).
*
* @param queue
* the queue to decorate, must not be null
* @param lock
* the lock to use, must not be null
* @throws NullPointerException
* if queue or lock is null
*/
protected SynchronizedQueue(final Queue queue, final Object lock) {
super(queue, lock);
}
/**
* Gets the queue being decorated.
*
* @return the decorated queue
*/
@Override
protected Queue decorated() {
return (Queue) super.decorated();
}
@Override
public E element() {
synchronized (lock) {
return decorated().element();
}
}
@Override
public boolean equals(final Object object) {
if (object == this) {
return true;
}
synchronized (lock) {
return decorated().equals(object);
}
}
// -----------------------------------------------------------------------
@Override
public int hashCode() {
synchronized (lock) {
return decorated().hashCode();
}
}
@Override
public boolean offer(final E e) {
synchronized (lock) {
return decorated().offer(e);
}
}
@Override
public E peek() {
synchronized (lock) {
return decorated().peek();
}
}
@Override
public E poll() {
synchronized (lock) {
return decorated().poll();
}
}
@Override
public E remove() {
synchronized (lock) {
return decorated().remove();
}
}
}